CN116973924A - Beam scanning module based on projection optical system, photoelectric device and electronic equipment - Google Patents
Beam scanning module based on projection optical system, photoelectric device and electronic equipment Download PDFInfo
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- G—PHYSICS
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
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Abstract
The application provides a beam scanning module based on a projection optical system, which comprises a light source module, an acousto-optic deflection module, the projection optical system and a beam expansion module. The light source module is used for emitting a strip-shaped collimated light beam. The acousto-optic deflection module deflects the strip-shaped collimated light beam along a first direction by a plurality of different preset deflection angles within a preset first deflection angle range according to the applied sound wave frequency, and the length direction of the strip-shaped collimated light beam is parallel to a second direction perpendicular to the first direction. The deflected light beam passes through a corresponding area on the focal plane of the projection optical system, and then is projected by the projection optical system along a corresponding preset emission direction in the detection range to form a sensing light beam, and the corresponding area moves on the focal plane along with the change of the deflection angle of the light beam. The beam expansion module is arranged on the light emitting side of the projection optical system and is used for expanding the divergence angle of the sensing beam along the second direction to form a strip-shaped sensing beam. The application also provides an optoelectronic device and electronic equipment comprising the light beam scanning module.
Description
Technical Field
The application belongs to the field of photoelectric detection, and particularly relates to a beam scanning module based on a projection optical system, a photoelectric device and electronic equipment.
Background
A Time of Flight (ToF) measurement principle calculates three-dimensional information such as a distance of an object from a Time of Flight of detected light reflected by the object in a measurement scene. The ToF measurement has the advantages of long sensing distance, high precision, low energy consumption and the like, and is widely applied to the fields of consumer electronics, intelligent driving, AR/VR and the like.
The detection device for ranging by using the ToF measurement principle has a limited angle of view, and a larger detection range needs to be obtained by continuously changing the emission direction of the detection light to scan. At present, one way to change the direction of light emission is to rotate the detection device by using a mechanical structure, however, this way often requires a plurality of discrete devices to be assembled into a mechanical rotation structure, the complexity of debugging and assembling the light path of emission/reception is high, the mechanical rotation structure is also easy to damage and misalign, and the appearance of the terminal equipment using the mechanical rotation structure is influenced by the larger size of the mechanical rotation structure. Another way to change the emission direction of the detection light is a mixed solid solution, mainly using a vibration component to drive an optical component to change the emission direction of the detection light. Although the cost and size of the hybrid solid state solution are significantly reduced relative to the mechanical rotation solution, the reliability of the system is still low, limiting the application scenarios of the detection device, since the vibrating components are also easily damaged.
Disclosure of Invention
In view of the above, the present application provides a beam scanning module, an optoelectronic device and an electronic device based on a projection optical system, which can improve the problems of the prior art.
In a first aspect, the present application provides a beam scanning module based on a projection optical system configured to emit a sensing beam for three-dimensional information detection to a detection range, comprising:
a light source module configured to emit a bar-shaped collimated light beam;
an acousto-optic deflection module configured to deflect the strip collimated beam in a preset first direction by a plurality of different preset deflection angles within a preset first deflection angle range according to an applied acoustic wave frequency;
the method comprises the steps of defining the direction of the maximum size of the strip-shaped collimated light beam as the length direction of the strip-shaped collimated light beam, wherein the length direction of the strip-shaped collimated light beam is parallel to a preset second direction, and the second direction and the first direction are mutually perpendicular;
a projection optical system configured to project the light beam deflected by the acousto-optic deflection module along a preset emission direction corresponding to a beam deflection angle within a detection range to form the sensing light beam;
the beam deflected by the acousto-optic deflection module passes through a corresponding area on a focal plane of the projection optical system and then is projected by the projection optical system, and the corresponding area moves on the focal plane along with the change of the deflection angle of the beam; a kind of electronic device with high-pressure air-conditioning system
And a beam expansion module disposed at an outgoing side of the projection optical system, the beam expansion module being configured to expand a divergence angle of the sensing beam in the second direction to form a long stripe-shaped sensing beam.
In a second aspect, the present application provides an optoelectronic device configured to perform distance detection of an object located within a predetermined detection range. The photoelectric device comprises a receiving module, a processing circuit and the light beam scanning module. The receiving module is configured to sense the light signals from the detection range and output corresponding light sensing signals, and the processing circuit is configured to analyze and process the light sensing signals to obtain three-dimensional information of the object in the detection range.
In a third aspect, the present application provides an electronic device comprising an application module and an optoelectronic apparatus as described above. The application module is configured to realize corresponding functions according to detection results of the photoelectric device.
The application has the beneficial effects that:
compared with the deflection of the sensing light beam realized by a mechanical rotation scheme and a mixed solid state scheme, the application realizes the continuous deflection of the sensing light beam within the preset deflection angle range by the pure solid state acousto-optic deflection module, does not need to rely on rotation and vibration of components, and has the beneficial effects of better reliability and compact size.
Drawings
The features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.
Fig. 1 is a schematic diagram of a functional module of an electronic device according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a functional module of an embodiment of the optoelectronic device shown in FIG. 1;
FIG. 3 is a schematic diagram of a statistical histogram obtained by the processing circuit shown in FIG. 2;
FIG. 4 is a schematic diagram of an embodiment of the beam scanning module shown in FIG. 2;
FIG. 5 is a schematic view of a portion of an optical path of an embodiment of the beam scanning module shown in FIG. 2;
FIG. 6 is a schematic view of a portion of an optical path of another embodiment of the beam scanning module shown in FIG. 2;
FIG. 7 is a schematic view of a portion of a light path of another embodiment of the beam scanning module shown in FIG. 2;
FIG. 8 is a schematic structural view of the acousto-optic deflection module shown in FIG. 2;
FIG. 9 is a schematic view of the optical paths of the acousto-optic deflection module and projection optics shown in FIG. 2;
FIG. 10 is a schematic view of the optical path of another embodiment of the acousto-optic deflection module and projection optical system shown in FIG. 2;
FIG. 11 is a schematic diagram illustrating an embodiment of a cylindrical beam expander lens of the beam scanning module shown in FIG. 10;
FIG. 12 is a side view of the optical path of the cylindrical beam expander lens of FIG. 11;
FIG. 13 is a schematic view of another embodiment of a cylindrical beam expander lens of the beam scanning module shown in FIG. 10;
FIG. 14 is a side view of the optical path of the cylindrical beam expander lens of FIG. 12;
FIG. 15 is a schematic diagram of a beam expansion module of the beam scanning module shown in FIG. 2;
FIG. 16 is a schematic diagram of another embodiment of the beam scanning module shown in FIG. 2;
FIG. 17 is a signal timing diagram of an optoelectronic device according to an embodiment of the present application;
fig. 18 is a schematic structural diagram of an electro-optical device as an automotive lidar according to an embodiment of the present application.
Detailed Description
Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the application. In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or as implicitly indicating the number or order of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the description of the present application, it should be noted that, unless explicitly specified or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically connected, electrically connected or communicated with each other; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements or interaction relationship between the two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
The following disclosure provides many different embodiments, or examples, for implementing different structures of the application. In order to simplify the present disclosure, only the components and arrangements of specific examples will be described below. They are, of course, merely examples and are not intended to limit the application. Furthermore, the present application may repeat use of reference numerals and/or letters in the various examples, and is intended to be simplified and clear illustration of the present application, without itself being indicative of the particular relationships between the various embodiments and/or configurations discussed. In addition, the various specific processes and materials provided in the following description of the present application are merely examples of implementation of the technical solutions of the present application, but those of ordinary skill in the art should recognize that the technical solutions of the present application may also be implemented by other processes and/or other materials not described below.
Further, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the application. It will be appreciated, however, by one skilled in the art that the inventive aspects may be practiced without one or more of the specific details, or with other structures, components, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the application.
An embodiment of the application provides a beam scanning module based on a projection optical system, which is configured to emit a sensing beam for three-dimensional information detection to a detection range and comprises a light source module, an acousto-optic deflection module, a projection optical system and a beam expansion module. The light source module is configured to emit a collimated beam of light in the shape of a bar. The acousto-optic deflection module is configured to deflect the strip-shaped collimated light beam in a preset first direction by a plurality of different preset deflection angles within a preset first deflection angle range according to the applied acoustic wave frequency; the direction of the maximum size of the strip-shaped collimated light beam is defined as the length direction of the strip-shaped collimated light beam, the length direction of the strip-shaped collimated light beam is parallel to a preset second direction, and the second direction and the first direction are mutually perpendicular. The projection optical system is configured to project the light beam deflected by the acousto-optic deflection module along a preset emission direction corresponding to a light beam deflection angle within a detection range to form the sensing light beam. The beam deflected by the acousto-optic deflection module passes through a corresponding area on a focal plane of the projection optical system and is projected by the projection optical system, and the corresponding area moves on the focal plane along with the change of the deflection angle of the beam. The beam expansion module is disposed on the light-emitting side of the projection optical system, and is configured to expand a divergence angle of the sensing beam in the second direction to form a long stripe-shaped sensing beam.
Optionally, in some embodiments, the focal plane is located between the acousto-optic deflection module and the projection optical system, a corresponding region on the focal plane being a secondary light source region to emit the sensing beam.
Optionally, in some embodiments, the two adjacent secondary light source regions respectively formed correspondingly on the focal plane before and after the acousto-optic deflection module performs the minimum angle deflection on the light beam are tangent to each other.
Optionally, in some embodiments, the first direction is a horizontal direction and the second direction is a vertical direction; alternatively, the first direction is a vertical direction, and the second direction is a horizontal direction.
Optionally, in some embodiments, the beam expansion module includes a refraction diffusion sheet, and a microstructure capable of modulating the beam is formed on the refraction diffusion sheet, and the microstructure performs a function of expanding the sensing beam divergence angle along a preset direction through refraction of the passing beam.
Optionally, in some embodiments, the beam expansion module includes a diffraction diffusion sheet, and a microstructure capable of modulating the beam is formed on the diffraction diffusion sheet, and the microstructure performs a function of expanding the sensing beam divergence angle along a preset direction through diffraction of the passing beam.
Optionally, in some embodiments, the beam expansion module includes a cylindrical beam expansion lens including an optical surface disposed curved along the second direction to expand a divergence angle of the sensing beam along the second direction.
Optionally, in some embodiments, the beam expansion module further includes a collimating lens disposed on an incident side of the cylindrical beam expansion lens and configured to collimate the sensing beam projected by the projection optical system along an optical axis before entering the cylindrical beam expansion lens, and an emission lens disposed on an exit side of the cylindrical beam expansion lens and configured to re-emit the sensing beam expanded by the cylindrical beam expansion lens by a divergence angle along a direction in which the sensing beam was originally projected from the projection optical system.
