Polarization spectrum target simulation source

Abstract

A polarization spectrum target simulation source provided by the present invention comprises a surface uniform and adjustable spectrum light source and an optical adjustment assembly, the surface uniform and adjustable spectrum light source is used for generating uniform light with a specific spectral region wavelength and is provided with an exit port for outputting the uniform light, and the optical adjustment assembly is arranged at the exit port. Comprising a first polaroid, a first space phase delay modulator, a Bayer optical filter, a second polaroid and a second space phase delay modulator which are sequentially arranged away from the exit port in the normal direction of the exit port, and is used for modulating the uniform light output by the exit port so as to output a multi-dimensional target simulation optical signal. The polarization spectrum target simulation source provided by the invention has controllable and adjustable multi-dimensional optical signal output capability, is suitable for laboratory testing of a multi-spectrum polarization imaging instrument and a load, is also beneficial to testing of self polarization characteristics of non-polarization optical equipment, and can simulate optical characteristics of polarization targets such as cloud and fog more accurately and perfectly.

Description

Technical Field

[0001] The invention belongs to the field of scene target simulators, and in particular relates to a polarization spectrum target simulation source. Background Art

[0002] In recent years, spaceborne polarization detection technology has been developing rapidly. Due to the scattered polarization characteristics of artificial targets, cloud phases, aerosols, etc., polarization observation can effectively expand the amount of information and improve the convergence and accuracy of subsequent inversion. At present, a variety of spaceborne polarization remote sensing payloads have been developed at home and abroad, among which the more influential ones are PACE-HARP and APS in the United States, POLDER in France, SPEX in the Netherlands, and SGLI in Japan. In addition, NASA is actively planning the next generation of payloads MSPI, and the corresponding European Space Agency ESA is expected to launch the newly developed multi-angle polarization camera 3MI in 2021, 2023, and 2025; Japan also has subsequent payload plans for SGLI. Although China started relatively late, it has also deployed multiple polarization payloads: such as multi-angle polarization imagers (GF-5-01, 02), polarization scanners POSP (GF-5-02), polarization cameras (Tiangong-2), etc., and continues to actively promote the development of this technology.

[0003] A key technical difficulty affecting the above payloads is the coupling between polarization detection, imaging, inversion and other processes, which often interfere with each other in several dimensions. In order to measure this interference, a controllable and adjustable target analog source with the ability to output optical signals in various dimensions such as polarization, spectrum, geometry, and light intensity is a necessary prerequisite.

[0004] However, the existing target simulation sources are basically star map simulation, guidance simulation, infrared target simulation, etc. (such as Li Deming et al., star sensor image simulation and target background motion characteristics analysis; Liu Xinran et al., optomechanical structure design of small target simulator based on LCOS splicing; Kuang Xiaotian et al., key technology research of target simulator based on digital micromirror device), most of which are limited to the two dimensions of geometry and light intensity, and do not have polarization simulation capabilities. NASA developed a multi-polarized light source (MPSP) in 2012, which uses LCOS liquid crystal spatial modulation projection to generate multi-spectral polarized light with controllable light intensity in time-sharing, but it cannot output images, making it difficult to achieve target shape simulation (geometric dimension simulation). Up to now, there has been no report on target simulation sources that can output quantitative multi-spectral polarization images. Summary of the invention

[0005] The purpose of the present invention is to provide a polarization spectral target simulation source, which is suitable for multi-spectral polarization imaging payloads / equipment, has adjustable and controllable optical signal output capabilities in various dimensions such as polarization, spectrum, geometry, and light intensity, and solves the technical problem that existing target simulation sources cannot take into account the quantitative output of polarization, spectrum, geometry, radiation and other dimensional signals.

