Reflection-type uniform dispersion imaging spectrometer

Abstract

The invention discloses a reflective uniform dispersion imaging spectrometer, which comprises a linear optical fiber array, a collimation optical system, a dispersion element and an imaging optical system, wherein the linear optical fiber array is arranged at a slit position of a focal plane of the telescope; emergent light of a telescope passes through the linear optical fiber array to obtain an intermediate image of a small view field, the intermediate image of the small view field passes through the collimation optical system to obtain collimated parallel light, the collimated parallel light passes through the dispersion element to obtain dispersion light, and the dispersion light passes through the imaging optical system to obtain a spectral image. The invention can greatly reduce the instantaneous field of view of the imaging spectrometer, and has the advantages of small volume and light weight.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of imaging spectrometer, and particularly relates to a reflection type uniform dispersion imaging spectrometer. BACKGROUND

[0002] The imaging spectrometer can obtain the characteristic spectral information of the target while imaging the target, so that the material composition of the target can be analyzed and the biochemical performance of the target can be diagnosed. At present, the mainstream dispersion type imaging spectrometer mainly adopts a slit to divide the field of view, so that the target information in the linear field of view can be sent to the subsequent spectral imaging system, and the spectral separation can be performed through a dispersion element. With the continuous progress of the research in the field of imaging spectrometers at home and abroad, the imaging spectrometer in the future will need to have a larger field of view, a wider spectral range and higher spatial and spectral resolution. However, with the increase of the field of view, the long'slit' shaped field of view inevitably introduces uncorrectable color distortion and spectral line bending, which is not conducive to the subsequent spectral data processing. SUMMARY

[0003] The present application solves the technical problem of overcoming the shortcomings of the prior art and providing a reflection type uniform dispersion imaging spectrometer, which greatly reduces the instantaneous field of view of the imaging spectrometer and has the advantages of small size and light weight.

[0004] The present application is achieved by the following technical solutions: a reflection type uniform dispersion imaging spectrometer, comprising: a linear optical fiber array, a collimating optical system, a dispersion element and an imaging optical system; wherein the linear optical fiber array is arranged at the slit position of the focal plane of a telescope; the outgoing light of the telescope obtains an intermediate image of a small field of view after passing through the linear optical fiber array, the intermediate image of the small field of view obtains collimated parallel light after passing through the collimating optical system, the collimated parallel light obtains dispersed light after passing through the dispersion element, and the dispersed light obtains a spectral image after passing through the imaging optical system.

[0005] In the above-mentioned reflection type uniform dispersion imaging spectrometer, the collimating optical system comprises a folding mirror plane mirror, a primary mirror, a secondary mirror and a three-mirror; wherein the folding mirror plane mirror, the primary mirror, the secondary mirror and the three-mirror are arranged in sequence along the light propagation direction; the primary mirror is a flat ellipsoidal surface; the secondary mirror is a spherical surface; and the three-mirror is a hyperboloid.

[0006] In the above-mentioned reflection type uniform dispersion imaging spectrometer, the vertex curvature radius of the primary mirror is obtained by the following formula: ; Wherein, R1 is the vertex curvature radius of the primary mirror, is the obscuration ratio of the three-mirror to the secondary mirror, and f is the focal length of the collimating optical system.

[0007] In the above-mentioned reflection type uniform dispersion imaging spectrometer, the vertex curvature radius of the secondary mirror is obtained by the following formula: ; wherein R2 is the vertex radius of curvature of the tertiary mirror, is the obscuration ratio of the tertiary mirror to the secondary mirror, and f is the focal length of the collimating optical system.

[0008] In the above-mentioned reflective uniform dispersion imaging spectrometer, the vertex radius of curvature of the tertiary mirror is obtained by the following formula: ; wherein R3 is the vertex radius of curvature of the tertiary mirror, and f is the focal length of the collimating optical system.

