Dual-channel hyperspectral imaging device and method based on sagnac interferometer

Abstract

The application discloses a kind of dual-channel hyperspectral imaging device and method based on Sagnac interferometer.The incident light from target collimates after passing through pre-imaging objective, diaphragm and collimating objective, and is incident to Wollaston prism again after passing through polarizer, and Wollaston prism shears incident light into different direction o light and e light, and after passing through Sagnac waveband division shear structure, different waveband o light and e light produce different lateral shear amount, and are emitted along different directions, pass through polaroid array and filter array, and finally form spatially separated two different waveband interference images on area array detector by post-imaging objective.The application can obtain two groups of interference images under different wavebands by once push scanning, and realizes high-resolution spectral imaging under wide waveband range.

Description

Technical Field

[0001] This invention belongs to the field of spectral imaging technology, and in particular to a dual-channel hyperspectral imaging device and method based on a Sagnac interferometer. Background Technology

[0002] Spectral imaging technology has a wide range of applications, playing a crucial role in geological exploration, atmospheric remote sensing, and military applications. With the development of imaging spectroscopy, wide-band, high-resolution detection has gained significant attention. However, in actual detection processes, the limited number of sampling points on the detector restricts the spectral range, resulting in a trade-off between spectral resolution and spectral range. High spectral resolution can only be achieved in a narrower band, while spectral resolution is limited across a wider band.

[0003] In traditional spectral interferometry systems, the optical path difference between adjacent wavelengths is the same, making it impossible to reduce the wavenumber interval between two spectral lines that differ by one fringe. Therefore, within the limited optical path difference range for imaging, the spectral resolution is limited. To improve the spectral resolution of interferometric imaging spectrometers, a conventional method is to place a dispersive element in the optical path to introduce dispersion shearing. By compressing the optical path difference between different wavelengths, the optical path difference of beams of different wavelengths is modulated, thereby improving the spectral resolution of the system. However, this method can only be achieved in a narrow band and cannot achieve high spectral resolution imaging over a wide band. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-channel hyperspectral imaging device and method based on a Sagnac interferometer, so as to solve the problem that the spectral resolution is limited in a wide band in traditional interferometric spectral imaging technology.

[0005] The technical solution to achieve the purpose of this invention is as follows: On the one hand, a dual-channel hyperspectral imaging device based on a Sagnac interferometer is provided. The device includes a front imaging objective, an aperture, a collimating objective, a polarizer, a Wollaston prism, a Sagnac band-splitting shearing structure, a polarizer array, a filter array, a rear imaging objective, and an area array detector arranged sequentially along the optical path.

[0006] Incident light from the target is imaged onto the aperture by the front imaging objective, then collimated by the collimating objective, and then incident on the Wollaston prism after passing through the polarizer. The Wollaston prism shears the incident light into o-rays and e-rays in different directions. After passing through the Sagnac band-splitting shearing structure, the o-rays and e-rays of different bands produce different lateral shearing amounts and exit in different directions. They pass through the polarizer array and filter array in sequence, and finally interfere on the area array detector after passing through the rear imaging objective, forming an interference image in two spatially separated bands.

[0007] Furthermore, the Wollaston prism is made of two calcite right-angled prisms with identical bottom surfaces glued together, and the optical axes of the two calcite right-angled prisms are orthogonal.

[0008] Furthermore, the Sagnac shear structure includes a beam splitter prism, a reflector, and a reflector plate. The surface of the reflector plate is coated with an optical thin film, which can simultaneously reflect and transmit light of different wavelengths.

[0009] Furthermore, the front surface of the reflector plate reflects waveband A and transmits waveband B, while the rear surface reflects waveband B. The light in the two wavebands produces different lateral shearing amounts.

[0010] Furthermore, the thickness of the reflector plate is adjustable to introduce different lateral shearing amounts for light of different wavelengths.

[0011] Furthermore, the polarizer array is a 2×1 array, and its transmission axis is in the same direction as the vibration direction of the o-ray and e-ray, respectively.

[0012] Furthermore, the filter array is a 2×1 array, which transmits wavelengths A and B respectively.

[0013] On the other hand, a dual-channel hyperspectral imaging method based on a Sagnac interferometer is provided, including the following steps:

[0014] Step 1: The incident light is imaged at the aperture by the front imaging objective, then collimated by the collimating objective to form a collimated beam, and then incident on the Wollaston prism after passing through the polarizer.

[0015] Step 2: The incident light is sheared into two beams, o-ray and e-ray, by the Wollaston prism, and the two outgoing beams are deflected upward and downward respectively;

[0016] Step 3: Two outgoing light beams are incident on the Sagnac waveband shearing structure. After passing through the front and rear surfaces of the reflector plate M2, different wavelengths of light produce different lateral shearing amounts. The o-light is deflected upwards and outgoing, while the e-light is deflected downwards and outgoing.

