阅读说明：本技术 基于被动成像的多谱段偏振光传输特性测试装置及方法 (Multi-spectral-band polarized light transmission characteristic testing device and method based on passive imaging ) 是由 付强 司琳琳 李英超 战俊彤 张萌 张肃 段锦 于 2021-06-24 设计创作，主要内容包括：基于被动成像的多谱段偏振光传输特性测试装置及方法,属于光电探测技术领域。测试装置包括前置光学子系统、可见光及短波红外偏振成像子系统、中波红外及长波红外偏振成像子系统、图像采集及处理子系统以及电路控制子系统。本发明基于被动成像原理,将多光谱技术和偏振技术相融合,可以在可见光、短波红外光、中波红外光以及长波红外光四个谱段进行工作,进而分析得到多谱段偏振光的传输特性,是对单谱段偏振光传输特性测试装置及方法的有益补充。其中波长调制单元Ⅰ和波长调制单元Ⅱ均采用声光可调滤波器或液晶可调滤波器,从而实现在宽谱段内入射光波的波长调试,避免了频繁更换滤光片引起的测量误差,提高了测量精度和工作效率。(A multi-spectral-band polarized light transmission characteristic testing device and method based on passive imaging belong to the technical field of photoelectric detection. The testing device comprises a preposed optical subsystem, a visible light and short wave infrared polarization imaging subsystem, a medium wave infrared and long wave infrared polarization imaging subsystem, an image acquisition and processing subsystem and a circuit control subsystem. The device and the method are based on a passive imaging principle, a multispectral technology and a polarization technology are fused, the device and the method can work in four spectral bands of visible light, short-wave infrared light, medium-wave infrared light and long-wave infrared light, and then the transmission characteristics of the multispectral polarized light are obtained through analysis, and the device and the method are beneficial to supplement of a single-spectral-band polarized light transmission characteristic testing device and method. The wavelength modulation unit I and the wavelength modulation unit II both adopt acousto-optic tunable filters or liquid crystal tunable filters, so that the wavelength of incident light waves in a wide spectrum band is debugged, the measurement error caused by frequent replacement of optical filters is avoided, and the measurement precision and the working efficiency are improved.)

1. Multi-spectral-band polarized light transmission characteristic testing device based on passive imaging is characterized in that: the system comprises a preposed optical subsystem (1), a visible light and short wave infrared polarization imaging subsystem (2), a medium wave infrared and long wave infrared polarization imaging subsystem (3), an image acquisition and processing subsystem (4) and a circuit control subsystem (5), wherein the preposed optical subsystem (1), the visible light and short wave infrared polarization imaging subsystem (2) and the medium wave infrared and long wave infrared polarization imaging subsystem (3) are jointly loaded on the same plane, and emergent light rays of the preposed optical subsystem (1) are respectively incident into the visible light and short wave infrared polarization imaging subsystem (2) and the medium wave infrared and long wave infrared polarization imaging subsystem (3); the optical axis of the visible light and short wave infrared polarization imaging subsystem (2) is parallel to the optical axis of the medium wave infrared and long wave infrared polarization imaging subsystem (3), and the visible light and short wave infrared polarization imaging subsystem (2) and the medium wave infrared and long wave infrared polarization imaging subsystem (3) are arranged in parallel; the image acquisition processing subsystem (4) comprises an image processing unit (41) and an image display unit (42); the image processing unit (41) is respectively and electrically connected with the preposed optical subsystem (1), the visible light and short wave infrared polarization imaging subsystem (2), the medium wave infrared and long wave infrared polarization imaging subsystem (3) and the image display unit (42); the circuit control subsystem (5) is respectively electrically connected with the visible light and short wave infrared polarization imaging subsystem (2) and the medium wave infrared and long wave infrared polarization imaging subsystem (3), and the circuit control subsystem (5) comprises a polarization modulation control unit (51) and a wavelength modulation control unit (52); the polarization modulation control unit (51) controls the rotation of each polaroid in the visible light and short wave infrared polarization imaging subsystem (2) and the medium wave infrared and long wave infrared polarization imaging subsystem (3) or the phase delay of the polarization modulation unit by controlling voltage; the wavelength modulation unit (52) completes the selection of the wavelength of each acousto-optic wavelength modulation unit in the visible light and short wave infrared polarization imaging subsystem (2) through controlling the voltage.

2. The apparatus for testing transmission characteristics of multi-spectral-band polarized light based on passive imaging as claimed in claim 1, wherein: the front optical subsystem (1) comprises a telescopic optical unit (11), a light splitting unit I (12) and a reflector unit I (13); the telescope optical unit (11) and the light splitting unit I (12) are transversely arranged in series and are coaxial, and the light splitting unit I (12) and the reflector unit I (13) are longitudinally arranged in series and are coaxial; light enters the system from the telescope optical unit (11) and is divided into two beams by the light splitting unit I (12), one beam enters the visible light and short wave infrared polarization imaging subsystem (2), and the other beam enters the medium wave infrared and long wave infrared polarization imaging subsystem (3) after being bent by the reflector unit I (13).

