CN110208999B - Image acquisition method and system - Google Patents
Image acquisition method and system Download PDFInfo
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- CN110208999B CN110208999B CN201910415637.XA CN201910415637A CN110208999B CN 110208999 B CN110208999 B CN 110208999B CN 201910415637 A CN201910415637 A CN 201910415637A CN 110208999 B CN110208999 B CN 110208999B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
- G02B27/288—Filters employing polarising elements, e.g. Lyot or Solc filters
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
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Abstract
The invention relates to the technical field of optical imaging, and discloses an image acquisition method and an image acquisition system, which realize the selection of an imaging area and the improvement of the overall performance in a new light beam deflection mode. The method comprises the following steps: a light beam filtering module and a light beam selecting module are arranged in front of the image sensor; the light beam selection module comprises at least one stage of lens group, and each stage of lens group consists of a polarization grating and an electric control liquid crystal box respectively; each electric control liquid crystal box is provided with at least two states; in the state set of the electric control liquid crystal boxes arranged by all the light beam selection modules, all the state subsets respectively correspond to image subregions which are not completely overlapped outside the lens one by one; and the corresponding electrically controlled liquid crystal boxes are programmed to realize the acquisition of the corresponding image sub-regions by state switching, and the relative displacement motion among the components does not occur in the switching process of the image sub-regions. The technology of the invention can be widely applied to application scenes such as multi-lane monitoring and the like.
Description
Technical Field
The invention relates to the technical field of optical imaging, in particular to an image acquisition method and system.
Background
In recent years, attention has been paid to a light beam control technique. Especially, the light field regulation and control technology based on the novel optical device is most popular in research. However, according to the existing camera technology, the devices capable of realizing ultra-high definition and large view field are usually very expensive and have many disadvantages.
Disclosure of Invention
The invention aims to disclose an image acquisition method and system, which realize the selection of an imaging area and the improvement of the overall performance in a novel light beam deflection mode.
To achieve the above object, the present invention discloses an image capturing method, comprising:
a light beam filtering module and a light beam selecting module are arranged in front of the image sensor; the light beam selection module comprises at least one stage of lens group, and each stage of lens group consists of a polarization grating and an electric control liquid crystal box respectively; each electric control liquid crystal box is provided with at least two states; in the state set of the electric control liquid crystal boxes arranged by all the light beam selection modules, all the state subsets respectively correspond to image subregions which are not completely overlapped outside the lens one by one;
and the corresponding electrically controlled liquid crystal boxes are programmed to realize the acquisition of the corresponding image sub-regions by state switching, and the relative displacement motion among the components does not occur in the switching process of the image sub-regions.
To achieve the above object, the present invention also discloses an image capturing system, comprising:
the light beam filtering module and the light beam selecting module are arranged in front of the image sensor;
the light beam selection module comprises at least one stage of lens group, and each stage of lens group consists of a polarization grating and an electric control liquid crystal box respectively; each electric control liquid crystal box is provided with at least two states; in the state set of the electric control liquid crystal boxes arranged by all the light beam selection modules, all the state subsets respectively correspond to image subregions which are not completely overlapped outside the lens one by one; and further comprising:
and the program control unit is used for program-controlling the corresponding electric control liquid crystal boxes to realize the acquisition of the corresponding image sub-regions through state switching, and does not generate relative displacement motion among the components in the switching process of the image sub-regions.
The invention has the following beneficial effects:
under the cooperation of the light beam filtering device, the state switching of the electric control liquid crystal box is used for realizing the selection and the switching of the external imaging area, and the deflection degree of the light beam and the number of the switchable subregions can be increased by the multi-stage arrangement of the lens group, thereby increasing the field angle. In the switching process, relative displacement motion among the assemblies does not occur (note: the assemblies are composed of the image sensor, the light beam filtering module and the light beam selecting module, do not represent other components of the whole image acquisition system, such as an operation button and the like, and do not generate displacement motion), the structure is simple and practical, the deployment and the operation are very convenient, and the overall performance is obviously improved.
Preferably, the inventive polarization grating is further adapted to: deflecting incident left-handed circularly polarized light into emergent right-handed circularly polarized light in the deflection process; and/or deflecting the incident right-handed circularly polarized light into the emergent left-handed circularly polarized light; and/or converting incident unpolarized light into left-handed circularly polarized light and right-handed circularly polarized light with opposite diffraction angles.
