A polarization multiplexed spectral imaging system based on acousto-optic tunable filter

Abstract

The application discloses a polarization multiplexed spectral imaging system based on an acousto-optic tunable filter and belongs to the technical field of spectral imaging. The system comprises, which are connected in sequence, a convergent incidence module, a spectral modulation module, a diffracted light separation correction module and an imaging module; the convergent incidence module converges and incides light into the spectral modulation module to obtain diffracted light and transmitted light with orthogonal polarization states containing specific spectra; the diffracted light separation correction module spatially separates the diffracted light and the transmitted light and shields the transmitted light, and compensates chromatic aberration and corrects inconsistency caused by polarization of the two beams of diffracted light through two branch lenses which are independent in parameters; and the imaging module combines and images the two beams of corrected diffracted light on the same pixel of a photoelectric detector, thereby solving the problem of large energy loss of a traditional acousto-optic tunable filter spectral imaging system caused by a front polarizer and realizing high-light-flux spectral imaging.

Description

Technical Field

[0001] This invention belongs to the field of spectral imaging technology in the field of optics, and more specifically, relates to a polarization multiplexing spectral imaging system based on an acousto-optic tunable filter. Background Technology

[0002] Spectral information is a valuable supplement to light intensity information and has wide and important applications in modern scientific research and industrial scenarios such as chemical composition analysis, remote sensing observation, medical detection, and characteristic target detection. Spectra can be divided into visible light, short-wave infrared, mid-wave infrared, and long-wave infrared spectra according to the detection wavelength. Among them, the spontaneous emission spectrum of mid-wave infrared typically corresponds to objects with temperatures between 300 and 700°C, such as molten metal, engine exhaust, and flames. Therefore, mid-wave infrared spectral information is often used for the detection of high-temperature targets.

[0003] An acousto-optic tunable filter (AOTF) is a spectral dispersive device combining acoustic, optical, and electronic technologies. By applying a radio frequency (RF) signal to a transducer attached to an acousto-optic crystal, an acoustic field is formed within the crystal, generating an acousto-optic grating. This grating is then used to produce diffracted light with a specific center wavelength via Bragg diffraction. AOTFs are characterized by high theoretical diffraction efficiency and flexible and rapid spectral control. By changing the frequency and power of the RF signal applied to the AOTF, high-speed and high-precision selection and control of the wavelength and intensity of the diffracted light can be achieved, thus showing broad development prospects in modern spectral analysis, precision optical measurement, and spectral imaging systems. Due to the polarization characteristics of the AOTF, unpolarized incident light is diffracted into two linearly polarized beams with orthogonal polarization states, each containing only specific spectral components, resulting in relatively weak energy. Therefore, to enhance the energy of the spectral channel, it is necessary to simultaneously utilize and superimpose the energy of both diffracted beams. However, AOTF devices are usually based on anisotropic crystals. The different polarization states of the two diffracted beams result in different refractive indices within the crystal, making it difficult for the images of the two diffracted beams to overlap during imaging. At the same time, the diffraction characteristics of AOTFs indicate that their diffraction angle is wavelength-dependent, thus introducing additional chromatic aberration, making image quality optimization in AOTF-based spectral imaging systems more challenging.

[0004] Currently, a common method to solve the problem of two diffracted beams failing to merge under unbiased incident conditions is to add a polarizer in front of the acousto-optic transducer (AOTF), converting the incident light into linearly polarized light in a specific direction. In this case, the AOTF device only has one linearly polarized outgoing beam, thus avoiding the problem of misalignment. Chinese Patent CN121007637A discloses an ultra-high-speed imaging device based on acousto-optic filtering modulation, including an embodiment with a linear polarizer and an AOTF, capable of generating narrowband illumination light using the AOTF and achieving spectral imaging through a subsequent system. However, this method and similar schemes suffer from at least 50% energy loss of the unbiased incident light due to the addition of a polarizer in front of the AOTF; furthermore, in spectral imaging applications, the energy within a single spectral channel is low, and the energy loss caused by the polarizer further limits the signal-to-noise ratio of the imaging. To address this, a polarization multiplexing spectral imaging system based on an acousto-optic tunable filter was designed. Through optical surface compensation and split lens design, the system achieved the image combining and chromatic aberration compensation of two polarized beams generated by non-polarized incident light, avoiding the energy loss problem caused by the AOTF pre-polarizer, effectively improving the light throughput of the spectral imaging system, and realizing high-quality imaging. Summary of the Invention

[0005] In view of the above-mentioned problems in the prior art, the purpose of this invention is to provide a polarization multiplexing spectral imaging system based on an acousto-optic tunable filter, and to provide a high-throughput spectral imaging scheme based on an acousto-optic tunable filter.