3. The apparatus for testing transmission characteristics of multi-spectral-band polarized light based on passive imaging as claimed in claim 1, wherein: the visible light and short wave infrared polarization imaging subsystem (2) comprises a light splitting unit II (21), a reflector unit II (22), a polarization modulation unit I (23), a polarization modulation unit II (24), a wavelength modulation unit I (25), an imaging lens unit I (26), a visible light polarization detector (27), a polarization modulation unit III (28), a polarization modulation unit IV (29), a wavelength modulation unit II (210), an imaging lens unit II (211) and a short wave infrared polarization detector (212); the light splitting unit II (21), the polarization modulation unit I (23), the polarization modulation unit II (24), the wavelength modulation unit I (25), the imaging lens unit I (26) and the visible light polarization detector (27) are sequentially transversely and serially arranged and have the same optical axis, and the light splitting unit II (21) and the reflector unit II (22) are longitudinally and serially arranged; the reflector unit II (22), the polarization modulation unit III (28), the polarization modulation unit IV (29), the wavelength modulation unit II (210), the imaging lens unit II (211) and the short-wave infrared polarization detector (212) are sequentially transversely arranged in series and have the same optical axis; the polarization modulation unit I (23), the polarization modulation unit II (24), the polarization modulation unit III (28) and the polarization modulation unit IV (29) are respectively electrically connected with the polarization modulation control unit (51); the wavelength modulation unit I (25) and the wavelength modulation unit II (210) are respectively electrically connected with the wavelength modulation unit (52).

4. The device for testing the transmission characteristics of multi-spectral-band polarized light based on passive imaging as claimed in claim 3, wherein: the wavelength modulation unit I (25) and the wavelength modulation unit II (210) are both acousto-optic tunable filters or liquid crystal tunable filters.

5. The device for testing the transmission characteristics of multi-spectral-band polarized light based on passive imaging as claimed in claim 3, wherein: the polarization modulation unit I (23), the polarization modulation unit II (24), the polarization modulation unit III (28) and the polarization modulation unit IV (29) are all liquid crystal phase retarders.

6. The apparatus for testing transmission characteristics of multi-spectral-band polarized light based on passive imaging as claimed in claim 1, wherein: the medium-wave infrared and long-wave infrared polarization imaging subsystem (3) comprises a light splitting unit III (31), a reflector unit III (32), a polaroid I (33), a light filter I (34), an imaging lens unit III (35), a medium-wave infrared polarization detector (36), a polaroid II (37), a light filter II (38), an imaging lens unit IV (39) and a long-wave infrared polarization detector (310); the light splitting unit III (31), the reflector unit III (32), the polaroid I (33), the optical filter I (34), the imaging lens unit III (35) and the medium wave infrared polarization detector (36) are sequentially arranged in series transversely and have the same optical axis, and the light splitting unit III (33) and the reflector unit III (34) are arranged in series longitudinally; the reflector unit III (34), the polaroid II (37), the optical filter II (38), the imaging lens unit IV (39) and the long-wave infrared polarization detector (310) are sequentially transversely arranged in series and are coaxial.

7. The method for testing the transmission characteristics of multi-spectral-band polarized light based on passive imaging, according to claim 1, is characterized in that: comprises the following steps which are sequentially carried out,

firstly, placing a target object at a zero-line-of-sight position of the passive imaging-based multi-spectral-band polarized light transmission characteristic testing device;

step two, turning on the visible light polarization detector (27), applying different voltages to the wavelength modulation unit I (25) by the circuit control subsystem (5) to complete wavelength selection, applying four groups of different voltages to the polarization modulation unit III (28) and the polarization modulation unit IV (29) by the circuit control subsystem (5) simultaneously aiming at each wavelength to enable the polarization modulation unit III (28) and the polarization modulation unit IV (29) to generate 4 different phase delays, correspondingly acquiring four different polarization images on the visible light polarization detector (27), and acquiring four polarization components, polarization degrees, polarization angles, linear polarization and circular polarization images of a visible light wave band on the display unit (42) after data processing is carried out by the image processing unit (41);