Optionally, in some embodiments, the system further includes a reflector, and the deflected light beam emitted from the acousto-optic deflection module enters the projection optical system after being reflected by the reflector.
Optionally, in some embodiments, the system further includes a liquid crystal polarization grating module, and the liquid crystal polarization grating module is disposed between the acousto-optic deflection module and the projection optical system, so as to deflect the light beam deflected by the acousto-optic deflection module by a preset deflection angle, where the liquid crystal polarization grating module and the acousto-optic deflection module both deflect the light beam along the first direction in the same plane.
Optionally, in some embodiments, the light source module further comprises beam shrinking optics configured to shrink the collimated beam of light to a predetermined size before transmitting to the acousto-optic deflection module.
Optionally, in some embodiments, the light source module further comprises a linear polarizer disposed on the optical path of the light beam before entering the acousto-optic deflection module, configured to convert the light beam into linearly polarized light having a preset polarization state before entering the acousto-optic deflection module.
Optionally, in some embodiments, the light source module further includes a polarization beam splitter, a polarization direction adjusting member and a light guiding member, the polarization beam splitter is disposed on an optical path before the light beam enters the acousto-optic deflection module, the polarization beam splitter splits the passing light beam into a first polarized light beam and a second polarized light beam, the first polarized light beam has a first polarization direction, the second polarized light beam has a second polarization direction different from the first polarization direction, the light guiding member is configured to guide a propagation direction of the first polarized light beam or the second polarized light beam or both the first polarized light beam and the second polarized light beam, so that the first polarized light beam and the second polarized light beam are incident to the acousto-optic deflection module along different optical paths, respectively, and the polarization direction adjusting member is configured to change the polarization direction of the first polarized light beam or the second polarized light beam so that both enter the acousto-optic deflection module in the same preset polarization direction.
Optionally, in some embodiments, the time when the decomposed first polarized light beam and the second polarized light beam reach the acousto-optic deflection module respectively has a preset time difference.
Optionally, in some embodiments, the first polarized light beam propagates to the acousto-optic deflection module through the polarizing beam splitter along a main optical axis along which a light beam enters the polarizing beam splitter in an incident direction, and the polarization direction adjusting element is disposed on the main optical axis and configured to change a first polarization direction of the first polarized light beam into the second polarization direction.
Optionally, in some embodiments, the second polarized light beam propagates to the acousto-optic deflection module along a bypass light path deviating from a main optical axis where the incident direction of the light beam is when the light beam is incident on the polarization beam splitter after passing through the polarization beam splitter, and the polarization direction adjusting element is disposed on the bypass light path and configured to change the second polarization direction of the second polarized light beam to the first polarization direction.
Optionally, in some embodiments, the polarization direction adjusting member comprises a liquid crystal layer configured to change the polarization direction of the passing light beam by adjusting the orientation of liquid crystal molecules within the liquid crystal layer.
Optionally, in some embodiments, the second polarized light beam enters the acousto-optic deflection module along a direction parallel to the first polarized light beam after being guided by the light guide member, and incident points of the first polarized light beam and the second polarized light beam on the acousto-optic deflection module are located in a preset incident area on the acousto-optic deflection module.
The embodiment of the application also provides an optoelectronic device which is configured to detect three-dimensional information of an object positioned in a preset detection range, and comprises the light beam scanning module, a receiving module and a processing circuit. The photoelectric device further comprises a receiving module and a processing module, wherein the receiving module is configured to sense the light signals from the detection range and output corresponding light sensing signals, and the processing module is configured to analyze and process the light sensing signals to obtain three-dimensional information of an object in the detection range.
The embodiment of the application also provides electronic equipment, which comprises the photoelectric device. The electronic equipment realizes corresponding functions according to the three-dimensional information obtained by the photoelectric device. The electronic device is, for example: cell phones, automobiles, robots, access control/monitoring systems, intelligent door locks, unmanned aerial vehicles, etc. The three-dimensional information is, for example: proximity information, depth information, distance information, coordinate information, and the like of an object within the detection range. The three-dimensional information may be used in fields such as 3D modeling, face recognition, automatic driving, machine vision, monitoring, unmanned aerial vehicle control, augmented Reality (Augmented Reality, AR)/Virtual Reality (VR), instant positioning and map construction (Simultaneous Localization and Mapping, SLAM), object proximity determination, etc., which is not limited in this application.
The optoelectronic device can be, for example, a laser radar and can be used for obtaining three-dimensional information of an object in a detection range. The laser radar is applied to the fields of intelligent driving vehicles, intelligent driving aircrafts, 3D printing, VR, AR, service robots and the like. Taking an intelligent driving vehicle as an example, a laser radar is arranged in the intelligent driving vehicle, and the laser radar can scan the surrounding environment by rapidly and repeatedly emitting laser beams so as to obtain point cloud data reflecting the morphology, the position and the movement condition of one or more objects in the surrounding environment. Specifically, the lidar emits a laser beam to the surrounding environment, receives an echo beam of the laser beam reflected by each object in the surrounding environment, and determines distance/depth information of each object by calculating a time delay (i.e., time of flight) between the emission time of the laser beam and the return time of the echo beam. Meanwhile, the laser radar can also determine angle information describing the orientation of the detection range of the laser beam, combine the distance/depth information of each object with the angle information of the laser beam to generate a three-dimensional map comprising each object in the scanned surrounding environment, and guide the intelligent driving of the unmanned vehicle by using the three-dimensional map.
Hereinafter, an embodiment of an electro-optical device applied to an electronic apparatus will be described in detail with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a functional module of an optoelectronic device according to an embodiment of the present application applied to an electronic device. Fig. 2 is a schematic functional block diagram of an optoelectronic device according to an embodiment of the present application.
Referring to fig. 1 and 2, the electronic device 1 comprises an optoelectronic device 10. The optoelectronic device 10 may detect the object 2 within a detection range to obtain three-dimensional information of the object 2, where the detection range may be defined as a three-dimensional space range in which the optoelectronic device 10 can effectively detect three-dimensional information, and may also be referred to as a field angle of the optoelectronic device 10. Such as, but not limited to, one or more of proximity information of the object 2, depth information of the surface of the object 2, distance information of the object 2, and spatial coordinate information of the object 2.
The electronic device 1 may include an application module 20, where the application module 20 is configured to perform a preset operation or implement a corresponding function according to a detection result of the optoelectronic device 10, for example, but not limited to: whether the object 2 appears in a detection range preset in front of the electronic equipment 1 can be judged according to the proximity information of the object 2; or, the movement of the electronic equipment 1 can be controlled to avoid the obstacle according to the distance information of the object 2; alternatively, 3D modeling, face recognition, machine vision, etc. may be implemented based on depth information of the surface of the object 2. The electronic device 1 may further comprise a storage medium 30, which storage medium 30 may provide support for storage requirements of the electronic device 1 and/or the optoelectronic apparatus 10 during operation. The electronic device 1 may further comprise a processor 40 which may provide support for data processing requirements of the electronic device 1 and/or the electro-optical apparatus 10 during operation.
Alternatively, in some embodiments, the optoelectronic device 10 may be, for example, a direct time of flight (direct Time of Flight, dtoff) measurement device that performs three-dimensional information sensing based on the dtoff principle. The dTOF measuring device can emit a sensing light beam in a detection range and receive the sensing light beam reflected by an object 2 in the detection range, the time difference between the emitting time and the receiving time of the reflected sensing light beam is called as the flight time t of the sensing light beam, and three-dimensional information of the object 2 can be obtained by calculating half the passing distance of the sensing light beam in the flight time tWherein c is the speed of light.
Alternatively, in other embodiments, the optoelectronic device 10 may be an iToF measurement device that senses three-dimensional information based on an indirect time-of-flight (indirect Time of Flight, iToF) measurement principle. The iToF measuring device obtains three-dimensional information of the object 2 by comparing the phase difference of the sensing beam when emitted and when received back by reflection.
In the following examples of the present application, the electro-optical device 10 is mainly described as a dtofmeasurement device.
Optionally, as shown in fig. 2, the optoelectronic device 10 includes a beam scanning module 12, a receiving module 14, and a processing circuit 15. The beam scanning module 12 is configured to emit a sensing beam to the detection range to detect three-dimensional information of the object 2 within the detection range, wherein a part of the sensing beam is reflected by the object 2 and returns, and the reflected sensing beam carries the three-dimensional information of the object 2, and a part of the reflected sensing beam can be sensed by the receiving module 14 to obtain the three-dimensional information of the object 2. The receiving module 14 is configured to sense the optical signal from the detection range and output a corresponding optical sensing signal, and by analyzing the optical sensing signal, three-dimensional information detection of the object 2 in the detection range can be realized. It is understood that the optical signal sensed by the receiving module 14 may be a photon, for example, a photon including a sensing beam reflected by the object 2 in the detection range and a photon of ambient light in the detection range. The processing circuit 15 is configured to analyze and process the light sensing signal to obtain a time when the sensing beam is sensed by the receiving module 14, and to obtain three-dimensional information of the object 2 according to a time difference between an emission time of the sensing beam and a reflected sensed time.
The processing circuitry 15 may be disposed on the optoelectronic device 10. Alternatively, in other embodiments, all or part of the functional units of the processing circuit 15 may be provided on the electronic device 1.
Alternatively, the sensing beam may be a laser pulse having a preset frequency. The beam scanning module 12 is configured to periodically emit the laser pulses as a sensing beam at a preset frequency within a detection frame.
Alternatively, the sensing beam is, for example, visible light, infrared light, or near infrared light, with wavelengths ranging, for example, from 390 nanometers (nm) to 780nm, from 700nm to 1400nm, from 800nm to 1000nm, from 900nm to 1600nm.
Referring to fig. 2 and fig. 3 together, fig. 3 is a schematic diagram of a statistical histogram obtained by the processing circuit 15 shown in fig. 2. Optionally, in some embodiments, the processing circuit 15 may include a timing unit 152, a statistics unit 154, a time-of-flight acquisition unit 156, and a three-dimensional information acquisition unit 158.