Further, the transmitted beam of the inventive polarization grating is concentrated in: deflecting incident left-handed circularly polarized light into a negative diffraction order; and/or deflecting incident right-handed circularly polarized light into a positive diffraction order; and/or the incident unpolarized light is deflected into left circularly polarized light with a positive diffraction order and right circularly polarized light with a negative diffraction order.
Therefore, the invention effectively avoids the inconvenience caused by the additional addition of a more complex multi-level diffraction processing device because other multi-level diffraction needs to be considered in the traditional grating.
The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 to 14 and fig. 17 to 30 are schematic diagrams respectively illustrating a corresponding relationship between image sub-region switching and an electric control liquid crystal cell state in an image acquisition process according to an embodiment of the present invention.
Fig. 15 is a schematic diagram illustrating a disposition relationship of the light beam filtering module between the light beam selecting module and the image sensor.
Fig. 16 is a schematic view of the disposition relationship of the light beam selection module between the light beam filtering module and the image sensor.
Fig. 31 to 34 are schematic views of alternative structures of a polarization grating, a TN-structure liquid crystal cell, an ECB-structure liquid crystal cell, and an OCB-structure liquid crystal cell, respectively.
Detailed Description
The embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways as defined and covered by the claims.
Example 1
As shown in fig. 1, the present embodiment discloses an image capturing method, including:
s1, arranging a light beam filtering module and a light beam selecting module in front of an image sensor; the light beam selection module comprises at least one stage of lens group, and each stage of lens group consists of a polarization grating and an electric control liquid crystal box respectively; each electric control liquid crystal box is provided with at least two states; in the state set of the electric control liquid crystal boxes arranged by all the light beam selection modules, all the state subsets respectively correspond to image sub-areas which are not completely overlapped outside the lens one by one.
And S2, the corresponding electronic control liquid crystal boxes are programmed to realize the acquisition of the corresponding image sub-regions in a state switching manner, and the relative displacement motion among the components does not occur in the switching process of the image sub-regions. Furthermore, the functional module for collecting and processing image data at the rear end can split the images of all the image sub-regions or splice the images into large-size images with high pixels and the like.
In this embodiment, the image sensor may be a CCD or CMOS structure, and the pixels of the image sensor may be of any pixel specification according to a specific application. Optionally, each polarization grating realizes beam diffraction and deflection by controlling a periodic structure of a material; for example: the polarization grating optical property modification material is made of liquid crystal and liquid crystal polymer, or a metal super surface or a medium super surface; the super-surface is an ultrathin two-dimensional array plane consisting of a series of sub-wavelength artificial microstructures, has the characteristics of relatively simple manufacture, relatively low loss, small volume, ultrathin thickness and the like, and can realize effective regulation and control on the aspects of amplitude, phase, propagation mode, polarization state and the like of electromagnetic waves.
Under the action of the polarization grating, the emergent light beam deflection angle is the vector superposition of the light beam incident angle and the polarization grating diffraction angle. Preferably, the polarization grating of the present embodiment is further configured to: deflecting incident left-handed circularly polarized light into emergent right-handed circularly polarized light in the deflection process; and/or deflecting the incident right-handed circularly polarized light into the emergent left-handed circularly polarized light; and/or converting incident unpolarized light into left-handed circularly polarized light and right-handed circularly polarized light with opposite diffraction angles. Further, the transmitted beam of the polarization grating is concentrated in:
deflecting incident left-handed circularly polarized light into a negative diffraction order; and/or
Deflecting the incident right-handed circularly polarized light into a positive diffraction order; and/or
The incident unpolarized light is polarized into left-circularly polarized light of positive diffraction order and right-circularly polarized light of negative diffraction order.
It is worth mentioning that: in the above expression, "and/or" relationship, for the polarization grating of the lens group closest to the external object image, there exist both the incident light in the unpolarized state and the left-handed circularly polarized light and the right-handed circularly polarized light, while for the polarization gratings of the other lens groups, there exist only the left-handed circularly polarized light and/or the right-handed circularly polarized light. Because different target areas have differences of light sources, the actual functions of the polarization gratings at different levels inside the polarization gratings are uncertain; however, for those skilled in the art, the corresponding techniques are clear and not easily ambiguous, and the detailed description is not repeated.