[0017] Step 4: The polarizer array selects the o-light and e-light respectively. After passing through the filter array, the light in band A of the o-light is transmitted and the light in band B of the e-light is transmitted.

[0018] Step 5: After the light from the two wavelengths passes through the rear imaging objective lens, it interferes on the area array detector, forming two interference patterns, one above the other.

[0019] Furthermore, the method also includes:

[0020] Step 6: The dual-channel hyperspectral imaging device based on the Sagnac interferometer is used to push-broom the imaging target, and the incident angle of the target light is changed to modulate the optical path difference, so as to obtain two sets of interference image sequences in different bands.

[0021] Step 7: Perform spectral restoration based on the obtained interference image information to obtain the spectral information of each target point in both bands.

[0022] Compared with the prior art, the significant advantages of this invention are:

[0023] 1) By employing Wollaston beam splitting and Sagnac shearing structures, multi-band interferometric imaging is achieved from two dimensions.

[0024] 2) The coating of the M2 reflector with the Sagnac shear structure can achieve wide-band detection while ensuring spectral resolution.

[0025] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a dual-channel hyperspectral imaging device based on a Sagnac interferometer in one embodiment.

[0027] Figure 2 This is a schematic diagram of beam splitting using a Wollaston prism in one embodiment.

[0028] Figure 3 This is a schematic diagram of the spatial structure of the Sagnac band-splitting device in one embodiment.

[0029] Figure 4 This is a cross-sectional schematic diagram of the reflector M2 in one embodiment.

[0030] Figure 5 This is a schematic diagram of a polarizer array in one embodiment.

[0031] Figure 6 This is a schematic diagram of a filter array in one embodiment. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0033] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0034] In one embodiment, combined Figure 1 A dual-channel hyperspectral imaging device based on a Sagnac interferometer is provided. The device includes a front imaging objective 1, an aperture 2, a collimating objective 3, a polarizer 4, a Wollaston prism 5, a Sagnac band-splitting structure 6, a polarizer array 7, a filter array 8, a rear imaging objective 9, and an area array detector 10 arranged sequentially along the optical path.

[0035] The incident light from the target is imaged onto the aperture 2 by the front imaging objective 1, then collimated by the collimating objective 3 to form a collimated beam, and then incident on the Wollaston prism 5 after passing through the polarizer 4. The Wollaston prism 5 shears the incident light into o-rays and e-rays in different directions. After passing through the Sagnac band-splitting shearing structure 6, the o-rays and e-rays of different bands produce different lateral shearing amounts and exit in different directions. They pass through the polarizer array 7 and the filter array 8 in sequence, and finally interfere on the area array detector 10 after passing through the rear imaging objective 9, forming an interference image in two spatially separated bands.

[0036] Furthermore, in one embodiment, the Wollaston prism 5 is formed by gluing together two calcite right-angle prisms with identical base surfaces, the optical axes of the two calcite right-angle prisms being orthogonal. (Combined) Figure 2 The Wollaston prism 5 splits the incident light into o-rays and e-rays in different directions, with both beams deflected at an angle of 0°.

[0037] Furthermore, combined Figure 3 The Sagnac band-splitting shearing structure 6 includes a beam splitter prism BS, a reflector M1, and a reflector plate M2. The thickness of M2 is d, the lateral shearing amount for band A is s1, and the lateral shearing amount for band B is s2. Combined with... Figure 4 The reflector plate M2 is coated with an optical thin film, which can simultaneously reflect and transmit light of different wavelengths. The front surface reflects wavelength A and transmits wavelength B, while the rear surface reflects wavelength B.

[0038] Furthermore, in one embodiment, combined with Figure 5 Polarizer array 7 is a 2×1 array, with its transmission axis pointing in the directions of the vibrations of the o-ray and e-ray, respectively. The arrows in the diagram represent these transmission axis directions. (Combined with...) Figure 6The filter array 8 is a 2×1 array, which can transmit wavelengths A and B respectively.

[0039] In one embodiment, a dual-channel hyperspectral imaging method based on a Sagnac interferometer is provided, comprising the following steps:

[0040] Step 1: The incident light is imaged at the aperture by the front imaging objective, then collimated by the collimating objective to form a collimated beam, and then incident on the Wollaston prism after passing through the polarizer.

[0041] Step 2: The incident light is sheared into two beams, o-ray and e-ray, by the Wollaston prism, and the two outgoing beams are deflected upward and downward respectively;

[0042] Step 3: Two outgoing light beams are incident on the Sagnac waveband shearing structure. After passing through the front and rear surfaces of the reflector plate M2, different wavelengths of light produce different lateral shearing amounts. The o-light is deflected upwards and outgoing, while the e-light is deflected downwards and outgoing.

