Hyper-spectral resolution imaging spectrometer system capable of eliminating spectral distortion

Abstract

The utility model relates to a hyper-spectral resolution imaging spectrometer system capable of eliminating spectral distortion, which comprises a real entrance pupil, a front-end system, a slit, a collimation system, a transmission plane prism grating, a plane correction prism group, a focusing lens group and an image plane which are arranged in sequence, and is characterized in that the real entrance pupil is used for determining an imaging aperture; the front-end system is used for projecting a target scene on the slit; the slit is used for receiving a target scene signal and limiting the field of view of the imaging spectrometer system; the collimation system is used for collimating the light beams passing through the slit; the transmission plane prism grating is used for splitting the light beams collimated by the collimation system to obtain diffracted light; the plane correction prism group is used for eliminating spectral distortion of the central wavelength of the diffracted light; the focusing lens group is used for eliminating spectral distortion generated by other working wavelengths in the diffracted light passing through the plane correction prism group; the image plane is used for receiving the light beams focused by the focusing lens group. According to the utility model, the spectral distortion of the imaging spectrometer is effectively eliminated.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of imaging spectrometer design, especially to a kind of super-spectral resolution imaging spectrometer system for eliminating spectral distortion. BACKGROUND

[0002] Imaging spectrometer can obtain the image and continuous spectrum of observation target simultaneously, and is widely used in the fields of agriculture and forestry monitoring, mineral resources exploration, ecological environment monitoring, military reconnaissance, deep space exploration and the like.Compared with curved grating dispersion type imaging spectrometer, flat grating dispersion type imaging spectrometer has relatively large aperture and high spectral resolution, and has more advantages in fine spectral detection field.The mainstream trend of spectral imaging technology development is to simultaneously consider large field of view (long slit) and high spectral resolution, but with the increase of slit length, the inherent spectral distortion (line bending and chromatic aberration) of flat grating will increase sharply, and it is difficult to correct to a low level at the same time, which seriously affects the consistency of instrument spectral response and reduces the detection accuracy of large field of view edge target.Among them, line bending refers to the deviation degree of different wavelength dispersion image of straight line target from straight line, and chromatic aberration refers to the difference of different wavelength slit magnification.

[0003] At present, there are various forms of design schemes using prism and grating spectral components, including prism grating, prism grating + prism, etc.Yang Zengpeng of Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences proposed a prism grating combination dispersion element for eliminating line bending in Acta Optica Sinica, and designed an imaging spectrometer with a wavelength range of 400-800nm and a spectral resolution of 0.5nm, and the system line bending and chromatic aberration is less than 1μm, but the slit of the system is short, only 14mm, and the spectral resolution is low.The TROPOMI payload short-wave infrared channel of European Space Agency's Sentinel-5 Precursor (S-5P) adopts a spectral component of silicon prism grating + correction prism, with a spectral resolution of 0.25nm and a slit length of 64mm, and the system residual spectral distortion is large.

[0004] In summary, the spectral distortion of existing imaging spectrometer is large and difficult to correct, which reduces the detection accuracy of the instrument and increases the difficulty of data post-processing. UTILITY MODEL CONTENT

[0005] Therefore, the technical problem to be solved by the utility model is to overcome the problem of large spectral distortion and difficult correction of the imaging spectrometer in the prior art.

[0006] To solve the above technical problems, the utility model provides a kind of super-spectral resolution imaging spectrometer system of eliminating spectral distortion, including the real entrance pupil, front system, slit, collimating system, transmission plane prism grating, plane correction prism group, focusing lens group and image plane that are sequentially arranged, wherein,

[0007] The real entrance pupil is used to determine the imaging aperture of the imaging spectrometer system;

[0008] The front system is used to project the target scene passing through the real entrance pupil on the slit;

[0009] The front system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a first spherical lens arranged in sequence;

[0010] The slit is used to receive the target scene signal and limit the field of view of the imaging spectrometer system;

[0011] The collimating system is used to collimate the light beam passing through the slit;

[0012] The collimating system includes a second spherical lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens arranged in sequence;

[0013] The transmission plane prism grating is used to split the light beam collimated by the collimating system to obtain diffracted light;

[0014] The plane correction prism group is used to eliminate the spectral distortion of the central wavelength of the diffracted light;

[0015] The focusing lens group is used to eliminate the spectral distortion of other working wavelengths except the central wavelength in the diffracted light after passing through the plane correction prism group;

[0016] The focusing lens group includes an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens and a third spherical lens arranged in sequence;

[0017] The image plane is used to receive the light beam focused by the focusing lens group.