[0009] In the above-mentioned reflective uniform dispersion imaging spectrometer, the distance of the fold mirror plane mirror to the primary mirror is obtained by the following formula: ; wherein d1 is the distance of the fold mirror plane mirror to the primary mirror, is the obscuration ratio of the tertiary mirror to the secondary mirror, and f is the focal length of the collimating optical system.

[0010] In the above-mentioned reflective uniform dispersion imaging spectrometer, the distance of the primary mirror to the secondary mirror is obtained by the following formula: ; wherein d2 is the distance of the primary mirror to the secondary mirror, is the obscuration ratio of the secondary mirror to the primary mirror, and f is the focal length of the collimating optical system.

[0011] In the above-mentioned reflective uniform dispersion imaging spectrometer, the distance of the secondary mirror to the tertiary mirror is obtained by the following formula: ; wherein d3 is the distance of the secondary mirror to the tertiary mirror, is the obscuration ratio of the tertiary mirror to the secondary mirror, and f is the focal length of the collimating optical system.

[0012] In the above-mentioned reflective uniform dispersion imaging spectrometer, the surface shape coefficients of the primary mirror, the surface shape coefficients of the secondary mirror and the surface shape coefficients of the tertiary mirror are obtained by the following formula: ; ; ; wherein S I is the third-order spherical aberration of the collimating optical system, S II is the third-order coma of the collimating optical system, S III is the third-order coma of the collimating optical system, is the magnification of the secondary mirror to the primary mirror, is the magnification of the tertiary mirror to the secondary mirror, The surface shape coefficient of the primary mirror, The surface shape coefficient of the secondary mirror, The surface shape coefficient of the tertiary mirror, The obscuration ratio of the secondary mirror to the primary mirror, The obscuration ratio of the tertiary mirror to the secondary mirror.

[0013] In the above-mentioned reflective uniform dispersion imaging spectrometer, the imaging optical system comprises a second tertiary mirror, a second secondary mirror and a second primary mirror; wherein the second tertiary mirror, the second secondary mirror and the second primary mirror are sequentially arranged along the light propagation direction; the second tertiary mirror, the second secondary mirror and the second primary mirror are all the same in material and optical parameters as the tertiary mirror, the secondary mirror and the primary mirror.

[0014] Compared with the prior art, the present application has the following beneficial effects: The present application breaks through the limitation of the traditional imaging spectrometer that it is difficult to correct the chromatic aberration and spectral line bending due to the long "slit", and can greatly reduce the instantaneous field of view of the imaging spectrometer while keeping the instantaneous field of view of the front-end telescope unchanged, has the advantages of small volume, light weight and high capacity utilization, and has important significance for promoting the development of China's space remote sensing technology. BRIEF DESCRIPTION OF DRAWINGS

[0015] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not intended to limit the scope of the present application. Moreover, like reference numerals designate like parts throughout the several views in the drawings. In the drawings: Figure 1 is the optical path diagram of the reflective uniform dispersion imaging spectrometer provided by the embodiment of the present application; Figure 2 is the field of view segmentation schematic diagram of the linear optical fiber array provided by the embodiment of the present application; Figure 3 is the linear optical fiber array schematic diagram provided by the embodiment of the present application; Figure 4 is the collimating optical system optical path diagram provided by the embodiment of the present application. DETAILED DESCRIPTION

[0016] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood, and so that the scope of the present disclosure can be completely conveyed to those skilled in the art. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict. The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0017] Figure 1 is a light path diagram of a reflective uniform dispersion imaging spectrometer provided by an embodiment of the present disclosure. As shown in Figure 1 , the reflective uniform dispersion imaging spectrometer comprises a linear fiber array 1, a collimating optical system 2, a dispersion element 3, and an imaging optical system 4; wherein the linear fiber array 1 is arranged at a slit position of a focal plane of a telescope; the exit light of the telescope obtains an intermediate image of a small field of view after passing through the linear fiber array 1, the intermediate image of the small field of view obtains collimated parallel light after passing through the collimating optical system 2, the collimated parallel light obtains dispersed light after passing through the dispersion element 3, and the dispersed light obtains a spectral image after passing through the imaging optical system 4.

