CN115065789B - Wide-spectrum-band dual-channel compression imaging method and system with real exit pupil - Google Patents
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Abstract
The invention discloses a wide-spectrum dual-channel compression imaging method and system with a real exit pupil, and belongs to the technical field of computational imaging. The invention realizes single exposure and simultaneously captures the two-channel image through wide-spectrum two-channel common image plane compression imaging with a real exit pupil. According to the invention, the mixed images acquired by the two-channel shared image plane are separated in a frequency domain compression mode, and the imaging view field is enlarged without adding a scanning device. The invention adopts reflective dual-channel compression imaging to realize dual-channel wide-spectrum imaging. The size and position of the real exit pupil and the cold stop of the detector to be used are matched through the front-mounted diaphragm. The invention realizes the concurrent imaging of large view field and long focal length through the wide-spectrum dual-channel compression imaging with the real exit pupil, and has the advantages of high resolution, narrow bandwidth, wide imaging spectrum, compact structure, high stability and good economy of an imaging system. The invention can be widely applied to a plurality of spectral bands such as ultraviolet, visible, short wave infrared, medium wave infrared, long wave infrared and the like.
Description
Technical Field
The invention belongs to the technical field of computational imaging, and relates to a wide-spectrum dual-channel compression imaging method and system with a real exit pupil.
Background
At present, the scientific technology is continuously developed, the times of high-speed development bring new requirements to the optical system, but the design of the traditional optical system faces serious bottlenecks, the needs of the times cannot be completely solved, and the computational imaging is generated. The computational imaging fully utilizes the advantages of high communication bandwidth and high floating point computational efficiency at present, relieves the pressure of an optical system, and has great application value in reducing the cost of the optical system and improving the performance and index of the optical system. Currently, the optical system has great application in the monitoring field and has wide prospect in various fields such as industrial production, smart cities, intelligent manufacturing, automation, sports games, urban public security and the like. These fields of application also continually place new demands and indices on the design of optical systems.
At present, an optical lens for monitoring is continuously pursued with a larger and larger field of view and a longer and longer focal length, wherein the larger and larger field of view means that a larger range can be monitored to acquire more abundant object information, and the longer and longer focal length improves the working distance and the spatial resolution of an optical system. But is limited by the theory of traditional optical design, the field of view and focal length are always a pair of contradictory quantities, and cannot be effectively improved at the same time. The traditional methods for solving the problems include detector splicing, compound eye, scanning and the like. However, the geometric multiple of the information amount is inevitably increased due to the splicing of the detectors, and in addition, the fields of view are lost due to the spliced parts of the detectors, so that the monitoring is not facilitated; the compound eye is difficult to design, and the tooling adjustment has great difficulty, so that the information quantity is greatly increased, and the cost is increased; the optical scanning can be carried out by adding an optical scanning mechanism, a steering engine and the like into an optical system, the reliability of the system can be greatly reduced by a complex motor system and a rotating mechanism, the volume and the weight of the system are obviously improved, and the time resolution is reduced. Therefore, there is a need for an optical solution that can properly solve the contradiction between the field of view and the focal length without introducing other contradictions.
In 2016, cheng Dewen et al at the university of Beijing university of technology, design ofall-REFLECTIVE DUAL-channel foveated IMAGING SYSTEMS based on freeform optics, propose a reflective dual-channel concave imaging optical system, which uses one channel for imaging in a large field of view and the other channel for a long focal length, so that both the large field of view and the long focal length are achieved, but the dual detectors are adopted, so that the system bandwidth is greatly increased, and the overall high resolution cannot be realized. In 2021, zhu Jun et al, university of Qinghai, in Simultaneous improvement offield-of-view andresolution IN AN IMAGING optical system, proposed a design method that simultaneously increased the field of view and focal length of the optical system, but that expanded the field of view by reducing the focal length of the fringe field of view, the resolution of the reduced fringe field of view more similar to that of the field of view by design distortion, and the resulting image was therefore not visually observable to the human eye.
