Polarized spectral target simulation source

Abstract

The present application provides a kind of polarized spectral target simulation source, including face uniform adjustable spectrum light source and optical adjustment component, the face uniform adjustable spectrum light source is used to generate the uniform light of specific spectral region wavelength, with the exit port for uniform light output, the optical adjustment component is set at exit port, including first polarizer, first spatial phase delay modulator, bayer filter, second polarizer and second spatial phase delay modulator, which are sequentially arranged away from exit port along the normal direction of exit port, for the modulation of uniform light output by exit port, to output multidimensional target simulation light signal.The present application provides a kind of polarized spectral target simulation source, with controllable adjustable multidimensional light signal output capability, and suitable for multispectral polarized imaging instrument and load laboratory test, also beneficial to non-polarized optical equipment test own polarizing characteristics, and can more accurately, perfect simulation cloud, fog and other polarized target optical characteristics.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of scene target simulator, in particular to a polarized spectral target simulation source. BACKGROUND

[0002] In recent years, the spaceborne polarization detection technology has been developing rapidly. Since the scattering polarization characteristics exist in artificial targets, cloud phase, aerosols, etc., the polarization observation method can effectively expand the information quantity and improve the convergence and accuracy of subsequent inversion. At present, various spaceborne polarization remote sensing payloads have been developed at home and abroad, among which the influential ones include PACE-HARP, APS of the United States, POLDER of France, SPEX of the Netherlands, SGLI of Japan, etc. Not only that, NASA is actively planning the next generation of payloads MSPI, and the corresponding ESA is expected to launch the newly developed multi-angle polarization camera 3MI successively in 2021, 2023 and 2025; Japan also has a follow-up payload plan for SGLI. Although the domestic start is relatively late, but also layout of multiple polarization load: such as multi-angle polarization imager (GF-5-01, 02), polarization scanner POSP (GF-5-02), polarization camera (Tiangong-2) and so on, and continue to actively promote the development of the technology.

[0003] A key technical problem affecting the above payloads is that there is coupling between polarization detection, imaging, inversion, etc. To measure this interference, a controllable and adjustable target simulation source with polarization, spectral, geometric, light intensity and other dimensional light signal output capabilities is necessary.

[0004] However, the existing target simulation sources are basically star simulation, guidance simulation, infrared target simulation, etc. (such as Li Deming et al., Star sensor image simulation and target background motion characteristic analysis; Liu Xiran et al., Small target simulator optical and mechanical structure design based on LCOS splicing; Qiang Xiaotian et al., Key technology research of target simulator based on digital micromirror device), most of which are limited to two dimensions of geometry and light intensity, and have no polarization simulation capability. NASA developed a multi-polarized light source (MPSP) in 2012, which uses LCOS liquid crystal spatial modulation projection to generate controllable light intensity multi-spectral polarized light in time, but cannot output images, and it is difficult to realize target shape simulation (geometric dimension simulation). So far, there is no report on a target simulation source that can output quantitative multi-spectral polarized images. SUMMARY

[0005] The present application aims to provide a polarized spectral target simulation source, which is suitable for a multi-spectral polarized imaging load / equipment, has adjustable and controllable light signal output capacity in the dimensions of polarization, spectrum, geometry, light intensity, etc., and solves the technical problem that the existing target simulation source cannot simultaneously output signals in the dimensions of quantified polarization, spectrum, geometry, radiation, etc.

[0006] To solve the above technical problem, the present application is implemented by the following technical scheme:

[0007] The present application provides a polarized spectral target simulation source, which comprises:

[0008] A surface-uniform adjustable spectrum light source is used to generate uniform light in a specific spectral region, and the surface-uniform adjustable spectrum light source has an exit for the uniform light output;

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

[0010] The optical adjustment assembly is used to modulate the uniform light output by the exit to output a multi-dimensional target simulation light signal.

[0011] In an embodiment of the present application, a support device is further included, and the optical adjustment assembly is attached to the exit by the support device.

[0012] In an embodiment of the present application, the optical adjustment assembly is fixedly installed at the exit.