The timing unit 152 is configured to determine a time of receipt of the optical signal sensed by the receiving module 14. The optoelectronic device 10 emits a plurality of sensing beams through the beam scanning module 12 during the detection process, the timing unit 152 starts timing when the beam scanning module 12 emits the sensing beams each time to record the receiving time of the optical signal sensed by the receiving module 14 between two adjacent sensing beam emissions, during which the receiving module 14 outputs a corresponding optical sensing signal each time an optical signal is received, and the timing unit 152 records the receiving time of the sensed optical signal according to the optical sensing signal output by the receiving module 14 and counts in time bins corresponding to the receiving time to form a corresponding optical signal count. The time bin is the minimum time unit Δt for the timing unit 152 to record the time of the generation of the photo-sensing signal, and can reflect the accuracy of time recording of the photo-sensing signal by the timing unit 152, and the finer the time bin, the higher the accuracy of recording time. Alternatively, the timing unit 152 may implement a timing function through a Time-to-Digital Converter, TDC) 1522. The TDC1522 may be connected to the corresponding photosensitive pixel 142 and configured to record a receiving time of the sensed light signal according to the light sensing signal generated by the corresponding photosensitive pixel 142. For example, the TDC1522 is triggered synchronously to start timing each time the sensing beam is emitted, and then stops timing in response to the photo-sensing signal generated by the corresponding photo-sensing pixel 142, and takes the counted time period as the reception time of the corresponding photo-signal of the excitation photo-sensing signal.
Optionally, in some embodiments, the timing unit 152 may include a count memory 1524, where the count memory 1524 has a count memory space allocated according to a time bin, and the TDC1522 adds one to the count memory space of the corresponding time bin every time the receiving time of the optical signal is recorded.
The statistics unit 154 is configured to count the optical signal counts accumulated in each time bin, so as to obtain a statistical histogram that can reflect the distribution of the number of optical signals sensed by the receiving module 14 over time. As shown in fig. 3, the abscissa of the statistical histogram represents the time stamp of each corresponding time bin, and the ordinate of the statistical histogram represents the light signal count value accumulated in each corresponding time bin. Optionally, the statistics unit 154 may include a histogram circuit 1544 (see fig. 2), the histogram circuit 1544 being configured to count the light signal counts within each time bin to generate a statistical histogram. It should be understood that the statistics unit 154 performs a statistical analysis on the counts of the optical signals corresponding to the accumulated counts during the multiple emission of the sensing beam in one detection frame, so that the counts have a mathematical statistical significance, and the emission times of the sensing beam in one detection frame may be up to hundreds, thousands, tens of thousands, or even millions.
During the sensing process, a large number of photons of ambient light are also sensed by the receiving module 14 to generate corresponding counts of the optical signals. The probability that photons of these ambient light are sensed leaving counts within each time bin tends to be the same, constituting Noise floors (Noise levels) within the detection range, which are measured at relatively high average levels in scenes of higher ambient light intensity and relatively low average levels in scenes of lower ambient light. On the basis, the sensing light beam reflected from the object 2 is sensed and the corresponding generated optical signal count is superposed on the noise back, so that the optical signal count in the time bin corresponding to the sensing time of the sensing light beam is obviously higher than the optical signal count of other time bins, and further a protruding signal peak is formed. It will be appreciated that the count value of the signal peak may be affected by factors such as the optical power of the sensing beam, the reflectivity of the object 2, the detection range of the optoelectronic device 10, and the width of the signal peak may be affected by factors such as the pulse width of the emitted sensing beam, the time jitter of the photoelectric conversion element of the receiving module 14 and the TDC 1522. Thus, the time-of-flight acquisition unit 156 can obtain the time-of-flight of the relevant sensing beam reflected back by the object 2 from the time difference between the time stamp t1 of the time bin corresponding to the peak value of the signal peak and the emission time t0 of the relevant sensing beam generating the signal peak. The three-dimensional information acquisition unit 158 may be configured to obtain three-dimensional information between the object 2 reflecting the sensing beam and the optoelectronic device 10 from the time of flight of the sensing beam determined by the statistical histogram, for example: the distance between the object 2 and the optoelectronic device 10 in the detection range.
It should be understood that the light beam scanning module 12 and the receiving module 14 are disposed adjacent to each other side by side, the light emitting surface of the light beam scanning module 12 and the light incident surface of the receiving module 14 face the same side of the optoelectronic device 10, and the distance between the light beam scanning module 12 and the receiving module 14 may be, for example, 2 millimeters (mm) to 20mm. Because the beam scanning module 12 and the receiving module 14 are relatively close to each other, the emission path of the sensing beam from the beam scanning module 12 to the object 2 and the return path from the object 2 to the receiving module 14 after reflection are not completely equal, but are far greater than the distance between the beam scanning module 12 and the receiving module 14, which can be regarded as approximately equal. Thus, the distance between the object 2 and the optoelectronic device 10 can be calculated from the product of half the time of flight t of the sensing beam reflected back by the object 2 and the speed of light c.
The receive module 14 may include a photosensor 140 and receive optics 144. The receiving optics 144 is disposed on the light-in side of the photosensor 140 and is configured to propagate an optical signal from a detection range to the photosensor 140 for sensing. For example, in some embodiments, the receiving optics 144 includes a receiving lens (not shown). Alternatively, the receiving lens may include one lens or a plurality of lenses. The photosensor 140 is configured to sense optical signals propagating from the detection range via the receiving optics 144 and output corresponding photo-sensing signals.
Optionally, in some embodiments, the receiving module 14 may further include a peripheral circuit (not shown) formed by one or more of a signal amplifier, an Analog-to-Digital Converter (ADC), and the like, and the peripheral circuit may be partially or fully integrated in the photosensor 140.
Alternatively, in some embodiments, the photosensor 140 includes a single photosensitive pixel 142 or includes a plurality of photosensitive pixels 142 to form a photosensitive pixel array, for example. The detection range of the optoelectronic device 10 may include a plurality of detection areas respectively located at different positions. Optionally, the photosensitive pixels 142 of the photosensor 140 have corresponding detection areas in a detection range, and optical signals returned from the detection areas propagate to the corresponding photosensitive pixels 142 via the receiving optics 144 for sensing. That is, the detection area corresponding to the photosensitive pixel 142 can be regarded as a spatial range covered by the angle of view of the photosensitive pixel 142 formed by the receiving optical device 144. It will be appreciated that the optical signal returned from the detection zone comprises a sensing beam projected to the detection zone and reflected back by the object 2 located within the detection zone, as well as photons of ambient light from the detection zone.
Alternatively, one of the photosensitive pixels 142 may include a single photoelectric conversion device or include a plurality of photoelectric conversion devices. The photoelectric conversion device is configured to sense a received optical signal and convert the received optical signal into a corresponding electrical signal to be output as the photo-sensing signal. Such as single photon avalanche diodes (Single Photon Avalanche Diode, SPADs), avalanche photodiodes (Avalanche Photon Diode, APDs), silicon photomultiplier tubes (Silicon Photomultiplier, sipms) arranged in parallel by a plurality of SPADs, and/or other suitable photoelectric conversion elements.
As shown in fig. 2, in some embodiments, the beam scanning module 12 includes a light source module 122, an acousto-optic deflection module 124, and a secondary deflection module 126. The light source module 122 is configured to emit a light beam, and the acousto-optic deflection module 124 is configured to deflect the light beam within a preset first deflection angle range according to the applied acoustic wave frequencyThe secondary deflection module 126 is configured to deflect the light beam emitted from the light source module 122 along the first direction by a plurality of different preset deflection angles, and the secondary deflection module 124 is configured to deflect the light beam deflected by the acousto-optic deflection module 124 within a preset second deflection angle range +.>The inner edge further deflects a preset angle along the first direction so as to respectively form sensing light beams with different emergent directions corresponding to different deflection angles. It should be understood that the first direction herein refers to a deflection direction of the light beam, which is different from the emission direction of the light beam, and the deflection direction of the light beam may be understood as a direction to which a trend is changed when the emission direction of the light beam is changed.
Alternatively, as shown in fig. 4, the light source module 122 is configured to emit a bar-shaped light beam, where the bar-shaped light beam may be understood as a light beam having a shape with a size in a predetermined direction that is significantly larger than that of other directions, and a direction having a maximum size may be defined as a length direction of the bar-shaped light beam for convenience of description. For example, the shape of the strip beam may be an elongated square, that is, the spot shape of the strip beam irradiated on the projection surface is an elongated square, the elongated square has a pair of long sides and a pair of short sides, and the extension direction of the long sides is the length direction of the strip beam. It should be understood that the shape of the strip beam is not limited to an elongated square, and may be, for example, an elongated strip with both ends having circular arc shapes. If the acousto-optic deflection module 124 deflects the passing light beam along the first direction, the length direction of the strip-shaped light beam emitted by the light source module 122 is parallel to a second direction, and the second direction is perpendicular to the first direction. Optionally, the first direction is a horizontal direction, and the second direction is a vertical direction; alternatively, the first direction is a vertical direction, and the second direction is a horizontal direction.
Referring to fig. 5 again, the light source module 122 includes one or more light emitting units 1220, and the light emitting units 1220 are configured to emit light beams. The light emitting unit 1220 may be a light emitting structure in the form of a vertical cavity surface emitting Laser (Vertical Cavity Surface Emitting Laser, VCSEL for short, or a vertical cavity surface emitting Laser), an edge emitting Laser (Edge Emitting Laser, EEL), a light emitting Diode (Light Emitting Diode, LED), a Laser Diode (LD), a fiber Laser, or the like. The edge emitting laser may be a Fabry Perot (FP) laser, a distributed feedback (Distribute Feedback, DFB) laser, an Electro-absorption modulated laser (Electro-absorption Modulated, EML), or the like, which is not limited in the embodiment of the present application.
Alternatively, the plurality of light emitting units 1220 on the light source module 122 may be arranged in a long stripe array, and the emitted light beams may be collimated into stripe light beams traveling parallel to the optical axis. Optionally, the light source module 122 may use an optical device such as a superlens or a cylindrical lens to collimate the light beam emitted from the light emitting unit 1220, so as to improve the collimation degree of the stripe-shaped light beam emitted from the light source module 122.
Optionally, in some embodiments, the light source module 122 may further include beam shrinking optics 1223, which may be used to narrow the cross-sectional dimension of the light beam, i.e., the dimension of the light beam in a cross-section perpendicular to the direction of light beam propagation. The beam shrinking optics 1223 may be disposed in the optical path of the light beam before entering the acousto-optic deflection module 124, and configured to shrink the light beam collimated by the first superlens 1222 to a predetermined size before transmitting the light beam to the acousto-optic deflection module 124. Since the incident area of the acousto-optic deflection module 124 for receiving the light beam has a certain size, in order to allow the light beam incident on the acousto-optic deflection module 124 to enter from the incident area, it is necessary to modulate the light beam to a size matching the incident area before transmitting to the acousto-optic deflection module 124. It should be understood that, in other embodiments, the beam shrinking optics 1223 may be omitted if the collimated light beam emitted by the light emitting unit 1220 has a size that meets the requirements of the incident acousto-optic deflection module 124.