Disclosure of Invention
In order to solve the contradiction problem of the optical imaging view field and the focal length and meet the cold diaphragm matching requirement of an infrared refrigeration optical system, the invention discloses a wide-spectrum dual-channel compression imaging method and a system with a real exit pupil. The technical problems to be solved are as follows: through wide-spectrum dual-channel shared image surface compression imaging, single exposure is realized, simultaneously, dual-channel wide-spectrum images are captured, the image processing data volume is reduced, the contradiction between an optical imaging view field and a focal length is solved, large-view-field and long-focal-length concurrent imaging is realized, the cold light diaphragm matching requirement of an infrared refrigeration optical system can be met, and the infrared refrigeration optical system has the advantages of high resolution, narrow bandwidth, wide imaging spectrum, compact structure, high stability and good economy.
Aiming at meeting the cold diaphragm matching requirement of an infrared refrigeration optical system, the infrared refrigeration optical system can be applied to visible and ultraviolet bands and infrared bands, and meets the use requirement of an infrared refrigeration detector.
The aim of the invention is achieved by the following technical scheme.
According to the wide-spectrum dual-channel compression imaging method with the real exit pupil, single exposure is realized and dual-channel images are captured simultaneously through the wide-spectrum dual-channel common image plane compression imaging with the real exit pupil, and under the condition of the same detector, compared with a traditional alternately-operated dual-channel imaging system, the time resolution of the compression imaging system is doubled, and the data volume is doubled under the same imaging time resolution precision requirement. The mixed image acquired by the two-channel shared image surface is separated in a frequency domain compression mode, and the imaging view field is enlarged without adding a scanning device, so that the structural compactness, stability and economical efficiency of the imaging system are improved. And realizing the imaging of the two-channel wide spectrum by adopting the reflective two-channel compression imaging. The wide-spectrum dual-channel compression imaging method with the real exit pupil can generate the real exit pupil in front of an image by leading the diaphragm, and the real exit pupil is matched with the size and the position of the cold stop of the detector to be used by matching the cold stop. In summary, the wide-spectrum dual-channel compression imaging with the real exit pupil solves the contradiction between the field of view and the focal length of the traditional optical imaging, realizes concurrent imaging with a large field of view and a long focal length, can be applied to various imaging systems of ultraviolet, visible, infrared and infrared refrigerating full wave bands, and has the advantages of high resolution, narrow bandwidth, wide imaging spectrum, compact structure, high stability and good economy of an imaging system.
The wide-spectrum dual-channel compression imaging method with the real exit pupil disclosed by the invention expands wide-spectrum dual-channel compression imaging with the real exit pupil into wide-spectrum multi-channel compression imaging with the real exit pupil, further expands the imaging field of view, improves the structural compactness, economy and resolution of an imaging system and compresses the bandwidth of the imaging system.
The wide-spectrum dual-channel compression imaging method with the real exit pupil adopts a wide-spectrum dual-channel frequency domain compression mode separation imaging with the real exit pupil, and comprises the following implementation steps:
Step one: and carrying out frequency domain coding on the imaging light beam obtained by the wide-spectrum dual-channel compressed imaging light path with the real exit pupil according to the following four constraint conditions, wherein the coding modulation is realized by placing a phase plate at the separation position of two diaphragms in front of the main mirror, and the imaging light beam after the frequency domain coding is obtained.
Condition one: the phase coding cannot enable the MTF of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil to have zero before the characteristic frequency, otherwise, information is lost;
Condition II: PSF of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil enables sampling positions of respective OTFs on an image frequency domain to be different, so that the information of the image is ensured not to be aliased on the frequency domain, and recovery by a recovery algorithm is facilitated;
and (3) a third condition: PSFs after different view field phase codes of each channel of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil are the same as much as possible, so that an image restoration algorithm is simplified greatly;
condition four: the PSF after the phase encoding of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil enables the area of OTF sampling to be as large as possible, so that the information of frequency domain sampling is increased, and the image restoration is facilitated.
Step two: and (3) exposing the frequency-domain coded imaging light beam obtained in the step (A) through a double-channel shared image plane to obtain a double-channel shared image plane mixed image.
The dual-channel shared image plane refers to that the dual channels share one area array photoelectric detector to capture a mixed image.
The intensity information i (x, y) of the mixed image captured by the area array photodetector is simplified as follows:
Wherein, Representing convolution, f 1(x,y)、f2 (x, y) represents object space information captured by two channels of a wide-band dual-channel compression imaging optical system having a real exit pupil, and PSF 1(x,y)、PSF2 (x, y) represents a point spread function of two channels of the wide-band dual-channel compression imaging optical system having a real exit pupil.
