CN117949087A - Polarization camera based on polarization modulation array and achromatic tetrahedral pyramid prism - Google Patents
Polarization camera based on polarization modulation array and achromatic tetrahedral pyramid prism Download PDFInfo
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- G—PHYSICS
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- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
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- G02B27/286—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another
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- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
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- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
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- G01J3/28—Investigating the spectrum
- G01J3/447—Polarisation spectrometry
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Abstract
The application provides a polarization camera based on a polarization modulation array and an achromatic four-sided pyramid prism, which comprises a front-mounted telescopic system, an achromatic lambda/4 wave plate array, a linear polaroid, a rear telescope, a field diaphragm, a rear collimating mirror, an optical filter, an achromatic four-sided pyramid prism, an imaging lens and an area array CCD which are sequentially arranged along the direction of a main optical axis. The incident light is collimated by a front-mounted telescopic system and then is changed into parallel light, the parallel light is divided into four beams of light with different modulation states by an achromatic lambda/4 wave plate array and a linear polaroid, and the four beams of light with different modulation states pass through a rear telescope, a field diaphragm, a rear collimating mirror, an optical filter, an achromatic four-sided pyramid prism and an imaging lens, four target images with different modulation states are respectively obtained in four quadrant areas of an area array CCD, and the four target images are restored to obtain the final target image. The crosstalk problem of the common sub-aperture type snapshot polarization camera can be greatly reduced, and the advantage of sub-aperture type polarization imaging is also maintained.
Description
Technical Field
The application belongs to a polarization camera, and particularly relates to a polarization camera based on a polarization modulation array and an achromatic tetrahedral pyramid prism.
Background
Spectral polarization imaging technology is a high-new technology involving optics, mechanics, electronics, computers, etc. Conventional cameras record the intensity of light in the observation wavelength range, depicting the topographical features of the target. The polarization camera is added with a small amount of spectrum channels and all polarization information based on the traditional camera technology. Spectral information is closely related to the structure of a substance, called a substance optical "fingerprint", and can be used for component analysis of a target substance, and polarization information can describe the reflection and scattering characteristics of the substance, reflect the surface characteristics, shape, texture, roughness, and the like of the object. The information provided by polarization is largely independent of spectrum or intensity and therefore has the potential to enhance the optical detection effect. The spectral polarization imaging technology can play an important role in the fields of reconnaissance, camouflage identification, atmospheric environment monitoring, biomedicine, industrial detection, agriculture, ocean remote sensing and the like.
The polarization camera is classified into a time-division type, an amplitude-division type, a focal plane array type, a aperture-division type, and the like according to the combination of the polarization analyzer and the camera. The time-sharing type imaging method is not suitable for polarization imaging of dynamic scenes, and a moving target cannot be detected by time-sharing type imaging; the amplitude division type requires that the response of each detector is consistent, the design size is large, the detector is sensitive to vibration, and the cost is high; the focal plane array type spatial resolution is low, all Stokes parameters cannot be measured, a mosaic effect caused by a visual angle error exists, and the cost is high; the spatial resolution of the sub-aperture type is only half that of the sub-amplitude type, and crosstalk exists between the respective partitions.
Disclosure of Invention
The application aims to solve the problems in the prior art and provides a polarization camera based on a polarization modulation array and an achromatic tetrahedral pyramid prism.
In order to achieve the above purpose, the application is realized by adopting the following technical scheme:
A polarization camera based on a polarization modulation array and an achromatic tetrahedral pyramid prism comprises a front-end telescope system, an achromatic lambda/4 wave plate array, a linear polaroid, a rear telescope, a field diaphragm, a rear collimating mirror, an optical filter, an achromatic tetrahedral pyramid prism, an imaging lens and an area array CCD which are sequentially arranged along the direction of a main optical axis;
the incident light is collimated by a front-mounted telescopic system and then is changed into parallel light, the parallel light is divided into four beams of light with different modulation states by an achromatic lambda/4 wave plate array and a linear polaroid, and the four beams of light with different modulation states pass through a rear telescope, a field diaphragm, a rear collimating mirror, an optical filter, an achromatic four-sided pyramid prism and an imaging lens, four target images with different modulation states are respectively obtained in four quadrant areas of an area array CCD, and the four target images are restored to obtain the final target image.
