阅读说明：本技术 基于七孔径的稀疏合成孔径成像系统及其相位校正方法 (Sparse synthetic aperture imaging system based on seven apertures and phase correction method thereof ) 是由 聂亮 孟咪莎 于洵 刘宝元 陈靖 于 2021-07-09 设计创作，主要内容包括：本发明涉及高分辨率光学成像技术领域,具体涉及一种基于七孔径的稀疏合成孔径成像系统及其相位校正方法。可用于提高系统的成像分辨能力,并有效减少共相误差对成像系统的影响。本发明由合束光学系统以及图像采集系统组成,经过平行光管的反射光波经子孔径阵列后,通过相位校正系统完成倾斜误差和平移误差的校正,对每个子孔径进行相位闭环校正,实现七路成像光波共相位,最后成像光波经过光束合束系统以及图像采集系统实现高分辨率成像。本发明结构简单紧凑且能有效实现相位误差的校正功能,环境适应性强,在准确性和实时性方面相较同类系统有所改善。(The invention relates to the technical field of high-resolution optical imaging, in particular to a sparse synthetic aperture imaging system based on seven apertures and a phase correction method thereof. The method can be used for improving the imaging resolution of the system and effectively reducing the influence of the common phase error on the imaging system. The invention is composed of a beam combining optical system and an image acquisition system, after reflected light waves passing through a collimator pass through a sub-aperture array, the correction of tilt error and translation error is completed through a phase correction system, phase closed loop correction is carried out on each sub-aperture, the common phase of seven paths of imaging light waves is realized, and finally the imaging light waves pass through the beam combining system and the image acquisition system to realize high-resolution imaging. The phase error correction system is simple and compact in structure, capable of effectively achieving the phase error correction function, high in environmental adaptability and improved in accuracy and real-time performance compared with similar systems.)

1. A sparse synthetic aperture imaging system based on seven apertures is composed of a telescope subsystem, a phase correction system, a beam combination optical system and an image acquisition system;

the telescope subsystem is a sparse aperture sub-aperture array consisting of a plurality of Cassegrain telescope subsystems (1);

the phase correction system comprises a plurality of quick reflectors (2) and a plurality of quick reflectors (3);

the beam combining optical system comprises a plurality of corner-cutting reflectors (4), a main reflector (5) and a circular reflector (6), and the number of the quick reflectors (2), the quick reflectors (3) and the corner-cutting reflectors (4) is the same as that of the Cassegrain telescope subsystem (1);

the image acquisition system comprises a CCD camera (7) and a computer (8);

the fast reflector (2), the fast reflector (3) and the corner cut reflector (4) are sequentially arranged on an emergent light path of each Cassegrain telescope subsystem (1) and are used for reflecting imaging light waves of the subsystems and adjusting phase errors of sparse synthetic apertures;

the emergent light paths of the corner-cutting reflectors (4) sequentially penetrate through the main reflector (5), the round reflector (6), the CCD camera (7) and the computer (8);

and the computer (8) is respectively and electrically connected with the CCD camera (7) and the phase correction system.

2. A seven aperture based sparse synthetic aperture imaging system as claimed in claim 1 wherein: the cassegrain telescope subsystem (1) is provided with 7.

3. A seven aperture based sparse synthetic aperture imaging system according to claim 1 or 2, wherein: and one-dimensional and two-dimensional deflection piezoelectric ceramic displacement platforms are respectively arranged behind the quick reflector (2) and the quick reflector (3).

4. The phase correction method of a sparse synthetic aperture imaging system based on seven apertures according to claim 1, wherein: the method comprises the following steps:

1) after the light waves reflected by the target are imaged by the sparse aperture sub-aperture array, the imaging light waves are reflected by the fast reflector (2) and the fast reflector (3), finally imaged on the CCD camera (7) through the corner cut reflector (4), the main mirror (5) and the circular reflector (6), and the final imaging result is collected through the computer (8);

2) according to image information collected by a CCD camera (7), an image is processed by utilizing an already known image definition evaluation function, if the evaluation function is not optimal, a blind optimization algorithm is adopted to continue global control, a new controller voltage is generated every time iteration is carried out, a piezoelectric ceramic displacement platform behind a quick reflector (2) and a quick reflector (3) can be controlled by programming, the inclination error and the translation error of each sub-aperture are corrected, the common phase of each path of light beam is realized, and the high-resolution imaging image can be directly obtained on the CCD camera (7).