Step three: and (3) carrying out Fourier transform on the wide-spectrum dual-channel shared image surface mixed image with the real exit pupil obtained in the step (II) to obtain a spectrogram of the shared image surface mixed image, carrying out image restoration on the spectrogram through a compressed sensing restoration algorithm, and respectively restoring object side images of two imaging channels from one image, namely realizing frequency domain compression mode separation imaging.
And (3) carrying out Fourier transform on the two-channel shared image surface mixed image obtained in the step (II) to obtain a spectrogram of the shared image surface mixed image as shown in the formula (1).
The inverse problem of wide-band two-channel frequency domain compression imaging with real exit pupil is converted into a compressed sensing restoration problem on the frequency domain:
And (3) taking the frequency domain compressed sensing restoration problem shown in the formula (3) as an objective function of image restoration, carrying out image restoration on the spectrogram through a compressed sensing restoration algorithm, and respectively restoring object side images of two imaging channels from one image, namely realizing frequency domain compression mode separation imaging.
By adopting the wide-spectrum two-channel frequency domain compression mode with a real exit pupil for separation imaging, two separation images can be obtained, and preferably, the two separation images are spliced according to the two-channel visual field relation, so that the visual effect of imaging is improved on the basis of expanding the visual field.
The invention also discloses a wide-spectrum dual-channel compression imaging system with the real exit pupil, which is used for realizing the wide-spectrum dual-channel compression imaging method with the real exit pupil. The wide-spectrum dual-channel compression imaging system with the real exit pupil comprises a first phase plate, a second phase plate, a first main mirror, a second main mirror, a secondary mirror, a three-mirror, a cold diaphragm (real exit pupil), an area array photoelectric detector and an image restoration system. The components are arranged in sequence in the propagation direction of the light.
The first phase plate is positioned at the forefront end of the optical first channel and is also an aperture diaphragm of the first channel in the dual-channel compression imaging system, and provides a special phase for an imaging light beam passing through the optical first channel to carry out phase encoding. The phase plate is a glass plate with a predetermined face that encodes the imaging beam to modulate the PSF and OTF of the optical first channel in the dual channel compression imaging system. The phase plate profile should be matched to the amount and phase of modulation of the desired phase modulation, which modulates the sampling characteristics of the optical first channel so that it meets the four conditions in step one.
The second phase plate is positioned at the forefront end of the optical second channel and is also an aperture diaphragm of the second channel in the dual-channel compression imaging system, and provides a special phase for the imaging light beam passing through the optical second channel to carry out phase encoding. The phase plate is a glass plate with a predetermined profile that encodes the imaging beam to modulate the PSF and OTF of the optical first channel in the dual channel compression imaging system. The phase plate profile should be matched to the amount and phase of modulation of the desired phase modulation, which modulates the sampling characteristics of the optical first channel so that it meets the four conditions in step one.
The first phase plate and the second phase plate perform phase modulation on the imaging light beam through the surface type parameters, the modulation of the imaging light beam meets the relevant rule of compressed sensing, so that a subsequent image restoration system can restore an acquired image, and the specific rule meets four conditions in the step one.
The first primary mirror is positioned in the optical first channel, behind the first phase plate in the optical path, for compressing the light beam, assuming a certain optical power and correcting aberrations.
The second primary mirror is located in the optical second channel, behind the second phase plate in the optical path, for compressing the light beam, assuming a certain optical power and correcting aberrations.
The secondary mirror is shared by two optical channels and is positioned behind the first main mirror and the second main mirror in the optical path, and is used for providing certain focal power and aberration correction capability for the first channel and the second channel of the dual-channel compression imaging system and reflecting the light beams passing through the first main mirror and the second main mirror to the three mirrors.
The three mirrors are shared by the two optical channels, are positioned behind the secondary mirror in the optical path, and are used for providing certain focal power and aberration correction capability for the first channel and the second channel of the dual-channel compression imaging system, converging light beams, and converging the light beams reflected to the three mirrors by the secondary mirror to the image surface.
The real exit pupil (cold stop) is located behind the three mirrors in the optical path and in front of the optical system image plane, and its distance from the image plane should be in accordance with the selected infrared refrigeration detector data, for providing appropriate conditions for cold stop matching of the infrared refrigeration detector.