Preferably, the prestage telescope system comprises a prestage telescope, a field lens and a prestage collimating lens which are sequentially arranged along a main optical axis, wherein the prestage telescope is an aperture diaphragm;
The achromatic lambda/4 wave plate array is positioned at the image plane position of the front telescope.
Preferably, the achromatic λ/4 plate array includes a first achromatic λ/4 plate, a second achromatic λ/4 plate, a third achromatic λ/4 plate, and a fourth achromatic λ/4 plate;
The direction of the main optical axis is taken as the positive direction of the z axis, a space rectangular coordinate system xyz is established, and the coordinate system xyz meets the right-hand rule;
The included angle between the fast axis direction of the first achromatic lambda/4 wave plate and the positive x-axis direction is 40 degrees, the included angle between the fast axis direction of the second achromatic lambda/4 wave plate and the positive x-axis direction is-40 degrees, the included angle between the fast axis direction of the third achromatic lambda/4 wave plate and the positive x-axis direction is 75 degrees, and the included angles between the fast axis direction of the fourth achromatic lambda/4 wave plate and the positive x-axis direction are-75 degrees respectively.
Preferably, the included angle between the vibration transmission direction of the linear polarizer and the positive direction of the x-axis is 90 degrees.
Preferably, the four face sizes and the structural angles of the achromatic tetrahedral pyramid prism are all the same; the apexes of the achromatic tetrahedral pyramid prisms protrude outward and toward the filter.
Preferably, the achromatic tetrahedral pyramid prism is located on an image plane of the achromatic λ/4 wave plate array, and four planes of the achromatic tetrahedral pyramid prism are in one-to-one correspondence with the first achromatic λ/4 wave plate, the second achromatic λ/4 wave plate, the third achromatic λ/4 wave plate, and the fourth achromatic λ/4 wave plate, respectively.
Preferably, the photosensitive surface of the area array CCD is located on the image space focal plane of the imaging lens.
Preferably, the incident light is described by Stokes vectors;
S 0 component of the four light beams with different modulation states And/>The method comprises the following steps of:
Wherein S 0 represents the total intensity of the incident light beam, S 1 represents the difference between the intensities of the incident light in the direction of 0 ° and the linearly polarized light in the direction of 90 °, S 2 represents the difference between the intensities of the incident light in the direction of 45 ° and the linearly polarized light in the direction of 135 °, and S 3 represents the difference between the intensities of the incident light in the direction of right-handed circularly polarized light and the light in the direction of left-handed circularly polarized light.
Preferably, the mueller matrices of the first, second, third and fourth achromatic λ/4 plates are all calculated by:
Wherein M R (θ) represents the Mueller matrix of the achromatic λ/4 plate, and θ represents the angle between the fast axis direction of the achromatic λ/4 plate and the positive x axis direction;
The mueller matrix of the linear polarizer is calculated by:
Wherein M p (sigma) represents the Mueller matrix of the linear polarizer, and sigma represents the positive angle between the transmission vibration direction of the linear polarizer and the x-axis.
Preferably, the restoring obtains a final target image, including:
Recovery is performed by the following formula:
compared with the prior art, the application has the following beneficial effects:
The application provides a polarization camera based on a polarization modulation array and an achromatic four-sided pyramid prism, which modulates incident light in four different states through an achromatic lambda/4 wave plate array and a linear polarizer, then a light path is turned over through the achromatic four-sided pyramid prism matched with the incident light, and finally the incident light is imaged on an area array CCD through an imaging lens. The crosstalk problem of a common split aperture type snapshot polarization camera can be greatly reduced, namely, light between sub-subareas enters each other, so that the subarea image cannot completely reflect a real image. Meanwhile, the advantages of the split aperture type polarization imaging are maintained, the moving target can be subjected to snapshot type polarization imaging, and the registration is relatively easier.
Drawings
For a clearer description of the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an embodiment of a polarization camera of the present application based on a polarization modulating array and achromatic tetrahedral pyramid prism;
FIG. 2 is a schematic view of a front telescope and a front collimator in an embodiment of the application;
FIG. 3 is a schematic diagram of an achromatic lambda/4 wave plate array according to an embodiment of the present application;
fig. 4 is a schematic view of an achromatic tetrahedral pyramid prism according to an embodiment of the present application.