[0006] In order to solve the above technical problems, the present invention is implemented through the following technical solutions:

[0007] The present invention provides a polarization spectrum target simulation source, which comprises:

[0008] A surface uniform spectral tunable light source, used to generate uniform light of a wavelength in a specific spectral region, the surface uniform spectral tunable light source having an exit port for outputting the uniform light;

[0009] An optical adjustment component is arranged at the exit, and the optical adjustment component includes a first polarizer, a first spatial phase delay modulator, a Bayer filter, a second polarizer and a second spatial phase delay modulator which are arranged in sequence away from the exit along the normal direction of the exit;

[0010] The optical adjustment component is used to modulate the uniform light output from the exit port to output a multi-dimensional target analog optical signal.

[0011] In one embodiment of the present invention, a supporting device is further included, and the optical adjustment component is mounted on the exit through the supporting device.

[0012] In one embodiment of the present invention, the optical adjustment component is fixedly installed at the emission port.

[0013] In one embodiment of the present invention, the first polarizer, the first spatial phase delay modulator, the Bayer filter, the second polarizer and the second spatial phase delay modulator are bonded together by ultraviolet photosensitive adhesive.

[0014] In one embodiment of the present invention, a protective window is further included, and the protective window is attached to a side of the optical adjustment component away from the emission port.

[0015] In one embodiment of the present invention, the surface layer of the protective window is coated with an infrared attenuation film layer to reduce the emitted infrared light component.

[0016] In one embodiment of the present invention, the optical adjustment component further includes a third spatial phase delay modulator, and the third spatial phase delay modulator is mounted on a side of the second spatial phase delay modulator away from the second polarizer.

[0017] In one embodiment of the present invention, the transmission direction of the polarizer of the optical adjustment component and the phase of each pixel of the spatial phase delay modulator are adjustable.

[0018] In one embodiment of the present invention, the Bayer filter includes a color pixel array, and each color pixel includes sub-pixels of four different colors.

[0019] In one embodiment of the present invention, the sub-pixels of the Bayer filter and the pixels of the spatial phase delay modulator are of the same size and aligned with each other.

[0020] The present invention provides a polarization spectrum target simulation source, comprising: a surface uniform tunable spectrum light source, for generating uniform light of a wavelength in a specific spectral region, the surface uniform tunable spectrum light source having an exit port for outputting the uniform light, an optical adjustment component, arranged at the exit port, the optical adjustment component comprising a first polarizer, a first spatial phase delay modulator, a Bayer filter, a second polarizer and a second spatial phase delay modulator, which are arranged in sequence away from the exit port along the normal direction of the exit port, wherein the optical adjustment component is used to modulate the uniform light output from the exit port to output a multi-dimensional target simulation optical signal. A polarization spectrum target simulation source provided by the present invention can be controllable and adjustable and has the ability to output optical signals in comprehensive multiple dimensions such as polarization, spectrum, geometry, and light intensity, filling the gap in the prior art that there is no such target simulation source. In addition, the polarization spectrum target simulation source is suitable for laboratory testing of multi-spectral polarization imaging instruments and payloads, and is also beneficial for non-polarized optical equipment to test its own polarization characteristics. In addition, the polarization spectrum target simulation source is beneficial for laboratory simulation of natural scenes, such as being able to more accurately and completely simulate the optical characteristics of polarization targets such as clouds and fog.

[0021] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A schematic diagram of the system composition of a polarization spectrum target simulation source provided by an exemplary embodiment of the present application.

[0024] Figure 2 A schematic diagram of an optical signal modulation process of a polarization spectrum target simulation source provided by an exemplary embodiment of the present application.

[0025] Figure 3 A schematic structural diagram of a polarization spectrum target simulation source provided as an exemplary embodiment of the present application.

[0026] Figure 4 A schematic diagram of the local structure of a polarization spectrum target simulation source provided as an exemplary embodiment of the present application.