The area array photoelectric detector is used for recording and quantifying the optical image formed by the front optical system into an electronic image. An infrared refrigeration CCD can be used, and the size of the cold diaphragm is required to be customized according to the size and shape of the front real exit pupil.
The image restoration module is used for respectively calculating the information of the two optical channels from the image captured by the area array photoelectric detector. The image restoration module is provided with a calculation storage terminal and an image restoration algorithm, the image restoration algorithm adopts a traditional compressed sensing restoration algorithm to restore a mixed image captured by photoelectric detection devices such as CCD or CMOS, the problem is firstly converted into a frequency domain according to the coding principle and the formula deduction described in the step three, and the image is restored by using the compressed sensing restoration algorithm in the frequency domain.
The beneficial effects are that:
1. According to the wide-spectrum dual-channel compression imaging method and system with the real exit pupil, two channels share one image plane, so that under the condition that the detector area array is limited, the focal length and the view field of an optical system can be improved, wide-area high-resolution monitoring of a target scene can be realized, more target details can be captured by high resolution, the target recognition probability can be greatly improved, the monitoring range can be greatly improved by wide area, the target tracking is facilitated, and particularly, the target recognition probability of a monitoring tracking system is remarkably improved for targets with high maneuvering performance.
2. According to the wide-spectrum dual-channel compression imaging method and system with the real exit pupil, provided by the invention, the compressed sensing theory is adopted, and the object side images of two channels are separated from the single Zhang Gongyong image plane mixed image through the frequency domain compressed sensing restoration algorithm, so that the simultaneous promotion of the view field and the focal length is realized, and the time resolution of the system is not reduced. In addition, because the two-channel image surfaces are shared, the detector can obtain double light energy in the traditional imaging, can realize high signal-to-noise ratio images with lower exposure time and improve the time resolution of the system, and therefore, the method has great benefits for tracking targets with high maneuvering performance. The target tracking efficiency of the monitoring tracking system is remarkably improved.
3. According to the wide-spectrum dual-channel compression imaging method and system with the real exit pupil, the image surfaces are shared, the dual channels work simultaneously, and the compressed sensing restoration algorithm is combined, so that images of respective object sides of the two channels at the same moment can be separated from a shared image surface mixed image, and the effect of reducing the data quantity by half is achieved. The method can effectively solve the defects of high bandwidth requirement of the existing high-definition lens and short storage time of the monitoring video, and provides a new solution for a video transmission scheme of large-view-field high-definition monitoring.
4. The wide-spectrum dual-channel compression imaging method and system with the real exit pupil adopt the method and system for carrying out frequency domain coding at the pupil instead of intensity coding on the intermediate image plane, so that coding can be realized without secondary imaging, the volume, the weight and the cost of an optical system are obviously reduced, and the adjustment difficulty is reduced.
5. The invention discloses a wide-spectrum dual-channel compression imaging method and a system with a real exit pupil, which adopt the front diaphragm to enable the real exit pupil to exist in a system light path, thereby being convenient for matching with the cold diaphragm of a used refrigeration detector. Therefore, the invention can be widely applied to ultraviolet, visible, infrared and refrigeration type and non-refrigeration type all-band multisystem detection imaging applications.
Drawings
FIG. 1 is a flow chart of a wide-band dual-channel compression imaging method with a real exit pupil;
FIG. 2 is a flowchart of an image restoration algorithm for implementing the method of the present invention;
FIG. 3 is a schematic diagram of a system structure according to an embodiment of the present invention;
FIG. 4 is an image for algorithm simulation in an embodiment of the present invention, which represents object information collected by two channels, respectively;
FIG. 5 shows PSFs for two channels, respectively, in an embodiment of the present invention;
FIG. 6 is a blended image obtained by two channels operating simultaneously in which information collected by the two channels is blended together in an embodiment of the present invention;
fig. 7 illustrates object information captured by the two channels recovered from fig. 6 by the image recovery system in accordance with an embodiment of the present invention.
Wherein: 1-first phase plate, 2-second phase plate, 3-first primary mirror, 4-second primary mirror, 5-secondary mirror, 6-three mirrors, 7-real exit pupil, 8-area array photodetector, 9 image restoration system.