Wherein: 1-front telescope system, 1.1-front telescope, 1.2-front collimating mirror, 1.3-field lens, 2-achromatic lambda/4 wave plate array, 2.1-first achromatic lambda/4 wave plate, 2.2-second achromatic lambda/4 wave plate, 2.3-third achromatic lambda/4 wave plate, 2.4-fourth achromatic lambda/4 wave plate, 3-linear polarizer, 4-rear telescope, 5-field stop, 6-rear collimating mirror, 7-filter, 8-achromatic tetrahedral pyramid prism, 8.1-first face, 8.2-second face, 8.3-third face, 8.4-fourth face, 9-imaging lens, 10-area array CCD.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the embodiments of the present application, it should be noted that, if the terms "upper," "lower," "horizontal," "inner," and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present application and simplifying the description, and does not indicate or imply that the apparatus or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
Furthermore, the term "horizontal" if present does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. As "horizontal" merely means that its direction is more horizontal than "vertical", and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the embodiments of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" should be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
The polarization camera is generally classified into a time-sharing type, an amplitude-dividing type, a focal plane array-dividing type, and an aperture-dividing type according to the combination of the polarization analyzer and the camera. The working characteristics and advantages and disadvantages of various types of polarization cameras are as follows:
The time-sharing polarization camera is characterized in that a rotating polarization device (comprising a linear polarizer and a retarder) is arranged in the camera, different polarization modulation states of a target are measured through rotating the polarization device for multiple times, and then Stokes parameters of the target are solved. The advantage of this type of polarized camera is that it is relatively simple in structure and convenient for subsequent data processing. The disadvantage is that moving objects cannot be detected and are therefore unsuitable for polarization imaging of dynamic scenes.
The amplitude division type beam splitter is generally adopted to divide incident light into multiple paths, and a plurality of polarization devices and CCD detectors are adopted to perform simultaneous imaging, so that the principle is relatively simple, and snapshot can be realized. The disadvantage is that the measurement of the same target through different branch light paths requires strict registration of the components of each branch and the use of multiple (typically four) detectors to detect different light intensities, the response of each detector being consistent, but in practice this corresponding requirement is generally difficult to meet. In addition, the design size of the amplitude-division type polarization camera is large, the polarization camera is sensitive to vibration, and the cost is high.
The focal plane array type polarization camera is based on the development of micro-optics polarization elements and focal plane technology, directly combines the polarization elements with a focal plane array to realize measurement of Stokes parameters, and can also realize 'snapshot' polarization imaging of a moving target, but has lower spatial resolution, can not measure all Stokes parameters, has 'mosaic' effect caused by visual angle errors, and has higher cost.
The aperture-division type polarization camera forms four identical images on a focal plane by inserting a relay imaging lens group into the aperture of an optical path, wherein each image contains a polarization modulation state, and finally, all Stokes parameters can be obtained through simple operation of the four images. Registration is easier than with an amplitude-division type polarization camera, but spatial resolution is reduced to half that of an amplitude-division type polarization camera, and crosstalk exists between the individual partitions.
Based on the problems of the existing polarization camera, the application provides a polarization camera based on a polarization modulation array and an achromatic tetrahedral pyramid prism. The application is described in further detail below with reference to examples and figures:
As an embodiment of the present disclosure, a polarization camera based on a polarization modulation array and an achromatic tetrahedral pyramid prism includes a front telescopic system 1, an achromatic λ/4 wave plate array 2, a linear polarizer 3, a rear telescope 4, a field stop 5, a rear collimator 6, an optical filter 7, an achromatic tetrahedral pyramid prism 8, an imaging lens 9, and an area array CCD10, which are sequentially disposed along a main optical axis direction.
The incident light is collimated by the front telescope system 1 and then is changed into parallel light, the parallel light is divided into four beams of light with different modulation states by the achromatic lambda/4 wave plate array 2 and the linear polaroid 3, and the four beams of light with different modulation states are respectively subjected to four quadrant regions of the area array CCD10 to obtain four target images with different modulation states after passing through the rear telescope 4, the field diaphragm 5, the rear collimator 6, the optical filter 7, the achromatic four-sided pyramid prism 8 and the imaging lens 9, and then are restored to obtain a final target image.