[0018] In an embodiment of the utility model, the optical power of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the first spherical lens is positive, positive, negative, negative, positive and negative in sequence;

[0019] The first lens, the second lens, the third lens, the fourth lens and the fifth lens are spherical or aspherical lenses.

[0020] In an embodiment of the utility model, the optical power of the second spherical lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens is negative, negative, positive, positive, negative and positive in sequence;

[0021] The sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are spherical or aspherical lenses.

[0022] In an embodiment of the utility model, the lens in the pre-system and the lens in the collimation system structure are symmetrical about the slit, and the types of optical glass material adopted are also symmetrical about the slit, and the ratio of the focal length of the pre-system and the collimation system ranges from 0.1 to 5.

[0023] In an embodiment of the utility model, the optical power of the eleventh lens, the twelfth lens, the thirteenth lens, the fourteenth lens, the fifteenth lens and the third spherical lens is positive, positive, negative, negative, positive and negative in turn.

[0024] The eleventh lens, the twelfth lens, the thirteenth lens, the fourteenth lens and the fifteenth lens are spherical or aspherical lenses.

[0025] In an embodiment of the utility model, the ratio of the focal length of the pre-system and the focusing lens group ranges from 0.2 to 3.

[0026] In an embodiment of the utility model, the transmission plane prism grating comprises a transmission dispersion prism and a plane transmission grating, wherein the incident light first passes through the transmission dispersion prism for primary dispersion, and then passes through the plane transmission grating for secondary dispersion; the dispersion contribution ratio of the transmission dispersion prism and the plane transmission grating to the imaging spectrometer system is 1:100-1:10.

[0027] The plane transmission grating has a line pair number of 600lp / mm-3000lp / mm and a diffraction order of +1 order.

[0028] In an embodiment of the utility model, the material of the transmission dispersion prism is fused quartz, and the top angle ranges from 5° to 70°.

[0029] In an embodiment of the utility model, the plane correction prism group comprises 1-5 plane prisms.

[0030] In an embodiment of the utility model, the focusing lens group has negative distortion, and the negative distortion ranges from -10% to -0.01%.

[0031] The above technical solution of the utility model has the following advantages compared with the prior art:

[0032] The imaging spectrometer system of the utility model realizes the design of long slit, super high spectral resolution imaging and low spectral distortion, can eliminate spectral distortion (including spectral line bending and chromatic distortion) to the greatest extent, effectively improves the detection precision, and can be used in the field of large field of view super high spectral resolution spaceborne greenhouse gas monitoring.

[0033] The imaging spectrometer system of the utility model has simple and reliable structure design, great adjustability, wide application range and high practicability. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to make the content of the utility model more easily be clearly understood, the following according to the specific embodiment of the utility model and combining with the drawings, the utility model is further detailed.

[0035] Figure 1 It is the structure schematic diagram of the hyperspectral resolution imaging spectrometer system of the utility model for eliminating spectral distortion;

[0036] Figure 2 It is the structure schematic diagram of the front system in the embodiment of the utility model;

[0037] Figure 3 It is the structure schematic diagram of the collimating system in the embodiment of the utility model;

[0038] Figure 4 It is the structure schematic diagram of the focusing lens group in the embodiment of the utility model;

[0039] Figure 5 It is the structure schematic diagram of the transmission plane prism grating in the embodiment of the utility model;

[0040] Figure 6 It is the image plane schematic diagram after eliminating the spectral distortion of the central wavelength of diffracted light by the plane correction prism group in the embodiment of the utility model;

[0041] Figure 7 It is the spectral distortion schematic diagram of the imaging spectrometer system of the utility model. DETAILED DESCRIPTION

[0042] The utility model is further explained in conjunction with the drawings and specific embodiments, so that the person skilled in the art can better understand the utility model and can be implemented, but the embodiment is not as the limitation of the utility model.

[0043] Embodiment one

[0044] Referring to Figure 1 The utility model relates to a kind of hyperspectral resolution imaging spectrometer systems for eliminating spectral distortion, including sequentially arranged real pupil 1, front system 2, slit 3, collimating system 4, transmission plane prism grating 5, plane correction prism group 6, focusing lens group 7 and image plane 8, wherein,

[0045] The real pupil 1 (equivalent to aperture diaphragm) is used to determine the imaging aperture of the imaging spectrometer system;

[0046] The front system 2 is used for projecting the target scene passing through the real entrance pupil 1 on the slit 3;

[0047] The slit 3 is used for receiving the target scene signal and limiting the field of view of the imaging spectrometer system;

[0048] The collimation system 4 is used for collimating the light beam passing through the slit 3, and the length of the slit 3 is 15mm-200mm;

[0049] The transmission plane prism grating 5 is used for dispersing the light beam collimated by the collimation system 4 to obtain diffracted light;

[0050] The plane correction prism group 6 is used for eliminating the spectral distortion of the central wavelength of the diffracted light;

[0051] The focusing lens group 7 is used for eliminating the spectral distortion of the diffracted light caused by the working wavelengths other than the central wavelength after passing through the plane correction prism group 6;

[0052] The image plane 8 is used for receiving the light beam focused by the focusing lens group 7.

