Variable spectral resolution imaging spectrum system

Abstract

The invention discloses a variable spectral resolution imaging spectrum system. Belongs to the technical field of push-broom imaging spectrum systems. The technical problem that a spectral imaging system in the prior art cannot change spectral resolution at any time according to spectral characteristics of a target is solved. The system comprises a front telescope system, a slit, a collimation system, a light splitting system, an imaging system and a detector. The front telescope system is used for imaging a distant target light beam to a slit, the collimation system is used for adjusting the light beam passing through the slit into a parallel light beam, the light splitting system is a grating-prism combined system and is used for dispersing the parallel light beam, and the imaging system is used for focusing the light beam passing through the light splitting system to a detector. According to the variable-spectral-resolution imaging spectrum system, multiple purposes can be achieved by adjusting the focal lengths of the collimation system and the imaging system.

Description

Technical Field

[0001] This invention belongs to the technical field of pushbroom imaging spectral systems, and specifically relates to a variable spectral resolution imaging spectral system. Background Technology

[0002] Pushbroom imaging spectroscopic systems are efficient data acquisition tools that can acquire both spatial and spectral information of a target by scanning it in space.

[0003] The spectral resolution of traditional imaging spectrometers is fixed after design and manufacturing, making it difficult to cope with complex and ever-changing detection environments and mission requirements.

[0004] In scenarios such as agricultural monitoring and geological exploration, the spectral characteristics of targets vary greatly. For targets with broad spectral characteristics, a lower spectral resolution mode is needed for rapid general surveys to improve detection efficiency; for targets that require identification of fine spectral characteristics, a higher spectral resolution mode is needed to achieve accurate identification.

[0005] Currently, Chinese invention patent application CN114112037 A, entitled "A Variable Spectral Resolution Spectrometer and Design Method," discloses a variable spectral resolution spectrometer and its design method based on multiple off-axis convex (OAC) gratings. This method replaces the convex gratings in the traditional Offner structure with multiple OAC gratings. Each beam of light, after diffraction from the OAC sub-gratings, forms a sub-spectral image on the image plane. The spectral resolution of these images varies depending on the parameters of the OAC sub-gratings, enabling the acquisition of different spectral resolution images in a single scan. However, this design employs a reflective structure, which presents challenges in assembly and adjustment, as well as high manufacturing costs. It is more suitable for high-performance aerospace-grade remote sensing payloads and high-standard laboratory spectral analysis, and is not suitable for commercial use. Summary of the Invention

[0006] To address the technical problems of high assembly and adjustment difficulty and high processing cost in existing spectral imaging systems, and to enable adjustment of spectral resolution based on the spectral characteristics of the target, this invention provides a variable spectral resolution imaging spectral system.

[0007] Taking the direction of the incident light as the starting point, the system sequentially includes: Front-mounted telescope system, slit, collimation system, beam splitting system, imaging system, and detector; The forward telescope system images the distant target beam onto the slit; the collimation system adjusts the beam passing through the slit into a parallel beam; the beam splitting system is a grating-prism combination system; the beam splitting system disperses the parallel beam; and the imaging system focuses the beam passing through the beam splitting system onto the detector. The collimation system includes lens group 1, lens group 2 and lens group 3; the imaging system (05) includes lens group 4, lens group 5 and lens group 6; Switching between 1nm and 3nm spectral resolution can be achieved by changing the center thickness between lens group 1 and lens group 2, lens group 2 and lens group 3, lens group 4 and lens group 5, and lens group 5 and lens group 6.

[0008] Furthermore, taking the incident light direction as the starting point, the forward telescope system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens; the first lens is a biconvex lens, the second lens is a biconcave lens, the third lens is a biconvex lens, the fourth lens is a meniscus lens, the fifth lens is a biconcave lens, the sixth lens is a biconvex lens, and the seventh lens is a meniscus lens.

[0009] Furthermore, the slit is disposed on a parallel flat plate.

[0010] Furthermore, in the collimation system, lens group 1 includes an eighth lens; taking the incident light direction as the starting point, lens group 2 sequentially includes a ninth lens, a tenth lens, and an eleventh lens; taking the incident light direction as the starting point, lens group 3 sequentially includes a twelfth lens, a thirteenth lens, and a fourteenth lens. The eighth lens is a meniscus lens, the ninth lens is a biconvex lens, the tenth lens is a meniscus lens, the eleventh lens is a biconvex lens, the twelfth lens is a biconvex lens, and the thirteenth and fourteenth lenses are combined to form a cemented doublet lens, wherein the thirteenth lens is a biconcave lens and the fourteenth lens is a biconvex lens.

[0011] Furthermore, in the beam splitting system, the grating is a transmission grating, and the prism and grating are made of the same material.