The polarization modulation array formed by the achromatic lambda/4 wave plate array 2 and the linear polaroid 3 modulates the polarization information of incident light, then four target scene images with different polarization modulation states are obtained on the area array CCD10 through the achromatic tetrahedral pyramid prism 8 and the imaging lens 9, and the full Stokes parameters of each pixel point in the target image can be restored through simple operation of the four target field lens 1.3 images. The problems of poor timeliness, low signal to noise ratio and the like existing in conventional measurement of the full polarization parameters are solved, the problem of crosstalk among all partitions of the aperture-division type polarization camera is solved, the probability of influence of noise on the polarization camera is reduced, the whole light path is simple, and the aperture-division type polarization camera is easy to apply to other imaging systems according to actual demands, and has wide applicability.
As shown in fig. 1, as another embodiment of the present disclosure, a polarization camera based on a polarization modulation array and an achromatic four-sided pyramid prism includes a front-mounted telescopic system 1, an achromatic λ/4 wave plate array 2, a linear polarizer 3, a rear telescope 4, a field stop 5, a rear collimator 6, a filter 7, an achromatic four-sided pyramid prism 8, an imaging lens 9, and an area CCD10, which are sequentially arranged in the main optical axis direction. The prestige telescope system 1 comprises a presupposition telescope 1.1, a field lens 1.3 and a preshaping collimating lens 1.2 which are sequentially arranged along a main optical axis, wherein the preshaping telescope 1.1 and the preshaping collimating lens 1.2 are shown in figure 2. The pre-telescope 1.1 is the aperture stop of the optical system and satisfies the optical imaging relationship: the aperture diaphragm sequentially passes through the field lens 1.3 and the pre-collimating lens 1.2 and then is imaged on the achromatic lambda/4 wave plate array 2, namely the achromatic lambda/4 wave plate array 2 is positioned at the image plane position of the aperture diaphragm.
For convenience of subsequent description, a space rectangular coordinate system xyz is constructed, the main optical axis of incident light is taken as the positive direction of the z axis, and the coordinate system xyz meets the right-hand rule.
As shown in fig. 3, the achromatic λ/4 plate array 2 includes a first achromatic λ/4 plate 2.1, a second achromatic λ/4 plate 2.2, a third achromatic λ/4 plate 2.3, and a fourth achromatic λ/4 plate 2.4. The included angle between the fast axis direction of the first achromatic lambda/4 wave plate 2.1 and the positive x-axis direction is 40 degrees, the included angle between the fast axis direction of the second achromatic lambda/4 wave plate 2.2 and the positive x-axis direction is-40 degrees, the included angle between the fast axis direction of the third achromatic lambda/4 wave plate 2.3 and the positive x-axis direction is 75 degrees, and the included angle between the fast axis direction of the fourth achromatic lambda/4 wave plate 2.4 and the positive x-axis direction is-75 degrees. The included angle between the vibration transmission direction of the linear polarizer 3 and the positive direction of the x-axis is 90 degrees. As shown in fig. 4, the four faces of the achromatic tetrahedral pyramid prism 8 are the first face 8.1, the second face 8.2, the third face 8.3 and the fourth face 8.4, respectively, having the same size and structural angle, and the vertices of the achromatic tetrahedral pyramid prism 8 protrude outward, toward the optical filter 7. The achromatic lambda/4 wave plate array 2 is imaged on the achromatic tetrahedral pyramid prism 8 through the rear telescope 4 and the rear collimator 6, that is, the achromatic tetrahedral pyramid prism 8 is located on the image plane of the achromatic lambda/4 wave plate, and the first achromatic lambda/4 wave plate 2.1 corresponds to the first face 8.1 of the achromatic tetrahedral pyramid prism 8, the second achromatic lambda/4 wave plate 2.2 corresponds to the second face 8.2 of the achromatic tetrahedral pyramid prism 8, the third achromatic lambda/4 wave plate 2.3 corresponds to the third face 8.3 of the achromatic tetrahedral pyramid prism 8, and the fourth achromatic lambda/4 wave plate 2.4 corresponds to the fourth face 8.4 of the achromatic tetrahedral pyramid prism 8. The photosensitive surface of the area array CCD10 is located on the image-side focal plane of the imaging lens 9.
Based on the above-mentioned polarized camera, the working principle of the polarized camera of the application is as follows:
According to the principle of polarized optics, a space point (x, y) emits incident light, and a Stokes vector S (x, y, λ) of the light beam is:
Wherein S 0 represents the total intensity of the incident light beam, S 1 represents the difference between the intensities of the incident light beam linearly polarized in the 0 ° direction and the incident light beam linearly polarized in the 90 ° direction, S 2 represents the difference between the intensities of the incident light beam linearly polarized in the 45 ° direction and the incident light beam linearly polarized in the 135 ° direction, S 3 represents the difference between the intensities of the incident light beam linearly polarized in the right-handed circularly polarized direction and the left-handed circularly polarized light beam, (x, y) is the spatial coordinate of the target, and λ is the wavelength of the detection target.