step three, turning on the short-wave infrared polarization detector (212), applying different voltages to the wavelength modulation unit II (210) by the circuit control subsystem (5) respectively to complete wavelength selection, applying four groups of different voltages to the two polarization modulation units by the circuit control subsystem (5) simultaneously aiming at each wavelength to enable the two polarization modulation units to generate 4 different phase delays, correspondingly obtaining four different polarization images on the short-wave infrared polarization detector (212), and finally performing data processing by the image processing unit (41) to obtain four polarization components, polarization degrees, polarization angles, linear polarization and circular polarization images of a short-wave infrared band on the display unit (42);

opening the medium wave infrared polarization detector (36), controlling the wire grid polarizer I (33) to rotate by 0 degrees, 45 degrees, 90 degrees and 135 degrees by the circuit control subsystem (5) respectively, acquiring corresponding polarization images on the medium wave infrared polarization detector (36), and finally obtaining four polarization components, polarization degrees, polarization angles, linear polarizations and circular polarization images of a medium wave infrared band on the display unit (42) after data processing is carried out by the image processing unit (41);

step five, the long-wave infrared polarization detector (310) is turned on, the circuit control subsystem (5) controls the wire grid polarizer II (37) to rotate by 0 degrees, 45 degrees, 90 degrees and 135 degrees respectively, corresponding polarization images are acquired by the long-wave infrared polarization detector (310), and the four polarization components, the polarization degrees, the polarization angles, the linear polarizations and the circular polarization images of the long-wave infrared wave bands are finally obtained on the display unit (42) after data processing is carried out by the image processing unit (41);

placing the target object according to the set sight distance, imaging the target object respectively, setting a specific environment for simulation between the target object and the experimental device, and repeating the second step to the fifth step to obtain four polarization components, polarization degrees, polarization angles, linear polarization images and circular polarization images of each spectrum band of the specific environment under the set sight distance;

and seventhly, calculating by using MATLAB software through a representation formula of the contrast and the spatial frequency, respectively obtaining the contrast and the spatial frequency of the polarized image target and the background at the zero-line-of-sight position and the set-line-of-sight position, respectively comparing the contrast of the polarized image target and the background at each set-line-of-sight position and the spatial frequency and the zero-line-of-sight position, respectively comparing the two parameters of the contrast, the spatial frequency value of the image is larger, the higher the contrast is visually represented, the higher the contrast is, the stronger the identification and detection capability of the polarized imaging system on the target is, the better the transmission characteristic of the polarized light corresponding to the spectrum band in a complex medium is, and the measurement of the transmission characteristic of visible light, short wave infrared, medium wave infrared and long wave infrared in a specific environment is completed.

8. The method for testing the transmission characteristics of multi-spectral-band polarized light based on passive imaging as claimed in claim 7, wherein: the particular environment includes sea fog, land fog, sea-land fog, mountain grain fog, city fog, extreme fog, atmosphere, or turbulence.

Technical Field

The invention belongs to the technical field of photoelectric detection, and particularly relates to a multi-spectral-band polarized light transmission characteristic testing device and method based on passive imaging.

Background

Photoelectric information acquisition is divided into an active mode and a passive mode. The passive detection mode realizes target detection and identification through the visibility and the infrared radiation of a detected target, and has the advantages of no emission of any characteristic signal, good concealment and the like, so the passive detection mode is widely applied in military affairs.

With the development of scientific technology and the needs of production and life, imaging detection is also required more widely, and the general imaging detection mainly detects the intensity information of the spectrum of the reflected light of the target object, so that the information of the size, shape, type, orientation and the like of the target object is obtained, and then the target object is analyzed, identified, tracked and the like. When the background environment of the imaging target object is severe, such as fog or haze, non-uniform illumination, low illumination, etc., the target object is affected by complicated background noise too much to be detected by the intensity information of light alone. In order to accurately and effectively identify and detect a specific target, especially a small special target with hiding capability, in a complex background environment, a new challenge is provided for imaging detection.

In order to realize more accurate detection of a target in a complex background environment, polarization information of light needs to be utilized, and in such a case, efficient and accurate measurement of transmission characteristics of polarized light is particularly important.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the device and the method for testing the transmission characteristics of the multi-spectral-band polarized light based on the passive imaging are used for solving the technical problem that a specific target in a complex background environment is difficult to accurately and effectively identify.