[0012] Furthermore, in the imaging system, taking the incident light direction as the starting point, lens group 4 sequentially includes the fifteenth lens, the sixteenth lens, and the seventeenth lens; taking the incident light direction as the starting point, lens group 5 sequentially includes the eighteenth lens, the nineteenth lens, and the twentieth lens; and lens group 6 includes the twenty-first lens.

[0013] Furthermore, the system's field of view... satisfy With an F-number of 3, it can achieve two spectral resolution settings: 1 nm and 3 nm.

[0014] Furthermore, at a spectral resolution of 1 nm, the center thickness between lens group 1 and lens group 2 is 0.65 mm, the center thickness between lens group 2 and lens group 3 is 159 mm, the center thickness between lens group 4 and lens group 5 is 148.78 mm, and the center thickness between lens group 5 and lens group 6 is 0.5 mm. At a spectral resolution of 3 nm, the center thickness between lens group 1 and lens group 2 is 11.95 mm, the center thickness between lens group 2 and lens group 3 is 0.56 mm, the center thickness between lens group 4 and lens group 5 is 14.04 mm, and the center thickness between lens group 5 and lens group 6 is 9 mm.

[0015] The beneficial effects of the system described in this invention are as follows: 1. Multi-functional: Through zoom, a single device can quickly switch between two spectral resolutions, high 1nm and low 3nm, replacing multiple spectrometers with fixed resolutions and reducing purchase and maintenance costs. 2. Excellent image quality: It adopts a grating-prism (GP) dispersion combination and a global aspherical lens design, which overcomes the problems of high difficulty and high cost in aspherical processing while ensuring high performance.

[0016] 3. High adaptability: The resolution can be adjusted in real time according to the needs of the observation task, which significantly improves the efficiency and data value of remote sensing.

[0017] 4. Based on optical design software simulation and image quality evaluation, the system achieves a modulation transfer function (MTF) better than 0.5 at the Nyquist frequency across the entire field of view and wavelength range in both 1nm and 3nm spectral resolution modes. Attached Figure Description Figure 1 This is a structural diagram of the variable spectral resolution imaging spectral system in an embodiment of the present invention; Figure 2 This is an optical structure diagram of the front telescope system of the variable spectral resolution imaging spectral system in an embodiment of the present invention; Figure 3 This is an optical structure diagram of the variable spectral resolution imaging spectral system in an embodiment of the present invention at a spectral resolution of 1 nm. Figure 4 This is an optical structure diagram of the variable spectral resolution imaging spectral system in an embodiment of the present invention at a spectral resolution of 3 nm. Figure 5 This is a modulation transfer function diagram at 450 nm for a variable spectral resolution imaging spectral system in an embodiment of the present invention at a spectral resolution of 1 nm. Figure 6 The modulation transfer function at 700 nm is shown for the variable spectral resolution imaging spectral system in this embodiment of the invention at a spectral resolution of 1 nm. Figure 7 This is a modulation transfer function diagram at 450 nm for the variable spectral resolution imaging spectral system in this embodiment of the invention, with a spectral resolution of 3 nm. Figure 8 This is a modulation transfer function diagram at 700 nm for a variable spectral resolution imaging spectral system in an embodiment of the present invention, when the spectral resolution is 3 nm. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0019] Pushbroom imaging spectroscopic systems are efficient data acquisition tools that can acquire both spatial and spectral information of a target by scanning it in space.

[0020] Traditional imaging spectrometers have fixed spectral resolution after design and manufacturing, making them ill-suited for complex and ever-changing detection environments and mission requirements. This embodiment fundamentally solves this problem through a variable spectral resolution design.

[0021] This technology combines the advantages of imaging and spectral analysis, making it widely applicable and promising in multiple fields. The variable spectral resolution imaging spectrometer in this embodiment, by overcoming the limitations of traditional fixed resolution, achieves a leap forward in detection capability, working efficiency, and system economy, and has extremely broad application prospects in agriculture, environment, resources, and many other fields.

[0022] In scenarios such as agricultural monitoring and geological exploration, the spectral characteristics of targets vary greatly. For targets with broad spectral characteristics, a lower spectral resolution mode can be used for rapid surveying to improve detection efficiency; for targets requiring the identification of fine spectral features, a high spectral resolution mode can be switched to achieve accurate identification. One device can replace multiple traditional devices with different resolutions.

[0023] During a single flight or observation mission, the spectral resolution can be adjusted in real time according to changes in the flight area, lighting conditions, and target characteristics, so that the instrument is always in the best working condition and obtains the most scientifically valuable data.

