Space-based infrared coding spectral imaging optical system and imaging method thereof

Abstract

The invention discloses a space-based infrared coding spectral imaging optical system and an imaging method thereof, and belongs to the technical field of optics, the space-based infrared coding spectral imaging optical system is composed of a long-wave infrared channel and a medium-wave infrared channel, the two channels share a three-mirror system for primary image imaging, a light splitter is adopted for light splitting, medium-wave infrared light is reflected, long-wave infrared light is transmitted, and collimation is performed after light splitting. Dispersion and aliasing of spectrums are carried out in a biprism mode, each sub-channel is composed of a front prism, a main optical lens, a relay lens 1, a coding plate (a primary imaging surface), a relay lens 2, a rear prism and the like, data acquisition is carried out after dispersion aliasing is carried out, and resolving imaging is carried out by adopting a spectrum coding algorithm.

Description

Technical Field

[0001] The invention relates to a space-based infrared coding spectrum imaging optical system and an imaging method thereof, belonging to the technical field of optics. Background Art

[0002] Due to the particularity of infrared spectrum (spectral bandwidth, long wavelength, and great influence of the atmosphere), spectral imaging technology is much more difficult to implement in the infrared band than in the visible light band, but it also has incomparable advantages. Infrared spectral video imaging technology for complex environments can synchronously obtain the spatial distribution information and spectral information of the target's own infrared radiation in real time to form a spectral data cube, which has very significant effects in many fields such as ocean detection, agriculture, forestry, animal husbandry, and environmental pollution. With the increase in the speed and precision of space-based detection, new performance requirements are put forward for imaging spectral systems. With the continuous increase in the number of spectra, the use of traditional imaging methods may not be able to meet the requirements of target detection and resolution capabilities. The replacement of detection targets also requires further information acquisition speed. At present, there are many schemes for using spectra to detect targets, but they all have their own shortcomings in terms of speed and spectral resolution.

[0003] The traditional methods for acquiring spectral information are mainly grating spectrometers and interference spectrometers, which are difficult to meet the needs of multi-dimensional information video data acquisition for this project. It is necessary to explore new spectral video acquisition methods. The shortcomings of traditional imaging technology for spectral detection are analyzed as follows:

[0004] (1) Traditional grating spectrometer: The grating is essentially a slit placed in front of the dispersion element. Using two-dimensional array imaging, the spectral information of one spatial dimension is collected at a point in time. It is necessary to perform a one-dimensional scan in another spatial dimension to obtain the spectral information of the two-dimensional spatial plane.

[0005] (2) Traditional interference spectrometer: Interference spectral imaging technology is also called Fourier transform spectral imaging technology. It is an indirect spectral imaging technology that obtains interference intensity information and requires Fourier transform to obtain the spectral information of the target. Interference spectral imaging technology includes spatial modulation type and time modulation type. Since the spatial modulation type still has a slit in the optical path, the energy utilization rate is limited. The time modulation type mainly uses Michelson interferometer, which requires a moving mechanism to perform frequency domain (spectral) scanning, pixel-level FFT reconstruction, and high-precision adjustment. At a point in time, a certain spectral information in two-dimensional space is collected, which needs to be scanned and imaged in the spectral domain. Due to the limitations of the current multi-spectral detection system, the spectral resolution is low and the detection speed is slow. The infrared system is different from the visible light spectrum detection and is more difficult to design. Most infrared cameras are based on total energy detection or a detection system with several fixed spectral bands. For the detection of targets with large radiation differences and large speed differences, they have shortcomings such as low spectral detection efficiency, difficult classification, and a small number of detectable targets. Summary of the invention

[0006] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to provide a space-based infrared coded spectrum imaging optical system and an imaging method thereof, and to solve the problems of low spectrum band and slow detection rate of space infrared detection system.

[0007] The technical solution of the present invention is: a space-based infrared coding spectrum imaging optical system, comprising:

[0008] The primary image receiving module uses three reflectors to receive information into a primary image and sends the primary image to the spectral coding imaging module;

[0009] The spectrally coded imaging module uses a beam splitter to split the primary image into a medium-wave image and a long-wave image, and sends them to the medium-wave infrared collimation module and the long-wave infrared collimation module respectively;

[0010] The medium-wave infrared collimation module and the long-wave infrared collimation module both use collimation lenses to collimate the light of the medium-wave image and the long-wave image respectively, and vertically incident on their respective dispersion modules;

[0011] The dispersion module disperses the collected parallel light and makes it incident on the encoding module;

[0012] An encoding module encodes incident light information and sends the encoded information to a dispersion collection module;

[0013] The dispersion collection module spectrally converges the collected coded information and sends it to the focusing module;

[0014] The focusing module outputs the spectral convergence information to the external array detector.

[0015] Furthermore, the primary image receiving module is a coaxial three-reverse-biased viewing field system structure consisting of three reflectors and a plane mirror, and the reflectors form a 45° angle with the optical path.