[0027] The reference numerals are as follows:

[0028] 1 uniform spectral adjustable light source

[0029] 2. First polarizer

[0030] 3. The first spatial phase delay modulator

[0031] 4 Bayer filter

[0032] 5 Second polarizer

[0033] 6. Second spatial phase delay modulator

[0034] 7Third spatial phase delay modulator

[0035] 8 Protective window

[0036] 101 Light source box

[0037] 102 Halogen lamp

[0038] 103 Filter Wheel

[0039] 104 Aperture DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] In order to solve the technical problem that the existing target simulation source cannot take into account the quantitative output of polarization, spectrum, geometry, radiation and other dimensional signals, the present invention provides a polarization spectrum target simulation light source, including: a surface uniform adjustable spectrum light source, used to generate uniform light of a specific spectral region wavelength, the surface uniform adjustable spectrum light source has an exit for outputting the uniform light, an optical adjustment component, arranged at the exit, the optical adjustment component includes a first polarizer, a first spatial phase delay modulator, a Bayer filter, a second polarizer and a second spatial phase delay modulator arranged in sequence away from the exit along the normal direction of the exit, wherein the optical adjustment component is used to modulate the uniform light output from the exit to output a multi-dimensional target simulation light signal. These embodiments will be discussed in detail below.

[0042] In an exemplary embodiment of the present application, the polarization spectrum target simulation light source includes a surface uniform tunable spectrum light source 1 , an optical adjustment component (not shown) and a protective window 8 .

[0043] For details, please refer to Figure 1 As shown, Figure 1 The schematic diagram of the system composition of the polarized spectrum target simulation light source is as follows. The polarized spectrum target simulation light source includes a surface uniform adjustable spectrum light source 1, an optical adjustment component (not shown) and a protective window 8. The optical adjustment component (not shown) includes a first polarizer 2, a first spatial phase delay modulator 3, a Bayer filter 4, a second polarizer 5 and a second spatial phase delay modulator 6. The surface uniform adjustable spectrum light source 1 is used to generate uniform light of a specific spectral region wavelength. The optical adjustment component (not shown) is used to modulate the uniform light output from the exit to output a multi-dimensional target simulation light signal. The surface uniform adjustable spectrum light source 1 can convert a wide-spectrum light source into a specified narrow-band light through a spectroscopic spectrum selection device, or directly use a combination of multiple narrow-spectrum light sources, such as a combination of LED light sources of multiple colors. The spectroscopic spectrum selection device can be similar to the way a monochromator outputs light, or it can be a way of switching and selecting a wavelength band through a filter. The working principle of the monochromator includes: the light source provides a beam of continuous wide-spectrum light to the monochromator, the continuous wide-spectrum light is dispersed into beams of different wavelengths by a dispersion system, and the selection system selects a beam of a specific wavelength range according to user needs.

[0044] For further information, please refer to Figure 2As shown, the output light of the surface uniform adjustable spectrum light source 1 is surface uniform and has good uniformity. The surface uniform adjustable spectrum light source itself has the ability to output narrow-band light in a wider spectral range, and can also output full-spectrum light, which increases the output spectrum freedom for the polarization spectrum target simulation source. The polarizer is an optical device that can convert incident light into linearly polarized light, and its shape is sheet-like or film-like. The spatial phase delay modulator includes a certain number of pixel arrays arranged in a rectangular array, such as a 256×256 pixel array, and the spatial phase delay modulator can be electrically driven so that the phase delay of each pixel of the spatial phase delay modulator can be adjusted within a certain range. In this embodiment, the phase delay adjustment range of each pixel of the spatial phase delay modulator is 0 to π / 2. Of course, in other embodiments, spatial phase delay modulators with other adjustment ranges can also be used if the adjustment range requirements are met.

[0045] In an exemplary embodiment of the present application, the surface uniform tunable spectrum light source 1 has an exit port for the uniform light output, and the optical adjustment component (not shown) is arranged at the exit port, and the optical adjustment component (not shown) includes a first polarizer 2, a first spatial phase delay modulator 3, a Bayer filter 4, a second polarizer 5 and a second spatial phase delay modulator 6 which are arranged in a normal direction of the exit port and away from the exit port in sequence.