Therefore, based on this embodiment, in the transmission process of the light beam, it is assumed that the included angle between the virtual grating groove directions of the two polarization gratings is Φ. When incident light passes through a polarization grating, the included angle between emergent light and incident light is the diffraction angle theta of the polarization grating 1 The emergent light and the incident light are positioned on the same plane, and the plane is vertical to the direction of the first polarization virtual grating reticle; when the light beam enters the second polarization grating, the incident angle of the light beam can be divided into angle components theta x = theta in the direction vertical to the virtual grating ruling direction of the second polarization grating 1 * cos Φ and the angular component θ y = θ y parallel to the virtual grating line direction of the second polarization grating 1 * sin phi. After passing through the second polarization grating, the angular component increases to θ 1 *cosΦ+θ 2 (θ 2 The second polarization grating diffraction angle). While the angle θ y remains unchanged. The final emergent direction theta is the vector superposition of thetax and thetay, and:
θ 2 ＝(θ 1 *cosΦ+θ 2 ) 2 +(θ 1 *sinΦ) 2 。
optionally, the beam filtering device of the present invention comprises a linear polarizer. Preferably, this embodiment may further include a lens disposed between the image sensor and the linear polarizer as a part of the beam filtering device to filter out incident light that is deflected to an excessively large non-target image area after penetrating through the linear polarizer.
In this embodiment, based on different types of liquid crystal cells, the state control between each stage of lens groups is also changed correspondingly. Two optional cases are as follows:
in the first case, a liquid crystal box of the lens group adopts a TN structure, and the corresponding two states include a transmission state under high voltage and a transmission state under low voltage for converting left-handed circularly polarized light into right-handed circularly polarized light and converting right-handed circularly polarized light into left-handed circularly polarized light; correspondingly, the beam filtering module further comprises a 1/4 wave plate arranged between the linear polaroid and the lens group at the nearest stage.
And under the second condition, the liquid crystal box of the lens group adopts an ECB or OCB structure and is used for converting the left-handed circularly polarized light into the right-handed circularly polarized light and converting the right-handed circularly polarized light into the left-handed circularly polarized light, and the ECB or OCB structure is as follows: the effective retardation of the liquid crystal cells in the first lens group closest to the linear polarizer is switched between 1/4 wavelength and 3/4 wavelength, and the effective retardation of the liquid crystal cells in the other lens groups is switched between 0 and 1/2 wavelength.
Optionally, the electrically controlled liquid crystal cell and the polarization grating in the lens assembly of this embodiment may be integrated into a whole.
In view of the above, referring to fig. 1 to 14, the principle of synchronously driving the switching of the external imaging region by the liquid crystal cell state switching in the present embodiment includes:
as shown in fig. 1 to 6, the beam selection module employs a single-stage lens set. As shown in fig. 7 to 14, the beam selection module employs two stages of mirror sets.
In the single-stage lens set shown in fig. 1 and 2, the electrically controlled liquid crystal cell adopts a TN structure, and the electrically controlled liquid crystal cell of fig. 1 is in a high voltage state, and the electrically controlled liquid crystal cell of fig. 2 is in a low voltage state. The TN structure electric control liquid crystal box is equivalent to only transmitting light beams under the high voltage state, and converts left-handed circularly polarized light into right-handed circularly polarized light and converts right-handed circularly polarized light into left-handed circularly polarized light under the low voltage state; correspondingly, the 1/4 wave plate is used for converting left-handed (i.e. clockwise) circularly polarized light into horizontally linearly polarized light and converting right-handed (i.e. counterclockwise) circularly polarized light into vertically linearly polarized light, and the linearly polarizing plate adopts a horizontally linearly polarizing plate, so as to filter vertically linearly polarized light. Therefore, the electric control liquid crystal box respectively corresponds to two different sub-areas of the external image to respectively enter the lens and finally form an image in a high voltage state and a low voltage state.
The liquid crystal cells of fig. 3 and 4 adopt an ECB structure or an OCB structure, and the ECB structure or the OCB structure electrically controlled liquid crystal cell can be regarded as a replacement of the combined function of the 1/4 wave plate and TN structure electrically controlled liquid crystal cell in fig. 1 and 2; but the difference is that the states of the specific switching are different, namely: the effective retardation of the ECB structure or OCB structure electrically controlled liquid crystal cell is switched between 1/4 wavelength and 3/4 wavelength, wherein the effective retardation of FIG. 3 is 3/4 wavelength, and the effective retardation of FIG. 4 is 1/4 wavelength.