[0024] The variable spectral resolution imaging system proposed in this embodiment converges light through a front-mounted telescope system 01 into a slit 06, which acts as a spatial filter, capturing a line of the target's field of view. The beam is then collimated into parallel light by a collimation system 03 and incident on a beam-splitting system 04 composed of a grating-prism (GP). The GP array disperses the parallel beam. Finally, the beam carrying spectral information is converged by an imaging system 05 onto a detector 06, completing the acquisition of spatial and spectral information. The system operates in the spectral range of 450nm-700nm, with a field of view angle of... satisfy This system can extract spectral information from light within the 450nm-700nm spectral range. It employs a global surface lens design, effectively reducing manufacturing costs. The variable spectral resolution imaging system has an F-number of 3, and both the collimation system 03 and imaging system 05 are zoom systems, allowing for adjustment of spectral resolution at 1nm and 3nm levels, thus meeting the requirements for multispectral resolution. like Figure 1 As shown, the system comprises, in sequence: The system consists of a front-mounted telescope system 01, a slit 02, a collimation system 03, a beam splitting system 04, an imaging system 05, and a detector 06. The front telescope system 01 images the distant target beam onto the slit 02. The collimation system 03 adjusts the beam passing through the slit 02 into a parallel beam. The beam splitting system 04 is a grating-prism combination system. The beam splitting system 04 disperses the parallel beam. The imaging system 05 focuses the beam passing through the beam splitting system 04 onto the detector 06.

[0025] like Figure 3 As shown, the collimation system 03 includes lens group 1, lens group 2 and lens group 3; the imaging system 05 includes lens group 4, lens group 5 and lens group 6. The spectral resolution is switched by changing the center thickness between lens group 1 and lens group 2, lens group 2 and lens group 3, lens group 4 and lens group 5, and lens group 5 and lens group 6. At a spectral resolution of 1 nm, such as... Figure 3 As shown, the center thickness between lens group 1 and lens group 2 is 0.65 mm, the center thickness between lens group 2 and lens group 3 is 159 mm, the center thickness between lens group 4 and lens group 5 is 148.78 mm, and the center thickness between lens group 5 and lens group 6 is 0.5 mm. At a spectral resolution of 3 nm, such as Figure 4 As shown, the center thickness between lens group 1 and lens group 2 is 11.95 mm, the center thickness between lens group 2 and lens group 3 is 0.56 mm, the center thickness between lens group 4 and lens group 5 is 14.04 mm, and the center thickness between lens group 5 and lens group 6 is 9 mm.

[0026] like Figure 2 As shown, taking the incident light direction as the starting point, the front telescope system 01 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, and a seventh lens 7; the first lens 1 is a biconvex lens, the second lens 2 is a biconcave lens, the third lens 3 is a biconvex lens, the fourth lens 4 is a meniscus lens, the fifth lens 5 is a biconcave lens, the sixth lens 6 is a biconvex lens, and the seventh lens 7 is a meniscus lens.

[0027] Slit 02 is set on a parallel flat plate.

[0028] In the collimation system 03, lens group 1 includes the eighth lens 8; taking the incident light direction as the starting point, lens group 2 includes the ninth lens 9, the tenth lens 10 and the eleventh lens 11 in sequence; taking the incident light direction as the starting point, lens group 3 includes the twelfth lens 12, the thirteenth lens 13 and the fourteenth lens 14 in sequence. The eighth lens 8 is a meniscus lens, the ninth lens 9 is a biconvex lens, the tenth lens 10 is a meniscus lens, the eleventh lens 11 is a biconvex lens, the twelfth lens 12 is a biconvex lens, and the thirteenth lens 13 and the fourteenth lens 14 are combined to form a cemented doublet lens, wherein the thirteenth lens 13 is a biconcave lens and the fourteenth lens 14 is a biconvex lens.

[0029] In the beam splitting system 04, grating 07 is a transmission grating, and prism 08 and grating 07 are made of the same material.

[0030] The beam splitting system 04 is a grating-prism (GP) combination system. The apex angle of the prism 08 is 8.39° and its center thickness is 5mm. The grating 07 is a transmission grating with a line density of 150 lines / mm. The materials of the prism 08 and the grating 07 are H-BAK7.

[0031] In the imaging system 05, taking the incident light direction as the starting point, the lens group 4 sequentially includes the fifteenth lens 15, the sixteenth lens 16, and the seventeenth lens 17; taking the incident light direction as the starting point, the lens group 5 sequentially includes the eighteenth lens 18, the nineteenth lens 19, and the twentieth lens 20; the lens group 4 includes the twenty-first lens 21.

[0032] As shown in Table 1, a preferred embodiment provides specific parameter settings for each device in the system, where A is the center thickness between lens group 1 and lens group 2; B is the center thickness between lens group 2 and lens group 3; C is the center thickness between lens group 4 and lens group 5; and D is the center thickness between lens group 5 and lens group 6. (The last sentence appears to be incomplete and possibly refers to a spectral resolution setting.) When the spectral resolution is 1 nm, A is 0.65, B is 159, C is 148.78, and D is 0.5; when the spectral resolution is 3 nm, A is 11.95, B is 0.56, C is 14.04, and D is 9.