[0018] This embodiment uses a linear fiber array to replace a slit placed on a focal plane of a telescope, the other end of the linear fiber array is folded to divide an image into two parallel short fiber line sub-fields of view, and finally the images and spectral data of the sub-fields of view connected at the head and tail can be processed to realize the function of linear fiber field of view division, restore the image and spectral data of the original field of view, and greatly reduce the instantaneous field of view of the imaging spectrometer under the premise of keeping the instantaneous field of view of the front-end telescope unchanged, thereby having the advantages of small volume and light mass, as shown in Figure 2 and Figure 3 .

[0019] The exit light of the linear fiber array 1 is telecentric on the image side, the collimating optical system 2 comprises a fold mirror plane mirror, a primary mirror, a secondary mirror, and a third mirror; the dispersion element 3 comprises a prism group of multiple different glass materials, and the imaging optical system 4 (a second third mirror, a second secondary mirror, and a second primary mirror) has an effect opposite to that of the collimating optical system 2, and has the same optical parameters as the collimating optical system 2, thereby having symmetry; wherein the primary mirror is a prolate ellipsoid, the secondary mirror is a spherical surface, and the third mirror is a hyperboloid.

[0020] As shown in Figure 4 , the collimating optical system 2 comprises a fold mirror plane mirror, a primary mirror, a secondary mirror, and a third mirror; wherein the fold mirror plane mirror, the primary mirror, the secondary mirror, and the third mirror are sequentially arranged along the light propagation direction; the primary mirror is a prolate ellipsoid, the secondary mirror is a spherical surface, and the third mirror is a hyperboloid.

[0021] The vertex curvature radius of the primary mirror is obtained by the following formula: ; wherein R1 is the vertex curvature radius of the primary mirror, is the obscuration ratio of the tertiary mirror to the secondary mirror, and f is the focal length of the collimating optical system.

[0022] The vertex curvature radius of the secondary mirror is obtained by the following formula: ; wherein R2 is the vertex curvature radius of the secondary mirror, is the obscuration ratio of the tertiary mirror to the secondary mirror, and f is the focal length of the collimating optical system.

[0023] The vertex curvature radius of the tertiary mirror is obtained by the following formula: ; wherein R3 is the vertex curvature radius of the tertiary mirror, and f is the focal length of the collimating optical system.

[0024] The distance of the folding mirror plane mirror to the primary mirror is obtained by the following formula: ; wherein d1 is the distance of the folding mirror plane mirror to the primary mirror, is the obscuration ratio of the tertiary mirror to the secondary mirror, and f is the focal length of the collimating optical system.

[0025] The distance of the primary mirror to the secondary mirror is obtained by the following formula: ; wherein d2 is the distance of the primary mirror to the secondary mirror, is the obscuration ratio of the secondary mirror to the primary mirror, and f is the focal length of the collimating optical system.

[0026] The distance of the secondary mirror to the tertiary mirror is obtained by the following formula: ; wherein d3 is the distance of the secondary mirror to the tertiary mirror, is the obscuration ratio of the tertiary mirror to the secondary mirror, and f is the focal length of the collimating optical system.

[0027] The surface shape coefficient of the primary mirror, the surface shape coefficient of the secondary mirror, and the surface shape coefficient of the tertiary mirror are obtained by the following formula: ; ; ; wherein S I is the third-order spherical aberration of the collimating optical system, S II is the third-order coma of the collimating optical system, S III is the third-order coma of the collimating optical system, Magnification of the secondary mirror to the primary mirror, Magnification of the tertiary mirror to the secondary mirror, Surface figure coefficient of the primary mirror, Surface figure coefficient of the secondary mirror, Surface figure coefficient of the tertiary mirror, Obstruction ratio of the secondary mirror to the primary mirror, Obstruction ratio of the tertiary mirror to the secondary mirror.