[0053] It is worth mentioning that the imaging spectrometer system constructed in the embodiment adopts a full transmission structure, the spectral range is 747nm-777nm, the spectral resolution is 0.06nm, the dispersion width of the image plane 8 is 30mm, and the minimum spectral distortion value is 0-2μm.

[0054] Further, referring to Figure 2 The front system 2 includes a first lens 201, a second lens 202, a third lens 203, a fourth lens 204, a fifth lens 205 and a first spherical lens 206 arranged in sequence, and the optical power of each lens arranged in sequence is positive, positive, negative, negative, positive and negative in sequence.

[0055] The first lens 201, the second lens 202, the third lens 203, the fourth lens 204 and the fifth lens 205 are spherical or aspherical lenses, and if they are spherical lenses, the front and rear halves of the spherical lenses are spherical.

[0056] The distance between the first lens 201 and the second lens 202 is 5-20mm;

[0057] The distance between the second lens 202 and the third lens 203 is 10-20mm;

[0058] The distance between the third lens 203 and the fourth lens 204 is 80-100mm;

[0059] The distance between the fourth lens 204 and the fifth lens 205 is 60-80mm;

[0060] The interval between the fifth lens 205 and the first spherical lens 206 ranges from 40 to 80 mm.

[0061] Further, referring to Figure 3 , the collimating system 4 comprises a second spherical lens 401, a sixth lens 402, a seventh lens 403, an eighth lens 404, a ninth lens 405, and a tenth lens 406 arranged in sequence, and the optical power of each lens arranged in sequence is negative, negative, positive, positive, negative, and positive in sequence.

[0062] The sixth lens 402, the seventh lens 403, the eighth lens 404, the ninth lens 405, and the tenth lens 406 are spherical or aspherical lenses, and if they are spherical lenses, the front and rear halves of the spherical lenses are spherical.

[0063] The interval between the second spherical lens 401 and the sixth lens 402 ranges from 60 to 120 mm.

[0064] The interval between the sixth lens 402 and the seventh lens 403 ranges from 100 to 140 mm.

[0065] The interval between the seventh lens 403 and the eighth lens 404 ranges from 90 to 130 mm.

[0066] The interval between the eighth lens 404 and the ninth lens 405 ranges from 10 to 20 mm.

[0067] The interval between the ninth lens 405 and the tenth lens 406 ranges from 5 to 20 mm.

[0068] Further, the lenses in the pre-system 2 and the lenses in the collimating system 4 structure are symmetrical about the slit 3, and the types of optical glass materials used are also symmetrical about the slit 3, and the ratio of the focal lengths of the pre-system 2 and the collimating system 4 ranges from 0.1 to 5.

[0069] Further, referring to Figure 4 , the focusing lens group 7 comprises an eleventh lens 701, a twelfth lens 702, a thirteenth lens 703, a fourteenth lens 704, a fifteenth lens 705, and a third spherical lens 706 arranged in sequence, and the optical power of each lens arranged in sequence is positive, positive, negative, negative, positive, and negative in sequence.

[0070] The eleventh lens 701, the twelfth lens 702, the thirteenth lens 703, the fourteenth lens 704, and the fifteenth lens 705 are spherical or aspherical lenses, and if they are spherical lenses, the front and rear halves of the spherical lenses are spherical.

[0071] The interval between the eleventh lens 701 and the twelfth lens 702 ranges from 5 to 20 mm.

[0072] The interval between the twelfth lens 702 and the thirteenth lens 703 ranges from 10 mm to 20 mm;

[0073] The interval between the thirteenth lens 703 and the fourteenth lens 704 ranges from 80 mm to 120 mm;

[0074] The interval between the fourteenth lens 704 and the fifteenth lens 705 ranges from 60 mm to 80 mm;

[0075] The interval between the fifteenth lens 705 and the third spherical lens 706 ranges from 40 mm to 100 mm.

[0076] Further, the focusing lens group 7 has negative distortion, and the distortion ranges from -10% to -0.01%.

[0077] Further, the ratio of the focal length of the front system 2 and the focusing lens group 7 ranges from 0.2 to 3.