[0013] In an embodiment of the present application, the first polarizer, the first spatial phase delay modulator, the Bayer filter, the second polarizer, and the second spatial phase delay modulator are bonded by ultraviolet light-sensitive glue.

[0014] In an embodiment of the present application, a protective window sheet is further included, and the protective window sheet is attached to the side of the optical adjustment assembly away from the exit.

[0015] In an embodiment of the present application, an infrared attenuation film layer is coated on the surface of the protective window sheet to reduce the infrared light component of the exit.

[0016] In an embodiment of the present application, the optical adjustment assembly further comprises a third spatial phase delay modulator, and the third spatial phase delay modulator is attached to the side of the second spatial phase delay modulator away from the second polarizer.

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

[0018] In one embodiment of the present application, the Bayer filter comprises an array of color pixels, each of which comprises four sub-pixels of different colors.

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

[0020] The present application provides a polarized spectral target simulation source, comprising: a surface-uniform adjustable spectral light source for generating uniform light of a specific spectral region wavelength, the surface-uniform adjustable spectral light source having an exit port for the uniform light output, an optical adjustment assembly arranged at the exit port, the optical adjustment assembly comprising, in sequence away from the exit port along the normal direction of the exit port, a first polarizer, a first spatial phase delay modulator, a Bayer filter, a second polarizer, and a second spatial phase delay modulator, wherein the optical adjustment assembly is used to modulate the uniform light output by the exit port to output a multi-dimensional target simulation light signal. The polarized spectral target simulation source provided by the present application can realize controllable and adjustable light signal output with polarization, spectrum, geometry, light intensity, and other comprehensive multiple dimensions, filling the gap in the prior art that there is no such target simulation source. In addition, the polarized spectral target simulation source is suitable for laboratory testing of multispectral polarization imaging instruments and loads, and is also conducive to testing the polarization characteristics of non-polarized optical equipment. In addition, the polarized spectral target simulation source is conducive to simulating natural scenes in the laboratory, such as more accurately and perfectly simulating the optical characteristics of polarized targets such as clouds and fog.

[0021] Of course, implementing any product of the present application does not necessarily require all the advantages described above to be achieved at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed for the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

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

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

[0025] Figure 3 A structure diagram of a polarized spectral target simulation source provided for an example embodiment of the present application.

[0026] Figure 4 A partial structure diagram of a polarized spectral target simulation source provided for an example embodiment of the present application.

[0027] Reference signs are as follows:

[0028] 1 uniform spectral light source

[0029] 2 first polarizer

[0030] 3 first spatial phase delay modulator

[0031] 4 Berek filter

[0032] 5 second polarizer

[0033] 6 second spatial phase delay modulator

[0034] 7 third spatial phase delay modulator

[0035] 8 protective window

[0036] 101 light source box

[0037] 102 halogen tungsten lamp

[0038] 103 filter wheel

[0039] 104 diaphragm DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0041] In order to solve the technical problem that the existing target simulation source cannot consider the quantitative output of polarization, spectrum, geometry, radiation and other dimensional signals, the present application provides a polarized spectrum target simulation light source, comprising: a surface-uniform adjustable spectrum light source for generating uniform light of a specific spectral region wavelength, the surface-uniform adjustable spectrum light source has an exit port for the uniform light output, an optical adjustment assembly arranged at the exit port, the optical adjustment assembly comprises 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 port along the normal direction of the exit port, wherein the optical adjustment assembly is used for modulating the uniform light output by the exit port to output a multi-dimensional target simulation light signal. The embodiments will be described in detail below.

[0042] In an exemplary embodiment of the present application, the polarized spectrum target simulation light source comprises a surface-uniform adjustable spectrum light source 1, an optical adjustment assembly (not shown) and a protective window sheet 8.