[0028] The imaging optical system 4 comprises a second tertiary mirror, a second secondary mirror and a second primary mirror; wherein the second tertiary mirror, the second secondary mirror and the second primary mirror are sequentially arranged along the light propagation direction; the second tertiary mirror, the second secondary mirror and the second primary mirror are all the same in material and optical parameters as the tertiary mirror, the secondary mirror and the primary mirror respectively.

[0029] The vertex curvature radius of the primary mirror, the vertex curvature radius of the secondary mirror, the vertex curvature radius of the tertiary mirror and the distance between the primary mirror and the secondary mirror are obtained by the following formula: ; ; ; ; ; ; Wherein, R1 is the vertex curvature radius of the primary mirror, R2 is the vertex curvature radius of the secondary mirror, R3 is the vertex curvature radius of the tertiary mirror, d1 is the distance between the object plane and the primary mirror, d2 is the distance between the primary mirror and the secondary mirror, d3 is the distance between the secondary mirror and the tertiary mirror, f is the focal length of the entire off-axis three-mirror system, and α1 and α2 are the obstruction ratios of the secondary mirror to the primary mirror and the tertiary mirror to the secondary mirror respectively.

[0030] The surface figure coefficient of the primary mirror is: =-0.255; wherein, is the surface figure coefficient of the primary mirror; the surface figure coefficient of the secondary mirror is: =0; wherein, is the surface figure coefficient of the secondary mirror; the surface figure coefficient of the tertiary mirror is: =-3.26; wherein, is the surface figure coefficient of the tertiary mirror. And are obtained by the following formula:

[0031]

[0032]

[0033] wherein S I is the third order spherical aberration of the collimating optical system, S II is the third order coma of the collimating optical system, S III is the third order coma of the collimating optical system, β1 and β2 are the magnifications of the secondary mirror to the primary mirror, and the tertiary mirror to the secondary mirror.

[0034] The vertex curvature radius of the primary mirror is -167.77 mm, the Conic coefficient of the primary mirror is 0.255, the distance between the primary mirror and the secondary mirror is 94.36 mm, and the clear aperture of the primary mirror is 66 mm.

[0035] The vertex curvature radius of the secondary mirror is 123.68 mm, the Conic coefficient of the secondary mirror is 0, the distance between the secondary mirror and the tertiary mirror is 85.34 mm, and the clear aperture of the secondary mirror is 29 mm.

[0036] The vertex curvature radius of the tertiary mirror is 421.88 mm, the Conic coefficient of the tertiary mirror is -3.26, and the clear aperture of the tertiary mirror is 74 mm.

[0037] The dispersion element 3 adopts a prism group combined by multiple glass materials, and the glass materials along the optical axis are H-K5, H-LAF50B, H-LAF51A and H-LAF54 in sequence.

[0038] The imaging optical system 4 and the collimating optical system 2 are just opposite to each other, and the optical parameters of the imaging optical system 4 are consistent with the optical parameters of the collimating optical system 2, and the imaging optical system 4 has symmetry.

[0039] The embodiment breaks through the limitation that the traditional imaging spectrometer is difficult to correct the color distortion and the spectral line bending due to the long “slit”, can greatly reduce the instantaneous field of view of the imaging spectrometer under the premise of keeping the instantaneous field of view of the front-end telescope unchanged, has the advantages of small volume, light mass and high capacity utilization, and has important significance for promoting the development of space remote sensing technology in China.

[0040] Although the present application has been disclosed with reference to the preferred embodiments above, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not depart from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

Claims

1. A reflective uniform dispersive imaging spectrometer, characterized in that... include: A linear fiber array (1), a collimating optical system (2), a dispersive element (3), and an imaging optical system (4); among which, The linear fiber array (1) is positioned at the slit position of the telescope's focal plane; The outgoing light from the telescope passes through the linear fiber array (1) to obtain an intermediate image with a small field of view. The intermediate image with a small field of view passes through the collimating optical system (2) to obtain collimated parallel light. The collimated parallel light passes through the dispersive element (3) to obtain dispersed light. The dispersed light passes through the imaging optical system (4) to obtain a spectral image.