Fig. 5 and 6 are different from fig. 3 and 4 in that an ECB structure or an OCB structure is integrated with a polarization grating during a manufacturing process, wherein the effective retardation of fig. 5 is 1/4 wavelength, and the effective retardation of fig. 6 is 3/4 wavelength.
Fig. 7 to 10 illustrate the single-stage lens set structure of fig. 1 and 2 being extended to two stages, both of which employ TN liquid crystal cells. Wherein:
fig. 7 is a diagram showing the correspondence between the acquired image sub-regions of the liquid crystal cell 1 in the high voltage state and the liquid crystal cell 2 in the high voltage state.
Fig. 8 is a diagram showing the correspondence between the acquired image sub-regions of the liquid crystal cell 1 at a low voltage and the liquid crystal cell 2 at a low voltage.
Fig. 9 is a diagram showing the correspondence between the acquired image sub-regions of the liquid crystal cell 1 in the low voltage state and the liquid crystal cell 2 in the high voltage state.
Fig. 10 is a diagram showing the correspondence between the sub-regions of the image collected by the liquid crystal cell 1 in the high voltage state and the liquid crystal cell 2 in the low voltage state.
By analogy, when the number of stages of the lens group similar to those shown in FIG. 7 to FIG. 10 is N, the number of corresponding image sub-regions is 2 N 。
Similarly, fig. 11 to 14 extend the single-stage lens set structure of fig. 3 and 4 into two stages, both of which employ liquid crystal cells of ECB or OCB structure. Wherein:
FIG. 11 is a diagram showing the relationship between the sub-regions of the acquired image in the state where the effective retardation of the liquid crystal cell 1 is 0 and the effective retardation of the liquid crystal cell 2 is 1/4 wavelength.
FIG. 12 is a diagram showing the relationship between the sub-regions of the acquired image in the state where the effective retardation of the liquid crystal cell 1 is 1/2 wavelength and the effective retardation of the liquid crystal cell 2 is 1/4 wavelength.
FIG. 13 is a diagram showing the relationship between the sub-regions of the acquired image in the state where the effective retardation of the liquid crystal cell 1 is 0 and the effective retardation of the liquid crystal cell 2 is 3/4 wavelength.
FIG. 14 is a diagram showing the relationship between the sub-regions of the acquired image in the state where the effective retardation of the liquid crystal cell 1 is 1/2 wavelength and the effective retardation of the liquid crystal cell 2 is 3/4 wavelength.
By analogy, when the number of the lens groups similar to those in fig. 11 to 14 is N, the number of the corresponding image sub-regions is also 2 N 。
Fig. 1 to 14 illustrate the light beam filtering module disposed between the light beam selecting module and the image sensor, as shown in fig. 15. As a variant, the person skilled in the art can also envisage: as an equivalent alternative, the beam selection module may also be disposed between the beam filtering module and the image sensor, as shown in fig. 16.
As shown in fig. 17-22, the beam selection module employs a single stage of lens sets. As shown in fig. 23 to 30, the beam selection module employs two stages of mirror sets.
In the single-stage lens set shown in fig. 17 and 18, the electrically controlled liquid crystal cell adopts a TN structure, and the electrically controlled liquid crystal cell of fig. 17 is in a high voltage state, and the electrically controlled liquid crystal cell of fig. 18 is in a low voltage state. The TN structure electric control liquid crystal box is equivalent to only transmitting light beams under the high voltage state, and converts left-handed circularly polarized light into right-handed circularly polarized light and converts right-handed circularly polarized light into left-handed circularly polarized light under the low voltage state; correspondingly, the 1/4 wave plate is used for converting left-handed (i.e. clockwise) circularly polarized light into horizontally linearly polarized light and converting right-handed (i.e. counterclockwise) circularly polarized light into vertically linearly polarized light, and the linearly polarizing plate adopts a horizontally linearly polarizing plate, so as to filter vertically linearly polarized light. Therefore, the electric control liquid crystal box respectively corresponds to two different sub-areas of the external image to respectively enter the lens and finally form an image in a high voltage state and a low voltage state.
The liquid crystal cells of fig. 19 and 20 employ an ECB structure or an OCB structure which electrically controls the liquid crystal cell to some extent, which can be regarded as an alternative to the combined functions of the 1/4 plate and TN structure electrically controlled liquid crystal cells described above in fig. 1 and 2; but the difference is that the states of the specific switching are different, namely: the effective retardation of the ECB structure or OCB structure electrically controlled liquid crystal cell is switched between 1/4 wavelength and 3/4 wavelength, wherein the effective retardation of FIG. 19 is 3/4 wavelength and the effective retardation of FIG. 20 is 1/4 wavelength.