Optionally, in some embodiments, the light source module 122 may further include a linear polarizer 1221. The linear polarizer 1221 is disposed on the optical path of the light beam before entering the acousto-optic deflection module 124, and is configured to convert the light beam into linearly polarized light having a predetermined polarization state before entering the acousto-optic deflection module 124. It should be understood that in other embodiments, the linear polarizer 1221 may be omitted if other optical elements can convert the light beam to linearly polarized light in a predetermined deflection state before the light beam is transmitted to the acousto-optic deflection module 124.
In the embodiment of fig. 5, the beam reduction optics 1223 are disposed between the light emitting unit 1220 and the linear polarizer 1221. Alternatively, in other embodiments, the arrangement order of the beam shrinking optics 1223 and the linear polarizer on the optical path may be interchanged, so long as both are disposed in the optical path before the light beam enters the acousto-optic deflection module 124, which is not particularly limited by the present application.
Optionally, as shown in fig. 6 and 7, in some embodiments, the light source module 122 may further include a polarizing beam splitter 1224, a polarization direction adjusting member 1226, and a light guide 1228. The polarization beam splitter 1224 is disposed on the optical path before the light beam enters the acousto-optic deflection module 124, and splits the passing light beam into a first polarized light beam and a second polarized light beam, wherein the first polarized light beam has a first polarization direction, and the second polarized light beam has a second polarization direction. The second polarization direction is different from the first polarization direction, for example: the first polarization direction and the second polarization direction are mutually orthogonal. The light guide 1228 is configured to direct the direction of propagation of the first polarized light beam or the second polarized light beam or both the first polarized light beam and the second polarized light beam such that the first polarized light beam and the second polarized light beam are incident to the acousto-optic deflection module 124 along different light paths, respectively. The polarization direction adjuster 1226 is configured to change the polarization direction of the first polarized light beam or the second polarized light beam such that both enter the acousto-optic deflection module 124 with the same preset polarization direction.
Specifically, for example, the polarizing beam splitter 1224 may be a polarizing prism formed by combining two calcite rectangular prisms along an inclined plane, for example: the first polarized light beam propagates to the acousto-optic deflection module 124 through the combined interface of the polarizing beam splitter 1224 along the main optical axis where the light beam is incident, the second polarized light beam is reflected by the combined interface of the polarizing beam splitter 1224 to deviate from the main optical axis where the light beam is incident, and then propagates to the acousto-optic deflection module 124 through the light guide 1228 along the side branch optical path deviating from the main optical axis. It should be noted that, the main optical axis herein refers to the directions in which different optical devices in the optical beam scanning module 12 are aligned with each other along respective optical axes, which can be understood as the propagation directions of the light beam emitted by the light source module 122 after being collimated and passing through the optical devices in sequence, for example: the direction of the zero-order beam after the beam passes through the acousto-optic deflection module 124.
It should be understood that, in other embodiments, the first polarized light beam and the second polarized light beam obtained by decomposing the light beam by the polarizing beam splitter 1224 may not propagate along the main optical axis where the incident direction of the light beam is located, but may propagate along different optical paths to the acousto-optic deflection module 124 after being guided by the light guide 1228.
Optionally, the polarization direction adjusting member 1226 includes a liquid crystal layer, and the polarization direction of the passing light beam may be changed by adjusting the orientation of liquid crystal molecules in the liquid crystal layer. As shown in fig. 6, the polarization direction adjusting member 1226 may be disposed on the main optical axis of the beam scanning module 12 and configured to change the first polarization direction of the first polarized beam to the second polarization direction. Alternatively, as shown in fig. 7, the polarization direction adjuster 1226 may be disposed on the bypass optical path and configured to change the second polarization direction of the second polarized light beam to the first polarization direction.
As shown in fig. 6, the light guide 1228 is, for example, a plurality of reflective optical elements, and guides the second polarized light beam into the acousto-optic deflection module 124 in a direction parallel to the first polarized light beam by a plurality of reflections. Alternatively, in other embodiments, the light guide 1228 may be an optical fiber.
Optionally, by reasonably setting a first optical path through which the first polarized light beam passes on the main optical axis and a second optical path through which the second polarized light beam passes on the side branch optical path, the time when the decomposed first polarized light beam and second polarized light beam respectively reach the acousto-optic deflection module 124 may have a preset time difference. The time difference between the first polarized light beam and the second polarized light beam, which are obtained by decomposing the same light beam emitted from the corresponding light emitting unit 1220, reaching the acousto-optic deflection module 124, respectively, may be equal to the emission period of the sensing light beam pulse periodically emitted from the light beam scanning module 12, that is, the time interval between two sensing light beam pulses sequentially emitted. Thus, the corresponding light emitting unit 1220 emits a single light beam to obtain two sensing light beam pulses emitted by the light beam scanning module 12.
It should be understood that, by arranging the polarization beam splitter 1224, the corresponding polarization direction adjusting member 1226 and the light guiding member 1228 in the optical path of the light beam scanning module 12, not only can the light beam emitted by the light emitting unit 1220 meet the polarization state requirement of the incident acousto-optic deflection module 124, but also the separated second polarized light beam can be fully utilized for detection, so as to improve the utilization efficiency of the light emitting power of the light beam scanning module 12.
As shown in fig. 8, in some embodiments, the acousto-optic deflection module 124 includes an acousto-optic interaction medium 1241 and an acoustic wave generator 1242. The acousto-optic interaction medium 1241 has a predetermined light incident surface 1244, a predetermined light emergent surface 1246 and a predetermined sound wave incident surface 1248. The sound wave generator 1242 is disposed on the sound wave incident surface 1248 and configured to generate sound waves propagating in a predetermined direction in the acousto-optic interaction medium 1241. The light beam emitted by the light source module 122 enters the acousto-optic interaction medium 1241 from the light incident surface 1244 along a preset incident angle, the acousto-optic interaction medium 1241 deflects the propagation direction of the light beam under the action of the sound wave, and the deflected light beam is emitted from the light emergent surface 1246.
The incident angle may be defined as an angle between an incident direction of the light beam and a normal direction of the light incident surface 1244. Optionally, in some embodiments, the material of the acousto-optic interaction medium 1241 is tellurium dioxide (TeO 2 ) The range of the incidence angle is 2-10 degrees, and the propagation direction of the sound wave in the tellurium dioxide crystal and the lattice direction [1, 0 ] of the tellurium dioxide crystal]With a predetermined off-axis angle theta therebetween α (not shown).
Alternatively, in some embodiments, the acoustic wave generator 1242 may be a piezoelectric transducer that generates ultrasonic waves to propagate into the acousto-optic interaction medium 1241 to deflect the propagation direction of the light beam passing through the acousto-optic interaction medium 1241 along a preset incident angle.
It should be understood that, the propagation of the acoustic wave in the acousto-optic interaction medium 1241 may cause the refractive index inside the acousto-optic interaction medium 1241 to change, by reasonably configuring parameters, the incident beam may cause abnormal bragg diffraction in the acousto-optic interaction medium 1241 under the action of the acoustic wave, the propagation direction of the formed diffracted beam may deflect compared with the propagation direction of the incident beam, and the deflection angle α may be related to the frequency f of the acoustic wave by the following formula:
wherein θ d For the exit angle of the diffracted beam, the propagation direction of the diffracted beam is represented by θ i For the incident angle of the incident beam, which represents the propagation direction of the incident beam, λ is the wavelength of the incident and diffracted beams, n is the refractive index of acousto-optic interaction medium 1241, and V is the off-axis angle θ α The relevant function value is denoted as v=v (θ a ) The above reasonably configured parameters include the wavelength, polarization state, incident angle, propagation direction, frequency, propagation direction, etc. of the incident beam. Thus, by varying the frequency of the sound wave applied to the acousto-optic interaction medium 1241, the deflection angle of the light beam passing through the acousto-optic interaction medium 1241 can be controlled, and when the frequency of the sound wave is changed to Δf, the deflection angle of the light beam is correspondingly changed, i.e. the scan angle is
The deflection angle α and the scan angle Δα refer to angles inside the acousto-optic interaction medium 1241, and in practical applications, angles outside the acousto-optic interaction medium 1241 are used, and it is known from the law of refraction that the angles outside the acousto-optic interaction medium 1241 need to be multiplied by corresponding refractive index factors. Furthermore, since the time required for the acoustic wave to propagate is required, when the frequency of the acoustic wave is just changed from f1 to f2, the acousto-optic interaction medium 1241 is changed from f1 to f2 only in the part next to the acoustic wave generator 1242, the deflection angle of the light beam is changed from α1 to α2, and the deflection time τ required for the light beam to complete one deflection is considered to be equal to the transit time of the acoustic wave when the deflection angle of the light beam is changed by adjusting the acoustic wave frequency, if the acoustic wave propagates through the entire region where the light beam passes in the acousto-optic interaction medium 1241, that is, the width of the acousto-optic interaction medium 1241, the required time is called the transit time, the acoustic wave frequency in the entire acousto-optic interaction medium 1241 is changed from f1 to f2 after the transit time, and the deflection angle of the light beam is completely changed to α2, and therefore the deflection time τ required for the light beam to complete one deflection can be considered to be equal to the transit time of the acoustic wave when the deflection angle is adjusted:
Wherein W is the width of acousto-optic interaction medium 1241 and V is the off-axis angle θ α The relevant function value is denoted as v=v (θ a )。
The diffracted beam in the acousto-optic interaction medium 1241, the incident beam and the wave vector of the acoustic wave need to satisfy the momentum matching condition to form a stable coherent diffracted beam in the acousto-optic interaction medium 1241, the incident angle of the beam generating abnormal bragg diffraction will change along with the change of the acoustic wave frequency, however, in practical application, the incident angle of the beam of the acousto-optic interaction medium 1241 remains unchanged, the momentum matching condition is no longer satisfied along with the change of the acoustic wave frequency, the farther the momentum matching condition is deviated, the more the diffraction efficiency is reduced, and the acoustic wave frequency range capable of effectively completing abnormal bragg diffraction is called as the bragg bandwidth. Optionally, in some embodiments, the wavelength of the sensing beam is 905nm, the material of the acousto-optic interaction medium 1241 is tellurium dioxide crystal, the bragg bandwidth of the corresponding formed acousto-optic deflection module 124 is about 30 megahertz (MHz), the scanning angle is about 40 milliradians (mrad), that is, about 2.3 degrees, the deflection time τ required to complete one beam deflection is about 10 microseconds (μs), the accuracy of the change of the acoustic wave frequency is about 30 kilohertz (KHz), and the accuracy of the change of the corresponding scanning angle is about 0.04mrad. Realizing acousto-optic deflection in tellurium dioxide crystal by utilizing anomalous Bragg diffraction requires that the incident light beam has a dextrorotation e light component, alternatively, if the incident light beam is linear polarization e light, the diffracted light beam emitted after the acousto-optic deflection is linear polarization o light; if the incident light beam is right circularly polarized light, the diffracted light beam emitted after acousto-optic deflection is left circularly polarized light. The utilization of the outgoing diffracted beam is determined by the ellipticity of the eigenmode dextrorotatory e-light of the incident beam, which is determined by the wavelength of the incident light, the angle of incidence and the material properties of the acousto-optic interaction medium 1241.