[0046] For details, please refer to Figure 3 and Figure 4 As shown, Figure 3 is a schematic diagram of the structure of the polarization spectrum target simulation source, Figure 4 yes Figure 3 A partial enlarged view, in this embodiment, the surface uniform adjustable spectrum light source 1 adopts an adjustable spectrum integrating sphere, the adjustable spectrum integrating sphere includes a sphere and a light source device, the light source device includes a light source box 101, a halogen tungsten lamp 102, a filter wheel 103 and an aperture 104. In the front half of the sphere of the adjustable spectrum integrating sphere, that is, the hemispherical part close to the optical adjustment component, a plurality of the light source devices are evenly arranged, so that the outlet of the adjustable spectrum integrating sphere can output uniform light of a wavelength in a specific spectral region. In this embodiment, the optional wavelengths of the surface uniform adjustable spectrum light source 1 include four types, namely 490nm±20nm, 550nm±20nm, 670nm±20nm, and 400-700nm white light. The optical adjustment component (not shown) is fixedly installed at the exit of the surface uniform spectral adjustable light source 1, and the first polarizer 2, the first spatial phase delay modulator 3, the Bayer filter 4, the second polarizer 5 and the second spatial phase delay modulator 6 are tightly combined in sequence along the normal direction of the exit.

[0047] In an exemplary embodiment of the present application, the polarization spectrum target simulation source further includes a supporting device, and the optical adjustment component (not shown) is mounted at the exit through the supporting device. Specifically, in other embodiments, the optical adjustment component (not shown) can be supported by the supporting device, such as a bracket, a pillar, etc., so that the optical adjustment component (not shown) is placed in close contact with the exit of the surface uniform tunable spectrum light source 1.

[0048] In an exemplary embodiment of the present application, the first polarizer 2, the first spatial phase delay modulator 3, the Bayer filter 4, the second polarizer 5 and the second spatial phase delay modulator 6 are bonded together by ultraviolet photosensitive adhesive. It should be noted that, in this embodiment, ultraviolet photosensitive adhesive is evenly coated between the various optical elements included in the optical adjustment component (not shown), and after the Bayer filter 4 and the spatial phase delay modulator are aligned under a microscope, ultraviolet light is irradiated to cure the ultraviolet photosensitive adhesive to ensure that the bonding between the various optical elements is firm.

[0049] In an exemplary embodiment of the present application, the polarization spectrum target simulation source further includes a protective window 8, and the protective window 8 is attached to a side of the optical adjustment component (not shown) away from the emission port.

[0050] For details, please refer to Figure 3 and Figure 4 As shown, the protective window sheet 8 is attached to the side of the optical adjustment component away from the emission port by means of UV-sensitive adhesive. The protective window sheet 8 can be used to protect the optical adjustment component (not shown) from external collision damage at the physical level. Furthermore, the surface of the protective window sheet 8 can also be coated with an infrared attenuation film layer to act as a filter to reduce the emitted infrared light component. It should be noted that in other embodiments, the protective window sheet 8 can also be removed, that is, the component can be installed or removed.

[0051] In an exemplary embodiment of the present application, the optical adjustment component (not shown) further includes a third spatial phase delay modulator 7 to form a two-stage spatial phase delay modulator to expand the modulation range of the phase delay. The third spatial phase delay modulator 7 is mounted on the side of the second spatial phase delay modulator 6 away from the second polarizer 6. It should be noted that, in this embodiment, the third spatial phase delay modulator 7 is also mounted on the side of the second spatial phase delay modulator 6 away from the second polarizer 6 by ultraviolet photosensitive adhesive. In addition, in other embodiments, in certain specific application fields, only a first-stage spatial phase delay modulator may be used to expand the modulation range of the phase delay.

[0052] In an exemplary embodiment of the present application, the transmission direction of the polarizer of the optical adjustment component (not shown) and the phase of each pixel of the spatial phase delay modulator are adjustable. It should be noted that the polarizer can allow the light wave component parallel to its transmission direction to pass through, and absorb the light wave component perpendicular to its transmission direction. The spatial phase delay modulator is a device that can control the light beam to have different phase delays at each pixel, and its external performance is similar to that each pixel has an adjustable phase delay wave plate.