Fig. 21 and 22 are different from fig. 19 and 20 in that an ECB structure or an OCB structure is integrated with a polarization grating during a manufacturing process, wherein the effective retardation of fig. 21 is 3/4 wavelength, and the effective retardation of fig. 22 is 1/4 wavelength.
Fig. 23-26 extend the single stage lens package structure of fig. 17 and 18 to two stages, both employing TN mode liquid crystal cells. Wherein:
fig. 23 is a diagram showing the correspondence between the acquired image sub-regions of the liquid crystal cell 1 in the high voltage state and the liquid crystal cell 2 in the high voltage state.
Fig. 24 is a diagram showing the correspondence relationship between the sub-regions of the acquired image of the liquid crystal cell 1 in the low voltage state and the sub-regions of the acquired image of the liquid crystal cell 2 in the low voltage state.
Fig. 25 is a diagram showing the correspondence between the image sub-regions acquired by the liquid crystal cell 1 in the low voltage state and the liquid crystal cell 2 in the high voltage state.
Fig. 26 is a diagram showing the correspondence between the image sub-regions acquired by the liquid crystal cell 1 in the high voltage state and the liquid crystal cell 2 in the low voltage state.
Similarly, fig. 27-30 extend the single stage lens package structure of fig. 19 and 20 to two stages, both using ECB or OCB liquid crystal cells. Wherein:
FIG. 27 is a diagram showing the relationship between the sub-regions of the acquired image in the state where the effective retardation of the liquid crystal cell 2 is 0 and the effective retardation of the liquid crystal cell 1 is 1/4 wavelength.
FIG. 28 is a diagram showing the relationship between the sub-regions of the acquired image in the state where the effective retardation of the liquid crystal cell 2 is 1/2 wavelength and the effective retardation of the liquid crystal cell 1 is 1/4 wavelength.
FIG. 29 is a diagram showing the relationship between the sub-regions of the acquired image in the state where the effective retardation of the liquid crystal cell 2 is 0 and the effective retardation of the liquid crystal cell 1 is 3/4 wavelength.
FIG. 30 is a diagram showing the relationship between the sub-regions of the acquired image in the state where the effective retardation of the liquid crystal cell 1 is 1/2 wavelength and the effective retardation of the liquid crystal cell 2 is 3/4 wavelength.
Based on the scenes shown in fig. 17 to 30, when the beam selection module is disposed between the beam filtering module and the image sensor, a lens disposed between the image sensor and the beam selection module is used as a part of the beam filtering apparatus to filter out incident light that has passed through the beam selection module and then deflected to an excessively large non-target object region.
Therefore, the embodiment of the invention realizes the selection of the external image subarea by matching with the state selection of the electric control liquid crystal box under the deflection property of the polarization grating. And the actual deployment situation of the present embodiment includes any one of the following situations one or two:
in the first case, a liquid crystal box of the lens group adopts a TN structure, and the corresponding two states include a transmission state under high voltage and a transmission state under low voltage for converting left circularly polarized light into right circularly polarized light and converting right circularly polarized light into left circularly polarized light; correspondingly, the beam filtering module further comprises a 1/4 wave plate arranged between the linear polarizer and the lens group at the nearest stage, wherein the positions of the TN structure liquid crystal box and the polarization grating can be interchanged; or
And under the second condition, the liquid crystal box of the lens group adopts an ECB or OCB structure and is used for converting the left-handed circularly polarized light into the right-handed circularly polarized light and converting the right-handed circularly polarized light into the left-handed circularly polarized light, and the ECB or OCB structure is as follows: the effective retardation of the liquid crystal boxes in the first-stage lens group closest to the linear polaroid is switched between 1/4 wavelength and 3/4 wavelength, and the effective retardation of the liquid crystal boxes in the other lens groups at all stages is switched between 0 and 1/2 wavelength, wherein the liquid crystal boxes in the first-stage lens group closest to the linear polaroid are arranged facing the linear polaroid, and the positions of the liquid crystal boxes in the other lens groups at all stages and the polarization grating can be interchanged.
Alternatively, the surface structure of the polarization grating of the present embodiment is shown in fig. 31, the liquid crystal cell structure of the TN structure is shown in fig. 32, the liquid crystal cell structure of the ECB structure is shown in fig. 33, and the liquid crystal cell structure of the OCB structure is shown in fig. 34.