The acousto-optic deflection module 124 can deflect the passing light beam with high precision, but the angle range of the deflected light beam is too small, so that the secondary deflection module 126 can be arranged on the light emitting side of the acousto-optic deflection module 124 to deflect the light beam deflected by the acousto-optic deflection module 124 further along the first direction, so as to meet the requirement of high-angle and high-precision scanning. It should be appreciated that the secondary deflection module 126 deflects the light beam over a wide range of angles, at least to meet the application requirements of a wide angle scan scene.
As shown in fig. 5-7, in some embodiments, the secondary deflection module 126 may be a projection optical system, and the projection optical system 126 is configured to project the light beam deflected by the acousto-optic deflection module 124 along a corresponding preset emission direction within the detection range to form the sensing light beam. The length direction of the strip beam emitted by the light source module 122 is the second direction, the acousto-optic deflection module 124 deflects the strip beam along the first direction, and the projection optical system 126 projects the strip beam deflected by the acousto-optic deflection module 124 along a corresponding preset emission direction within the detection range to form a strip sensing beam. It should be understood that, compared to the incident direction of the strip beam deflected by the acousto-optic deflection module 124 and incident to the projection optical system 126, the preset emitting direction of the projection optical system 126 deflects by a larger angle along the first direction, and the deflection angle of the preset emitting direction and the incident angle of the strip beam deflected by the acousto-optic deflection module 124 form a corresponding positive correlation, for example: the larger the incident angle between the incident direction of the deflected bar-shaped light beam and the optical axis of the projection optical system 126, the larger the emission angle formed between the emission direction of the bar-shaped light beam projected by the projection optical system 126 and the optical axis of the projection optical system 126.
As shown in fig. 9, the projection optical system 126 is disposed on the light emitting side of the acousto-optic deflection module 124, and is configured to project the light beam deflected by the acousto-optic deflection module 124 in a preset emission direction further deflected along the first direction, so as to form the sensing light beam. The emission direction of the sensing beam, which is deflected by the projection optical system 126, is related to the deflection angle of the beam passing through the acousto-optic deflection module 124. The focal plane of the projection optical system 126 is located between the projection optical system 126 and the acousto-optic deflection module 124, and the light beam deflected by the acousto-optic deflection module 124 is projected by the projection optical system 126 after passing through a corresponding area on the focal plane of the projection optical system 126.
According to the huyghen-fresnel principle, the area of the beam passing through the focal plane of the projection optical system 126 during propagation can be used as a secondary light source, and the light wave emitted by the secondary light source is deflected by the projection optical system 126 to form the sensing beam. Thus, the area passing through the focal plane of the projection optical system 126 during the propagation of the light beam deflected by the acousto-optic deflection module 124 can be defined as the secondary light source area 125 formed by the corresponding light beam at the focal plane under the deflection angle, by adjusting the frequency of the sound wave applied to the acousto-optic interaction medium 1241, the secondary light source area 125 formed by the light beam deflected by the acousto-optic deflection module 124 can be moved at the focal plane of the projection optical system 126, the sensing light beam formed by the light beam generated by the secondary light source area 125 is projected by the projection optical system 126, the projection direction of the sensing light beam is correspondingly deflected along with the movement of the secondary light source area 125 at the focal plane, and the second preset deflection angle range is further realized A one-dimensional, large-angle, continuous scanning of the sensing beam along the first direction. Since the light beam is further deflected in the first direction during projection by the projection optical system 126, the second deflection angle range +.>Will be +_ greater than said first deflection angle range>Larger.
The light beams deflected by the acousto-optic deflection module 124 at different angles form a plurality of different secondary light source regions 125 arranged in sequence on the focal plane, respectively. The secondary light source region 125 formed corresponding to the light beam with the larger deflection angle is relatively closer to the edge in the focal plane, and the secondary light source region 125 formed corresponding to the light beam with the smaller deflection angle is relatively closer to the middle in the focal plane. That is, if an imaging plane is placed on the focal plane, the beams deflected by the acousto-optic deflection module 124 at different angles form far-field light spots at the positions of the plurality of secondary light source regions 125 on the focal plane, respectively, the far-field light spot formed by the beam with the largest deflection angle is located at the most edge of the plurality of far-field light spot positions on the focal plane, and the far-field light spot formed by the beam with the smallest undeflected or deflected angle is located at the middle position of the plurality of far-field light spot positions on the focal plane.
Optionally, in some embodiments, by reasonably setting the positional relationship between the acousto-optic deflection module 124 and the projection optical system 126, the two adjacent secondary light source regions 125 respectively formed in front of and behind the minimum angle deflection (that is, the deflection accuracy of the beam by the acousto-optic deflection module 124) that can be achieved by the acousto-optic deflection module 124 on the beam may be tangent to each other on the focal plane of the projection optical system 126. That is, if an imaging plane is placed on the focal plane, the two far-field light spots formed at different positions on the focal plane before and after the acousto-optic deflection module 124 performs the minimum angle deflection on the light beam are tangent to each other. It should be appreciated that in other embodiments, the acousto-optic deflection module 124 may be configured to separate or partially overlap the light beam from each other through the region at the focal plane of the projection optical system 126 before and after the minimum angular deflection of the light beam, respectively.
In order to facilitate explanation of the quantitative relationship between the deflection angle of the beam by the acousto-optic deflection module 124 and the emission angle of the deflected beam projected by the projection optical system 126, assuming that the focal length of the projection optical system 126 is f, the distance between the focal plane of the projection optical system 126 and the center of the acousto-optic deflection module 124 is l, and the deflection accuracy of the beam by the acousto-optic deflection module 124 is δα, the minimum angle δα that the acousto-optic deflection module 124 can achieve for the beam is formed between two adjacent secondary light source regions 125 correspondingly formed on the focal plane before and after the deflection The inter-heart distance d is approximately l.delta.alpha, and the deflection accuracy psi=d/f of the corresponding formed sensing beam is projected by the projection optical system 126. If the aperture of the secondary light source area 125 formed correspondingly on the focal plane of the projection optical system 126 is a, the divergence angle Φ=a/f of the sensing light beam formed correspondingly after being projected by the projection optical system 126 is set as the aperture of the secondary light source area 125. It should be appreciated that for ease of illustration, only light rays of the beam that pass through the optical center of the projection optical system 126 are shown in fig. 9. The acousto-optic deflection module 124 and the projection optical system 126 cooperate to provide a second deflection angle range for the light beamThe number of the plurality of secondary light source regions 125 formed in correspondence with the light beams deflected by the acousto-optic deflection module 124 at different angles on the focal plane of the projection optical system 126 is related to the deflection accuracy δα of the light beams by the acousto-optic deflection module 124.
Optionally, in some embodiments, the projection optical system 126 includes a projection lens 1260, the projection lens 1260 being a convex lens, a focal plane of the convex lens being a focal plane of the projection optical system 126. Since the secondary light source area 125 formed by the light beam on the focal plane corresponds to the light source arranged on the focal plane and emits light to the convex lens, the sensing light beam projected along the preset direction formed by the light beam with the same deflection angle after passing through the convex lens is a parallel light beam according to the imaging principle of the convex lens. It should be appreciated that the projection optical system 126 may be a single lens or a combination of lenses including a plurality of lenses. If the projection optical system 126 is a lens combination of a plurality of lenses, the focal plane is an equivalent focal plane of the lens combination.
It should be understood that, in the case where the function of the acousto-optic deflection module 124 and the performance requirement of the application scene are required to be considered, the distance l between the focal plane of the projection optical system 126 and the center of the acousto-optic deflection module 124 may be relatively long, which is disadvantageous for miniaturization of the module. As shown in fig. 10, in some embodiments, the beam scanning module 12 may further include a reflecting element 127, and the beam deflected by the acousto-optic deflection module 124 is reflected by the reflecting element 127, then passes through the focal plane of the projection optical system 126, and is further projected by the projection optical system 126. In this case, the optical axis of the acousto-optic deflection module 124 is defined as a first optical axis, the optical axis of the projection optical system 126 is defined as a second optical axis, and the first optical axis and the second optical axis are not on the same straight line, but may be at a predetermined angle with each other. Therefore, the distance l between the focal plane of the projection optical system 126 and the center of the acousto-optic deflection module 124 can be split into a first portion l1 along the first optical axis and a second portion l2 along the second optical axis, so that the length of the distance l in a single direction is reduced, and the length of each portion of the distance l in different directions can be adjusted by changing the position and the inclination angle of the reflecting member 127, which is beneficial to the requirement of the miniaturized design of the module. Optionally, the first optical axis of the acousto-optic deflection module 124 and the second optical axis of the projection optical system 126 are disposed perpendicular to each other.
As shown in fig. 5-7, in some embodiments, the beam scanning module 12 may further include a beam adjuster 123. The beam adjuster 123 may be disposed between the acousto-optic deflection module 124 and the projection optical system 126 and configured to adjust the beam of light prior to entering the projection optical system 126.
Optionally, the beam adjuster 123 may include converging optics for converging the beam deflected by the acousto-optic deflection module 124. Referring to fig. 9, as mentioned above, the light beams deflected by the acousto-optic deflection module 124 form sequentially arranged secondary light source regions 125 on the focal plane of the projection optical system 126 corresponding to each deflection angle, and the divergence angle of the light beams affects the space occupied by all the secondary light source regions 125 on the focal plane, so as to determine the size of the projection optical system 126. For the case where the beam divergence angle after acousto-optic deflection is large, it is necessary to appropriately reduce the beam divergence angle before the beam enters the projection optical system 126, so as to reduce the size of the projection optical system 126 to be configured. Thus, the converging optics may reduce the size of the projection optics 126 to be configured by converging the light beam to reduce the divergence angle of the light beam as it passes through the focal plane of the projection optics 126, such as: the size of the projection lens 1260 may be reduced. It should be appreciated that in some embodiments, the converging optics may be omitted if the divergence angle of the beam deflected by the acousto-optic deflection module 124 is small.