Detailed Description
For a better description of the objects and advantages of the present invention, the following description will be given with reference to the accompanying drawings and examples.
Example 1:
The present embodiment discloses
As shown in fig. 1, the embodiment discloses a wide-spectrum dual-channel compression imaging method with a real exit pupil, which specifically includes the following implementation steps:
The wide-spectrum dual-channel compression imaging method with the real exit pupil adopts a wide-spectrum dual-channel frequency domain compression mode separation imaging with the real exit pupil, and comprises the following implementation steps:
Step one: and carrying out frequency domain coding on the imaging light beam obtained by the wide-spectrum dual-channel compressed imaging light path with the real exit pupil according to the following four constraint conditions, wherein the coding modulation is realized by placing a phase plate at the separation position of two diaphragms in front of the main mirror, and the imaging light beam after the frequency domain coding is obtained.
Condition one: the phase coding cannot enable the MTF of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil to have zero before the characteristic frequency, otherwise, information is lost;
Condition II: PSF of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil enables sampling positions of respective OTFs on an image frequency domain to be different, so that the information of the image is ensured not to be aliased on the frequency domain, and recovery by a recovery algorithm is facilitated;
and (3) a third condition: PSFs after different view field phase codes of each channel of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil are the same as much as possible, so that an image restoration algorithm is simplified greatly;
condition four: the PSF after the phase encoding of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil enables the area of OTF sampling to be as large as possible, so that the information of frequency domain sampling is increased, and the image restoration is facilitated.
The PSFs of the two channels of the wide band dual channel compression imaging optical system with real exit pupil encoded in this embodiment are shown in fig. 5.
Step two: and (3) exposing the obtained frequency domain coded imaging light beam in the step (I) through a double-channel shared image plane to obtain a double-channel shared image plane mixed image, as shown in fig. 6.
The dual-channel shared image plane refers to that the dual channels share one area array photoelectric detector to capture a mixed image.
The intensity information i (x, y) of the mixed image captured by the area array photodetector is simplified as follows:
Wherein, Representing convolution, f 1(x,y)、f2 (x, y) represents object space information captured by two channels of a wide-band dual-channel compression imaging optical system having a real exit pupil, and PSF 1(x,y)、PSF2 (x, y) represents a point spread function of two channels of the wide-band dual-channel compression imaging optical system having a real exit pupil.
Step three: and (3) carrying out Fourier transform on the wide-spectrum dual-channel shared image surface mixed image with the real exit pupil obtained in the step (II) to obtain a spectrogram of the shared image surface mixed image, carrying out image restoration on the spectrogram through a compressed sensing restoration algorithm, and respectively restoring object side images of two imaging channels from one image, namely realizing frequency domain compression mode separation imaging.
And (3) carrying out Fourier transform on the two-channel shared image surface mixed image obtained in the step (II) to obtain a spectrogram of the shared image surface mixed image as shown in the formula (4).
The inverse problem of wide-band two-channel frequency domain compression imaging with real exit pupil is converted into a compressed sensing restoration problem on the frequency domain:
And (3) taking the frequency domain compressed sensing restoration problem shown in the formula (6) as an objective function of image restoration, carrying out image restoration on the spectrogram through a compressed sensing restoration algorithm, and respectively restoring object side images of two imaging channels from one image, namely realizing frequency domain compression mode separation imaging. In this embodiment, the TWIST algorithm is adopted to recover the problem, and other convex optimization algorithms can also be adopted.
By adopting the wide-spectrum two-channel frequency domain compression mode with a real exit pupil for separation imaging, two separation images can be obtained, and preferably, the two separation images are spliced according to the two-channel visual field relation, so that the visual effect of imaging is improved on the basis of expanding the visual field. In this embodiment, since the images adopted in the image simulation have no correspondence, no image stitching is performed, and the restoration result is shown in fig. 7.
The invention also discloses a wide-spectrum dual-channel compression imaging system with the real exit pupil, which is used for realizing the wide-spectrum dual-channel compression imaging method with the real exit pupil. The wide-spectrum dual-channel compression imaging system with the real exit pupil comprises a first phase plate, a second phase plate, a first main mirror, a second main mirror, a secondary mirror, a three-mirror, a cold diaphragm (real exit pupil), an area array photoelectric detector and an image restoration system. The components are arranged in sequence in the propagation direction of the light. The system structure is shown in fig. 3.