The Mueller (Mueller) matrices for the four achromatic λ/4 plates in achromatic λ/4 plate array 3 are:
Wherein M R (θ) represents the Mueller matrix of the achromatic λ/4 plate, and θ is the angle between the fast axis direction and the positive x axis direction of the achromatic λ/4 plate.
The Mueller (Mueller) matrix of the linear polarizer is:
Wherein M p (σ) represents a muller matrix of the linear polarizer 3, and σ represents a positive angle between a vibration transmission direction of the linear polarizer 3 and the x-axis.
The incident light is collimated by the pre-telescopic system 1, the achromatic lambda/4 wave plate array 2 and the linear polaroid 3 are modulated to form four light beams with different polarization states, wherein the polarization state of any light beam is represented as [ S 0 S1 S2 S3]T ] by Stokes vectors, and the polarization state of any light beam is:
Wherein, As for the polarization state of any beam, θ 1 is the angle between the fast axis direction and the x axis forward direction of the achromatic λ/4 plate corresponding to the beam, and θ 2 is the angle between the vibration transmission direction and the x axis forward direction of the linear polarizer 3 corresponding to the beam.
Since the area CCD10 is responsive only to the total light intensity, i.e., S 0, only the case of the S 0 component modulation of the incident light is considered. The incident light is collimated by the front-end telescopic system 1 and then is changed into parallel light, and after the parallel light passes through the achromatic lambda/4 wave plate array 2 and the linear polaroid 3, the parallel light is decomposed into four beams of light with different modulation states, and S 0 components of the four beams of light with different modulation states are respectively:
Then, the image is finally formed on an area array CCD10 through a rear telescope 4, a field diaphragm 5, a rear collimating lens 6, an optical filter 7, an achromatic tetrahedral pyramid prism 8 and an imaging lens 9. Since the lens and achromatic tetrahedral pyramid prism 8 do not change the polarization modulation state of the light, the images of the four sub-areas on the area CCD10 have different polarization modulation states and can be represented by equations (1) through (4), so that all Stokes parameters of the incident light pass through The recovery is as follows:
The overall Stokes spectrum of the incident light is obtained S 0 S1 S2 S3]T.
The present application modulates the polarization state of the target image and images four different quadrant areas on the area array CCD10 by the combination of the polarization modulation array and the achromatic tetrahedral pyramid prism 8. Because the aperture diaphragm of the system images at the achromatic lambda/4 wave plate array 2 and images on the achromatic tetrahedral pyramid prism 8 through the following optical system, pupil matching is realized, and the crosstalk problem between all the subareas of the split aperture type polarization camera is overcome. In addition, through optimizing the polarization modulation module, especially the achromatic lambda/4 wave plate fast axis direction, the influence of noise on the polarization camera is reduced, and the signal to noise ratio of the system is improved. The system has simple light path and is easy to be applied to various or even hyperspectral imaging systems according to actual requirements.
The above is only a preferred embodiment of the present application, and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. The polarization camera based on the polarization modulation array and the achromatic tetrahedral pyramid prism is characterized by comprising a front-mounted telescopic system (1), an achromatic lambda/4 wave plate array (2), a linear polaroid (3), a rear telescope (4), a field diaphragm (5), a rear collimating mirror (6), an optical filter (7), an achromatic tetrahedral pyramid prism (8), an imaging lens (9) and an area array CCD (10) which are sequentially arranged along the direction of a main optical axis;
The incident light is collimated by a front-mounted telescopic system (1) and then is changed into parallel light, the parallel light is divided into four beams of light with different modulation states by an achromatic lambda/4 wave plate array (2) and a linear polaroid (3), the four beams of light with different modulation states pass through a rear telescope (4), a view field diaphragm (5), a rear collimating mirror (6), a light filter (7), an achromatic four-sided pyramid prism (8) and an imaging lens (9), four target images with different modulation states are respectively obtained in four quadrant areas of an area array CCD (10), and the four target images are restored to obtain the final target image.