Alternatively, the beam adjuster 123 may include a liquid crystal polarization grating (Liquid Crystal Polarization Grating, LCPG) module disposed between the acousto-optic deflection module 124 and the focal plane of the projection optical system 126, the LCPG module being configured to further deflect the beam deflected by the acousto-optic deflection module 124 by a preset deflection angle to expand the beam deflection angle range before entering the projection optical system 126, thereby enabling shortening the distance l between the focal plane of the projection optical system 126 and the center of the acousto-optic deflection module 124 while achieving the same beam scanning performance. Since the angle interval between different preset deflection angles of the LCPG module to the light beam is relatively large, the deflection angle interval of the LCPG module to the light beam and the first deflection angle range of the acousto-optic deflection module 124 to the deflection of the light beam are configuredEquivalently, the range of deflection angles of the beam by the acousto-optic deflection module 124 can be multiplied by the LCPG module. It should be understood that the LCPG module includes at least one LCPG sheet, and the cascade manner between different LCPG sheets may be binary, binary-like, or ternary, which is not limited in this regard by the present application.
It should be appreciated that in some embodiments, the beam conditioner 123 may also include both converging optics and an LCPG module.
Since the acousto-optic deflection module 124 and the projection optical system 126 both deflect the light beam in the first direction, only one-dimensional scanning of the detection range by the light beam is achieved. To achieve a two-dimensional scanning of the detection range by the sensing beam, as shown in fig. 4, in some embodiments, the beam scanning module 12 further includes a beam expansion module 129. The beam expansion module 129 is arranged on the light exit side of the projection optical system 126, i.e. on the side of the projection optical system 126 facing away from the acousto-optic deflection module 124, or the projection optical system 126 is located between the acousto-optic deflection module 124 and the beam expansion module 129. The beam expansion module 129 is configured to expand the divergence angle of the beam along the second direction to form an elongated sensing beam, and define the direction of the maximum size of the sensing beam as the length direction thereof, wherein the length direction of the elongated sensing beam is parallel to the second direction, and the second direction is perpendicular to the first direction.
Alternatively, the beam expansion module 129 may include a diffusion sheet, where a microstructure capable of modulating the beam is formed on the diffusion sheet, and the diffusion sheet is configured to expand a divergence angle of the beam along a second direction to form an elongated sensing beam, and define a direction in which the sensing beam has a maximum size as a length direction thereof, where the length direction of the elongated sensing beam is parallel to the second direction, and the second direction is perpendicular to the first direction.
Optionally, the diffusion sheet is a refractive diffusion sheet, and the microstructure performs a function of expanding a sensing beam divergence angle along a preset direction by refracting the passing beam. Alternatively, the diffusion sheet may be a diffraction diffusion sheet, and the microstructure performs a function of expanding a sensing beam divergence angle in a predetermined direction by diffracting the passing beam.
Optionally, referring to fig. 11-14, the beam expansion module 129 may include a cylindrical beam expansion lens 1290. The cylindrical beam expanding lens 1290 includes an optical surface curved in a beam expanding direction to bend the light beam passing through the cylindrical beam expanding lens 1290 in the beam expanding direction. In some embodiments, the beam expansion direction is a vertical direction, i.e., the Z-axis direction in the coordinate system described above. It should be understood that the curvature of the optical surface along the beam expansion direction may be described by a change in curvature and/or slope of points on the optical surface along the beam expansion direction that are sequentially arranged along the predetermined direction.
As shown in fig. 11 and 12, in some embodiments, the cylindrical beam expanding lens 1290 may be a plano-concave cylindrical lens. The shape of the plano-concave cylindrical lens can be described by taking the orthogonal rectangular coordinate system established by taking the scanning direction of the light beam as the X axis, the expanding direction of the light beam as the Z axis and the emitting direction of the zero-order sensing light beam as the Y axis as a reference. The plano-concave cylindrical lens includes a light entrance surface 1292 and a light exit surface 1294 that are sequentially arranged along a Y axis in which the zero-order sensing beam emission direction is located. At least one of the light entrance surface 1292 and the light exit surface 1294 is an optical surface curved in the beam expanding direction. Optionally, the light incident surface 1292 is a concave curved surface recessed toward the Y axis where the zero-order sensing beam is emitted, and may be used as an optical curved surface of the beam passing through by the cylindrical beam expanding lens 1290. Optionally, in some embodiments, the light incident surface 1292 has a curvature that varies along a Z axis in which the beam expansion direction is located. That is, the curvature of each point on the light incident surface 1292 changes with the change of the coordinate of the point on the Z axis in which the beam expansion direction is located, and as shown in fig. 12, the light incident surface 1292 is a corresponding curved surface section line 1295 on a cross section formed by the plane of the coordinate system YOZ in which the point is located, and the curvature of the point refers to the curvature of the curved surface section line 1295 along the tangential direction of the point. It should be appreciated that the cross-section forming the curved stub 1295 may also be a plane perpendicular to the beam scanning direction.
Optionally, in some embodiments, the light incident surface 1292 is kept straight along the horizontal direction, and an intersecting line between the light incident surface 1292 and a plane parallel to the X-axis along which the horizontal direction is located is a straight line, that is, a connecting line between two points on the light incident surface 1292 aligned along the X-axis along which the horizontal direction is located is a straight line. However, the application is not limited thereto, and in other embodiments, the intersection line between the light incident surface 1292 and the plane parallel to the X-axis in which the horizontal direction is located may be a curved line.
Alternatively, the light-emitting surface 1294 may be a plane perpendicular to the Y axis in which the zero-order sensing beam emits. However, the present application is not limited thereto, and in other embodiments, the light-emitting surface 1294 may be a non-planar surface, or the light-emitting surface 1294 may be a plane that is not perpendicular to the Y-axis in which the zero-order sensing beam is emitted.
As shown in fig. 13 and 14, in some embodiments, the cylindrical beam expanding lens 1290 may be a plano-convex cylindrical lens. The shape of the plano-convex cylindrical lens can be described by taking the orthogonal rectangular coordinate system established by taking the scanning direction of the light beam as an X axis, the expanding direction of the light beam as a Z axis and the emitting direction of the zero-order sensing light beam as a Y axis as a reference. The plano-convex cylindrical lens includes a light entrance surface 1292 and a light exit surface 1294 that are sequentially disposed along a Y axis in which the zero-order sensing beam emission direction is located. At least one of the light entrance surface 1292 and the light exit surface 1294 is an optical curved surface curved in the beam expanding direction. Optionally, the light incident surface 1292 is a convex curved surface protruding away from the Y axis where the zero-order sensing beam is emitted, and can be used as an optical surface of the beam passing through by the cylindrical beam expanding lens 1290. Optionally, in some embodiments, the light incident surface 1292 has a curvature that varies along a Z axis in which the beam expansion direction is located. That is, the curvature of each point on the light incident surface 1292 changes with the change of the coordinate of the point on the Z axis in which the beam expansion direction is located, and as shown in fig. 13, the light incident surface 1292 is a corresponding curved surface section line 1295 on a cross section formed by the plane of the coordinate system YOZ in which the point is located, and the curvature of the point refers to the curvature of the curved surface section line 1295 along the tangential direction of the point. It should be understood that the cross-section forming the curved stub 1295 may also refer to a plane perpendicular to the beam scanning direction.
Optionally, in some embodiments, the light incident surface 1292 is kept flat along a horizontal direction, and an intersection line between the light incident surface 1292 and a plane parallel to the horizontal direction (i.e., the X-axis direction) is a straight line. That is, the line between two points aligned in the horizontal direction (i.e., the X-axis direction) on the light incident surface 1292 is a straight line. However, the application is not limited thereto, and in other embodiments, the intersection line between the light incident surface 1292 and the plane parallel to the horizontal direction (i.e. the X-axis direction) may be curved.
Alternatively, the light-emitting surface 1294 may be a plane perpendicular to the emission direction (i.e., Y-axis direction) of the zero-order sensing beam. However, the application is not limited thereto, and in other embodiments, the light-emitting surface 1294 may be non-planar, or the light-emitting surface 1294 may not be perpendicular to the emitting direction (i.e. Y-axis direction) of the zero-order sensing beam.
As shown in fig. 12 and 14, optionally, the optical axis of the cylindrical beam expander 1290 is disposed along the emitting direction (i.e., Z-axis direction) of the zero-order sensing beam, which is located in the middle of the angular range of the deflected beam by the acousto-optic deflection module 124. Since the acousto-optic deflection module 124 deflects the light beam only along the first direction, the light beam deflected by the acousto-optic deflection module 124 is located at the middle position of the detection range from the angle perpendicular to the first direction, the divergence angle of the light beam along the beam expansion direction after being expanded by the cylindrical beam expansion lens 1290 is symmetrically distributed about the optical axis of the cylindrical beam expansion lens 1290, if the divergence angle of the light beam along the beam expansion direction after being expanded by the cylindrical beam expansion lens 1290 is 2θ, the maximum deviation angle of the light beam after being bent by the cylindrical beam expansion lens 1290 compared with the optical axis is θ, and θ satisfies the following relation:
Where D is the beam diameter and f is the focal length of cylindrical beam expander lens 1290. For example, if the divergence angle of the sensing beam expanded by the beam expander 1290 is preset to be 70 degrees, θ=0.61 rad, and the focal length
It should be understood that the curvature change of the light incident surface 1292 of the cylindrical beam expander 1290 along the beam expansion direction may be set according to any one or more of the beam diameter when the sensing beam is incident, the divergence angle of the sensing beam after being expanded by the cylindrical beam expander 1290, the refractive index of the material of the cylindrical beam expander 1290, and the thickness of the cylindrical beam expander 1290 along the Y axis where the zero-order sensing beam is emitted.
Alternatively, in other embodiments, the curvature change of the light incident surface 1292 of the cylindrical beam expanding lens 1290 along the Z axis where the beam expanding direction is located may be described by the slope change of each point on the light incident surface 1292 distributed along the beam expanding direction. As shown in fig. 12, a YOZ plane is defined by a Z axis in which a beam expansion direction is located and a Y axis in which a zero-order beam is emitted, and in a cross section of the cylindrical beam expander 1290 formed by the YOZ plane, a first curved-surface truncated line 1295 is correspondingly formed on the light incident surface 1292 of the cylindrical beam expander 1290, and a slope of each point on the first curved-surface truncated line 1295 varies according to a Y-axis coordinate of the point. That is, in the cross section perpendicular to the beam scanning direction of the cylindrical beam expander lens 1290, the slope of each point on the first curved surface truncated line 1295 formed by the light incident surface 1292 varies with the position of the point on the Y axis of the beam expanding direction. Taking the cylindrical beam expanding lens 1290 as a plano-concave cylindrical lens as an example, the light incident surface 1292 is a concave curved surface recessed toward the zero-order beam emitting direction, and the slope of each point distributed from top to bottom along the Z axis of the beam expanding direction on the first curved surface truncated line 1295 formed by the light incident surface 1292 gradually decreases. That is, the slope of each point on the light incident surface 1292 varies with the position of the point on the Z-axis in which the beam expansion direction is located. As shown in fig. 14, taking the cylindrical beam expanding lens 1290 as an example of a plano-convex cylindrical lens, the light incident surface 1292 is an outer convex surface protruding away from the emitting direction of the zero-order sensing beam, and the slope of each point, which is distributed from top to bottom along the Z axis of the beam expanding direction, on the first curved surface truncated line 1295 formed by the light incident surface 1292 is gradually increased. That is, the slope of each point on the light entrance surface 1292 varies with the position of the point on the Y-axis in which the beam expansion direction is located.