The first phase plate is positioned at the forefront end of the optical first channel and is also an aperture diaphragm of the first channel in the dual-channel compression imaging system, and provides a special phase for an imaging light beam passing through the optical first channel to carry out phase encoding. The phase plate is a glass plate with a predetermined face that encodes the imaging beam to modulate the PSF and OTF of the optical first channel in the dual channel compression imaging system. The phase plate profile should be matched to the amount and phase of modulation of the desired phase modulation, which modulates the sampling characteristics of the optical first channel so that it meets the four conditions in step one.
The second phase plate is positioned at the forefront end of the optical second channel and is also an aperture diaphragm of the second channel in the dual-channel compression imaging system, and provides a special phase for the imaging light beam passing through the optical second channel to carry out phase encoding. The phase plate is a glass plate with a predetermined profile that encodes the imaging beam to modulate the PSF and OTF of the optical first channel in the dual channel compression imaging system. The phase plate profile should be matched to the amount and phase of modulation of the desired phase modulation, which modulates the sampling characteristics of the optical first channel so that it meets the four conditions in step one.
The first phase plate and the second phase plate perform phase modulation on the imaging light beam through the surface type parameters, the modulation of the imaging light beam meets the relevant rule of compressed sensing, so that a subsequent image restoration system can restore an acquired image, and the specific rule meets four conditions in the step one. The phase plate type in this embodiment employs a cubic phase plate.
The first primary mirror is positioned in the optical first channel, behind the first phase plate in the optical path, for compressing the light beam, assuming a certain optical power and correcting aberrations.
The second primary mirror is located in the optical second channel, behind the second phase plate in the optical path, for compressing the light beam, assuming a certain optical power and correcting aberrations.
The secondary mirror is shared by two optical channels and is positioned behind the first main mirror and the second main mirror in the optical path, and is used for providing certain focal power and aberration correction capability for the first channel and the second channel of the dual-channel compression imaging system and reflecting the light beams passing through the first main mirror and the second main mirror to the three mirrors.
The three mirrors are shared by the two optical channels, are positioned behind the secondary mirror in the optical path, and are used for providing certain focal power and aberration correction capability for the first channel and the second channel of the dual-channel compression imaging system, converging light beams, and converging the light beams reflected to the three mirrors by the secondary mirror to the image surface.
The real exit pupil (cold stop) is located behind the three mirrors in the optical path and in front of the optical system image plane, and its distance from the image plane should be in accordance with the selected infrared refrigeration detector data, for providing appropriate conditions for cold stop matching of the infrared refrigeration detector.
The area array photoelectric detector is used for recording and quantifying the optical image formed by the front optical system into an electronic image. An infrared refrigeration CCD can be used, and the size of the cold diaphragm is required to be customized according to the size and shape of the front real exit pupil.
The image restoration module is used for respectively calculating the information of the two optical channels from the image captured by the area array photoelectric detector. The image restoration module is provided with a calculation storage terminal and an image restoration algorithm, the image restoration algorithm adopts a traditional compressed sensing restoration algorithm to restore a mixed image captured by photoelectric detection devices such as CCD or CMOS, the problem is firstly converted into a frequency domain according to the coding principle and the formula deduction described in the step three, and the image is restored by using the compressed sensing restoration algorithm in the frequency domain.