[0043] Specifically, please refer to Figure 1 shown, Figure 1 is a system composition schematic diagram of the polarized spectrum target simulation light source, the polarized spectrum target simulation light source comprises a surface-uniform adjustable spectrum light source 1, an optical adjustment assembly (not shown) and a protective window sheet 8, the optical adjustment assembly (not shown) comprises 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 for generating uniform light of a specific spectral region wavelength, and the optical adjustment assembly (not shown) is used for modulating the uniform light output by the exit port 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 light splitting and spectrum selecting device, or directly use a combination of multiple narrow spectrum light sources, for example, a combination of multiple color LED light sources. The light splitting and spectrum selecting device can be similar to the output light mode of a monochromator, or can be a wave band selection mode through a filter switching. The working principle of the monochromator includes that a light source provides a continuous wide spectrum light for the monochromator, the continuous wide spectrum light is dispersed into light beams of different wavelengths through a dispersion system, and a selection system selects a light beam of a specific wavelength range according to user demand.

[0044] Further, please continue to refer to Figure 2As shown, the output light of the surface-uniform tunable spectral light source 1 is surface-uniform, with good uniformity. The surface-uniform tunable spectral light source itself has the ability to output narrow-band light in a wide spectral range, and can also output full-spectrum light, increasing the output spectral degree of freedom of the polarized spectral target simulation source. The polarizer is an optical device that can convert incident light into linearly polarized light, and its shape is in the form of a sheet or a film. The spatial phase delay modulator includes a certain number of pixels arranged in a rectangular array, such as a 256x256 pixel array, and the spatial phase delay modulator can be electrically controlled to adjust the phase delay of each pixel within a certain range. In this embodiment, the phase delay of each pixel of the spatial phase delay modulator is adjusted within a range of 0 to π / 2. Of course, in other embodiments, other adjustment ranges of spatial phase delay modulators can also be used as long as the adjustment range requirements are met.

[0045] In an example embodiment of the present application, the surface-uniform tunable spectral light source 1 has an exit port for the uniform light output, and the optical adjustment assembly (not shown) is arranged at the exit port. The optical adjustment assembly (not shown) includes, in order from the normal direction of the exit port, 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.

[0046] Specifically, please refer to Figure 3 and Figure 4 As shown, Figure 3 is a structural schematic diagram of the polarized spectral target simulation source, Figure 4 is Figure 3 a partial enlarged view. In this embodiment, the surface-uniform tunable spectral light source 1 uses a tunable spectral integrating sphere, which 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 a diaphragm 104. A plurality of light source devices are uniformly arranged in the front half of the sphere of the tunable spectral integrating sphere, i.e., the half-sphere portion close to the optical adjustment assembly, so that the exit port of the tunable spectral integrating sphere outputs uniform light of a specific spectral region wavelength. In this embodiment, the selectable wavelengths of the surface-uniform tunable spectral light source 1 include 490nm±20nm, 550nm±20nm, 670nm±20nm, 400-700nm white light, and the like. The optical adjustment assembly (not shown) is fixedly installed at the exit port of the surface-uniform tunable spectral 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 sequentially and closely combined along the normal direction of the exit port.

[0047] In an exemplary embodiment of the present application, the polarized spectral target simulation source further comprises a supporting device, and the optical adjustment assembly (not shown) is attached to the exit port by the supporting device. Specifically, in other embodiments, the optical adjustment assembly (not shown) can be supported by the supporting device, such as a bracket, a column, etc., so that the optical adjustment assembly (not shown) is attached to the exit port of the surface-uniform adjustable spectral 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 by ultraviolet light-sensitive glue. It should be noted that in this embodiment, the ultraviolet light-sensitive glue is uniformly coated between each optical element of the optical adjustment assembly (not shown), and after the alignment of the Bayer filter 4 and the spatial phase delay modulator under a microscope, ultraviolet light is irradiated to solidify the ultraviolet light-sensitive glue, so as to ensure the firm bonding between the optical elements.

[0049] In an exemplary embodiment of the present application, the polarized spectral target simulation source further comprises a protective window 8 attached to a side of the optical adjustment assembly (not shown) away from the exit port.