2. The polarization camera based on the polarization modulation array and the achromatic tetrahedral pyramid prism according to claim 1, wherein the pre-telescope system (1) comprises a pre-telescope (1.1), a field lens (1.3) and a pre-collimator lens (1.2) sequentially arranged along a main optical axis, the pre-telescope (1.1) being an aperture stop;
the achromatic lambda/4 wave plate array (2) is positioned at the image plane position of the front telescope (1.1).
3. A polarization camera based on a polarization modulating array and an achromatic tetrahedral pyramid prism according to claim 1 or 2, characterized in that the achromatic λ/4 plate array (2) comprises a first achromatic λ/4 plate (2.1), a second achromatic λ/4 plate (2.2), a third achromatic λ/4 plate (2.3) and a fourth achromatic λ/4 plate (2.4);
The direction of the main optical axis is taken as the positive direction of the z axis, a space rectangular coordinate system xyz is established, and the coordinate system xyz meets the right-hand rule;
The included angle between the fast axis direction of the first achromatic lambda/4 wave plate (2.1) and the positive x-axis direction is 40 degrees, the included angle between the fast axis direction of the second achromatic lambda/4 wave plate (2.2) and the positive x-axis direction is-40 degrees, the included angle between the fast axis direction of the third achromatic lambda/4 wave plate (2.3) and the positive x-axis direction is 75 degrees, and the included angles between the fast axis direction of the fourth achromatic lambda/4 wave plate (2.4) and the positive x-axis direction are respectively-75 degrees.
4. A polarization camera based on a polarization modulating array and achromatic tetrahedral pyramid prism according to claim 3, wherein the transmission direction of the linear polarizer (3) is at an angle of 90 ° to the x-axis forward direction.
5. A polarization camera based on a polarization modulating array and an achromatic tetrahedral pyramid prism according to claim 4, characterized in that the four face sizes and the structural angles of the achromatic tetrahedral pyramid prism (8) are all the same; the apexes of the achromatic tetrahedral pyramid prisms (8) protrude outward and face the optical filter (7).
6. The polarization camera based on the polarization modulation array and the achromatic tetrahedral pyramid prism according to claim 5, wherein the achromatic tetrahedral pyramid prism (8) is located on an image plane of the achromatic λ/4 wave plate array (2), and four planes of the achromatic tetrahedral pyramid prism (8) are in one-to-one correspondence with the first achromatic λ/4 wave plate (2.1), the second achromatic λ/4 wave plate (2.2), the third achromatic λ/4 wave plate (2.3), and the fourth achromatic λ/4 wave plate (2.4), respectively.
7. A polarization camera based on a polarization modulating array and an achromatic tetrahedral pyramid prism according to claim 6, wherein the photosurface of the area array CCD (10) is located at the image-side focal plane of the imaging lens (9).
8. The polarization camera based on a polarization modulation array and an achromatic tetrahedral pyramid prism according to claim 1, wherein the incident light is described by Stokes vectors; s 0 component of the four light beams with different modulation statesAnd/>The method comprises the following steps of:
Wherein S 0 represents the total intensity of the incident light beam, S 1 represents the difference between the intensities of the incident light in the direction of 0 ° and the linearly polarized light in the direction of 90 °, S 2 represents the difference between the intensities of the incident light in the direction of 45 ° and the linearly polarized light in the direction of 135 °, and S 3 represents the difference between the intensities of the incident light in the direction of right-handed circularly polarized light and the light in the direction of left-handed circularly polarized light.
9. The polarization camera based on polarization modulating array and achromatic tetrahedral pyramid prism according to claim 1, wherein the mueller matrices of the first achromatic λ/4 plate (2.1), the second achromatic λ/4 plate (2.2), the third achromatic λ/4 plate (2.3) and the fourth achromatic λ/4 plate (2.4) are all calculated by:
Wherein M R (θ) represents the Mueller matrix of the achromatic λ/4 plate, and θ represents the angle between the fast axis direction of the achromatic λ/4 plate and the positive x axis direction;
the Mueller matrix of the linear polarizer (3) is calculated by:
Wherein M p (sigma) represents the Mueller matrix of the linear polarizer (3), and sigma represents the positive angle between the vibration transmission direction and the x-axis of the linear polarizer (3).
10. The polarization camera based on a polarization modulation array and an achromatic tetrahedral pyramid prism according to claim 1, wherein the restoration results in a final target image, comprising:
Recovery is performed by the following formula:
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