The specific optical surface parameters of the system used in this example are shown in table 1:
table 1 optical system parameter table unit: mm (mm)
The global coordinates of the optical surface in this embodiment are shown in table 2:
table 2 optical surface global coordinate parameter table
Units: mm (mm)
| XSC | YSC | ZSC | ASC | BSC | CSC | |
| First phase plate | 0 | 137.4123 | 1.8643 | -2.6760 | 0 | 0 |
| Second phase plate | 0 | 85.1106 | -2.2780 | -1.6797 | 0 | 0 |
| First main mirror | 0 | -17.6748 | 134.12610 | -6.4997 | 0 | 0 |
| Second main mirror | 0 | -17.6748 | 134.12610 | -6.4997 | 0 | 0 |
| Secondary mirror | 0 | 0 | 0 | 0 | 0 | 0 |
| Three mirrors | 0 | 10.1854 | 151.4154 | 5.2785 | 0 | 0 |
| Image plane | 0 | -18.6441 | 25.8763 | 9.9928 | 0 | 0 |
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims (4)
1. A wide-spectrum dual-channel compression imaging method with a real exit pupil is characterized by comprising the following steps of: by adopting the wide-spectrum dual-channel common image plane compression imaging with the real exit pupil, single exposure is realized, and simultaneously, the dual-channel image is captured, and under the condition of the same detector, compared with the traditional dual-channel imaging system working alternately, the time resolution of the compression imaging system is doubled; and the data volume is reduced by one time under the same imaging frame rate requirement; the mixed image acquired by the two-channel shared image surface is separated in a frequency domain compression mode, and the imaging view field is enlarged without adding a scanning device, so that the structural compactness, stability and economy of an imaging system are improved; adopting reflective double-channel compression imaging to realize double-channel wide-spectrum imaging; the wide-spectrum dual-channel compression imaging method with the real exit pupil can generate the real exit pupil in front of an image by leading the diaphragm, and the real exit pupil is matched with the size and the position of the cold diaphragm of the detector to be used by matching the cold diaphragm, so that the method is suitable for refrigeration type infrared imaging; through wide-spectrum dual-channel compression imaging with a real exit pupil, the contradiction between an optical imaging view field and a focal length is solved, and concurrent imaging of a large view field and a long focal length is realized;
The method comprises the steps of,
Step one: carrying out frequency domain coding on an imaging light beam obtained by a wide-spectrum dual-channel compression imaging light path with a real exit pupil according to the following four constraint conditions, wherein the coding modulation is realized by placing a phase plate at two diaphragm separation positions in front of a main mirror, so as to obtain the imaging light beam after the frequency domain coding;
Condition one: the phase coding cannot enable the MTF of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil to have zero before the characteristic frequency, otherwise, information is lost;
Condition II: PSF of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil enables sampling positions of respective OTFs on an image frequency domain to be different, so that the information of the image is ensured not to be aliased on the frequency domain, and recovery by a recovery algorithm is facilitated;
and (3) a third condition: PSFs after different view field phase codes of each channel of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil are the same as much as possible, so that an image restoration algorithm is simplified greatly;
Condition four: the PSF after the phase encoding of the wide-spectrum dual-channel compression imaging optical system with the real exit pupil enables the OTF sampling area to be as large as possible, so that the frequency domain sampling information is increased, and the image restoration is facilitated;
Step two: exposing the obtained imaging light beam after the frequency domain coding in the step one through a double-channel shared image plane to obtain a double-channel shared image plane mixed image;
In the second step, the second step is to carry out the process,
The dual-channel shared image plane refers to a dual-channel shared area array photoelectric detector for capturing a mixed image;
the intensity information i (x, y) of the mixed image captured by the area array photodetector is simplified as follows:
Wherein, Representing convolution, f 1(x,y)、f2 (x, y) representing object space information captured by two channels of a wide-band dual-channel compression imaging optical system having a real exit pupil, PSF 1(x,y)、PSF2 (x, y) representing a point spread function of two channels of the wide-band dual-channel compression imaging optical system having a real exit pupil;
Step three: obtaining a spectrogram of the shared image plane mixed image by Fourier transformation to a frequency domain, carrying out image restoration on the spectrogram through a compressed sensing restoration algorithm, and respectively restoring object side images of two imaging channels from one image, namely realizing frequency domain compression mode separation imaging;
The implementation method of the third step is that,
Performing Fourier transform on the two-channel shared image surface mixed image obtained in the step two to obtain a spectrogram of the shared image surface mixed image as shown in the formula (2);
The inverse problem of wide-band two-channel frequency domain compression imaging with real exit pupil is converted into a compressed sensing restoration problem on the frequency domain:
And (3) taking the frequency domain compressed sensing restoration problem shown in the formula (3) as an objective function of image restoration, carrying out image restoration on the spectrogram through a compressed sensing restoration algorithm, and respectively restoring object side images of two imaging channels from one image, namely realizing frequency domain compression mode separation imaging.
2. A wide-band dual-channel compression imaging method with real exit pupil as set forth in claim 1, wherein: used in ultraviolet, visible, infrared, and refrigerated or uncooled multisystem full-band imaging applications.