[0006] The technical solution of this invention is:

[0007] A polarization multiplexing spectral imaging system based on an acousto-optic tunable filter, comprising:

[0008] A converging incident module consisting of a secondary mirror, a primary mirror, a first lens, and a second lens; the secondary mirror, primary mirror, first lens, and second lens of the converging incident module are sequentially placed on the same optical axis.

[0009] A spectral modulation module consisting of a front window, an acousto-optic tunable filter, and a rear window; the front window, the acousto-optic tunable filter, and the rear window of the spectral modulation module are sequentially placed on the same optical axis.

[0010] A diffraction light separation and correction module consisting of a third lens, a fourth lens, a light-blocking aperture, a first splitting lens, and a second splitting lens; the third lens, the fourth lens, and the light-blocking aperture of the diffraction light separation and correction module are sequentially placed on the same optical axis, and the first splitting lens and the second splitting lens are respectively connected to the optical path of the fourth lens.

[0011] An imaging module consisting of a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a photodetector; the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the photodetector of the imaging module are placed sequentially on the same optical axis.

[0012] The converging incident light module converges the incident light to the incident spectral modulation module, resulting in two diffracted beams containing only specific spectral channels and orthogonal polarization states, and two transmitted beams generated by birefringence. The diffraction beam separation and correction module spatially separates the diffracted and transmitted beams emitted from the converging incident spectral modulation module, blocks the transmitted beam, and corrects the chromatic aberration and aberrations caused by the different polarization states of the two diffracted beams. The imaging module then merges the corrected two diffracted beams to image them at the same location, as shown in the instruction manual. Figure 1 As shown, the solid lines emitted from AOTF represent diffracted o-rays, and the dashed lines represent diffracted e-rays.

[0013] When unpolarized light is incident on an AOTF device, the polarization states of the transmitted and diffracted light are as shown in the attached instruction manual. Figure 2 As shown in the diagram, red represents diffracted light and blue represents transmitted light. The diffracted light contains only the specific spectrum obtained through acousto-optic tuning, while the transmitted light includes the remaining portion of the incident spectrum. There is a certain angle between the exit directions of the diffracted and transmitted light from the AOTF device; this angle is called the separation angle of the AOTF device. In a uniaxial acousto-optic crystal, the refractive index of the diffracted o-ray (which does not propagate along the optical axis) is different from that of the diffracted e-ray. This will cause the image points formed by two diffracted beams emitted from the same point within the crystal after refraction at the crystal-air interface to be at different points, as shown in the attached manual. Figure 3 As shown. Let the refractive indices of the two diffracted beams in the crystal be respectively... If the length of the crystal is L, then after refraction, the distance between the images of the two diffracted beams under the paraxial approximation condition is approximately:

[0014]

[0015] For tellurium dioxide crystals commonly used in AOTF devices, its At this point, the image spacing between the two diffracted beams is 2.75% of the light transmission length L of the AOTF device; and the light transmission length of the AOTF device is usually quite long, typically on the order of tens of millimeters, resulting in a large image spacing between the two diffracted beams. Therefore, the images of the two diffracted beams do not overlap. To image the two diffracted beams at the same position on the image plane, correction is required in the optical path after the AOTF device.

[0016] Besides the inconsistency caused by the different polarization states between the two diffracted beams, the diffracted light from the AOTF device also exhibits chromatic aberration due to two factors: the different separation angles of diffracted light at different wavelengths and the different refractive indices of diffracted light at different wavelengths. The separation angle α of the AOTF device is the angle between the diffracted light and the incident light, and it is related to the driving frequency f and the wavelength λ.

[0017]

[0018] Among them, V α Let n be the speed of sound in the crystal, and n be the refractive index of the diffracted light. In practical applications of AOTF devices, the incident angle of the light is generally kept constant, and the center wavelength of the diffracted light is controlled by adjusting the driving frequency. Therefore, different wavelengths of diffracted light have different diffraction angles in the AOTF device, and the angles at which they exit the AOTF device are also different, resulting in chromatic aberration.