[0078] Further, referring to Figure 5 , the transmission plane prism grating 5 comprises a transmission dispersion prism 5-1 and a plane transmission grating 5-2, the plane transmission grating 5-2 and the transmission dispersion prism 5-1 are in one structure, and the plane transmission grating 5-2 is located on a plane of the transmission dispersion prism 5-1, wherein the incident light first passes through the transmission dispersion prism 5-1 for primary dispersion, and then passes through the plane transmission grating 5-2 for secondary dispersion; the transmission dispersion prism 5-1 and the plane transmission grating 5-2 have a dispersion contribution ratio of 1:100 to 1:10 to the imaging spectrometer system. The material of the transmission dispersion prism 5-1 is fused quartz, and the top angle of the transmission dispersion prism 5-1 ranges from 5° to 70°. The base of the plane transmission grating 5-2 is fused quartz, the line pair number is 600 lp / mm to 3000 lp / mm, the diffraction order is +1 order, and the parameters of the plane transmission grating 5-2 can realize the super-spectral resolution of 0.04 nm to 0.3 nm of the imaging spectrometer system.

[0079] Further, the plane correction prism group 6 comprises 1 to 5 plane prisms, and the interval between adjacent plane prisms ranges from 60 mm to 80 mm. The material of the plane prism is any one of fused quartz, N-BK7, H-K9L, monocrystalline silicon, zinc selenide, zinc sulfide or germanium.

[0080] Further, in the embodiment, the intervals between the real entrance pupil 1 and the front system 2, the slit 3, the collimation system 4, the transmission plane prism grating 5, the plane correction prism group 6, the focusing lens group 7 and the image plane 8 range from 50 mm to 100 mm, 10 mm to 20 mm, 10 mm to 20 mm, 50 mm to 100 mm, 20 mm to 40 mm, 50 mm to 100 mm and 10 mm to 30 mm, respectively.

[0081] Please refer toFigure 6 This diagram illustrates the image plane after the spectral distortion of the center wavelength of the diffracted light is eliminated by the planar correction prism group 6. The solid line corresponding to λ2 represents the slit image (distortion-free) at the center wavelength of the image plane, the solid lines corresponding to λ1 and λ3 represent the slit images at the edge wavelengths of the image plane, and the dashed line represents the ideal image plane without spectral distortion. The minimum spectral line curvature and chromatic aberration achievable by the imaging spectrometer system after passing through the focusing lens group 7 are:

[0082]

[0083] Where λ1 is the short wavelength at the edge, λ3 is the long wavelength at the edge, and ΔL min It is the minimum value of spectral line curvature, ΔH min It is the minimum value of color distortion, ΔL Smile (λ3) and ΔL Smile (λ1) represents the spectral line bending at the long and short wavelengths at the edges, respectively, ΔH Keystone (λ 32 ) and ΔH Keystone (λ 12 These are the chromatic aberrations of the long and short wavelengths at the edges, respectively.

[0084] Experimental Analysis

[0085] Please see Figure 7 , Figure 7 The spectral distortion (including line bending and chromatic aberration) of the imaging spectrometer system is shown. Line bending is represented by distortion values ​​of 0.747 μm, 0.762 μm, and 0.777 μm, corresponding to short wavelengths at the edges, center wavelengths, and long wavelengths at the edges, respectively. Chromatic aberration is represented by distortion values ​​of 0.747 μm and 0.777 μm, corresponding to short wavelengths at the edges and long wavelengths at the edges, respectively. Distortion values ​​for both line bending and chromatic aberration are given at 0, 0.25, 0.5, 0.75, and 1 field of view (field of view is...). Figure 7 The horizontal axis corresponding to the schematic diagram of chromatic aberration and spectral line bending is shown below. (Normalized FOV represents the field-of-view normalization value, Smith Distortion represents the degree of spectral line bending, and Keystone represents the degree of chromatic aberration.) Figure 7 It is easy to see that the maximum value of spectral line bending and color distortion is about 1 μm, indicating that the spectral distortion of the imaging spectrometer system of this invention is small.