As shown in fig. 15, in some embodiments, the beam expansion module 129 includes a collimating lens 1291, a cylindrical beam expansion lens 1290, and an emission lens 1293, where the collimating lens 1291, cylindrical beam expansion lens 1290, and emission lens 1293 are disposed in order along the emission direction of the zero order beam. Alternatively, the optical axis of the collimating lens 1291, the optical axis of the cylindrical beam expanding lens 1290, and the optical axis of the emitting lens 1293 are disposed along the same straight line to constitute the optical axis of the beam expanding module 129. The optical axis of the beam expansion module 129 is aligned with the emission direction of the zero-order beam of the acousto-optic deflection module 124. Wherein the zero-order beam refers to a beam at an intermediate angular position within the beam deflection angle range of the acousto-optic deflection module 124. It should be appreciated that the zero order beam emission direction is also the straight line direction in which the optical axis of the acousto-optic deflection module 124 is located.
The collimating lens 1291 is configured to collimate the light beam emitted after being deflected by the acousto-optic deflection module 124 in a direction parallel to the optical axis of the cylindrical beam expanding lens 1290. Optionally, in some embodiments, the collimating lens 1291 is a thin convex lens.
The cylindrical beam expanding lens 1290 is configured to expand the divergence angle of the light beam collimated by the collimating lens 1291 in a preset second direction. The cylindrical beam expanding lens 1290 includes an optical surface curved in a beam expanding direction to bend the light beam passing through the cylindrical beam expanding lens 1290 in the beam expanding direction. Optionally, in some embodiments, the cylindrical beam expanding lens 1290 may be a cylindrical lens, such as: the plano-concave cylindrical lens in fig. 11 and 12 or the plano-convex cylindrical lens in fig. 13 and 14 as described above are not described here again. The X-axis of the plano-concave cylindrical lens and the plano-convex cylindrical lens along the scanning direction of the light beam remains straight, but since the collimating lens 1291 has collimated the light beam along the optical axis direction, the incident direction of the collimated light beam is perpendicular to the scanning direction of the light beam in which the plano-concave cylindrical lens and the plano-convex cylindrical lens remain straight. Thus, the collimated light beam can not be distorted after passing through the plano-concave cylindrical lens or the plano-convex cylindrical lens for beam expansion.
The emission lens 1293 is configured to emit the light beam having the divergence angle expanded by the cylindrical beam expanding lens 1290 in the direction in which the light beam was originally emitted from the acousto-optic deflection module 124 as the sensing light beam of the electro-optical device 10. Since the light beam collimated by the collimating lens 1291 is incident on the cylindrical beam expanding lens 1290 along the Y axis parallel to the optical axis direction or the zero-order light beam emitting direction, the X axis of the cylindrical beam expanding lens 1290 along the light beam scanning direction remains straight, and the light beam incident on the optical axis is expanded by the cylindrical beam expanding lens 1290 and then only expands along the light beam expanding direction, while the projections on the XOY plane defined by the light beam scanning direction and the zero-order light beam emitting direction remain in parallel relation. In this case, the expanded beam does not distort but does not reflect the emission angle deflected by the acousto-optic deflection module 124, so that the expanded beam can be deflected back to the direction originally emitted from the acousto-optic deflection module 124 by the emission lens 1293. Optionally, in some embodiments, the emission lens 1293 is a thin concave lens.
It should be understood that the lenses mentioned in the above description of embodiments of the application, for example: the projection lens 1260, the collimator lens 1291, the cylindrical beam expander lens 1290, the emitter lens 1293, and the like may be a single lens or a lens group including a plurality of lenses, and the present application is not limited thereto.
It can be seen that the beam distortion caused by transmitting through the plano-concave cylindrical lens or the plano-convex cylindrical lens from different angles can be reduced by collimating the light beams deflected in different directions by the acousto-optic deflection module 124 and then expanding the light beams by the cylindrical beam expander 1290.
For convenience in describing the scanning manner of the elongated sensing beam, as shown in fig. 4, the propagation direction of the undeflected zero-order beam after passing through the acousto-optic deflection module 124 and the projection optical system 126 is taken as the Y axis, the horizontal direction is taken as the X axis, the vertical direction is taken as the Z axis, and an orthogonal rectangular coordinate system is established, so that the horizontal plane is an XOY plane, and the vertical plane is a YOZ plane. In the embodiment of fig. 4, the first direction is a horizontal direction, that is, the elongated sensing beam emitted by the beam scanning module 12 deflects along the horizontal direction where the X axis is located, and the second direction is a vertical direction, that is, the length direction of the elongated sensing beam formed by expanding the divergence angle by the beam expanding module 129 is parallel to the vertical direction where the Z axis is located. The process of deflecting the elongated sensing beam along the X-axis by the acousto-optic deflection module 124 and the projection optical system 126 can realize two-dimensional scanning in the horizontal direction and the vertical direction. It should be understood that the coordinate system may also be set up in fig. 5-7 and fig. 11-14 to facilitate description of the propagation of the light beam in the optical path.
It should be appreciated that in other embodiments, the first direction may be a vertical direction and the second direction may be a horizontal direction. That is, the elongated sensing beam emitted from the beam scanning module 12 deflects along the vertical direction along the Z axis, the length direction of the elongated sensing beam formed by expanding the divergence angle by the beam expanding module 129 is parallel to the horizontal direction along the Y axis, and the two-dimensional scanning along the vertical direction and the horizontal direction can be realized in the process of deflecting along the Z axis by the acousto-optic deflection module 124 and the projection optical system 126.
Specifically, in some embodiments, if the acousto-optic deflection module 124 deflects a first deflection angle range of the light beamAt 2.3 ° with a deflection accuracy of 0.0092 °, the acousto-optic deflection module 124 needs to deflect the light beam by 250 different deflection angles, and 250 secondary light source regions 125 are formed correspondingly on the focal plane of the projection optical system 126. If the aperture a=50μm of the formed secondary light source region 125 and the focal length f= 28.65mm of the projection optical system 126, the projected sensing beam has a deflection accuracy of 0.1 ° in the first direction, and can cover an angle of view of 25 °, i.e. the second deflection angle range of the projection optical system 126 is 25 °. On the light-emitting side of the projection optical system 126, a two-dimensional scan of 25×60 ° can be achieved by expanding the divergence angle of the projected sensing beam to 60 ° in the second direction by the beam expansion module 129.
Alternatively, as shown in fig. 16, in some embodiments, an LCPG module as the beam adjuster 123 may also be disposed between the projection optical system 126 and the beam expansion module 129. That is, on the optical axis of the beam scanning module 12, the light source module 122, the acousto-optic deflection module 124, the projection optical system 126, the LCPG module 123 and the beam expansion module 129 are sequentially arranged along the emitting direction of the light beam, the light beam is projected along the preset direction by the projection optical system 126 after being primarily deflected along the first direction by the acousto-optic deflection module 124, is secondarily deflected along the first direction by the LCPG module 123, and finally the divergence angle of the light beam is expanded along the second direction by the beam expansion module 129 to form the sensing light beam. Such an arrangement may enable the acousto-optic deflection module 124 to deflect a first range of deflection angles of the light beamMay be suitably small so that the distance l between the focal plane of the projection optical system 126 and the center of the acousto-optic deflection module 124 can be shortened while achieving the same beam scanning performance. For example, the acousto-optic deflection module 124 and the projection optical system 126 can achieve a beam scan with a deflection accuracy of 0.1 ° and a deflection angle range of 15 ° in a first plane, the LCPG module 123 can expand the deflection angle range by 4 times to achieve a beam scan of 60 ° in the first plane, and the beam expansion module 129 can expand the divergence angle of the beam to 25 ° in a second plane, that is, can achieve a beam scan of 60 ° ×25 ° ° Is a two-dimensional scan of (2). In this case, a complete scan is completed, the acousto-optic deflection module 124 only needs to deflect the light beam 150 times, that is, 150 secondary light source areas 125 are correspondingly formed on the focal plane of the projection optical system 126 during the deflection process of the light beam by the acousto-optic deflection module 124, and the response time required for deflecting the light beam by the upper LCPG module 123 is considered to be about 40 milliseconds (ms) in total, and the number of emission times of the sensing light beam for each emission direction is 200, so that the scanning frame rate can reach 10Hz.
As shown in fig. 2, the optoelectronic device 10 further includes a control circuit 18, where the control circuit 18 is configured to control the beam scanning module 12 to emit a sensing beam to scan the detection range, and control the receiving module 14 to sense a beam returned from the detection range in coordination with the scanning of the sensing beam. Optionally, in some embodiments, the control circuit 18 may include a light source control unit 182, an acousto-optic deflection control unit 184, and a sensing control unit 188.
The light source control unit 182 is configured to control the light emitting unit 1220 to periodically emit the sensing beam pulse at a preset frequency. As described above, in order to make the time-dependent single photon counting method used for dtif measurement have a mathematical statistical significance, the light source control unit 182 controls the corresponding light emitting unit 1220 to emit a plurality of sensing beam pulses at a preset frequency within one detection frame, such as: the time period between the emission moments of adjacent two sensing beam pulses may be defined as one emission period of said sensing beam pulses, several tens, several hundreds, several thousands, several tens of thousands, even millions.
The sensing control unit 188 is configured to control the photosensitive pixels 142 to perform sensing at a sensing period corresponding to an emission period of the associated light emitting unit 1220 to count in response to the light signal returned from the detection range. Since the light emitting unit 1220 periodically emits the sensing beam pulse at a preset frequency, the corresponding photosensitive pixel 142 periodically performs sensing at the same preset frequency as the emission period under the control of the sensing control unit 188. Optionally, the sensing control unit 188 may also control a portion of the photosensitive pixels 142 thereof to cooperate with the receiving optical device 144 to correspondingly sense the optical signals returned from the preset different directions.