[0019] On the other hand, different wavelengths of light have different refractive indices within the acousto-optic crystal, which will cause a chromatic focal shift in the emitted light, as shown in the instruction manual. Figure 4 As shown. Under paraxial conditions, the chromatic focal shift d(λ) caused by refraction of light of different wavelengths is:

[0020]

[0021] Where n(λ) is the refractive index of light with wavelength λ in the crystal. Since the refractive indices of o-ray and e-ray are different in the crystal, the color difference between the diffracted o-ray and e-ray is also different for the above-mentioned color difference. Therefore, compensating for the two diffracted beams separately can achieve better results when compensating for color difference.

[0022] To achieve the separation and separate compensation of the two diffracted beams, this invention designs a converging incident module, a spectral modulation module, and a diffracted beam separation correction module. The converging incident module's lens group converges the incident light into a converged beam with an aperture angle no greater than the separation angle of the AOTF device. The spectral modulation module then converts the emitted diffracted o-beam, diffracted e-beam, and transmitted light into spatially separated parallel beams by the third and fourth lenses of the diffracted beam separation correction module. The transmitted light is then eliminated by a light-blocking aperture. The diffracted o-beam undergoes chromatic aberration compensation through a first split lens, and the diffracted e-beam undergoes chromatic aberration compensation through a second split lens. The tilt, eccentricity, and thickness of the first and second split lenses are different to correct the inconsistencies between the diffracted o-beam and e-beam caused by different polarization states. After inconsistency correction and chromatic aberration compensation are completed, the subsequent imaging lens group can directly image the two diffracted beams and achieve image merging. (See the appendix of the specification.) Figure 1 .

[0023] The beneficial effects of this invention are:

[0024] (1) The present invention corrects the inconsistency and chromatic aberration introduced by the AOTF device through an optical system, and at the same time utilizes the two diffracted beams of the AOTF device to avoid at least 50% energy loss caused by polarizers in traditional methods, thereby improving the light flux of the spectral imaging system.

[0025] (2) The present invention uses AOTF devices as spectral splitting elements, which have the characteristics of adjustable band, flexible electronic control tuning, and all-solid-state without mechanical moving parts. The system has fast spectral switching response speed and high stability. Attached Figure Description

[0026] Figure 1 This is a structural diagram of the present invention; in the diagram: 100-converging incident spectrum modulation module; 101-secondary mirror; 102-primary mirror; 103-first lens; 104-second lens; 105-front window; 106-acousto-optic tunable filter (AOTF); 107-rear window; 200-diffraction light separation and correction module; 201-third lens; 202-fourth lens; 203-light-blocking aperture; 204-first splitter lens; 205-second splitter lens; 300-imaging module; 301-fifth lens; 302-sixth lens; 303-seventh lens; 304-eighth lens; 305-photodetector.

[0027] Figure 2 This is a schematic diagram of the polarization state of the emitted light from the AOTF.

[0028] Figure 3 This is a schematic diagram of the inconsistency in AOTF diffraction.

[0029] Figure 4 A schematic diagram of the color focal shift generated by the AOTF crystal;

[0030] Figure 5 To simplify the optical path parameter diagram;

[0031] Figure 6 The diagram shows the points at each field of view in the embodiment. In the diagram, red represents diffracted o-light and yellow represents diffracted e-light. The numerical pairs after the word "object plane" above each sub-diagram represent the two-dimensional field of view, and the numerical pairs after the word "image plane" below represent the position on the photodetector plane corresponding to the object plane field of view. The solid circle in the center represents the size range of the Airy disk, with a radius of 26.7 μm. Detailed Implementation

[0032] The present invention will be described in detail below with reference to specific embodiments.

[0033] See the attached instruction manual. Figure 1 The present invention includes:

[0034] A converging incident module (100) is composed of a secondary mirror (101), a primary mirror (102), a first lens (103), and a second lens (104); the secondary mirror (101), the primary mirror (102), the first lens (103), and the second lens (104) of the converging incident module (100) are placed on the same optical axis in sequence.

[0035] A spectral modulation module (200) is composed of a front window (201), an acousto-optic tunable filter (202), and a rear window (203); the front window (201), the acousto-optic tunable filter (202), and the rear window (203) of the spectral modulation module are placed sequentially on the same optical axis.

[0036] A diffraction light separation and correction module (300) is composed of a third lens (301), a fourth lens (302), a light-blocking aperture (303), a first splitting lens (304), and a second splitting lens (305); the third lens (301), the fourth lens (302), and the light-blocking aperture (303) of the diffraction light separation and correction module are placed on the same optical axis in sequence, and the first splitting lens (304) and the second splitting lens (305) are respectively connected to the optical path of the fourth lens (302).