The multispectral polarized light transmission characteristic testing device based on passive imaging comprises a preposed optical subsystem, a visible light and short wave infrared polarization imaging subsystem, a medium wave infrared and long wave infrared polarization imaging subsystem, an image acquisition and processing subsystem and a circuit control subsystem, wherein the preposed optical subsystem, the visible light and short wave infrared polarization imaging subsystem and the medium wave infrared and long wave infrared polarization imaging subsystem are jointly arranged on the same plane, and emergent light rays of the preposed optical subsystem are respectively incident into the visible light and short wave infrared polarization imaging subsystem and the medium wave infrared and long wave infrared polarization imaging subsystem; the optical axis of the visible light and short wave infrared polarization imaging subsystem is parallel to the optical axis of the medium wave infrared and long wave infrared polarization imaging subsystem, and the visible light and short wave infrared polarization imaging subsystem and the medium wave infrared and long wave infrared polarization imaging subsystem are arranged in parallel; the image acquisition processing subsystem comprises an image processing unit and an image display unit; the image processing unit is respectively and electrically connected with the preposed optical subsystem, the visible light and short wave infrared polarization imaging subsystem, the medium wave infrared and long wave infrared polarization imaging subsystem and the image display unit; the circuit control subsystem is electrically connected with the visible light and short wave infrared polarization imaging subsystem and the medium wave infrared and long wave infrared polarization imaging subsystem respectively, and comprises a polarization modulation control unit and a wavelength modulation control unit; the polarization modulation control unit controls the rotation of each polaroid in the visible light and short wave infrared polarization imaging subsystem and the medium wave infrared and long wave infrared polarization imaging subsystem or the phase delay of the polarization modulation unit by controlling voltage; the wavelength modulation unit completes the selection of the wavelength by each acousto-optic wavelength modulation unit in the visible light and short wave infrared polarization imaging subsystem through controlling the voltage.

The front optical subsystem comprises a telescopic optical unit, a light splitting unit I and a reflector unit I; the telescope optical unit and the light splitting unit I are transversely arranged in series and have the same optical axis, and the light splitting unit I and the reflector unit I are longitudinally arranged in series and have the same optical axis; light enters the system from the telescope optical unit and then is divided into two beams by the light splitting unit I, one beam enters the visible light and short wave infrared polarization imaging subsystem, and the other beam enters the medium wave infrared and long wave infrared polarization imaging subsystem after being refracted by the reflector unit I.

The visible light and short wave infrared polarization imaging subsystem comprises a light splitting unit II, a reflector unit II, a polarization modulation unit I, a polarization modulation unit II, a wavelength modulation unit I, an imaging lens unit I, a visible light polarization detector, a polarization modulation unit III, a polarization modulation unit IV, a wavelength modulation unit II, an imaging lens unit II and a short wave infrared polarization detector; the light splitting unit II, the polarization modulation unit I, the polarization modulation unit II, the wavelength modulation unit I, the imaging lens unit I and the visible light polarization detector are sequentially transversely and serially arranged and have the same optical axis, and the light splitting unit II and the reflector unit II are longitudinally and serially arranged; the reflector unit II, the polarization modulation unit III, the polarization modulation unit IV, the wavelength modulation unit II, the imaging lens unit II and the short wave infrared polarization detector are sequentially transversely arranged in series and have the same optical axis; the polarization modulation unit I, the polarization modulation unit II, the polarization modulation unit III and the polarization modulation unit IV are respectively electrically connected with the polarization modulation control unit; the wavelength modulation unit I and the wavelength modulation unit II are respectively electrically connected with the wavelength modulation unit.

The wavelength modulation unit I and the wavelength modulation unit II are both acousto-optic tunable filters or liquid crystal tunable filters.

The polarization modulation unit I, the polarization modulation unit II, the polarization modulation unit III and the polarization modulation unit IV are all liquid crystal phase retarders.

The medium-wave infrared and long-wave infrared polarization imaging subsystem comprises a light splitting unit III, a reflector unit III, a polaroid I, a light filter I, an imaging lens unit III, a medium-wave infrared polarization detector, a polaroid II, a light filter II, an imaging lens unit IV and a long-wave infrared polarization detector; the light splitting unit III, the reflector unit III, the polaroid I, the optical filter I, the imaging lens unit III and the medium wave infrared polarization detector are sequentially arranged in series in the transverse direction and have the same optical axis, and the light splitting unit III and the reflector unit III are arranged in series in the longitudinal direction; the reflector unit III, the polaroid II, the optical filter II, the imaging lens unit IV and the long-wave infrared polarization detector are sequentially transversely and serially arranged and have the same optical axis.

The multispectral polarized light transmission characteristic testing method based on passive imaging comprises the following steps,

firstly, placing a target object at a zero-line-of-sight position of the passive imaging-based multi-spectral-band polarized light transmission characteristic testing device;

step two, turning on the visible light polarization detector, applying different voltages to the wavelength modulation unit I by the circuit control subsystem to complete wavelength selection, applying four groups of different voltages to the polarization modulation unit III and the polarization modulation unit IV by the circuit control subsystem simultaneously aiming at each wavelength to enable the polarization modulation unit III and the polarization modulation unit IV to generate 4 different phase delays, correspondingly obtaining four different polarization images on the visible light polarization detector, and obtaining four polarization components, polarization degrees, polarization angles, linear polarizations and circular polarization images of a visible light wave band on the display unit after data processing is carried out by the image processing unit;