[0033] Table 1:

[0034] The modulation transfer function of the variable spectral resolution imaging spectral system using the above parameters is plotted, such as... Figure 5-8 As shown, the system exhibits a modulation transfer function (MTF) better than 0.5 at the Nyquist frequency across the entire field of view and spectral band in both 1nm and 3nm spectral resolution modes, indicating that the system possesses excellent imaging quality.

Claims

1. A variable spectral resolution imaging spectral system, characterized in that, Taking the direction of the incident light as the starting point, the system sequentially includes: The front telescope system (01), slit (02), collimation system (03), beam splitting system (04), imaging system (05) and detector (06); The front telescope system (01) images the distant target beam onto the slit (02), the collimation system (03) adjusts the beam passing through the slit (02) into a parallel beam, the beam splitting system (04) is a grating-prism combination system, the beam splitting system (04) disperses the parallel beam, and the imaging system (05) focuses the beam passing through the beam splitting system (04) onto the detector (06). The collimation system (03) includes lens group 1, lens group 2 and lens group 3; the imaging system (05) includes lens group 4, lens group 5 and lens group 6; Switching between 1nm and 3nm spectral resolution can be achieved by changing the center thickness between lens group 1 and lens group 2, lens group 2 and lens group 3, lens group 4 and lens group 5, and lens group 5 and lens group 6.

2. The variable spectral resolution imaging spectral system according to claim 1, characterized in that, Taking the incident light direction as the starting point, the front telescope system (01) includes a first lens (1), a second lens (2), a third lens (3), a fourth lens (4), a fifth lens (5), a sixth lens (6), and a seventh lens (7); the first lens (1) is a biconvex lens, the second lens (2) is a biconcave lens, the third lens (3) is a biconvex lens, the fourth lens (4) is a meniscus lens, and the fifth lens (5) is a biconcave lens. The sixth lens (6) is a biconvex lens, and the seventh lens (7) is a meniscus lens.

3. The variable spectral resolution imaging spectral system according to claim 2, characterized in that, The slit (02) is set on a parallel plate.

4. The variable spectral resolution imaging spectroscopic system according to claim 3, characterized in that, In the collimation system (03), lens group 1 includes an eighth lens (8); with the incident light direction as the starting point, lens group 2 includes a ninth lens (9), a tenth lens (10) and an eleventh lens (11) in sequence; with the incident light direction as the starting point, lens group 3 includes a twelfth lens (12), a thirteenth lens (13) and a fourteenth lens (14) in sequence. The eighth lens (8) is a meniscus lens, the ninth lens (9) is a biconvex lens, the tenth lens (10) is a meniscus lens, the eleventh lens (11) is a biconvex lens, the twelfth lens (12) is a biconvex lens, and the thirteenth lens (13) and the fourteenth lens (14) are combined to form a cemented doublet lens, wherein the thirteenth lens (13) is a biconcave lens and the fourteenth lens (14) is a biconvex lens.

5. The variable spectral resolution imaging system according to claim 4, characterized in that, In the spectral system (04), the grating (07) is a transmission grating, and the prism (08) and the grating (07) are made of the same material.

6. The variable spectral resolution imaging spectral system according to claim 5, characterized in that, In the imaging system (05), with the incident light direction as the starting point, the lens group 4 sequentially includes the fifteenth lens (15), the sixteenth lens (16), and the seventeenth lens (17); with the incident light direction as the starting point, the lens group 5 sequentially includes the eighteenth lens (18), the nineteenth lens (19), and the twentieth lens (20). Lens group 6 includes the twenty-first lens (21).

7. The variable spectral resolution imaging spectroscopic system according to claim 6, characterized in that, The system field of view satisfy With an F-number of 3, it can achieve two spectral resolution settings: 1 nm and 3 nm.

8. The variable spectral resolution imaging spectroscopic system according to claim 7, characterized in that, At a spectral resolution of 1 nm, the center thickness between lens group 1 and lens group 2 is 0.65 mm, the center thickness between lens group 2 and lens group 3 is 159 mm, the center thickness between lens group 4 and lens group 5 is 148.78 mm, and the center thickness between lens group 5 and lens group 6 is 0.5 mm. At a spectral resolution of 3 nm, the center thickness between lens group 1 and lens group 2 is 11.95 mm, the center thickness between lens group 2 and lens group 3 is 0.56 mm, the center thickness between lens group 4 and lens group 5 is 14.04 mm, and the center thickness between lens group 5 and lens group 6 is 9 mm.

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