[0037] An imaging system (400) consisting of a fifth lens (401), a sixth lens (402), a seventh lens (403), an eighth lens (404), and a photodetector (405); wherein the fifth lens (401), the sixth lens (402), the seventh lens (403), the eighth lens (404), and the photodetector (405) of the imaging system are placed sequentially on the same optical axis.

[0038] The working principle of this invention is as follows:

[0039] See the attached instruction manual. Figure 1 The incident light is reflected sequentially on the primary mirror (102) and the secondary mirror (101), and then passes through the first lens (103) and the second lens (104) to become a converging beam. After passing through the front window (201), it is incident on the acousto-optic tunable filter (202). The aperture angle of the converging beam is not greater than the minimum value of the separation angle of the acousto-optic tunable filter (202) in the system's operating band.

[0040] See the attached instruction manual. Figure 1 , Figure 2 After the converging beam is incident on the acousto-optic tunable filter (202), it becomes two linearly polarized diffracted beams (diffracted o-beam and diffracted e-beam) with specific spectra and orthogonal polarization states, and two linearly polarized transmitted beams with orthogonal polarization states. Figure 1The diffracted o-ray is represented by a solid line, and the diffracted e-ray is represented by a dashed line. The transmitted light is eliminated at the light-blocking stop (303) after passing through the rear window (203), the third lens (301), and the fourth lens (302) in sequence. Therefore, it is not... Figure 1 The diffracted o-ray and diffracted e-ray are drawn in the middle. After passing through the rear window (203), the third lens (301), and the fourth lens (302) in sequence, they are separated from each other and do not pass through the light-blocking aperture (303). The diffracted o-ray passes through the first splitting lens (304), and the diffracted e-ray passes through the second splitting lens (305) to compensate for the chromatic aberration in the two diffracted beams respectively. The thickness, eccentricity relative to the optical axis, and tilt of the first splitting lens (304) and the second splitting lens (305) are independent of each other, so as to correct the inconsistency between the diffracted o-ray and the diffracted e-ray.

[0041] See the attached instruction manual. Figure 1 The diffracted o-ray and diffracted e-ray are emitted from the diffraction light separation and correction module (300) and enter the imaging module (400). They pass through the fifth lens (401) and the sixth lens (402) in sequence to form an image, and then pass through the seventh lens (403) and the eighth lens (404) in sequence to form an image on the photodetector (405). The centroid of the image points of the diffracted o-ray and diffracted e-ray from the same field of view is located on the same pixel of the photodetector (405).

[0042] In some embodiments, the system operates in the infrared band, and the photodetector (405) is an infrared detector that requires cold aperture matching. Therefore, the imaging module (400) adopts a secondary imaging design to match such embodiments.

[0043] Furthermore, the optical parameters of the imaging module (400) are constrained by the parameters of the acousto-optic tunable filter (202) and the photodetector (405) in the system. See the appendix to the instruction manual. Figure 5 The dashed lines represent diffracted light. The system field of view is 2ω, the entrance pupil diameter is D, the converging beam aperture angle of the incident acousto-optic tunable filter (202) is 2θ, the diameter of the acousto-optic tunable filter (202) is 2H, the minimum separation angle within the working band is β, and the diameter of the photodetector (405) is 2h. The secondary mirror (101) to the second lens (104) are equivalent to lenses with a focal length of f1. The F-number of this lens group is F1, and the object-side field of view is 2ω1=2ω. The third lens (301) and the fourth lens (302) are equivalent to lenses with a focal length of f2. For transmitted light, the F-number of this lens group is F2, and the image-side field of view is 2ω2. The fifth lens (401) to the eighth lens (404) are equivalent to lenses with a focal length of f3. The F-number of this lens group is F3, and the object-side field of view is 2ω3. Figure 5 The geometric relationships in the equation are:

[0044]

[0045] See the attached instruction manual. Figure 5 The rear focal plane of lens group f1 coincides with the front focal plane of lens group f2. For the transmitted light emitted from the acousto-optic tunable filter (202), its exit pupil diameter after passing through lens group f2 is D2, satisfying F1 = F2, therefore:

[0046]