[0016] Furthermore, the beam splitter is used to split the primary image into a medium-wave image and a long-wave image, and the two channels share the imaging system.

[0017] Furthermore, the spectral encoding imaging module is a semi-transparent and semi-reflective lens.

[0018] Furthermore, the dispersion module is a 30° wedge-shaped dispersion prism.

[0019] Furthermore, the encoding unit size of the encoding module is twice the detector pixel size.

[0020] Furthermore, the dispersion collection module includes a spectrum convergence prism; the spectrum convergence prism is a reversely placed 30° wedge-shaped dispersion prism.

[0021] Furthermore, the focusing module is an imaging lens.

[0022] Furthermore, the spectrally encoded imaging module adopts a 4f system of symmetrical imaging of collimation-dispersion-primary image-focusing.

[0023] The space-based infrared coded spectrum imaging method implemented by the space-based infrared coded spectrum imaging optical system comprises:

[0024] Three reflectors are used to receive information and form an image;

[0025] A beam splitter is used to split the primary image into a medium-wave image and a long-wave image;

[0026] A collimating lens is used to collimate the light of the medium-wave image and the long-wave image respectively;

[0027] Disperse the collimated parallel light;

[0028] Encode the dispersed optical information;

[0029] Spectrally converge the encoded information;

[0030] Output the spectral convergence information to an external detector.

[0031] The advantages of the present invention compared with the prior art are:

[0032] (1) The present invention symmetrically places a beam splitter and a wedge-shaped dispersion prism to form a multi-band dispersion and dispersion collection module to obtain continuous large-scale spectral information of multiple spectral bands. Compared with traditional total energy detection, the amount of spectral information obtained is greatly improved;

[0033] (2) The present invention encodes the spectral information through the encoding module, locates the spectral information as a reference point for restoration information, and improves the restoration accuracy;

[0034] (3) The present invention expands the spectrum through a dispersion prism module and directly collects the information to the area array detector without a slit, thereby achieving rapid imaging for direct acquisition of large-scale information. Compared with the traditional interferometer, the push-scan device is eliminated, and the collection method is simpler and more feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0036] Figure 1The present invention is an imaging flow chart of a space-based infrared coded spectrum imaging optical system;

[0037] Figure 2 is the optical system light path diagram;

[0038] Figure 3 This is a light path diagram of the collimated medium-wave / long-wave infrared spectral encoding imaging module S2 according to an embodiment of the present invention;

[0039] Figure 4 Schematic diagram of the prism-to-prism optical system;

[0040] Figure 5 This is a schematic diagram of the MTF imaging results of the medium-wave infrared optical system;

[0041] Figure 6 Schematic diagram of the MTF imaging results of the long-wave infrared optical system. DETAILED DESCRIPTION

[0042] In order to better understand the above technical scheme, the technical scheme of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical scheme of the present invention, rather than limitations on the technical scheme of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0043] The following is a further detailed description of a space-based infrared coded spectrum imaging optical system and an imaging method thereof provided by an embodiment of the present invention in conjunction with the accompanying drawings. Figure 1 , the specific implementation method may include: a long-wave infrared channel and a medium-wave infrared channel are composed, the two channels share a three-reflection system, a beam splitter is used for splitting, the medium-wave infrared is reflected, the long-wave outer infrared is transmitted, and the splitting is performed after collimation. A double prism method is used to disperse and alias the spectrum. Each sub-channel is composed of a front prism, a main optical lens, a relay lens 1, a coding plate (primary imaging surface), a relay lens 2, a rear prism, etc., and data is collected after dispersion and aliasing, and a spectral coding algorithm is used to solve the imaging. The present invention solves the above technical problems by the following technical scheme, including the following parts:

[0044] The primary image receiving module S1 is a coaxial three-reverse-biased viewing field system structure consisting of three reflectors and a plane mirror, and the reflectors form a 45° angle with the optical path.

[0045] The spectral encoding imaging module S2 includes: two channels, a long-wave infrared channel and a medium-wave infrared channel, a dual-channel shared imaging system, a reflection medium-wave infrared collimation module S3, and a transmission long-wave outer infrared collimation module S4.

[0046] The spectrally coded imaging module S2 is composed of a semi-transparent and semi-reflective lens, with an optical axis angle of 45°.

[0047] The dispersion module S5 is composed of a 30° wedge-shaped dispersion prism.

[0048] The encoding unit size of the encoding module S6 is twice the size of the detector pixel.

[0049] In the dispersion collection module S7, the spectrum converging prism used is a reversely placed 30° wedge-shaped dispersion prism.

[0050] The focusing module S8 is an imaging lens.

[0051] The spectrally coded imaging module S2 adopts a 4f system structure design of symmetrical imaging of collimation-dispersion-primary image-focusing.