[0053] In an exemplary embodiment of the present application, the Bayer filter 4 includes a color pixel array, and each color pixel includes four sub-pixels of different colors. Figure 2 As shown, in this embodiment, the Bayer filter adopts an RGBW Bayer filter to ensure the radiation brightness of white light, wherein the sub-pixel size of each color pixel of the Bayer filter 4 is 50 microns.

[0054] In an exemplary embodiment of the present application, the sub-pixels of the Bayer filter 4 are the same size as the pixels of the spatial phase delay modulator and are aligned with each other. Specifically, the size of a single pixel of the spatial phase delay modulator is 50 microns, and the corresponding sub-pixel size of the Bayer filter 4 is also 50 microns. The pixels are observed through a microscope to ensure that the sub-pixels of the Bayer filter 4 are aligned with the pixels of the spatial phase delay modulator. It should be noted that the spatial phase delay modulator includes a first spatial phase delay modulator 3, a second spatial phase delay modulator 6 and a third spatial phase delay modulator 7. In addition, the accuracy of pixel alignment must ensure that the error does not exceed one tenth of the pixel size.

[0055] In an exemplary embodiment of the present application, see Figure 2 As shown, the simulation process of the optical signal of the polarization spectrum target simulation source includes the following steps:

[0056] S100: the uniform light emitted by the surface uniform spectral tunable light source 1 passes through the first polarizer 2, and the non-polarized light (that is, the uniform light) is converted into linearly polarized light by the first polarizer 2;

[0057] S200: the linearly polarized light passes through the first spatial phase delay modulator 3, and the linearly polarized light is phase-modulated by the first spatial phase delay modulator 3, so that the linearly polarized light originally vibrating in the same plane becomes a light wave vibrating in different planes with different phases, and after synthesis, an elliptically polarized light is formed;

[0058] S300: the elliptically polarized light passes through a Bayer filter 4, and the elliptically polarized light is spectrally modulated by the Bayer filter 4, wherein the grayscale of each pixel after the elliptically polarized light passes through the Bayer filter 4 is different;

[0059] S400: After the elliptically polarized light is filtered by the Bayer filter 4, it is modulated in grayscale by the second polarizer 5. By adjusting the transmission direction of the second polarizer 5, the intensity of the light passing through the second polarizer can be controlled, thereby changing the brightness level of the output light;

[0060] S500: Mix the 2×2 pixel spectra, perform 2×2 pixel phase modulation through the second spatial phase delay modulator 6, and then perform re-modulation through the third spatial phase delay modulator 7 to expand the polarization state output capability;

[0061] S600: Perform 2×2 pixel correction output spectrum through the protection window 8, and obtain the final output analog light signal.

[0062] It should be noted that, in this embodiment, after the first polarizer 2, the first spatial phase delay modulator 3, the Bayer filter 4, and the second polarizer 5 are tightly attached and aligned under a microscope by ultraviolet photosensitive glue, the ultraviolet photosensitive glue is cured by irradiating ultraviolet light to ensure that the bonding between the optical elements is firm. First, a test is performed to determine that the entire body composed of the first polarizer 2, the first spatial phase delay modulator 3, the Bayer filter 4, and the second polarizer 5 has different grayscale performances for each pixel after uniform light is transmitted, and can be modulated normally. After determining that it can be modulated normally, the second spatial phase delay modulator 6 and the third spatial phase delay modulator 7 are mounted on the side of the second polarizer 5 away from the Bayer filter in the same manner, that is, the second spatial phase delay modulator 6 and the third spatial phase delay modulator 7 are mounted on the side of the second polarizer 5 away from the Bayer filter by ultraviolet photosensitive glue, and after alignment under a microscope, ultraviolet light is irradiated to cure the ultraviolet photosensitive glue to form the optical adjustment component (not shown). Finally, the protective window 8 is mounted on the optical adjustment component (not shown) to provide another degree of freedom for spectrum modulation.

