CN114858278A - Common-path large-aperture time modulation interference spectrum imaging device and method - Google Patents
Common-path large-aperture time modulation interference spectrum imaging device and method Download PDFInfo
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Abstract
The invention belongs to the technical field of optics, and discloses a common-path large-aperture time modulation interference spectrum imaging device and method. The device comprises a triangular common-path interferometer which is of an asymmetric structure and is provided with a moving mirror scanning mechanism for generating an optical path difference changing along with time, and the device works in a staring observation mode. The invention not only can keep the advantages of the traditional time-space combined modulation interference spectrum imaging technology in the aspects of common light path and large aperture, but also can obtain high spectral resolution, and has the advantages of high stability, high flux, high signal-to-noise ratio and the like.
Description
Technical Field
The invention belongs to the technical field of optics, and particularly relates to a common-path large-aperture time modulation interference spectrum imaging device and method.
Background
The interference spectrum (imaging) technology is based on the principle of interference type light splitting technology, and is an important technology type in the optical detection technology and the spectrum (imaging) technology. There are three main types of interference spectroscopy (imaging) techniques that have emerged: time modulation (dynamic) based on michelson interferometer, spatial modulation (static) based on lateral shearing interferometer, and space-time joint modulation (static) based on lateral shearing interferometer. Several types of interference spectroscopy (imaging) devices have been developed based on these techniques, but they have some disadvantages. The time modulation type interference spectrum (imaging) instrument generates a changed optical path difference through the movement of a movable mirror in the Michelson interferometer, and performs Fourier transformation on the interference fringes at different acquired optical path differences to obtain spectrum information. The technology has high light flux and high signal-to-noise ratio, particularly, the spectral resolution can be very high by means of great optical path difference generated by the linear motion of the movable mirror, and can far exceed the prior any other spectrum detection technology, but because the speed and the attitude control in the motion of the movable mirror have very high requirements on the calibration precision of an interferometer, the stability of an optical machine is poor, and the technology is difficult to be applied to motion platforms such as vehicle-mounted, airborne, shipborne, mobile robots, satellite-borne and the like. The time modulation type interference spectrum (imaging) instrument works in a staring observation mode, namely scanning integration of a movable mirror inside the instrument is needed to obtain interference patterns at different moments. The spatial modulation type lateral shearing interferometer depending on the common optical path has high stability, good real-time performance and simple structure, but the spectral resolution is limited by the number and the size of detector units, so the resolution is lower. The space-time combined modulation type structure is similar to the space modulation type structure, the stability is high, the detection sensitivity can be higher than that of a space modulation interference spectrometer and a dispersion type spectrometer, but the requirement on the stability of a platform is high, and the spectral resolution is similar to that of the space modulation type structure and is lower. The spatial modulation and the spatio-temporal joint modulation type work in a line scanning or window scanning mode.
The large-aperture static interference spectrum (imaging) instrument is a main form of a space-time joint modulation interference spectrum (imaging) instrument, adopts a common-path light splitting technology based on a Sagnac triangular transverse shearing interferometer, has large aperture due to no slit, and is static due to no movable mirror in the interferometer; it relies on the motion of the scanning visual field of the platform to obtain different optical path differences of the same target under different visual fields. However, the low spectral resolution limits the application of such spectrometers. How to realize the purpose of not only keeping the advantages of the traditional space-time joint modulation interference spectrum (imaging) technology in the aspects of common optical path and large aperture, but also obtaining high spectral resolution is a problem to be solved in the field.
Disclosure of Invention
The invention provides a common-path large-aperture time modulation interference spectrum imaging device and method, and solves the problem that the large-aperture time modulation interference spectrum imaging device and method in the prior art cannot not only keep the advantages of a space-time joint modulation interference spectrum (imaging) technology, but also obtain high spectral resolution.
The invention provides a common-path large-aperture time modulation interference spectrum imaging device, which comprises: the system comprises a triangular common-path interferometer, wherein the triangular common-path interferometer is of an asymmetric structure, a moving mirror scanning mechanism used for generating optical path difference changing along with time is arranged in the triangular common-path interferometer, and the common-path large-aperture time modulation interference spectrum imaging device works in a staring observation mode.