step three, turning on the short wave infrared polarization detector, applying different voltages on the wavelength modulation unit II by the circuit control subsystem to complete wavelength selection, applying four groups of different voltages on the two polarization modulation units by the circuit control subsystem simultaneously aiming at each wavelength to enable the two polarization modulation units to generate 4 different phase delays, correspondingly obtaining four different polarization images on the short wave infrared polarization detector, and finally obtaining four polarization components, polarization degrees, polarization angles, linear polarization and circular polarization images of the short wave infrared band on the display unit after data processing is carried out by the image processing unit;

opening the medium wave infrared polarization detector, controlling the wire grid polarizer I to rotate by 0 degrees, 45 degrees, 90 degrees and 135 degrees by the circuit control subsystem, acquiring corresponding polarization images on the medium wave infrared polarization detector, and finally obtaining four polarization components, polarization degrees, polarization angles, linear polarizations and circular polarization images of the medium wave infrared band on the display unit after data processing is carried out by the image processing unit;

step five, opening the long-wave infrared polarization detector, controlling the wire grid polarizer II to rotate by 0 degrees, 45 degrees, 90 degrees and 135 degrees by the circuit control subsystem, acquiring corresponding polarization images on the long-wave infrared polarization detector, and finally obtaining four polarization components, polarization degrees, polarization angles, linear polarization and circular polarization images of the long-wave infrared band on the display unit after data processing is carried out by the image processing unit;

placing the target object according to the set sight distance, imaging the target object respectively, setting a specific environment for simulation between the target object and the experimental device, and repeating the second step to the fifth step to obtain four polarization components, polarization degrees, polarization angles, linear polarization images and circular polarization images of each spectrum band of the specific environment under the set sight distance;

and seventhly, calculating by using MATLAB software through a representation formula of the contrast and the spatial frequency, respectively obtaining the contrast and the spatial frequency of the polarized image target and the background at the zero-line-of-sight position and the set-line-of-sight position, respectively comparing the contrast of the polarized image target and the background at each set-line-of-sight position and the spatial frequency and the zero-line-of-sight position, respectively comparing the two parameters of the contrast, the spatial frequency value of the image is larger, the higher the contrast is visually represented, the higher the contrast is, the stronger the identification and detection capability of the polarized imaging system on the target is, the better the transmission characteristic of the polarized light corresponding to the spectrum band in a complex medium is, and the measurement of the transmission characteristic of visible light, short wave infrared, medium wave infrared and long wave infrared in a specific environment is completed.

The particular environment includes sea fog, land fog, sea-land fog, mountain grain fog, city fog, extreme fog, atmosphere, or turbulence.

Through the design scheme, the invention can bring the following beneficial effects:

based on the passive imaging principle, the invention fuses the multispectral technology and the polarization technology, can work in four spectral bands of visible light (0.4-0.8 mu m), short-wave infrared light (0.9-1.7 mu m), medium-wave infrared light (3-5 mu m) and long-wave infrared light (8-12 mu m), and further analyzes the transmission characteristic of the multispectral polarized light, thereby being beneficial to supplement of the device and the method for testing the transmission characteristic of the single-spectral-band polarized light; the wavelength modulation unit I and the wavelength modulation unit II both adopt acousto-optic tunable filters or Liquid Crystal Tunable Filters (LCTF), so that the wavelength of incident light waves in a wide spectrum band is debugged, the measurement error caused by frequent replacement of optical filters is avoided, the measurement precision is improved by 40%, the working efficiency is improved by 2-3 times, and the polarized light transmission characteristic test experiment based on passive imaging can be better completed.

Drawings

The invention is further described with reference to the following figures and detailed description:

fig. 1 is a block diagram of a device for testing transmission characteristics of multi-spectral-band polarized light based on passive imaging and a method thereof according to the present invention.

FIG. 2 is a schematic diagram illustrating the principle of a testing method in the passive imaging-based multi-spectral-band polarized light transmission characteristic testing apparatus and method according to the present invention.

In the figure, 1-a preposed optical subsystem, 2-a visible light and short wave infrared polarization imaging subsystem, 3-a medium wave infrared and long wave infrared polarization imaging subsystem, 4-an image acquisition and processing subsystem, 5-a circuit control subsystem, 11-a telescope optical unit, 12-a light splitting unit I, 13-a reflector unit I, 21-a light splitting unit II, 22-a reflector unit II, 23-a polarization modulation unit I, 24-a polarization modulation unit II, 25-a wavelength modulation unit I, 26-an imaging lens unit I, 27-a visible light polarization detector, 28-a polarization modulation unit III, 29-a polarization modulation unit IV, 210-a wavelength modulation unit II, 211-an imaging lens unit II, 212-a short wave infrared polarization detector, 31-a light splitting unit III, a 32-a reflector unit III, a 33-a polarizing film I, a 34-an optical filter I, a 35-an imaging lens unit III, a 36-medium wave infrared polarization detector, a 37-a polarizing film II, a 38-an optical filter II, a 39-an imaging lens unit IV, a 310-long wave infrared polarization detector, a 41-an image processing unit, a 42-an image display unit, a 51-a polarization modulation control unit and a 52-a wavelength modulation control unit.