In summary, the image acquisition method disclosed in this embodiment has the following beneficial effects:
under the cooperation of the light beam filtering device, the state switching of the electric control liquid crystal box is used for realizing the selection and the switching of the external imaging area, and the deflection degree of the light beam and the number of the switchable subregions can be increased by the multi-stage arrangement of the lens group, thereby increasing the field angle. In the switching process, relative displacement motion between the assemblies does not occur, the structure is simple and practical, the deployment and the operation are very convenient, and the overall performance can be obviously improved.
Example 2
Corresponding to the above device embodiments, the present embodiment discloses an image capturing system.
The system of the embodiment comprises:
the light beam filtering module and the light beam selecting module are arranged in front of the image sensor;
the light beam selection module comprises at least one stage of lens group, and each stage of lens group consists of a polarization grating and an electric control liquid crystal box respectively; each electric control liquid crystal box is provided with at least two states; in the state set of the electric control liquid crystal boxes arranged by all the light beam selection modules, all the state subsets respectively correspond to image subregions which are not completely overlapped outside the lens one by one; and further comprising:
and the program control unit is used for program-controlling the corresponding electric control liquid crystal boxes to realize the acquisition of the corresponding image sub-regions through state switching, and does not generate relative displacement motion among the components in the switching process of the image sub-regions.
Preferably, each polarization grating realizes light beam diffraction and deflection by controlling a periodic structure of a material, and an outgoing light beam deflection angle is a vector superposition of a light beam incident angle and a polarization grating diffraction angle.
Optionally, the polarization grating is further configured to: deflecting incident left-handed circularly polarized light into emergent right-handed circularly polarized light in the deflection process; and/or deflecting the incident right-handed circularly polarized light into the emergent left-handed circularly polarized light; and/or converting incident unpolarized light into left-handed circularly polarized light and right-handed circularly polarized light with opposite diffraction angles.
More specifically, the transmitted beam of the polarization grating is concentrated in: deflecting incident left-handed circularly polarized light into a negative diffraction order; and/or deflecting incident right-handed circularly polarized light into a positive diffraction order; and/or deflecting the incident unpolarized light into left circularly polarized light of positive diffraction order and right circularly polarized light of negative diffraction order.
Optionally, the polarization grating optical property modifying material is made of liquid crystal and liquid crystal polymer; or the polarization grating optical property modifying material is made of a metal super surface or a medium super surface.
In this embodiment, optionally, the following may be implemented: the light beam filtering module is arranged between the light beam selecting module and the image sensor. It can also be: the light beam selection module is arranged between the light beam filtering module and the image sensor.
In a specific application scenario, the beam filtering module includes a linear polarizer.
Further: when the light beam filtering module is arranged between the light beam selecting module and the image sensor, the light beam filtering device further comprises a lens arranged between the image sensor and the linear polaroid, and the lens is used for filtering out incident light which penetrates through the linear polaroid and then is deflected to an overlarge non-target object image area. Or else: when the light beam selection module is arranged between the light beam filtering module and the image sensor, a lens arranged between the image sensor and the light beam selection module is used as a part of the light beam filtering device to filter out incident light which is deflected to an overlarge non-target object image area after penetrating through the light beam selection module.
Similarly, the liquid crystal cell of the lens set of this embodiment may adopt a TN structure, and the two corresponding states include a transmission state at a high voltage and a transmission state at a low voltage for converting left-handed circularly polarized light into right-handed circularly polarized light and a transmission state at a low voltage for converting right-handed circularly polarized light into left-handed circularly polarized light; correspondingly, the beam filtering module further comprises a 1/4 wave plate arranged between the linear polaroid and the lens group at the nearest stage.
Or, the liquid crystal cell of the lens set of this embodiment adopts an ECB or OCB structure, and is configured to convert left-handed circularly polarized light into right-handed circularly polarized light and convert right-handed circularly polarized light into left-handed circularly polarized light, and: the effective retardation of the liquid crystal cells in the first lens group closest to the linear polarizer is switched between 1/4 wavelength and 3/4 wavelength, and the effective retardation of the liquid crystal cells in the other lens groups is switched between 0 and 1/2 wavelength.
Preferably, the electrically controlled liquid crystal cell and the polarization grating in the lens assembly of this embodiment are integrated into a whole.