Preferably, the triangular common-path interferometer comprises a beam splitter, a first plane mirror, a second plane mirror, a first optical path adjusting component and a second optical path adjusting component; the first optical path adjusting component and the second optical path adjusting component are combined to form the moving mirror scanning mechanism, the first optical path adjusting component and the second optical path adjusting component are respectively arranged in two arms of an interferometer, the two arms respectively generate a first optical path and a second optical path, and the first optical path and the second optical path are combined to form an optical path difference which is periodically changed near a zero optical path difference; the target light enters the triangular common-path interferometer as parallel light, and the beam splitter splits the parallel light into a first transmitted beam and a first reflected beam; the first reflected light beam sequentially passes through the first plane mirror, the first optical path adjusting assembly and the second plane mirror, returns to the beam splitter again, and is divided into a second transmitted light beam and a second reflected light beam by the beam splitter; the first transmitted beam sequentially passes through the second plane mirror, the second optical path adjusting assembly and the first plane mirror, then returns to the beam splitter again, and is divided into a third transmitted beam and a third reflected beam by the beam splitter; the second reflected light beam and the third transmitted light beam exit in a first direction, and the second transmitted light beam and the third reflected light beam exit in a second direction.
Preferably, one of the first optical path adjusting assembly and the second optical path adjusting assembly is a movable mirror, and the other is a fixed mirror; the optical path adjusting component as a movable mirror comprises an optical path adjusting device and a motor, wherein the optical path adjusting device moves under the driving of the motor; the optical path adjusting unit as a fixed mirror includes only an optical path adjusting device.
Preferably, the optical path adjusting device in the optical path adjusting assembly serving as the movable mirror adopts a first prism, the optical path adjusting device in the optical path adjusting assembly serving as the fixed mirror adopts a second prism, and the emergent surface of the light beam after passing through the first prism or the second prism is parallel to the incident surface; the first prism is driven by the motor to rotate, and the rotating shaft of the motor is perpendicular to the propagation direction of the light beam; the posture of the second prism has certain-angle inclination relative to the vertical incident plane of the light beam, and the second prism is used for compensating the zero dispersion effect and increasing the zero-crossing optical path difference position.
Preferably, the first prism is composed of a prism pair, and the two prisms in the prism pair rotate in opposite directions.
Preferably, the first optical path adjusting assembly and the second optical path adjusting assembly are both moving mirrors; the first optical path adjusting component comprises a first optical path adjusting device and a first motor, and the second optical path adjusting component comprises a second optical path adjusting device and a second motor; the first optical path adjusting device moves under the driving of the first motor, and the second optical path adjusting device moves under the driving of the second motor.
Preferably, the common-path large-aperture time-modulation interference spectrum imaging device further includes: the device comprises a convergence assembly, a detection acquisition module and a signal processing module; the target surface of the detection acquisition module is positioned on the back focal plane of the convergence assembly, and the signal processing module is connected with the detection acquisition module; the convergence assembly is used for enabling the light beams emitted by the triangular common-path interferometer to form interference and image the light beams to the detection acquisition module; the detection acquisition module is used for sampling and collecting interference fringe signals at different moments and converting the interference fringe signals into electric signals to obtain detection information; and the signal processing module is used for carrying out spectrum restoration according to the detection information to obtain spectrum information.
Preferably, the common-path large-aperture time-modulation interference spectrum imaging device further includes: a front-end assembly; the front-mounted assembly comprises a convergent lens, a diaphragm and a collimating lens which are sequentially arranged along a light path; the target light is changed into parallel light after passing through the front-mounted assembly and is incident to the triangular common-path interferometer.
On the other hand, the common-path large-aperture time modulation interference spectrum imaging method is realized by adopting the common-path large-aperture time modulation interference spectrum imaging device, and the common-path large-aperture time modulation interference spectrum imaging device works in a staring observation mode by arranging a moving mirror scanning mechanism for generating an optical path difference changing along with time in a triangular common-path interferometer.
Preferably, the common-path large-aperture time-modulation interference spectrum imaging method includes the following steps:
step 4, sampling and collecting interference fringe signals at different moments through the detection and collection module, and converting the interference fringe signals into electric signals to obtain detection information;
and 5, performing spectrum restoration through a signal processing module according to the detection information to obtain spectrum information.
One or more technical schemes provided by the invention at least have the following technical effects or advantages:
the common-path large-aperture time modulation interference spectrum imaging device comprises a triangular common-path interferometer, wherein the triangular common-path interferometer is of an asymmetric structure and is provided with a moving mirror scanning mechanism for generating optical path difference changing along with time, and the common-path large-aperture time modulation interference spectrum imaging device works in a staring observation mode. The invention adopts the common-path light splitting technology based on the Sagnac triangular transverse shearing interferometer, has the characteristic of large aperture due to no slit, has the characteristic of high stability due to the common-path technology, and can generate the optical path difference changing along with time through the movement of the movable mirror scanning mechanism due to the movable mirror scanning mechanism arranged in the interferometer, thereby realizing high spectral resolution.