Detailed Description

The invention is further explained with reference to the accompanying drawings, and the device for measuring the transmission characteristics of the multi-spectral-band polarized light based on passive imaging shown in fig. 1 is characterized by comprising a preposed optical subsystem 1, a visible light and short wave infrared polarization imaging subsystem 2, a medium wave infrared and long wave infrared polarization imaging subsystem 3, an image acquisition and processing subsystem 4 and a circuit control subsystem 5. The preposed optical subsystem 1, the visible light and short wave infrared polarization imaging subsystem 2 and the medium wave infrared and long wave infrared polarization imaging subsystem 3 are jointly arranged on the same plane; the system comprises a preposed optical subsystem 1, a visible light and short wave infrared polarization imaging subsystem 2, a medium wave infrared and long wave infrared polarization imaging subsystem 3, a circuit control subsystem 5, a visible light and short wave infrared polarization imaging subsystem 2, a medium wave infrared and long wave infrared polarization imaging subsystem 3, an image acquisition and processing subsystem 4, a medium wave infrared and long wave infrared polarization imaging subsystem 3 and an image acquisition and processing subsystem 4, wherein the preposed optical subsystem 1 is in optical connection with the visible light and short wave infrared polarization imaging subsystem 2 and the medium wave infrared and long wave infrared polarization imaging subsystem 3, the visible light and short wave infrared polarization imaging subsystem 2 is in electrical connection with the circuit control subsystem 5, the medium wave infrared and long wave infrared polarization imaging subsystem 3 is in electrical connection with the image acquisition and processing subsystem 4, and optical axes of the visible light and short wave infrared polarization imaging subsystem 2 and the medium wave infrared and long wave infrared polarization imaging subsystem 3 are arranged in parallel and in parallel.

The front optical subsystem 1 comprises a BEF02-B Galileo telescopic optical unit 11 of Shenzhen LBTEK company, a BV-050-VIS optical unit I12 of Meadowlark optics company and a Schott companyBB0511-E02 mirror unit I13; the telescope optical unit 11 and the light splitting unit I12 are transversely arranged in series and are coaxial, and the light splitting unit I12 and the reflector unit I13 are longitudinally arranged in series and are coaxial; light enters the system from the telescopic optical unit 11 and is divided into two beams by the light splitting unit I12, one beam enters the visible light and short wave infrared polarization imaging subsystem 2, and the other beam enters the medium wave infrared and long wave infrared polarization imaging subsystem 3 after being refracted by the reflector unit I13.

The visible light and short wave infrared polarization imaging subsystem 2 comprises American MeadowBV-050-IR Spectroscopy Unit II 21, lark optics, Schott USABB211-E04 mirror unit II 22, Thorlabs LCC1411-A polarization modulation unit I23, Thorlabs LCC1411-A polarization modulation unit II 24, Gooch, England&Housego TF550-300-4-6-GH57A wavelength modulation unit I25, Large galvano GCL-0102 imaging lens Unit I26, Thorabs S805MU1 visible light polarization Detector 27, Thorabs LCC1411-B polarization modulation Unit III 28, Thorabs LCC1411-B polarization modulation Unit IV 29, Gooch, UK&Housego I-TF1650-1100-1-3-GH107 wavelength modulation unit II 210, large constant photoelectric GCL-0102 imaging lens unit II 211, Canada Photonic ZephiIR^TMA 1.7s short wave infrared polarization detector 212; the light splitting unit II 21, the polarization modulation unit I23, the polarization modulation unit II 24, the wavelength modulation unit I25, the imaging lens unit I26 and the visible light polarization detector 27 are transversely arranged in series and have the same optical axis, the light splitting unit II 21 and the reflector unit II 22 are longitudinally arranged in series, and the reflector unit II 22, the polarization modulation unit III 28, the polarization modulation unit IV 29, the wavelength modulation unit II 210, the imaging lens unit II 211 and the short wave infrared polarization detector 212 are transversely arranged in series and have the same optical axis; light rays entering the visible light and short wave infrared polarization imaging subsystem 2 are divided into two beams by the light splitting unit II 21, one beam is subjected to polarization state and wavelength modulation by the polarization modulation unit I23, the polarization modulation unit II 24 and the wavelength modulation unit I25 and is converged on the visible light polarization detector 27 to be imaged by the imaging lens unit 26, and the other beam is refracted by the reflector unit 22 and is subjected to polarization state and wavelength modulation by the polarization modulation unit III 28, the polarization modulation unit IV 29 and the wavelength modulation unit II 210 and is converged on the short wave infrared polarization detector 212 to be imaged by the imaging lens unit II 211.