[0086] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0087] Obviously, the above embodiments are only examples for clearly illustrating the present application and are not intended to limit the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments are not required to be enumerated. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A hyperspectral resolution imaging spectrometer system that eliminates spectral distortion, characterized by: The imaging spectrometer system comprises, in sequence, a real entrance pupil (1), a pre-system (2), a slit (3), a collimating system (4), a transmission plane prism grating (5), a plane correction prism group (6), a focusing lens group (7) and an image plane (8), wherein The real entrance pupil (1) is used for determining the imaging aperture of the imaging spectrometer system. The pre-system (2) is used for projecting a target scene passing through the real entrance pupil (1) on the slit (3). The pre-system (2) comprises, in sequence, a first lens (201), a second lens (202), a third lens (203), a fourth lens (204), a fifth lens (205) and a first spherical lens (206). The slit (3) is used for receiving a target scene signal and limiting the field of view of the imaging spectrometer system. The collimating system (4) is used for collimating the light beam passing through the slit (3). The collimating system (4) comprises, in sequence, a second spherical lens (401), a sixth lens (402), a seventh lens (403), an eighth lens (404), a ninth lens (405) and a tenth lens (406). The transmission plane prism grating (5) is used for splitting the light beam collimated by the collimating system (4) to obtain diffracted light. The plane correction prism group (6) is used for eliminating the spectral distortion of the central wavelength of the diffracted light. The focusing lens group (7) is used for eliminating the spectral distortion of the diffracted light caused by the working wavelengths other than the central wavelength after passing through the plane correction prism group (6). The focusing lens group (7) comprises, in sequence, an eleventh lens (701), a twelfth lens (702), a thirteenth lens (703), a fourteenth lens (704), a fifteenth lens (705) and a third spherical lens (706). The image plane (8) is used for receiving the light beam focused by the focusing lens group (7).

2. The spectrally-distortion-corrected, hyper-spectral resolution imaging spectrometer system according to claim 1, wherein: The focal powers of the first lens (201), the second lens (202), the third lens (203), the fourth lens (204), the fifth lens (205) and the first spherical lens (206) are positive, positive, negative, negative, positive and negative, respectively. The first lens (201), the second lens (202), the third lens (203), the fourth lens (204) and the fifth lens (205) are spherical or aspherical lenses.

3. The spectrally-distortion-corrected, hyper-spectral resolution imaging spectrometer system according to claim 1, wherein: The focal powers of the second spherical lens (401), the sixth lens (402), the seventh lens (403), the eighth lens (404), the ninth lens (405) and the tenth lens (406) are negative, negative, positive, positive, negative and positive, respectively. The sixth lens (402), the seventh lens (403), the eighth lens (404), the ninth lens (405) and the tenth lens (406) are spherical or aspherical lenses.

4. The spectrally-distortion-corrected, hyper-spectral resolution imaging spectrometer system according to claim 1, wherein: The lenses in the pre-system (2) and the lenses in the structure of the collimating system (4) are symmetrical about the slit (3), and the types of the optical glass materials adopted are also symmetrical about the slit (3), and the ratio of the focal lengths of the pre-system (2) and the collimating system (4) ranges from 0.1 to 5.

5. The spectrally-distortion-corrected, hyper-spectral resolution imaging spectrometer system according to claim 1, wherein: The optical powers of the eleventh lens (701), the twelfth lens (702), the thirteenth lens (703), the fourteenth lens (704), the fifteenth lens (705) and the third spherical lens (706) are positive, positive, negative, negative, positive and negative in turn. The eleventh lens (701), the twelfth lens (702), the thirteenth lens (703), the fourteenth lens (704) and the fifteenth lens (705) are spherical or aspherical lenses.

6. The spectrally-distortion-corrected, hyper-spectral resolution imaging spectrometer system according to claim 1, wherein: The ratio of the focal length of the front system (2) to the focal length of the focusing lens group (7) ranges from 0.2 to 3.

7. The spectrally-distortion-corrected, hyper-spectral resolution imaging spectrometer system according to claim 1, wherein: The transmission plane prism grating (5) comprises a transmission dispersion prism (5-1) and a plane transmission grating (5-2), wherein the incident light first passes through the transmission dispersion prism (5-1) for primary dispersion, and then passes through the plane transmission grating (5-2) for secondary dispersion; the transmission dispersion prism (5-1) and the plane transmission grating (5-2) have a dispersion contribution ratio of 1:100 to 1:10 to the imaging spectrometer system. The plane transmission grating (5-2) has a line pair number of 600 lp / mm to 3000 lp / mm and a diffraction order of +1.

8. The spectrally-distortion-cancelled, hyper-spectral resolution imaging spectrometer system according to claim 7, wherein: The transmission dispersion prism (5-1) is made of fused quartz and has an apex angle ranging from 5° to 70°.

9. The spectrally-distortion-corrected, hyper-spectral resolution imaging spectrometer system according to claim 1, wherein: The plane correction prism group (6) comprises 1 to 5 plane prisms.

10. The spectrally-distortion-corrected, hyper-spectral resolution imaging spectrometer system according to claim 1, wherein: The focusing lens group (7) has negative distortion, and the negative distortion ranges from -10% to -0.01%.

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