The invention firstly proposes the combination of the common light path and the time modulation interference spectrum (imaging) technology, and has important significance. The invention can overcome the problem of poor stability, has the advantages of high stability and strong anti-interference capability, and can keep the advantages of high flux, high signal-to-noise ratio, low stray light and the like. The invention not only can keep the advantages of the space-time joint modulation interference spectrum (imaging) technology, but also can obtain high spectral resolution.
In the conventional common optical path type interferometer, the optical path difference between two arms is fixed because the optical paths of the two arms of the interferometer are always fixed or the same, so that the time modulation working mode cannot be realized. The invention sets at least one dynamic optical path adjusting component as the moving mirror in the common optical path interferometer, and generates different optical path differences through the movement of the moving mirror at different moments, thereby obtaining a time integral interference pattern and reflecting the spectral information of a target.
In addition, the conventional time-modulation interference spectrum (imaging) instrument acquires interferograms at different time points due to the varying optical path difference, and two arms of a core interferometer component of the conventional time-modulation interference spectrum (imaging) instrument are relatively independent, namely, the conventional time-modulation interference spectrum (imaging) instrument is a non-common-path interferometer. The non-common-path and common-path interferometers are different types of interferometers, and the common-path interferometer adopts a common-path interferometer core component, breaks through the limitation of the traditional non-common-path interferometer, and realizes the time modulation interference spectrum (imaging) technology based on the common-path interferometer.
Drawings
Fig. 1 is an optical schematic diagram of an interference spectroscopy implemented by a common-path large-aperture time-modulation interference spectrum imaging apparatus provided in embodiment 1 of the present invention;
fig. 2 is an optical schematic diagram of an implementation of interference beam splitting by a common-path large-aperture time-modulation interference spectrum imaging apparatus according to embodiment 2 of the present invention;
fig. 3 is a schematic diagram of a common-path large-aperture time-modulation interference spectrum imaging apparatus according to embodiment 3 of the present invention.
The optical path measurement device comprises a 1-incident beam, a 2-beam splitter, a 3-first plane mirror, a 4-second plane mirror, a 5-first optical path adjusting device, a 6-second optical path adjusting device, a 7-motor, an 8-front assembly, a 9-convergence assembly, a 10-detection acquisition module and a 11-signal processing module, wherein the 3-first plane mirror is arranged on the front end of the optical path measuring device;
81-convergent lens, 82-diaphragm, 83-collimation lens.
Detailed Description
All current time-modulated interferometric spectroscopy (imaging) techniques suffer from a major problem, namely poor stability, low environmental adaptability and interference rejection. This is determined by the current time-modulated interferometric splitting technique itself, that is, non-common-path interferometric splitting (represented by michelson interferometric splitting) is adopted, and another type of interferometric splitting, that is, common-path splitting (represented by Sagnac interferometric splitting) is not adopted. The main advantage of the non-common-path interference light splitting technology is that the optical path can be made relatively short, two arms of the interferometer which are split by the beam splitter are separated, light beams respectively travel in the two arms, and the optical paths in the two arms can be different according to the difference of the arm lengths, so that the required optical path difference can be generated. However, the interference fringes are unstable because the formed interferometer is different due to the action of thermodynamic deformation and environmental change on two independent arms. The common-path interference beam splitting technology ensures that the paths of the two beams in the interferometer are the same or even completely overlapped, so that the thermodynamic deformation caused by the external environment such as vibration, temperature change and the like simultaneously acts on the two beams to be mutually offset, the formed interference fringes are very stable, and the interferometer is more stable and reliable.
The conventional common-path interference spectroscopy cannot be applied to a time modulation type interference spectrometer (imaging) because, for the gaze observation of a target in the same field of view, since the two beams split by the interferometer beam splitter travel along the same path, a variable optical path difference cannot be generated, then interferograms at different optical path differences cannot be obtained, and further fourier transform cannot be performed to obtain a spectrogram.
In order to retain the advantages of a space-time combined modulation interference spectrum (imaging) technology and obtain high spectral resolution, the invention provides a common-path large-aperture time modulation interference spectrum imaging device and a method, a common-path light splitting technology based on a Sagnac triangular transverse shearing interferometer is adopted, and a moving mirror scanning mechanism for generating a variable optical path difference is arranged in the interferometer; the invention works in a staring observation mode and is different from a view field scanning observation mode of a space-time joint modulation interference spectrum (imaging) instrument. The invention can overcome the problem of poor stability, has the advantages of high stability and strong anti-interference capability, and simultaneously keeps the advantages of high flux, high signal-to-noise ratio, low stray light and the like.