The medium-wave infrared and long-wave infrared polarization imaging subsystem 3 comprises a BV-100-UNC light splitting unit III 31 of American Meadowlark optics, a M254H45 reflector unit III 32 of American Thorabs, a WP25M-UB polaroid I33 of American Thorabs, an FB4000-500 optical filter of American Thorabs, a large constant photoelectricity GCL-0102 imaging lens unit III 35, a Tigris-640-MCT medium-wave infrared polarization detector 36 of Belgium Xeronics, a WP25M-IRC polaroid II 37 of American Thorabs, an FB10000-500 optical filter 38 of American Thorabs, a large constant photoelectricity GCL-0102 imaging lens unit IV 39 and an XT Zenmush infrared polarization detector 310 of Darby unmanned aerial vehicle; the light splitting unit III 31, the reflector unit III 32, the polaroid I33, the optical filter I34, the imaging lens unit III 35 and the medium wave infrared polarization detector 36 are transversely arranged in series and share the same optical axis, the light splitting unit III 31 and the reflector unit III 32 are longitudinally arranged in series, and the reflector unit III 32, the polaroid II 37, the optical filter II 38, the imaging lens unit IV 39 and the long wave infrared polarization detector 310 are transversely arranged in series and share the same optical axis. Light rays entering the medium-wave infrared and long-wave infrared polarization imaging subsystem 3 are divided into two beams by the light splitting unit III 31, one beam is subjected to polarization state and wavelength modulation by the polarizing film I33 and the optical filter I34 and is converged on the medium-wave infrared polarization detector 36 to be imaged by the imaging lens unit III 35, the other beam is converted by the reflector unit III 32 and is subjected to polarization state and wavelength modulation by the polarizing film II 37 and the optical filter II 38 and is converged on the long-wave infrared polarization detector 310 to be imaged by the imaging lens unit IV 39.

The image acquisition and processing subsystem 4 comprises an image processing unit 41 and an image display unit 42; the image processing unit comprises a computer and a software system corresponding to each spectral band detector in the computer; the image processing unit 41 is electrically connected with the image display unit 42; the image processing unit 41 collects image information collected by the visible light polarization detector 27, the short wave infrared polarization detector 212, the medium wave infrared polarization detector 36, and the long wave infrared polarization detector 310, performs fusion processing on the image information, and finally outputs the image information by the image display unit 42.

The circuit control unit 5 comprises a Thorlabs KLC101K-cube LC polarization modulation control unit 51 and a KURIOS-WB1 wavelength modulation control unit 52; the polarization modulation control unit 51 controls the rotation of the polarizer or the phase retardation of the polarization modulation unit by controlling the voltage, and the wavelength modulation unit 52 performs the selection of the wavelength by controlling the voltage.

As shown in fig. 2, the method for testing the transmission characteristics of multispectral polarized light based on passive imaging adopts the device for testing the transmission characteristics of multispectral polarized light based on passive imaging, and specifically includes the following steps:

step 1, building an experimental device according to the passive imaging-based multi-spectral-band polarization transmission characteristic testing device;

step 2, placing the target object at a zero-sight distance;

step 3, turning on the visible light polarization detector 27, applying different voltages to the wavelength modulation unit I25 by the circuit control unit 5 to complete wavelength selection, wherein different wavelengths correspond to different fixed voltage values, applying four groups of different voltages to the two polarization modulation units simultaneously by the circuit control unit aiming at each wavelength, so that the polarization modulation unit I23 and the polarization modulation unit II 24 generate 4 different phase delays, correspondingly obtaining four different polarization images on the visible light polarization detector 27, and finally obtaining four polarization components, polarization degrees, polarization angles, linear polarization and circular polarization images of a visible light waveband on the image display unit 42 after data processing is carried out by the image processing unit 41;

step 4, turning on the short wave infrared polarization detector 212, repeating the polarization and spectrum modulation method in step 3, and obtaining four polarization components, polarization degree, polarization angle, linear polarization and circular polarization images of the short wave infrared band on the image display unit 42;