[0047] That is, D tan ω = D2tan ω2. For the two diffracted beams of the AOTF device, their angular apertures are approximately equal to those of the transmitted beams. However, due to the existence of the separation angle, after the diffracted beams pass through lens group f2, the image-side field of view is still 2ω2, but the exit pupil diameter increases to D3. When the diffracted beams and the transmitted beams are completely separated, D3≈3D2. At the same time, the first split lens (304) and the second split lens (305) mainly play the role of correction and chromatic aberration compensation. Their focal lengths are extremely large, and it can be approximately assumed that the image-side field of view and the exit pupil diameter of the diffracted beams remain unchanged. Therefore, in order to make the diffracted image completely imaged on the photodetector (405), the entrance pupil of lens group f3 must cover D3, and its object-side field of view should match the image-side field of view of lens group f2, that is, ω3=ω2. In order to make the diffracted beams and the transmitted beams of the AOTF device completely separated while maximizing the incident light flux, we take θ=β / 2, and then we have:

[0048]

[0049] The F-number of lens group f3 is subject to this constraint:

[0050]

[0051] Example: This example is a mid-wave infrared polarization multiplexing spectral imaging system based on an acousto-optic tunable filter. The operating wavelength is 3.7~4.8μm, the system field of view is ±0.55°, and the entrance pupil diameter is 80mm. In this example, all lenses and windows are coated with double-sided anti-reflection films, achieving a transmittance of no less than 98.5% within the operating wavelength; all reflective surfaces are coated with reflective films, achieving a reflectivity of no less than 99% within the operating wavelength.

[0052] See the attached instruction manual. Figure 1 The device described in this embodiment includes a converging incident light module (100), a spectral modulation module (200), a diffraction light separation and correction module (300), and an imaging module (400). The spacing between the reflectors and lenses in this embodiment is the distance along the optical axis from the center of the rear surface of the preceding reflector / lens to the center of the front surface of the following reflector / lens.

[0053] See the attached instruction manual. Figure 1In this embodiment, the secondary mirror (101) to the second lens (104) of the converging incident module (100) converts the incident light with an entrance pupil diameter of 80mm into a converging beam with an aperture angle of 4.6°. The secondary mirror (101) has a diameter of 25mm, the primary mirror (102) has a diameter of 85mm, and the blocking ratio is 0.29.

[0054] See the attached instruction manual. Figure 1 The acousto-optic tunable filter (202) of the spectral modulation module (200) described in this embodiment is a tellurium dioxide acousto-optic tunable filter with a working band of 3.7~4.8μm, a driving frequency range of 90~110MHz, and a separation angle of not less than 4.7° within the working band.

[0055] See the attached instruction manual. Figure 1 In this embodiment, the third lens (301) and the fourth lens (302) of the diffraction light separation correction module (300) completely separate the transmitted light pupil emitted from the acousto-optic tunable filter (202) from the pupils of the two diffracted lights on their exit pupil surfaces. The pupil diameters of the transmitted light and the diffracted light are both 6.3 mm, and the total diameter of the exit pupil surface is 20 mm.

[0056] See the attached instruction manual. Figure 1 In this embodiment, the light-blocking aperture (303) of the diffraction light separation correction module (300) is a reflective surface that rotates 30° clockwise around the y-axis in a coordinate system with the optical principal axis as the z-axis, the direction perpendicular to the optical principal axis in the paper as the y-axis, and the positive direction of the y-axis as the vertical upward direction.

[0057] See the attached instruction manual. Figure 1 In this embodiment, the first splitter lens (304) of the diffraction light separation and correction module (300) has an eccentricity (distance from the geometric center to the optical axis) of 5.3 mm and a tilt (positive with the angle of clockwise rotation around the geometric center in the paper plane as positive) of -0.13°; the second splitter lens (305) has an eccentricity (distance from the geometric center to the optical axis) of 5.4 mm and a tilt (positive with the angle of clockwise rotation around the geometric center in the paper plane as positive) of 2.60°;

[0058] See the attached instruction manual. Figure 1 In this embodiment, the lens group (401) to (404) in the imaging module (400) is an imaging lens group with an entrance pupil diameter of 20mm, a focal length of 37mm, and an F number of 1.85. The distance from the light-blocking aperture (303) to the fifth lens (401) in the imaging module (400) is 20mm.

[0059] See the attached instruction manual. Figure 1 In this embodiment, the optical axis of the imaging module (400) is rotated 1° clockwise relative to the optical axis of the diffraction light separation correction module (300).