In order to better understand the technical solution, the technical solution will be described in detail with reference to the drawings and the specific embodiments.
Example 1:
Specifically, referring to fig. 1, the triangular common-path interferometer includes a beam splitter 2, a first plane mirror 3, a second plane mirror 4, a first optical path adjusting component and a second optical path adjusting component; the first optical path adjusting assembly and the second optical path adjusting assembly are combined to form the moving mirror scanning mechanism, the first optical path adjusting assembly and the second optical path adjusting assembly are respectively arranged in two arms of the interferometer, the two arms respectively generate a first optical path and a second optical path, and the first optical path and the second optical path are combined to form an optical path difference which is periodically changed near a zero optical path difference.
The target light (i.e. the incident light beam 1) enters the triangular common-path interferometer as parallel light, and the beam splitter 2 splits the parallel light into a first transmitted light beam and a first reflected light beam; the first reflected light beam sequentially passes through the first plane mirror 3, the first optical path adjusting assembly and the second plane mirror 4, then returns to the beam splitter 2 again, and is split into a second transmitted light beam and a second reflected light beam by the beam splitter 2; the first transmitted beam passes through the second plane mirror 4, the second optical path adjusting assembly and the first plane mirror 3 in sequence, then returns to the beam splitter 2 again, and is divided into a third transmitted beam and a third reflected beam by the beam splitter 2; the second reflected light beam and the third transmitted light beam exit in a first direction, and the second transmitted light beam and the third reflected light beam exit in a second direction.
One of the first optical path adjusting component and the second optical path adjusting component is a movable mirror, and the other optical path adjusting component is a fixed mirror; the optical path adjusting component as a movable mirror comprises an optical path adjusting device and a motor, wherein the optical path adjusting device moves under the driving of the motor; the optical path adjusting assembly as a fixed mirror includes only an optical path adjusting device.
The following description will be given by taking the optical path adjusting device as a prism and the moving manner of the movable mirror as rotation.
Referring to fig. 1, the first optical path adjusting device 5 is a fixed mirror, the second optical path adjusting device 6 is a movable mirror, and the second optical path adjusting device 6 moves under the driving of a motor 7. The optical path adjusting device (namely the second optical path adjusting device 6) in the optical path adjusting component as the movable mirror adopts a first prism, the optical path adjusting device (namely the first optical path adjusting device 5) in the optical path adjusting component as the fixed mirror adopts a second prism, the two prisms are used for changing the optical path, and the light beam incident surface and the emergent surface of the prisms are strictly parallel (within 5 "), so that the emergent surface of the light beam after passing through the first prism or the second prism is parallel to the incident surface. The first prism is driven by the motor 7 to rotate, and the rotating shaft of the motor 7 is perpendicular to the propagation direction of the light beam, and is a preferred embodiment to rotate perpendicular to the paper surface, so as to keep the outgoing light beam and the incoming light beam consistent in direction. The second prism is fixed in attitude and inclined at an angle with respect to the vertical incident plane of the light beam so as to compensate for the zero dispersion effect and increase the zero-cross retardation position (twice as compared with that at vertical incidence). When the rotating shaft of the motor 7 has certain shake, the first prism has certain deviation relative to an ideal posture, and a light beam emitted from the first prism has certain spatial position deviation, but because the incident surface and the emitting surface of the first prism are parallel, the transmission direction of the emitted light beam does not deviate, namely, self-compensation of posture errors caused by shake of an axis system when the light beam rotates the movable mirror is realized, and immunity of the shake errors of the interferometer and permanent collimation of two interference lights are realized. If the first prism is specifically composed of a pair of prisms arranged together, and the postures of the two prisms in the prism pair can be kept to be relatively changed (that is, the rotating directions of the motors are opposite, namely, the + θ angle and the- θ angle are respectively), the propagation directions of the light beams passing through the prism pair will always be kept consistent, and the light beams are always overlapped in space, so that a high interference modulation degree can be realized. The changed optical path is generated by the rotation of the first prism, the changed optical path is combined with the optical path fixed by the second prism to form an optical path difference which is periodically changed near a zero optical path difference, the optical path difference is changed from-L to 0 and then from 0 to + L, and the optical path difference passes through the position of the zero optical path difference, wherein L is the maximum optical path difference; so that interference patterns at corresponding different optical path differences at different moments can be obtained; then, obtaining a target spectrogram by performing Fourier transform and other spectrum recovery algorithms on the interference pattern; this is the time modulation type interference spectrum (imager) mode of operation.