[0050] Specifically, referring to FIGS. 1, 2 and 3, Figure 3 and Figure 4 As shown, the protective window 8 is attached to a side of the optical adjustment assembly (not shown) away from the exit port by ultraviolet light-sensitive glue. The protective window 8 can be used to protect the optical adjustment assembly (not shown) from external collision damage at the physical level. Further, the surface of the protective window 8 can be coated with an infrared attenuation film layer, which acts as a filter to reduce the infrared light component of the exit light. It should be noted that in other embodiments, the protective window 8 can also be removed, i.e., the element can be installed or removed.

[0051] In an exemplary embodiment of the present application, the optical adjustment assembly (not shown) further comprises 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 attached to a 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 attached to a side of the second spatial phase delay modulator 6 away from the second polarizer 6 by ultraviolet light-sensitive glue. In addition, in other embodiments, a one-stage spatial phase delay modulator can also be used to expand the modulation range of the phase delay in certain specific application fields.

[0052] In an example embodiment of the present application, the polarization direction of the polarizer of the optical adjustment assembly (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 light components parallel to its polarization direction to pass through, while absorbing light components perpendicular to its polarization direction. The spatial phase delay modulator is a device that can control different phase delays of light beams on each pixel, which is externally similar to a wave plate with an adjustable phase delay on each pixel.

[0053] In an example embodiment of the present application, the Bayer filter 4 includes an array of color pixels, each of which includes four sub-pixels of different colors. Specifically, please refer to Figure 2 In the embodiment shown, the Bayer filter in the present embodiment adopts an RGBW Bayer filter to ensure the radiant brightness of white light, wherein the size of each color pixel of the Bayer filter 4 is 50 microns.

[0054] In an example embodiment of the present application, the size of the sub-pixel of the Bayer filter 4 is the same as that of the pixel of the spatial phase delay modulator and they are aligned with each other. Specifically, the size of a single pixel of the spatial phase delay modulator is 50 microns, and the size of the corresponding sub-pixel of the Bayer filter 4 is also 50 microns. The sub-pixel of the Bayer filter 4 is aligned with the pixel of the spatial phase delay modulator by observing the pixel under a microscope. 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 the pixel alignment should ensure that the error does not exceed one-tenth of the size of a pixel.

[0055] In an example embodiment of the present application, please refer to Figure 2 As shown, the simulation process of the light signal of the polarized spectral target simulation source includes the following steps:

[0056] S100: The uniform light emitted by the surface-uniform adjustable spectral light source 1 passes through the first polarizer 2, and the first polarizer 2 converts the non-polarized light (i.e., the uniform light) into linearly polarized light;

[0057] S200: The linearly polarized light passes through the first spatial phase delay modulator 3, and the first spatial phase delay modulator 3 modulates the phase of the linearly polarized light, so that the linearly polarized light originally vibrating in the same plane becomes light waves with different phase vibrations in different planes. After synthesis, elliptically polarized light is formed.

[0058] S300: The elliptical polarized light passes through the Bayer filter 4, and the elliptical polarized light is spectrally modulated by the Bayer filter 4, wherein the gray scale of each pixel of the elliptical polarized light after passing through the Bayer filter 4 is different;

[0059] S400: After the elliptical polarized light passes through the Bayer filter 4, the gray scale of the elliptical polarized light is modulated by the second polarizer 5, and 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: The 2x2 pixel spectrum is mixed, and the 2x2 pixel phase is modulated by the second spatial phase delay modulator 6, and then modulated again by the third spatial phase delay modulator 7 to expand the polarization state output capability;

[0061] S600: The 2x2 pixel corrected output spectrum is obtained by the protective window 8, and the final output analog light signal is obtained.