[0063] Furthermore, in the present embodiment, the surface uniform spectrum light source 1 is an adjustable spectrum integrating sphere, the polarizer is a visible light metal wire grid polarizer, the Bayer filter is an RGBW Bayer filter, the spatial phase delay modulator is a transmissive liquid crystal spatial phase modulator, and the surface of the protective window is coated with an infrared attenuation film layer, which acts as a filter. In addition, since the integrating sphere can select multiple spectrum superpositions, the output spectrum can be made as close to the actual situation as possible. In the present embodiment, a ground object simulation pixel is actually composed of 2×2 pixels. Through the above-mentioned steps of light signal simulation and calibration of the emitted light radiation, it is possible to quantitatively output multiple separate spectra of polarized geometric target simulation signals, and also to output quantitative visible color polarized geometric target simulation signals. It is worth noting that in the present embodiment, the actual final output light signal is elliptically polarized light. In application, since the circular polarization component of natural objects is relatively small, it is feasible to replace part of the linear polarized light with elliptically polarized light.

[0064] In summary, the present invention provides a polarization spectrum target simulation source, including a surface uniform adjustable spectrum light source 1, a first polarizer 2, a first spatial phase delay modulator 3, a Bayer filter 4, a second polarizer 5, a second spatial phase delay modulator 6, a third spatial phase delay modulator 7 and a protective window 8. The polarization spectrum target simulation source performs phase modulation through a spatial phase delay modulator, and through grayscale modulation similar to the display principle of a liquid crystal display, and in conjunction with further double-layer spatial phase modulation, overall spectrum modulation and 2×2 merged pixel simulation processes, a target simulation with consistent chromaticity (equivalent to consistency under lower spectral resolution) and consistent polarization for each pixel is achieved independently. It should be noted that when the polarization spectrum target simulation source is used quantitatively, the radiance and spectrum emitted by the polarization spectrum target simulation source need to be calibrated.

[0065] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope involved in the present application is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

[0066] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A polarization spectrum target simulation source, characterized in that: include: A surface uniform spectral tunable light source, used to generate uniform light of a wavelength in a specific spectral region, the surface uniform spectral tunable light source having an exit port for outputting the uniform light; An optical adjustment component is arranged at the exit, and the optical adjustment component includes a first polarizer, a first spatial phase delay modulator, a Bayer filter, a second polarizer and a second spatial phase delay modulator which are arranged in sequence away from the exit along the normal direction of the exit; The optical adjustment component is used to modulate the uniform light output from the exit port to output a multi-dimensional target analog optical signal.

2. A polarization spectrum target simulation source according to claim 1, characterized in that: It also includes a supporting device, and the optical adjustment component is mounted on the exit through the supporting device.

3. A polarization spectrum target simulation source according to claim 1, characterized in that: The optical adjustment component is fixedly installed at the emission port.

4. The polarization spectrum target simulation source according to claim 1, characterized in that: The first polarizer, the first spatial phase delay modulator, the Bayer filter, the second polarizer and the second spatial phase delay modulator are bonded together by ultraviolet photosensitive adhesive.

5. The polarization spectrum target simulation source according to claim 1, characterized in that: It also includes a protective window sheet, which is attached to a side of the optical adjustment component away from the emission port.

6. The polarization spectrum target simulation source according to claim 5, characterized in that: The surface of the protective window is coated with an infrared attenuation film layer to reduce the emitted infrared light component.

7. The polarization spectrum target simulation source according to claim 1, characterized in that: The optical adjustment component also includes a third spatial phase delay modulator, which is mounted on a side of the second spatial phase delay modulator away from the second polarizer.

8. The polarization spectrum target simulation source according to claim 7, characterized in that: The transmission direction of the polarizer of the optical adjustment component and the phase of each pixel of the spatial phase delay modulator are both adjustable.

9. The polarization spectrum target simulation source according to claim 1, characterized in that: The Bayer filter includes a color pixel array, and each color pixel includes four sub-pixels of different colors.

10. A polarization spectrum target simulation source according to claim 9, characterized in that: The sub-pixels of the Bayer filter and the pixels of the spatial phase delay modulator are the same in size and aligned with each other.

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