2. The reflective uniform dispersive imaging spectrometer according to claim 1, characterized in that: The collimating optical system (2) includes a folding plane mirror, a primary mirror, a secondary mirror, and a third mirror; wherein, The folding mirror, the primary mirror, the secondary mirror, and the third mirror are arranged sequentially along the direction of light propagation. The primary mirror is an oblate spheroid; the secondary mirror is a sphere; and the tertiary mirror is a hyperboloid.

3. The reflectance-type uniform dispersive imaging spectrometer according to claim 2, characterized in that: The vertex radius of curvature of the primary mirror is obtained by the following formula: ； Where R1 is the vertex radius of curvature of the principal mirror. denoted by , where is the obstruction ratio of the three mirrors to the secondary mirror, and f is the focal length of the collimating optical system.

4. The reflectance-type uniform dispersive imaging spectrometer according to claim 2, characterized in that: The vertex radius of curvature of the secondary mirror is obtained by the following formula: ； Where R2 is the vertex radius of curvature of the secondary mirror. denoted by , where is the obstruction ratio of the three mirrors to the secondary mirror, and f is the focal length of the collimating optical system.

5. The reflectance-type uniform dispersive imaging spectrometer according to claim 2, characterized in that: The vertex radii of curvature of the three mirrors are obtained by the following formula: ； Where R3 is the vertex radius of curvature of the three mirrors, and f is the focal length of the collimating optical system.

6. The reflectance-type uniform dispersive imaging spectrometer according to claim 2, characterized in that: The distance from the plane mirror to the primary mirror of the folding mirror is obtained by the following formula: ； Where d1 is the distance from the plane mirror of the folding mirror to the primary mirror. denoted by , where is the obstruction ratio of the three mirrors to the secondary mirror, and f is the focal length of the collimating optical system.

7. The reflectance-type uniform dispersive imaging spectrometer according to claim 2, characterized in that: The distance between the primary mirror and the secondary mirror is obtained using the following formula: ； Wherein, d2 is the distance between the primary mirror and the secondary mirror. denoted by , where is the obstruction ratio of the secondary mirror to the primary mirror, and f is the focal length of the collimating optical system.

8. The reflective uniform dispersive imaging spectrometer according to claim 2, characterized in that: The distance between the secondary and tertiary mirrors is obtained using the following formula: ； Where d3 is the distance between the secondary mirror and the third mirror. denoted by , where is the obstruction ratio of the three mirrors to the secondary mirror, and f is the focal length of the collimating optical system.

9. The reflectance-type uniform dispersive imaging spectrometer according to claim 2, characterized in that: The surface shape coefficients of the primary mirror, the secondary mirror, and the third mirror are obtained using the following formulas: ； ； ； Among them, S I For the third-order spherical aberration of the collimating optical system, S II For the third-order coma of the collimating optical system, S III This refers to the third-order coma of a collimating optical system. The magnification of the secondary mirror relative to the primary mirror. This represents the magnification of the third mirror relative to the second mirror. The surface shape factor of the primary mirror. The surface shape coefficient of the secondary mirror. For the surface shape coefficients of the three mirrors, The obstruction ratio of the secondary mirror to the primary mirror. The obstruction ratio of the three mirrors to the secondary mirror.

10. The reflectance-type uniform dispersive imaging spectrometer according to claim 2, characterized in that: The imaging optical system (4) includes a second third mirror, a second secondary mirror, and a second primary mirror; wherein, The second and third mirrors, the second primary mirror, and the second primary mirror are arranged sequentially along the direction of light propagation; The second and third mirrors are made of the same material and have the same optical parameters as the first three mirrors. The second secondary mirror is made of the same material and has the same optical parameters as the second secondary mirror. The second primary mirror is made of the same material and has the same optical parameters as the primary mirror.

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