5. The phase correction method of a sparse synthetic aperture imaging system based on seven apertures according to claim 4, wherein: the iteration end point of the blind optimization algorithm depends on whether the sharpness evaluation index of the image acquired by the sparse synthetic aperture imaging system is optimal or not, when the index is not optimal, the voltage of the iteration controller is continued, when the index is optimal, the iteration is stopped, and at the moment, the seven-hole synthetic aperture system realizes common phase to obtain a high-resolution image.

6. The phase correction method of a sparse synthetic aperture imaging system based on seven apertures according to claim 5, wherein: the blind optimization algorithm is one of a Simulated Annealing (SA) algorithm, a random parallel gradient descent (SPGD) algorithm, a hill climbing method and a genetic algorithm.

Technical Field

The invention relates to the technical field of high-resolution optical imaging, in particular to a sparse synthetic aperture imaging system based on seven apertures and a phase correction method thereof.

Background

The large optical telescope is one of important tools for detecting a long-distance target, and is widely applied to the fields of weather forecast, earth resources, environment detection, astronomical observation, military ground reconnaissance, spatial situation perception and the like, but the limit angle resolution of an optical system is limited by the wavelength of light waves and the aperture of the optical system, and the minimum spatial resolvable angle of the telescope is inversely proportional to the aperture diameter of the system. With the increasing demands on the resolving power of the optical system, the system aperture of the optical system operating in a certain wavelength band is required to be increased. However, in practical applications, due to the limitations of various factors (such as manufacturing materials, manufacturing techniques, mechanical structures, emission volume and weight, etc.), the increase of the aperture of the single-aperture system becomes extremely difficult. The optical synthetic aperture imaging technology provides a new method for improving the resolution of an imaging system.

The synthetic aperture imaging technology is to replace the main mirror of the traditional single-aperture system with a precisely positioned sub-aperture array to achieve the purpose of increasing the aperture of the system. Different from various limitations on the increase of the aperture of the traditional single-aperture optical telescope, the imaging technology of the synthetic aperture optical system can promote the aperture of the optical system to develop in a crossing manner, not only can realize high-resolution imaging, but also can reduce the processing difficulty of the primary mirror, and particularly for a space-based telescope, the load volume and the weight can be reduced, and the emission cost can be reduced.

For all optical synthetic aperture imaging telescopes, the most important problem is to realize the common phase of all sub-apertures, and errors equivalent to wavelengths can be generated due to the assembly problem of the sub-apertures, the influence of factors such as the change of the gravity direction, wind-borne vibration, atmospheric translation errors and the like during observation, so that the phase error correction can be realized in real time to achieve the key process of the observation target of the optical synthetic aperture imaging telescope.

The existing phase correction method usually adopts a detection technology such as a phase difference method, a shack-hadamard method and the like to detect the aberration of the synthetic aperture imaging system and then correct the aberration, and additional optical elements such as a hadamard sensor, a spectroscope, a grating and the like are required to be utilized, which inevitably increases the complexity and the cost of the whole optical system, introduces additional mechanical errors and other system aberrations, influences the detection precision and the accuracy, and increases the difficulty of the common phase of each sub-aperture.

Disclosure of Invention

In view of the above, the present invention provides a sparse synthetic aperture imaging system based on seven apertures and a phase correction method thereof to solve the defects and shortcomings existing in the existing common phase problem.

In order to solve the problems in the prior art, the technical scheme of the invention is as follows: a sparse synthetic aperture imaging system based on seven apertures is composed of a telescope subsystem, a phase correction system, a beam combination optical system and an image acquisition system;

the telescope subsystem consists of a plurality of Cassegrain telescope subsystems to form a sparse aperture subaperture array;

the phase correction system comprises a plurality of quick reflectors and a plurality of quick reflectors;

the beam combining optical system comprises a plurality of corner-cutting reflectors, a main mirror and a circular reflector, and the number of the quick reflectors, the quick reflectors and the corner-cutting reflectors is the same as that of the Cassegrain telescope subsystems;

the image acquisition system comprises a CCD camera and a computer;

the fast reflector, the fast reflector and the corner cut reflector are sequentially arranged on an emergent light path of each Cassegrain telescope subsystem and are used for reflecting imaging light waves of the subsystems and adjusting phase errors of sparse synthetic apertures;

the emergent light paths of the plurality of corner-cut reflectors sequentially penetrate through the main reflector, the circular reflector, the CCD camera and the computer;

and the computer is respectively and electrically connected with the CCD camera and the phase correction system.

Further, there are 7 cassegrains telescope subsystems.