It should be noted that the first plane mirror 3 and the second plane mirror 4 function to form a triangular interferometer for reflecting light beams and adjusting the distribution of the light beams in space. The first plane mirror 3 and the second plane mirror 4 may be a single plane mirror, or may be replaced by a combination of a plurality of plane mirrors. Since the first optical path adjusting device 5 and the second optical path adjusting device 6 are configured to generate an optical path difference that changes with time, that is, the optical path adjusting device is configured to generate an interferogram that changes with time from a zero optical path difference to a maximum optical path difference, and obtain a target spectrogram through a spectral recovery algorithm such as fourier transform, so as to implement a time modulation type interference spectrum (imaging) instrument working mode, a combination of the first prism and the second prism may be replaced by a single prism, or the first prism and the second prism are both implemented by specifically using a prism combination. In addition, the first prism and the second prism can be replaced by other optical path adjusting structures such as prisms and reflecting mirror combinations with other structures. The movement of the prism may be a swing movement, a linear movement, or the like, in addition to a rotation. Correspondingly, the shaft of the motor 7 may be periodically rotated, or may be periodically oscillated or other periodic motion.
The invention is realized based on a triangular Sagnac interferometer, which can be composed of a semi-transparent semi-reflecting beam splitter, two plane reflectors and a pair of prisms, and the changed optical path difference is generated by a rotating prism combination pair. The target light enters the triangular interferometer as parallel light and is then split into a first transmitted light beam and a first reflected light beam by a semi-transparent semi-reflective beam splitter in the interferometer; the first transmitted light beam and the first reflected light beam pass through the fixed and variable optical path adjusting components respectively and then return to the beam splitter again; the transmitted light beam and the reflected light beam returning to the beam splitter are transmitted and reflected again by the beam splitter to form four lights, wherein each two lights are converged to generate interference, one path of interference light returns to the incident direction of the light source, and the other path of interference light propagates to the other direction (the incident direction of the light source is vertical in the figure 1).
The triangular interferometer can be in a hollow form formed by all devices independently, and the semi-transparent semi-reflecting beam splitter can be a cube beam splitter or a flat plate beam splitter; the triangular interferometer may also be a solid form composed of a prism coated reflective film and a transflective beam splitting film. The triangular interferometer needs to be an asymmetric structure, namely two reflecting surfaces of the interferometer are not strictly symmetrical about the axis of a beam splitting surface, but one of the two reflecting surfaces generates certain translation, and the translation amount depends on the design requirements of optical path difference, the diameter of a light beam, the required physical space size of the structure and the like. The light beam incident to the triangular interferometer is split by the interferometer beam splitter and then passes through the same devices in the interferometer, thereby forming the common-path interferometer.
Example 2:
For example, the first motor and the second motor are two different motors, and the first optical path adjusting device and the second optical path adjusting device may have different rotation directions and different rotation speeds.
For example, referring to fig. 2, the first motor and the second motor are the same motor, which is denoted as an electrode 7, the first optical path adjusting device 5 and the second optical path adjusting device 6 both adopt prisms, the two prisms are connected together to move, and an optical path difference varying with time is generated by setting a difference in material, size (e.g., length), rotational posture, or the like of the two prisms.
Example 3:
The target light becomes parallel light after passing through the front-end assembly 8 and is incident to the triangular common-path interferometer. Specifically, the front-end module 8 includes a converging lens 81, a diaphragm 82, and a collimating lens 83 sequentially disposed along the optical path, the target light is converged by the converging lens 81, the diaphragm 82 filters and limits the shape of the image plane of the converging lens 81 and prevents stray light, and the collimating lens 83 is configured to collimate light passing through the front-end optical system 8 into parallel light. The front optical system 8 may take various forms such as refraction, refraction and reflection, and the like, and aims to convert target radiation into parallel rays. In addition, according to design requirements, the collimating lens 83 of the front optical system 8 can be omitted to change into a converging light path, or the front optical system 8 can be directly omitted, so that the size and the weight of the instrument can be reduced.
The converging component 9 is used for forming interference on the light beams emitted by the triangular common-path interferometer and imaging the light beams onto the detection acquisition module 10. Specifically, when the first optical path adjusting device 5 is a fixed mirror and the second optical path adjusting device 6 is a movable mirror, the second reflected light beam and the third transmitted light beam converge to generate interference and are received by the detector of the detection and acquisition module 10. The converging element 9 may be a single lens or a combination of lenses which facilitate the elimination of aberrations. The converging means 9 may be refractive or reflective.