The acousto-optic deflection control unit 184 is configured to control the acousto-optic deflection module 124 within a corresponding first deflection angle rangeThe passing light beam is deflected by a preset deflection angle. As previously described, the acousto-optic deflection control unit 184 can control the deflection angle of the passing beam by the acousto-optic deflection module 124 by adjusting the frequency of the acoustic wave applied to the acousto-optic interaction medium 1241. The acousto-optic deflection module 124 requires a deflection time τ of about 10 microseconds to change the primary beam deflection angle. It should be appreciated that for each beam deflection angle, the beam scanning module 12 needs to emit a plurality of sensing beam pulses to detect the distance information in the direction of illumination of the beam deflection angle, and the corresponding photosensitive pixels 142 on the receiving module 14 operate synchronously to sense the return light signal from that direction. The number of sensing beam pulses sent by the beam scanning module 12 along different beam deflection angles may be different, for example, the number of sensing beam pulses sent along the direction may be set according to the distance detection furthest value to be met by the optoelectronic device 10 along the direction irradiated by each beam deflection angle, and similarly, the number of sensing periods in a detection frame may be set according to the distance detection furthest value to be met by the light receiving pixel 142 on the receiving module 14 configured to sense the light signal in the direction.
In use, the acousto-optic deflection control unit 184 controls the acousto-optic deflection module 124 to be within a corresponding first deflection angle rangeThe light beam is deflected with a preset acousto-optic deflection precision delta. The light source control unit 182 controls the light emitting unit 1220 to periodically emit a sensing beam pulse toward a direction corresponding to the beam deflection angle by a preset frequency and number of times, corresponding to each preset deflection angle of the beam, and the sensing control unit 188 controls the corresponding photosensitive pixel 142 to synchronously sense the light signal returned from the direction corresponding to the beam deflection angle to perform three-dimensional detection of the direction corresponding to the beam deflection angle.
Compared with the deflection of the sensing light beam realized by a mechanical rotation scheme and a mixed solid state scheme, the application realizes the quasi-continuous deflection of the sensing light beam within the preset deflection angle range by the pure solid state acousto-optic deflection module 124 and the projection optical system 126, does not need to rely on rotation and vibration of components, and has the beneficial effects of better reliability and compact size.
Referring to fig. 2, 16 and 17, in some embodiments, the beam scanning module 12 periodically emits laser pulses as sensing beams according to a preset frequency, and the laser pulses are projected to the detection range by emitting optical devices such as the acousto-optic deflection module 124, the secondary deflection module 126, the beam expansion module 129, etc., that is, the sensing beams may be periodic pulse beams with a preset frequency. The beam scanning module 12 may emit a plurality of laser pulses within one detection frame, and a period between two adjacent laser pulse emission moments may be defined as an emission period of the laser pulses. The corresponding photosensitive pixel 142 configured to sense the detection region irradiated with the laser pulse has a sensing period corresponding to the emission period of the laser pulse. For example, the corresponding photosensitive pixels 142 periodically perform sensing at the same preset frequency as the emission period, the sensing period having a start time and an end time coincident with the emission period. The photosensitive pixel 142 starts sensing photons returned from the detection range at the same time as each laser pulse is emitted, and the timing unit 152 determines the receiving time of the optical signal sensed by the photosensitive pixel 142 according to the optical sensing signal generated by the corresponding photosensitive pixel 142 sensing the photons. The statistics unit 154 counts the light signal receiving time determined by the timing unit 152 in a plurality of sensing periods of one detection frame in a corresponding time bin to generate a corresponding statistical histogram. The length of the sensing period is at least greater than the time of flight required for photons to traverse the distance detection furthest value to be met by the corresponding detection region to ensure that photons reflected back from the distance detection furthest value can be sensed and counted. Alternatively, in some embodiments, the length of the sensing period may be set correspondingly according to the distance required by the detection area to detect the furthest value. For example, the sensing period length of the photosensitive pixel 142 is in positive correlation with the distance detection furthest value to be satisfied by the corresponding detected detection region, and for the detection region with a larger distance detection furthest value, the sensing period of the photosensitive pixel 142 for performing the corresponding detection is longer; for a detection region where the distance detection furthest value is smaller, the sensing period of the photosensitive pixel 142 where the corresponding detection is performed is shorter.
Alternatively, in some embodiments, all or a portion of the functional elements of the control circuitry 18 and/or processing circuitry 15 may be firmware that is solidified within the storage medium 30 or computer software code that is stored within the storage medium 30 and executed by the corresponding one or more processors 40 to control the relevant components to implement the corresponding functions. Such as, but not limited to, an application processor (Application Processor, AP), a central processing unit (Central Processing Unit, CPU), a microcontroller (Micro Controller Unit, MCU), etc. The storage medium 30 includes, but is not limited to, flash Memory (Flash Memory), charged erasable programmable read-only storage medium (Electrically Erasable Programmable read only Memory, EEPROM), programmable read-only storage medium (Programmable read only Memory, PROM), hard disk, and the like.
Alternatively, in some embodiments, the processor 40 and/or storage medium 30 may be disposed within the optoelectronic device 10, such as: is integrated on the same circuit board as the beam scanning module 12 or the receiving module 14. Alternatively, in other embodiments, the processor 40 and/or the storage medium 30 may be located elsewhere in the electronic device 1, such as: on the main circuit board of the electronic device 1.
Optionally, in some embodiments, some or all of the functional units of the control circuit 18 and/or the processing circuit 15 may also be implemented in hardware, for example by any one or a combination of the following technologies: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like. It will be appreciated that the hardware described above for implementing the functions of the control circuit 18 and/or processing circuit 15 may be provided within the optoelectronic device 10. The hardware described above for implementing the functions of the control circuit 18 and/or the processing circuit 15 may also be provided in other locations of the electronic device 1, such as: is provided on a main circuit board of the electronic device 1.
As shown in fig. 18, in some embodiments, the optoelectronic device 10 is, for example, a lidar, and the electronic apparatus 1 is, for example, an automobile. The laser radar can be arranged at a plurality of different positions on the automobile to detect the distance information of objects in the peripheral range of the automobile and realize driving control according to the distance information.
Compared with the laser radar which adopts a mechanical rotation mode and a mixed solid state mode to realize the scanning of the sensing light beam, the laser radar provided by the application adopts the acousto-optic deflection module 124 and the secondary deflection module 126 which are all solid states to realize the deflection scanning of the sensing light beam, has higher reliability and more compact structure because no rotation or vibration component is needed, is easier to pass strict vehicle specification requirements, and has less influence on the appearance of an automobile.
It should be noted that, the technical solution to be protected by the present application may only satisfy one of the embodiments described above or simultaneously satisfy the embodiments described above, that is, the embodiment formed by combining one or more embodiments described above also belongs to the protection scope of the present application.
In the description of the present specification, reference to the terms "one embodiment," "certain embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
It is to be understood that portions of embodiments of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the plurality of functional units may be implemented in software or firmware stored in a storage medium and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.
The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the application.
Claims (10)
1. A beam scanning module based on a projection optical system, configured to emit a sensing beam for three-dimensional information detection toward a detection range, comprising:
a light source module configured to emit a bar-shaped collimated light beam;
an acousto-optic deflection module configured to deflect the strip collimated beam in a preset first direction by a plurality of different preset deflection angles within a preset first deflection angle range according to an applied acoustic wave frequency;
the method comprises the steps of defining the direction of the maximum size of the strip-shaped collimated light beam as the length direction of the strip-shaped collimated light beam, wherein the length direction of the strip-shaped collimated light beam is parallel to a preset second direction, and the second direction and the first direction are mutually perpendicular;
a projection optical system configured to project the light beam deflected by the acousto-optic deflection module along a preset emission direction corresponding to a beam deflection angle within a detection range to form the sensing light beam;
The beam deflected by the acousto-optic deflection module passes through a corresponding area on a focal plane of the projection optical system and then is projected by the projection optical system, and the corresponding area moves on the focal plane along with the change of the deflection angle of the beam; a kind of electronic device with high-pressure air-conditioning system
And a beam expansion module disposed at an outgoing side of the projection optical system, the beam expansion module being configured to expand a divergence angle of the sensing beam in the second direction to form a long stripe-shaped sensing beam.
2. The beam scanning module of claim 1, wherein the focal plane is located between the acousto-optic deflection module and the projection optical system, and a corresponding region on the focal plane acts as a secondary light source region to emit the sensing beam.
3. The beam scanning module according to claim 2, wherein two adjacent secondary light source regions respectively formed on the focal plane before and after the minimum angle deflection of the beam by the acousto-optic deflection module are tangent to each other.
4. The beam scanning module of claim 1, wherein the first direction is a horizontal direction and the second direction is a vertical direction; or alternatively
The first direction is a vertical direction, and the second direction is a horizontal direction.
5. The beam scanning module according to claim 1, wherein the beam expansion module includes a refraction diffusion sheet, and a microstructure capable of modulating the beam is formed on the refraction diffusion sheet, and the microstructure performs a function of expanding the sensing beam divergence angle along a predetermined direction by refracting the passing beam.
6. The beam scanning module according to claim 1, wherein the beam expansion module includes a diffraction diffusion sheet on which a microstructure capable of modulating a beam is formed, the microstructure realizing a function of expanding a sensing beam divergence angle in a predetermined direction by diffracting a passing beam.
7. The beam scanning module of claim 1, wherein the beam expansion module includes a cylindrical beam expansion lens including an optical surface curved along the second direction to expand the divergence angle of the sensing beam along the second direction.
8. The beam scanning module of claim 7, wherein the beam expansion module further comprises a collimating lens and an emitting lens, the collimating lens being disposed on an incident side of the cylindrical beam expansion lens and configured to collimate the sensing beam projected by the projection optical system along an optical axis before entering the cylindrical beam expansion lens, the emitting lens being disposed on an exit side of the cylindrical beam expansion lens and configured to re-emit the sensing beam expanded by the cylindrical beam expansion lens by a divergence angle in a direction in which the sensing beam was originally projected from the projection optical system.
9. The beam scanning module of claim 1, further comprising a reflecting member, wherein the deflected beam from the acousto-optic deflection module is reflected by the reflecting member before entering the projection optical system.
10. The beam scanning module according to claim 1, further comprising a liquid crystal polarization grating module disposed between the acousto-optic deflection module and the projection optical system to further deflect the beam deflected by the acousto-optic deflection module by a preset deflection angle, the liquid crystal polarization grating module and the acousto-optic deflection module both deflecting the beam in the first direction in the same plane.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310828924.XA CN116973924A (en) | 2023-07-06 | 2023-07-06 | Beam scanning module based on projection optical system, photoelectric device and electronic equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310828924.XA CN116973924A (en) | 2023-07-06 | 2023-07-06 | Beam scanning module based on projection optical system, photoelectric device and electronic equipment |
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| Publication Number | Publication Date |
|---|---|
| CN116973924A true CN116973924A (en) | 2023-10-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310828924.XA Pending CN116973924A (en) | 2023-07-06 | 2023-07-06 | Beam scanning module based on projection optical system, photoelectric device and electronic equipment |
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| Country | Link |
|---|---|
| CN (1) | CN116973924A (en) |
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2023
- 2023-07-06 CN CN202310828924.XA patent/CN116973924A/en active Pending
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