[0060] See the attached instruction manual. Figure 1 , Figure 6 In this embodiment, the photodetector (405) of the imaging module (400) is a mid-wave infrared imaging detector with 256×256 pixels, a pixel size of 30μm, and a working wavelength of 3.7~4.8μm. The distance between the centroids of the image points formed on the photodetector by the diffracted o-ray and diffracted e-ray from the same field of view is less than 15μm.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polarization multiplexing spectral imaging system based on an acousto-optic tunable filter, characterized in that, To address the issue of high energy loss caused by the pre-polarizer in traditional acousto-optic tunable filter-based spectral imaging systems, the system is designed as a polarization multiplexing spectral imaging system consisting of a converging incident module (100), a spectral modulation module (200), a diffraction beam separation and correction module (300), and an imaging module (400). The system generates two diffracted beams with orthogonal polarization states by passing the convergent incident unpolarized light through the acousto-optic tunable filter. These beams are then spatially separated from the transmitted light, and all transmitted light is blocked. Independently oriented split lenses correct the chromatic aberration and aberrations caused by the polarization state difference between the two diffracted beams. Finally, the corrected beams are merged and imaged at the same position on the detector. This avoids the energy loss caused by the pre-polarizer, effectively increasing the system's luminous flux while retaining the advantages of the acousto-optic tunable filter, such as flexible electronic tuning and high stability, thus achieving high-flux spectral imaging. The converging incident module (100) converges the incident light to the incident spectral modulation module (200), from which two beams of diffracted light containing only specific spectral channels and orthogonal polarization states and two beams of transmitted light are emitted; the diffraction light separation and correction module (300) separates the diffracted light and transmitted light emitted from the spectral modulation module (200) in space, blocks the transmitted light, corrects the color difference between the two diffracted beams and the aberration caused by the different polarization states of the two diffracted beams, and the imaging module (400) combines the corrected two diffracted beams into an image.

2. The polarization multiplexing spectral imaging system based on an acousto-optic tunable filter according to claim 1, characterized in that, The converging incident module (100) consists of a secondary mirror (101), a primary mirror (102), a first lens (103), and a second lens (104); the secondary mirror (101), the primary mirror (102), the first lens (103), and the second lens (104) are placed sequentially on the same optical axis.

3. The polarization multiplexing spectral imaging system based on an acousto-optic tunable filter according to claim 1, characterized in that, The spectral modulation module (200) consists of a front window (201), an acousto-optic tunable filter (202), and a rear window (203); the front window (201), the acousto-optic tunable filter (202), and the rear window (203) of the spectral modulation module are placed on the same optical axis in sequence.

4. The polarization multiplexing spectral imaging system based on an acousto-optic tunable filter according to claim 1, characterized in that, The diffraction light separation and correction module (300) is composed of a third lens (301), a fourth lens (302), a light-blocking aperture (303), a first splitting lens (304), and a second splitting lens (305); the third lens (301), the fourth lens (302), and the light-blocking aperture (303) are placed on the same optical axis in sequence.

5. The polarization multiplexing spectral imaging system based on an acousto-optic tunable filter according to claim 1, characterized in that, The imaging module (400) consists of a fifth lens (401), a sixth lens (402), a seventh lens (403), an eighth lens (404), and a photodetector (405); the fifth lens (401), the sixth lens (402), the seventh lens (403), the eighth lens (404), and the photodetector (405) are placed on the same optical axis in sequence.

6. A polarization multiplexing spectral imaging system based on an acousto-optic tunable filter according to claim 4, characterized in that, The third lens (301), fourth lens (302), and light-blocking aperture (303) of the converging incident module (100), spectral modulation module (200), and diffraction light separation correction module (300) are on the same optical axis. The first split lens (304), the second split lens (305), and the converging incident module (300) are not on the same optical axis. Furthermore, the tilt and eccentricity of the first split lens (304) and the second split lens (305) relative to the optical axis of the converging incident module (100) are independent of each other.

7. A polarization multiplexing spectral imaging system based on an acousto-optic tunable filter according to claim 4, characterized in that, The light-blocking aperture (303) is a reflector that reflects the transmitted energy emitted from the spectral modulation module (200) to the outside of the optical path.

8. A polarization multiplexing spectral imaging system based on an acousto-optic tunable filter according to claim 5, characterized in that, The optical axis of the imaging module (400) is independent of the optical axis of the diffraction light separation and correction module (300).

Images