[0052] In the solution provided in the embodiment of the present invention, the field of view of this example is 0.688°×0.688°, the focal length is 10000mm, the operating temperature is 20℃±3℃, and the dispersion of each spectrum segment on the detector is greater than 25 pixels. The long-wave infrared optical path spectrum segment is 8~10μm, the focal plane pixel size is: 30μm×30μm, and the scale is 4000*4000. The medium-wave infrared optical path spectrum segment is: 3~5μm, the medium-wave focal plane pixel size is: 20μm×20μm, and the scale is 6000*6000.

[0053] The system consists of a long-wave infrared channel and a medium-wave infrared channel. The two channels share a three-reflection system and use a beam splitter to split the light, reflecting the medium-wave infrared and transmitting the long-wave outer infrared. After splitting, the main optical lens is collimated. A double prism method is used to disperse and alias the spectrum. Each sub-channel is composed of a front prism, a relay lens 1, a coding plate (primary imaging surface), a relay lens 2, a rear prism, etc. After dispersion and aliasing, data collection is performed and a spectral coding algorithm is used to solve the imaging. The structure of the optical system primary imaging system is as follows: Figure 2 , 3 As shown in Figure 4, the system dimensions are approximately 3333 (X) × 3333 (Y) × 3100 (Z) mm.

[0054] See the table below for specific parameters.

[0055]

[0056] The MTF curve of the long-wave infrared channel transfer function is as follows: Figure 5 The average transmission function of the whole field of view is 0.49@16.7lp / mm.

[0057] The MTF curve of the medium wave infrared channel transfer function is as follows: Figure 6 The average transmission function of the whole field of view is 0.54@25lp / mm.

[0058] Based on the same inventive concept, the present invention also provides a space-based infrared coded spectrum imaging method implemented according to the space-based infrared coded spectrum imaging optical system, comprising:

[0059] Three reflectors are used to receive information and form an image;

[0060] A beam splitter is used to split the primary image into a medium-wave image and a long-wave image;

[0061] A collimating lens is used to collimate the light of the medium-wave image and the long-wave image respectively;

[0062] Disperse the collimated parallel light;

[0063] Encode the dispersed optical information;

[0064] Spectrally converge the encoded information;

[0065] Output the spectral convergence information to an external detector.

[0066] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0067] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A space-based infrared coded spectrum imaging optical system, characterized in that: include: The primary image receiving module uses three reflectors to receive information into a primary image and sends the primary image to the spectral coding imaging module; The spectrally coded imaging module uses a beam splitter to split the primary image into a medium-wave image and a long-wave image, and sends them to the medium-wave infrared collimation module and the long-wave infrared collimation module respectively; The medium-wave infrared collimation module and the long-wave infrared collimation module both use collimation lenses to collimate the light of the medium-wave image and the long-wave image respectively, and vertically incident on their respective dispersion modules; The dispersion module disperses the collected parallel light and makes it incident on the encoding module; An encoding module encodes incident light information and sends the encoded information to a dispersion collection module; The dispersion collection module spectrally converges the collected coded information and sends it to the focusing module; The focusing module outputs the spectral convergence information to the external array detector.

2. A space-based infrared coded spectrum imaging optical system according to claim 1, characterized in that: The primary image receiving module is a coaxial three-reverse-biased viewing field system structure consisting of three reflectors and a plane mirror, and the reflectors are at 45 degrees to the optical path.

3. The space-based infrared coded spectrum imaging optical system according to claim 1, characterized in that: The beam splitter is used to split the primary image into a medium-wave image and a long-wave image, and the two channels share the imaging system.

4. The space-based infrared coded spectrum imaging optical system according to claim 1, characterized in that: The spectral encoding imaging module is a semi-transparent and semi-reflective lens.

5. The space-based infrared coded spectrum imaging optical system according to claim 1, characterized in that: The dispersion module is a 30° wedge-shaped dispersion prism.

6. The space-based infrared coded spectrum imaging optical system according to claim 1, characterized in that: The encoding unit size of the encoding module is twice the detector pixel size.

7. The space-based infrared coded spectrum imaging optical system according to claim 1, characterized in that: The dispersion collection module includes a spectrum convergence prism; the spectrum convergence prism is a 30° wedge-shaped dispersion prism placed inversely.

8. The space-based infrared coded spectrum imaging optical system according to claim 1, characterized in that: The focusing module is an imaging lens.

9. The space-based infrared coded spectrum imaging optical system according to claim 1, characterized in that: The spectrum encoding imaging module adopts a 4f system of symmetrical imaging of collimation-dispersion-primary image-focusing.

10. The space-based infrared coded spectrum imaging method implemented by the space-based infrared coded spectrum imaging optical system according to claim 1, characterized in that: include: Three reflectors are used to receive information and form an image; A beam splitter is used to split the primary image into a medium-wave image and a long-wave image; A collimating lens is used to collimate the light of the medium-wave image and the long-wave image respectively; Disperse the collimated parallel light; Encode the dispersed optical information; Spectrally converge the encoded information; Output the spectral convergence information to an external detector.

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