The detection acquisition module 10 is used for sampling and collecting the interference fringe signals at different moments, and converting the interference fringe signals into electric signals to obtain detection information. The detection acquisition module 10 may further amplify, filter, and the like the signal after obtaining the electrical signal. The detection acquisition module 10 provides raw measurement data for realizing inversion of related parameters such as spectrum and image of target light. The detection and acquisition module 10 may be a CCD or other photoelectric conversion device according to the difference of the detection light source.
The signal processing module 11 is configured to perform spectrum restoration according to the detection information to obtain spectrum information. Specifically, the signal processing module 11 performs data processing and analysis on the interference signal acquired by the detection acquisition module 10, including preprocessing, error correction, spectral responsivity calibration correction, radiometric calibration correction, fourier transform, and the like of the original interferogram data, completes a spectrum recovery process, and acquires a spectrum and/or a high-resolution spectral image of the target (i.e., the incident light beam 1).
The spectrum application range of the invention is applicable from ultraviolet to far infrared and THz, and is mainly limited by the spectrum application ranges of the beam splitter and the prism, the reflector film layer, the convergence component and the detection acquisition module, namely, different beam splitter substrate materials and film layers thereof, prism materials and film layers thereof and the reflector film layer, detection spectrum response and the like are corresponded to different wave bands.
In addition, other forms of spectrometers/spectrometers (imagers) may also be derived based on the principles of the present invention. If a polarizing device is added in the light path, a time modulation type polarization spectrometer and a polarization spectrum (imaging) instrument can be formed.
Example 4:
embodiment 4 provides a common-path large-aperture time-modulation interference spectrum imaging method, which is implemented by using the common-path large-aperture time-modulation interference spectrum imaging apparatus according to the above embodiment, and the common-path large-aperture time-modulation interference spectrum imaging apparatus is operated in a staring observation mode by providing a moving mirror scanning mechanism for generating an optical path difference varying with time in a triangular common-path interferometer.
A specific method corresponding to the apparatus of example 3 is provided below.
A common-path large-aperture time modulation interference spectrum imaging method comprises the following steps:
step 4, sampling and collecting interference fringe signals at different moments through the detection and collection module, and converting the interference fringe signals into electric signals to obtain detection information;
and 5, performing spectrum restoration through a signal processing module according to the detection information to obtain spectrum information.
The common-path large-aperture time modulation interference spectrum imaging device and method provided by the embodiment of the invention at least comprise the following technical effects:
(1) the working mode of the time modulation type interference spectrum (imaging) instrument can be realized. In the conventional common optical path type interferometer, the optical path difference between two arms is fixed because the optical paths of the two arms of the interferometer are always fixed or the same, so that the time modulation working mode cannot be realized. However, the invention can generate different optical path differences through the movement of the movable mirror in the common-path interferometer at different moments, and further can obtain a time integration interference pattern, thereby reflecting the spectral information of the target.
(2) A common-path interferometer core may be employed. The invention breaks through the limitation of the traditional non-common-path interferometer and realizes the time modulation interference spectrum (imaging) technology based on the common-path interferometer.
(3) High stability. The interference light splitting technology is based on a common-path technology, and the stability of a common-path interference spectrum (imaging) instrument is high. The interferometer of the non-common-path technology adopted by the traditional time modulation interference spectrum (imaging) instrument is easily interfered by external thermodynamic change, and causes the change of optical path difference, so that the movement of interference fringes and the instability of phase positions are caused, and therefore, larger instrument errors can be brought, and the high-precision measurement is inaccurate. After the common-path light splitting technology is utilized, external thermodynamic changes act on two arms of the interferometer at the same time, so that generated optical path differences can be mutually offset, formed interference fringes are more stable, and the stability of the corresponding interferometer and the spectrum (imaging) instrument is high.
(4) The light flux is high. Because no slit is arranged in the large-aperture common-path time modulation interference spectrum (imaging) instrument system to limit the target imaging area and the spectral resolution, the system aperture is large, and the light flux is high.
(5) The application range is wide. Because the common-light-path light splitting mode is adopted, the stability of the time modulation interference spectrometer is greatly improved, and the anti-interference capability is enhanced, so that the vehicle-mounted motion platform, the ship-mounted motion platform, the mobile robot, the satellite-mounted motion platform and other motion platforms which can not be applied in the prior art can be used, and therefore, the application occasions are more, and the application field is wider.