In a similar way, the image acquisition system disclosed by the embodiment has the following beneficial effects:
under the cooperation of the light beam filtering device, the state switching of the electric control liquid crystal box is used for realizing the selection and the switching of the external imaging area, and the deflection degree of the light beam and the number of the switchable subregions can be increased by the multi-stage arrangement of the lens group, thereby increasing the field angle. In the switching process, relative displacement motion between the assemblies does not occur, the structure is simple and practical, the deployment and the operation are very convenient, and the overall performance can be obviously improved.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (16)
1. An image acquisition method, comprising:
a light beam filtering module and a light beam selecting module are arranged in front of the image sensor; the light beam selection module comprises at least one stage of lens group, and each stage of lens group consists of a polarization grating and an electric control liquid crystal box respectively; each electric control liquid crystal box is provided with at least two states; in the state set of the electric control liquid crystal boxes arranged by all the light beam selection modules, all the state subsets respectively correspond to image subregions which are not completely overlapped outside the lens one by one;
the corresponding electrically controlled liquid crystal boxes are programmed to realize the acquisition of corresponding image sub-regions by state switching, and the relative displacement motion among the components does not occur in the switching process of the image sub-regions;
disposing the beam filtering module between the beam selection module and the image sensor; or
Disposing the beam selection module between the beam filtering module and the image sensor;
the beam filtering module comprises a linear polarizer;
when the light beam filtering module is arranged between the light beam selecting module and the image sensor, a lens arranged between the image sensor and the linear polaroid is used as a part of the light beam filtering device to filter out incident light which is deflected to a large non-target object image area after penetrating through the linear polaroid; or
When the light beam selection module is arranged between the light beam filtering module and the image sensor, a lens arranged between the image sensor and the light beam selection module is used as a part of the light beam filtering device to filter out incident light which is deflected to an overlarge non-target object image area after penetrating through the light beam selection module.
2. The image acquisition method of claim 1, wherein each polarization grating implements beam diffraction and deflection by controlling the periodic structure of the material, and the exit beam deflection angle is a vector superposition of the beam incidence angle and the polarization grating diffraction angle.
3. The image acquisition method of claim 2, wherein the polarization grating is further configured to: deflecting incident left-handed circularly polarized light into emergent right-handed circularly polarized light in the deflection process; and/or
Deflecting the incident right-handed circularly polarized light into emergent left-handed circularly polarized light; and/or
The incident unpolarized light is converted into left-handed circularly polarized light and right-handed circularly polarized light with opposite diffraction angles.
4. The image acquisition method according to claim 3, characterized in that the transmitted beams of said polarization grating are concentrated in:
deflecting incident left-handed circularly polarized light into a negative diffraction order; and/or
Deflecting the incident right-handed circularly polarized light into a positive diffraction order; and/or
The incident unpolarized light is polarized into left-circularly polarized light of positive diffraction order and right-circularly polarized light of negative diffraction order.
5. The image capturing method of claim 4, wherein the polarization grating optical property modifying material is made of liquid crystal, liquid crystal polymer.
6. The image capturing method as claimed in claim 4, wherein the polarization grating optical property modifying material is made of a metal super surface or a dielectric super surface.
7. The image acquisition method according to claim 6, characterized by comprising any one of the following cases one or two:
in the first case, a liquid crystal box of the lens group adopts a TN structure, and the corresponding two states include a transmission state under high voltage and a transmission state under low voltage for converting left-handed circularly polarized light into right-handed circularly polarized light and converting right-handed circularly polarized light into left-handed circularly polarized light; correspondingly, the beam filtering module further comprises a 1/4 wave plate arranged between the linear polarizer and the lens group at the nearest stage, wherein the positions of the TN structure liquid crystal box and the polarization grating can be interchanged; or alternatively
And under the second condition, the liquid crystal box of the lens group adopts an ECB or OCB structure and is used for converting the left-handed circularly polarized light into the right-handed circularly polarized light and converting the right-handed circularly polarized light into the left-handed circularly polarized light, and the ECB or OCB structure is as follows: the effective retardation of the liquid crystal box in the first-stage lens group closest to the linear polaroid is switched between 1/4 wavelength and 3/4 wavelength, and the effective retardation of the liquid crystal boxes in other lens groups at each stage is switched between 0 and 1/2 wavelength, wherein the liquid crystal box in the first-stage lens group closest to the linear polaroid is arranged facing the linear polaroid, and the positions of the liquid crystal boxes in other lens groups at each stage and the polarization grating can be interchanged.