[0043] Step 4: The polarizer array selects the o-light and e-light respectively. After passing through the filter array, the light in band A of the o-light is transmitted and the light in band B of the e-light is transmitted.

[0044] Step 5: After the light from the two wavelengths passes through the rear imaging objective lens, it interferes on the area array detector, forming two interference patterns, one above the other.

[0045] Furthermore, in one embodiment, the method further includes:

[0046] Step 6: The dual-channel hyperspectral imaging device based on the Sagnac interferometer is used to push-broom the imaging target, and the incident angle of the target light is changed to modulate the optical path difference, so as to obtain two sets of interference image sequences in different bands.

[0047] Step 7: Perform spectral restoration based on the obtained interference image information to obtain the spectral information of each target point in both bands.

[0048] In summary, this invention employs a dual-channel hyperspectral imaging device based on a Sagnac interferometer. Through Wollaston prism beam splitting and Sagnac sheared M2 mirror coating, it achieves wide-band imaging while maintaining high spectral resolution. Spectral information in different bands can be obtained with a single push-broom operation. The device has a simple structure and excellent imaging quality.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention without departing from its spirit and scope should be included within the protection scope of the present invention.

Claims

1. A dual-channel hyperspectral imaging device based on a Sagnac interferometer, characterized in that, The device includes a front imaging objective, an aperture, a collimating objective, a polarizer, a Wollaston prism, a Sagnac band-splitting shearing structure, a polarizer array, a filter array, a rear imaging objective, and an area array detector arranged sequentially along the optical path. The incident light from the target is imaged onto the aperture by the front imaging objective, then collimated by the collimating objective, and then incident on the Wollaston prism after passing through the polarizer. The Wollaston prism shears the incident light into o-rays and e-rays in different directions. After passing through the Sagnac band-splitting shearing structure, the o-rays and e-rays of different bands produce different transverse shearing amounts and exit in different directions. They pass through the polarizer array and the filter array in sequence, and finally interfere on the area array detector after passing through the rear imaging objective, forming an interference image of two spatially separated bands. The Sagnac band splitting shearing structure includes a beam splitter prism, a reflector, and a reflector plate. The surface of the reflector plate is coated with an optical thin film, which can simultaneously reflect and transmit light of different bands. The front surface of the reflector plate reflects waveband A and transmits waveband B, while the rear surface reflects waveband B. The light in the two wavebands produces different lateral shearing amounts.

2. The dual-channel hyperspectral imaging device based on a Sagnac interferometer according to claim 1, characterized in that, The Wollaston prism is made of two calcite right-angled prisms with identical base surfaces glued together, and the optical axes of the two calcite right-angled prisms are orthogonal.

3. The dual-channel hyperspectral imaging device based on a Sagnac interferometer according to claim 2, characterized in that, The thickness of the reflector plate is adjustable, which is used to introduce different lateral shearing amounts for light of different wavelengths.

4. The dual-channel hyperspectral imaging device based on a Sagnac interferometer according to claim 3, characterized in that, The polarizer array is a 2×1 array, and its transmission axis is in the same direction as the vibration direction of the o-ray and e-ray, respectively.

5. The dual-channel hyperspectral imaging device based on a Sagnac interferometer according to claim 4, characterized in that, The filter array is a 2×1 array, which transmits wavelengths A and B respectively.

6. A dual-channel hyperspectral imaging method based on a Sagnac interferometer, using the apparatus described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: The incident light is imaged at the aperture by the front imaging objective, then collimated by the collimating objective to form a collimated beam, and then incident on the Wollaston prism after passing through the polarizer. Step 2: The incident light is sheared into two beams, o-ray and e-ray, by the Wollaston prism, and the two outgoing beams are deflected upward and downward respectively; Step 3: Two outgoing light beams are incident on the Sagnac band-splitting shearing structure. After passing through the front and rear surfaces of the reflector plate, different wavelengths of light produce different lateral shearing amounts. The o-light is deflected upwards and outgoing, while the e-light is deflected downwards and outgoing. Step 4: The polarizer array selects the o-light and e-light respectively. After passing through the filter array, the light in band A of the o-light is transmitted and the light in band B of the e-light is transmitted. Step 5: After the light from the two wavelengths passes through the rear imaging objective lens, it interferes on the area array detector, forming two interference patterns, one above the other.

7. The dual-channel hyperspectral imaging method based on a Sagnac interferometer according to claim 6, characterized in that, The method further includes: Step 6: The dual-channel hyperspectral imaging device based on the Sagnac interferometer is used to push-broom the imaging target, and the incident angle of the target light is changed to modulate the optical path difference, so as to obtain two sets of interferometric image sequences in different bands. Step 7: Perform spectral restoration based on the obtained interference image information to obtain the spectral information of each target point in both bands.

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