(6) Simple structure and easy miniaturization. The common-path time modulation interference light splitting scheme provided by the invention has the advantages that the core interferometer can only consist of the flat-plate beam splitter, the plane mirror and the prism, and the beam splitter compensation plate in the traditional time modulation interference spectrum (imaging) instrument is removed, so that the whole structure is very compact, the miniaturization is still facilitated under the condition of not losing the luminous flux, and the common-path time modulation interference light splitting scheme is suitable for being held by hands and is easy to carry various platforms.
(7) The sampling of the change of the optical path difference from-L to + L can be realized (L is the maximum optical path difference). The optical path difference between two arms of the traditional common optical path type interferometer is fixed, while the optical path adjusting devices are arranged in the two arms of the interferometer, and the postures of the optical path adjusting devices in the movable arms can be changed in a rotating mode, so that the optical path difference from-L to 0 and then from 0 to + L can be changed, and the interferometer can obtain a correspondingly changed interferogram through the position with zero optical path difference.
(8) The self-compensation of the shaking error of the rotating shaft of the movable mirror can be realized, and the permanent collimation of the interferometer can be realized. By strictly controlling the design and processing technology of the optical path adjusting device, the incident surface and the emergent surface of the light beam passing through the optical path adjusting device are strictly parallel, so that even if the optical path adjusting device generates a certain attitude inclination due to the shaking of a rotating shaft, the emergent light beam still keeps parallel to the incident light beam, and the propagation direction of the light beam is not deflected; the scheme can realize self-compensation of attitude errors caused by shafting shaking when the movable mirror rotates, so that immunity of shaking errors of the interferometer and permanent collimation of two beams of interference light are realized.
(9) A high degree of interference modulation can be achieved. A pair of optical path adjusting devices with consistent and opposite postures are arranged in a movable arm of the interferometer, and the incident surface and the emergent surface of a light beam of each optical path adjusting device are ensured to be strictly parallel, according to the reversible principle of an optical path, the light beam incident to the previous optical path adjusting device can be compensated by the next optical path adjusting device even if the posture of the optical path adjusting device is changed to generate spatial position deviation, so that the light beam is consistent with the ideal propagation direction when the posture of the light beam is not changed, the spatial position when the light beam returns to the beam splitter is also consistent with the ideal position when the posture of the light beam is not changed, the interference light beam is completely superposed on the space, the image plane interference problem (the interference modulation degree is reduced due to the existence of errors of a converging mirror group) generated by the spatial superposition of the light beam is avoided, and the high interference modulation degree can be realized.
(10) Is suitable for high-speed measurement. Because the prism generating the optical path difference adopts a mode of 360-degree continuous rotation work, the acceleration and deceleration processes in the traditional linear or swing process are avoided in the measuring process, the time utilization rate is improved, and the measuring frequency is improved. Meanwhile, the prism material generating the optical path difference can generate more than 8 zero-crossing points in a 360-degree period, namely more than 8 interferograms and spectrograms can be generated by rotating the prism for one circle, so that ultrahigh-speed spectral measurement becomes possible. The realization of the function not only improves the environmental interference resistance of the interference spectrum (imaging) instrument, but also enables the interference spectrum (imaging) instrument to be further expanded and applied to the high-speed spectrum measurement field, such as the aspects of flying targets, flames or even chemical reactions and the like.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (10)
1. A common-path large-aperture time-modulated interferometric spectral imaging apparatus, comprising: the system comprises a triangular common-path interferometer, wherein the triangular common-path interferometer is of an asymmetric structure, a moving mirror scanning mechanism used for generating optical path difference changing along with time is arranged in the triangular common-path interferometer, and the common-path large-aperture time modulation interference spectrum imaging device works in a staring observation mode.
2. The co-path large aperture time-modulated interferometric spectral imaging device of claim 1, wherein the triangular co-path interferometer comprises a beam splitter, a first planar mirror, a second planar mirror, a first optical path adjusting component and a second optical path adjusting component; the first optical path adjusting component and the second optical path adjusting component are combined to form the moving mirror scanning mechanism, the first optical path adjusting component and the second optical path adjusting component are respectively arranged in two arms of an interferometer, the two arms respectively generate a first optical path and a second optical path, and the first optical path and the second optical path are combined to form an optical path difference which is periodically changed near a zero optical path difference;
the target light enters the triangular common-path interferometer as parallel light, and the beam splitter splits the parallel light into a first transmitted beam and a first reflected beam; the first reflected light beam sequentially passes through the first plane mirror, the first optical path adjusting assembly and the second plane mirror, returns to the beam splitter again, and is divided into a second transmitted light beam and a second reflected light beam by the beam splitter; the first transmitted beam sequentially passes through the second plane mirror, the second optical path adjusting assembly and the first plane mirror, then returns to the beam splitter again, and is divided into a third transmitted beam and a third reflected beam by the beam splitter; the second reflected light beam and the third transmitted light beam exit in a first direction, and the second transmitted light beam and the third reflected light beam exit in a second direction.