3. A wide-band dual-channel compression imaging method with real exit pupil as set forth in claim 1, wherein: by adopting the wide-spectrum two-channel frequency domain compression mode with a real exit pupil for separation imaging, two separation images can be obtained, the two separation images are spliced according to the two-channel visual field relation, and the visual effect of imaging is improved on the basis of expanding the visual field.
4. A wide-band dual-channel compression imaging system with a real exit pupil for implementing a wide-band dual-channel compression imaging method with a real exit pupil as claimed in claim 1 or 3, characterized in that: the device comprises a first phase plate, a second phase plate, a first main mirror, a second main mirror, a secondary mirror, a three-mirror, a cold diaphragm, an area array photoelectric detector and an image restoration module; in the propagation direction of the light, the components are arranged in sequence on the respective channels;
The first phase plate is positioned at the forefront end of the optical first channel and is also an aperture diaphragm of the first channel in the wide-spectrum dual-channel compression imaging system with a real exit pupil, and the imaging light beam passing through the optical first channel is provided with a special phase to carry out phase encoding; the phase plate is a glass plate with a preset surface, and encodes an imaging light beam to modulate PSF and OTF of an optical first channel in the dual-channel compression imaging system; the phase plate type is matched with the modulation quantity and the phase of the required phase modulation, and modulates the sampling characteristic of the optical first channel so as to enable the sampling characteristic to meet the four conditions of the first step;
The second phase plate is positioned at the forefront end of the optical second channel and is also an aperture diaphragm of the second channel in the wide-spectrum dual-channel compression imaging system with a real exit pupil, and the imaging light beam passing through the optical second channel is provided with a special phase to carry out phase encoding; the phase plate is a glass plate with a preset surface, and encodes the imaging light beam to modulate PSF and OTF of an optical first channel in the dual-channel compression imaging system; the phase plate type is matched with the modulation quantity and the phase of the required phase modulation, and modulates the sampling characteristic of the optical first channel so as to enable the sampling characteristic to meet the four conditions of the first step;
The first phase plate and the second phase plate carry out phase modulation on the imaging light beam through the surface type parameters, the modulation of the imaging light beam meets the relevant rules of compressed sensing, so that the subsequent image restoration module restores the acquired image, and the specific rules meet the four conditions in the step one;
the first main mirror is positioned behind the first phase plate in the optical path in the optical first channel and is used for compressing the light beam, bearing a certain optical power and correcting aberration;
The second main mirror is positioned behind the second phase plate in the optical path and is used for compressing the light beam, bearing a certain optical power and correcting aberration;
The secondary mirror is shared by two optical channels and is positioned behind the first main mirror and the second main mirror in the optical path, and is used for providing certain focal power and aberration correction capability for the first channel and the second channel of the dual-channel compression imaging system and reflecting light beams passing through the first main mirror and the second main mirror to the three mirrors;
the three mirrors are shared by the two optical channels, are positioned behind the secondary mirror in the optical path, and are used for providing certain focal power and aberration correction capability for the first channel and the second channel of the dual-channel compression imaging system, converging light beams, and converging the light beams reflected to the three mirrors by the secondary mirror to an image surface;
The real exit pupil is positioned behind the three mirrors in the light path and in front of the image surface of the optical system, and the distance from the image surface of the real exit pupil accords with the selected infrared refrigeration detector data and is used for providing proper conditions for cold stop matching of the infrared refrigeration detector;
The area array photoelectric detector is used for recording and quantifying an optical image formed by the front optical system into an electronic image; the refrigeration CCD is adopted, and the size of the cold diaphragm is required to be customized according to the size and shape of the front real exit pupil;
The image restoration module is used for respectively calculating the information of the two optical channels from the image captured by the area array photoelectric detector; the image restoration module is provided with a calculation storage terminal and an image restoration algorithm, the image restoration algorithm adopts a traditional compressed sensing restoration algorithm to restore a mixed image captured by CCD or CMOS, firstly, problems are converted into a frequency domain according to the coding principle and the formula deduction described in the step three, and the image is restored by using the compressed sensing restoration algorithm in the frequency domain.
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| CN105511075A (en) * | 2016-01-13 | 2016-04-20 | 中国科学院上海技术物理研究所 | Two-dimensional image motion compensation optical system for large-field-of-view whisk-broom double-channel imager |
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