step 5, turning on the medium wave infrared polarization detector 36, controlling the polarizer I33 to rotate by 0 degrees, 45 degrees, 90 degrees and 135 degrees by the circuit control subsystem 5, respectively, acquiring corresponding polarization images on the medium wave infrared polarization detector 36, and finally obtaining I, Q, U, V four polarization components, polarization degrees, polarization angles, linear polarization and circular polarization images of the medium wave infrared band on the image display unit 42 after data processing is carried out by the image processing unit 41;

step 6, opening the long-wave infrared polarization detector 310, and obtaining the long-wave infrared band polarization degree and polarization angle images in the same way as the step 5;

and 7, repeating the steps 3 to 6, and imaging the target object within a certain visual distance, wherein the certain visual distance is L in the graph 2_nExpressed as the increment of each detector movement, l_iObtaining four polarization components, polarization degrees, polarization angles, linear polarization and circular polarization images of a plurality of spectral bands at a certain visual distance in a sea fog environment between a target object and an experimental device;

step 8, calculating and comparing the difference between the contrast and the spatial frequency of the polarized images at the zero-line-of-sight position and the certain-line-of-sight position, wherein the zero-line-of-sight position is L in the graph 2₀The certain visual distance is L in FIG. 2₁～L_nAnd the transmission characteristics of polarized light of each spectrum band under a specific environment are obtained from two dimensions of spatial frequency and contrast.

The polarization image of the passive polarization imaging system, namely the stokes polarization imaging system, is formed by a group of 1 × 4 non-offset component images to form an image vector combination, and for the stokes image, the image pixel combination represents the stokes parameter of the pixel receiving the light beam in the scene. At present, image receiving devices of various polarization measurement systems are light intensity receivers represented by CCDs and CMOSs, so that each component image in a polarization image is still a light intensity image after certain calculation, and each pixel of the component image represents a polarization parameter of a polarization vector of a point corresponding to a scene on the image component.

The contrast C of an object against the background refers to a measure of the different brightness levels between the brightest white and darkest black of the light and dark regions in an image, with a greater range of differences representing greater contrast. The high contrast is expressed as clear images, obvious details and multiple gray levels, generally speaking, the higher the contrast is, the stronger the identification and detection capability of the full-polarization imaging system on the target is, the more the features of the artificial target can be highlighted in the formed image, that is, the higher the contrast of the polarized image is, the better the transmission characteristic of the polarized light under a specific environment is.

For the definition of contrast, there are several characterization methods as follows:

wherein C represents the contrast of the target to the background; gt represents the average gray value of the target region; gb represents the average gray value of the background area. Since | g in the expression_t-g_bTo reduce the calculation fluctuation, it is proposed to use equation (3), and then change equation (4) according to the brightness of the target and the background, and to sum up, based on the analysis of the error theory, reduce the contrast difference caused by the large calculation fluctuation, and use equation (3) to calculate the contrast.

The spatial frequency SF reflects the total activity degree of an image space and the definition degree of an image, the larger the difference of the gray values of adjacent pixels is, the higher the visual expression is, the clearer the image is, and the characterization formula of the spatial frequency SF is defined as

In the formula, g (i, j) is the gray value at the pixel point (i, j); RF represents spatial line frequency; CF denotes the column frequency.

By means of a representation formula of contrast C and spatial frequency SF, the contrast and the spatial frequency of a polarized image target and a background are respectively obtained by utilizing MATLAB software for calculation, the larger the spatial frequency value of the image is, the higher the contrast is visually represented, the higher the contrast is, the stronger the identification and detection capability of a polarized imaging system on the target is, the better the transmission characteristic of the polarized light corresponding to a spectrum band in a complex medium is, and the measurement on the transmission characteristic of visible light, short-wave infrared light, medium-wave infrared light and long-wave infrared light in a specific environment is further completed.

The working process of the invention is as follows:

under different visual distances within a certain visual distance, the telescopic optical unit 11 collects visible light, short wave infrared, medium wave infrared and long wave infrared light of a target and a background, reflected light and scattered light of the target and the background respectively enter the visible light and short wave infrared polarization imaging subsystem 2 and the medium wave and long wave infrared polarization imaging subsystem 3 through the light splitting unit I12 to obtain corresponding visible light, short wave infrared, medium wave infrared and long wave infrared polarization images, the images are transmitted to the image acquisition and processing subsystem 4 to be fused to obtain corresponding I, Q, U, V four polarization components, polarization degrees, polarization angles, linear polarization and circular polarization images of the visible light, the short wave infrared, the medium wave infrared and the long wave infrared, and the contrast C and the spatial frequency SF of the polarization image target and the background under different visual distances are compared with the two parameters at the zero visual distance to finish the visible light, the short wave infrared, the medium wave infrared and the long wave infrared, And measuring the transmission characteristics of short-wave infrared light, medium-wave infrared light and long-wave infrared light in complex environments such as sea fog.