3. The common-path large-aperture time-modulated interference spectral imaging device according to claim 2, wherein one of the first optical path adjusting component and the second optical path adjusting component is a movable mirror, and the other is a fixed mirror; the optical path adjusting component as a movable mirror comprises an optical path adjusting device and a motor, wherein the optical path adjusting device moves under the driving of the motor; the optical path adjusting unit as a fixed mirror includes only an optical path adjusting device.
4. The common-path large-aperture time-modulation interference spectrum imaging device according to claim 3, wherein a first prism is adopted as an optical path adjusting device in the optical path adjusting assembly of the movable mirror, a second prism is adopted as an optical path adjusting device in the optical path adjusting assembly of the fixed mirror, and the emergent surface of the light beam after passing through the first prism or the second prism is parallel to the incident surface; the first prism is driven by the motor to rotate, and the rotating shaft of the motor is perpendicular to the propagation direction of the light beam; the posture of the second prism has certain-angle inclination relative to the vertical incident plane of the light beam, and the second prism is used for compensating the zero dispersion effect and increasing the zero-crossing optical path difference position.
5. The common-path large-aperture time-modulated interferometric spectral imaging device of claim 4, wherein the first prism is comprised of a prism pair, the two prisms of the prism pair rotating in opposite directions.
6. The common-path large-aperture time-modulated interferometric spectral imaging device of claim 2, wherein the first optical path adjusting component and the second optical path adjusting component are both moving mirrors; the first optical path adjusting component comprises a first optical path adjusting device and a first motor, and the second optical path adjusting component comprises a second optical path adjusting device and a second motor; the first optical path adjusting device moves under the driving of the first motor, and the second optical path adjusting device moves under the driving of the second motor.
7. A common-path large-aperture time-modulated interferometric spectral imaging device according to claim 2, further comprising: the device comprises a convergence assembly, a detection acquisition module and a signal processing module; the target surface of the detection acquisition module is positioned on the back focal plane of the convergence assembly, and the signal processing module is connected with the detection acquisition module; the convergence assembly is used for enabling the light beams emitted by the triangular common-path interferometer to form interference and image the light beams to the detection acquisition module; the detection acquisition module is used for sampling and collecting interference fringe signals at different moments and converting the interference fringe signals into electric signals to obtain detection information; and the signal processing module is used for carrying out spectrum restoration according to the detection information to obtain spectrum information.
8. A common-path large-aperture time-modulated interferometric spectral imaging device according to claim 2, further comprising: a front-end assembly; the front-mounted assembly comprises a convergent lens, a diaphragm and a collimating lens which are sequentially arranged along a light path; the target light is changed into parallel light after passing through the front-mounted assembly and is incident to the triangular common-path interferometer.
9. A common-path large-aperture time-modulation interference spectrum imaging method, which is realized by adopting the common-path large-aperture time-modulation interference spectrum imaging device as claimed in any one of claims 1 to 8, and the common-path large-aperture time-modulation interference spectrum imaging device works in a staring observation mode by arranging a moving mirror scanning mechanism for generating an optical path difference which changes along with time in a triangular common-path interferometer.
10. A common-path large-aperture time-modulated interferometric spectral imaging method as claimed in claim 9, comprising the steps of:
step 1, converting target light into parallel light after passing through a front-mounted assembly and irradiating the parallel light to the triangular common-path interferometer;
step 2, dividing the parallel light into a first transmitted light beam and a first reflected light beam through a beam splitter; the first reflected light beam sequentially passes through the first plane mirror, the first optical path adjusting assembly and the second plane mirror and then returns to the beam splitter again, and is divided into a second transmitted light beam and a second reflected light beam by the beam splitter; the first transmitted beam sequentially passes through the second plane mirror, the second optical path adjusting assembly and the first plane mirror, then returns to the beam splitter again, and is divided into a third transmitted beam and a third reflected beam by the beam splitter; the second reflected beam and the third transmitted beam exit in a first direction, and the second transmitted beam and the third reflected beam exit in a second direction;
step 3, forming interference on the light beams emitted by the triangular common-path interferometer through a convergence assembly and imaging the light beams to a detection acquisition module;
step 4, sampling and collecting interference fringe signals at different moments through the detection and collection module, and converting the interference fringe signals into electric signals to obtain detection information;
and 5, performing spectrum restoration through a signal processing module according to the detection information to obtain spectrum information.
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