8. The image capturing method according to claim 7, further comprising:
and integrating the electric control liquid crystal box and the polarization grating in the lens group.
9. An image acquisition system, comprising:
the light beam filtering module and the light beam selecting module are arranged in front of the image sensor;
the light beam selection module comprises at least one stage of lens group, and each stage of lens group consists of a polarization grating and an electric control liquid crystal box respectively; each electric control liquid crystal box is provided with at least two states; in the state set of the electric control liquid crystal boxes arranged by all the light beam selection modules, all the state subsets respectively correspond to image subregions which are not completely overlapped outside the lens one by one; and further comprising:
the program control unit is used for realizing the acquisition of the corresponding image subareas by program control of the corresponding electric control liquid crystal boxes in a state switching manner, and the relative displacement motion among the components does not occur in the switching process of the image subareas;
the light beam filtering module is arranged between the light beam selecting module and the image sensor; or
The light beam selection module is arranged between the light beam filtering module and the image sensor;
the beam filtering module comprises a linear polarizer;
when the light beam filtering module is arranged between the light beam selecting module and the image sensor, a lens arranged between the image sensor and the linear polaroid is used as a part of the light beam filtering device to filter out incident light which is deflected to a large non-target object image area after penetrating through the linear polaroid; or
When the light beam selection module is arranged between the light beam filtering module and the image sensor, a lens arranged between the image sensor and the light beam selection module is used as a part of the light beam filtering device to filter out incident light which is deflected to an overlarge non-target object image area after penetrating through the light beam selection module.
10. The image acquisition system of claim 9, wherein each polarization grating effects beam diffraction and deflection by controlling the periodic structure of the material, the exit beam deflection angle being a vector superposition of the beam incidence angle and the polarization grating diffraction angle.
11. The image acquisition system of claim 10, wherein the polarization grating is further configured to: deflecting incident left circularly polarized light into emergent right circularly polarized light in the deflection process; and/or
Deflecting the incident right-handed circularly polarized light into emergent left-handed circularly polarized light; and/or
The incident unpolarized light is converted into left-handed circularly polarized light and right-handed circularly polarized light with opposite diffraction angles.
12. The image acquisition system according to claim 10, characterized in that the transmitted beam of the polarization grating is concentrated in:
deflecting incident left-handed circularly polarized light into a negative diffraction order; and/or
Deflecting the incident right-handed circularly polarized light into a positive diffraction order; and/or
The incident unpolarized light is polarized into left-circularly polarized light of positive diffraction order and right-circularly polarized light of negative diffraction order.
13. The image acquisition system of claim 12 wherein the polarization grating optical property modifying material is made of liquid crystal, liquid crystal polymer.
14. The image acquisition system of claim 12, wherein the polarization grating optical property modifying material is made of a metallic or dielectric super-surface.
15. The image acquisition system according to claim 14, comprising any one of the following two deployments:
in the first case, a liquid crystal box of the lens group adopts a TN structure, and the corresponding two states include a transmission state under high voltage and a transmission state under low voltage for converting left-handed circularly polarized light into right-handed circularly polarized light and converting right-handed circularly polarized light into left-handed circularly polarized light; correspondingly, the beam filtering module further comprises a 1/4 wave plate arranged between the linear polarizer and the lens group at the nearest stage, wherein the positions of the TN structure liquid crystal box and the polarization grating can be interchanged; or
And in the second case, the liquid crystal boxes of the lens groups adopt ECB or OCB structures and are used for converting left-handed circularly polarized light into right-handed circularly polarized light and converting right-handed circularly polarized light into left-handed circularly polarized light, the effective retardation of the liquid crystal box in the first-stage lens group closest to the linear polarizer is switched between 1/4 wavelength and 3/4 wavelength, and the effective retardation of the liquid crystal boxes in other lens groups at all stages is switched between 0 and 1/2 wavelength, wherein the liquid crystal box in the first-stage lens group closest to the linear polarizer is arranged facing the linear polarizer, and the positions of the liquid crystal boxes in other lens groups at all stages and the polarization grating can be interchanged.
16. The image acquisition system of claim 15, wherein the electrically controlled liquid crystal cell of the set of lenses is integrated with a polarization grating.
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| CN105446049A (en) * | 2014-09-02 | 2016-03-30 | 深圳市墨克瑞光电子研究院 | Imaging device and imaging method |
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