[0062] It should be noted that in the present embodiment, the first polarizer 2, the first spatial phase delay modulator 3, the Bayer filter 4, and the second polarizer 5 are tightly attached by ultraviolet light sensitive glue and aligned under a microscope, and then cured by ultraviolet light to ensure that the optical elements are firmly glued. First, test to determine that the whole composed of the first polarizer 2, the first spatial phase delay modulator 3, the Bayer filter 4, and the second polarizer 5 can normally modulate after uniform light transmittance. After determining that it can normally modulate, the second spatial phase delay modulator 6 and the third spatial phase delay modulator 7 are attached to the side of the second polarizer 5 away from the Bayer filter in the same way, i.e. the second spatial phase delay modulator 6 and the third spatial phase delay modulator 7 are attached to the side of the second polarizer 5 away from the Bayer filter by ultraviolet light sensitive glue, and then aligned under a microscope and irradiated with ultraviolet light to cure the ultraviolet light sensitive glue, thereby forming the optical adjustment assembly (not shown). Finally, the protective window 8 is attached to the optical adjustment assembly (not shown), and again provides a modulation degree of freedom for the spectrum.

[0063] Further, in the 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 transmission type liquid crystal spatial phase modulator, and the protective window is coated with an infrared attenuation film layer to serve as a filter. In addition, the integrating sphere can be selected to superimpose multiple spectra to make the output spectrum as close to the actual situation as possible. In the embodiment, one ground object simulation pixel is actually composed of 2x2 pixels. Through the above light signal simulation steps and the calibration of the emitted light radiation, the polarization geometric target simulation signals of multiple individual spectra can be quantitatively output, and the quantitative visible color polarization geometric target simulation signals can also be output. It is worth noting that in the embodiment, the actual final output light signal is elliptical polarized light, and in the application, it is feasible to replace part of the linear polarized light with elliptical polarized light because the circular polarization component of natural ground objects is relatively small.

[0064] In summary, the application provides a polarization spectrum target simulation source, which comprises 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 is phase-modulated by the spatial phase delay modulators, gray-modulated by a principle similar to that of a liquid crystal display, and combined with further double-layer spatial phase modulation, spectrum overall modulation, and 2x2 combined pixel simulation process to realize the target simulation of each pixel with consistent chroma (equivalent to consistency at a lower spectrum resolution) and consistent polarization. It should be noted that when the polarization spectrum target simulation source is quantitatively used, the radiation and spectrum emitted by the polarization spectrum target simulation source need to be calibrated.

[0065] The above description is only the preferred embodiment of the application and the explanation of the applied technical principles, and those skilled in the art should understand that the scope involved in the application is not limited to the technical solutions formed by the specific combinations of the above technical features, and also covers other technical solutions formed by any combination of the above technical features or equivalent features without departing from the inventive concept, for example, the technical solutions formed by the mutual replacement of the above features and the technical features disclosed in the application (but not limited to) with similar functions.

[0066] In addition to the technical features described in the specification, the remaining technical features are known to those skilled in the art, and in order to highlight the innovative features of the application, the remaining technical features are not described here.

Claims

1. A polarization spectral target simulation source, characterized in that, include: A surface-uniform tunable spectral light source is used to generate uniform light at wavelengths in a specific spectral region, and the surface-uniform tunable spectral light source has an outlet for outputting the uniform light. An optical adjustment assembly is disposed at the emission port. The optical adjustment assembly includes a first polarizer, a first spatial phase delay modulator, a Bayer filter, a second polarizer, and a second spatial phase delay modulator disposed sequentially away from the emission port along the normal direction of the emission port. The optical adjustment assembly further includes a third spatial phase delay modulator, which is attached to the side of the second spatial phase delay modulator away from the second polarizer; The optical adjustment component is used to modulate the uniform light output from the outlet to output a multi-dimensional target analog light signal.

2. The polarization spectral target simulation source according to claim 1, characterized in that, It also includes a support device, through which the optical adjustment assembly is attached to the outlet.

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

4. The polarization spectral 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 with ultraviolet photosensitive adhesive.

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

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

7. The polarization spectral target simulation source according to claim 1, characterized in that, The transmission direction of the polarizer in the optical adjustment component and the phase of each pixel of the spatial phase delay modulator are both adjustable.

8. A polarization spectral target simulation source according to claim 1, characterized in that, The Bayer filter includes a color pixel array, with each color pixel comprising four different color sub-pixels.

9. A polarization spectral target simulation source according to claim 8, characterized in that, The sub-pixels of the Bayer filter are the same size as the pixels of the spatial phase delay modulator and are aligned with each other.

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