Furthermore, a piezoelectric ceramic displacement platform with one-dimensional deflection and a piezoelectric ceramic displacement platform with two-dimensional deflection are respectively arranged behind the fast reflector and the fast reflector.

A phase correction method of a sparse synthetic aperture imaging system based on seven apertures comprises the following steps:

1) after the light waves reflected by the target are imaged by the sparse aperture sub-aperture array, the imaging light waves are reflected by the fast reflector and the fast reflector, finally imaged on the CCD camera through the corner cut reflector, the main mirror and the circular reflector, and the final imaging result is collected through the computer;

2) according to image information collected by a CCD camera, processing an image by utilizing an already known image definition evaluation function, if the evaluation function is not optimal, continuously performing global control by adopting a blind optimization algorithm, generating a new voltage of a controller every time of iteration, programming a controllable fast reflector and a piezoelectric ceramic displacement platform behind the fast reflector, correcting the inclination error and the translation error of each sub-aperture, realizing the common phase of each path of light beam, and directly obtaining a high-resolution imaging image on the CCD camera.

Further, the iteration end point of the blind optimization algorithm depends on whether the sharpness evaluation index of the image acquired by the sparse synthetic aperture imaging system is optimal or not, when the index is not optimal, the voltage of the iteration controller is continued, when the index is optimal, the iteration is stopped, and at the moment, the seven-hole synthetic aperture system realizes the common phase to obtain the high-resolution image.

Further, the blind optimization algorithm is one of a Simulated Annealing (SA) algorithm, a random parallel gradient descent (SPGD) algorithm, a hill climbing method and a genetic algorithm.

Compared with the prior art, the invention has the following advantages:

1) compared with other sparse synthetic aperture imaging systems, the system provided by the invention has the advantages that the phase correction system is used, so that the whole system is simpler and more compact in structure, the volume and the quality of the system are reduced, and the adjustable range of the optical path is ensured;

2) the phase correction method can realize high-precision phase correction, the correction of a common-phase error is realized by adopting the fast reflector, the piezoelectric ceramic displacement platforms of one-dimensional deflection and two-dimensional deflection are programmable and controllable, and the fast common-phase closed loop test of a sparse synthetic aperture imaging system can be realized;

3) compared with the correction method of the traditional sparse aperture synthesis system, the phase correction method does not need additional optical devices for assistance, and does not introduce more mechanical errors or other system aberrations. The phase correction system is controlled by performing index evaluation on the far-field image, the common-phase error of each path is corrected, system aberration is not introduced, an additional optical element is not needed, and higher phase correction precision is achieved;

4) the phase correction method is not only suitable for the common-phase error correction of the phased telescope array, but also suitable for the common-phase error correction of the splicing sub-mirror system;

5) the phase correction method is suitable for high-resolution imaging of the point light source and high-resolution imaging of the extended target.

Description of the drawings:

FIG. 1 is a schematic structural diagram of a sparse synthetic aperture imaging system based on seven apertures proposed by the present invention; wherein, wherein: (a) is a system structure side view, (b) is a system structure diagram of a single path sub-aperture;

FIG. 2 is a plan view of the seven aperture telescope array system of the present invention;

FIG. 3 is a schematic block diagram of the phase correction method of the present invention;

fig. 4 is an imaging result of a single-aperture imaging system and an imaging result using a seven-aperture sparse synthetic aperture after phase correction, wherein (a) is an imaging diagram of the single-aperture system, and (b) is an imaging diagram of the seven-aperture sparse synthetic system;

description of the labeling: 1. a Cassegrain telescope subsystem; 2. a card fast mirror; 3. a fast reflector; 4. a corner cut mirror; 5. a primary mirror; 6. a circular reflector; 7. a CCD camera; 8. a computer;

Detailed Description

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are only a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The system realizes synthetic imaging by a seven-path sub-aperture phased telescope array, the imaging principle of the system is the Fizeau interference principle, and high-resolution imaging of a target can be directly realized.

The invention relates to a sparse synthetic aperture imaging system based on seven apertures, which is composed of a telescope subsystem, a phase correction system, a beam combining optical system and an image acquisition system, as shown in figure 1; the telescope subsystem comprises a sparse aperture sub-aperture array consisting of seven Cassegrain telescope subsystems 1, a phase correction system consisting of a quick reflector 2 and a quick reflector 3, a beam combining system consisting of a corner-cut reflector 4, a main mirror 5 and a circular reflector 6, and an image acquisition system consisting of a CCD camera 7 and a computer 8.

The sparse aperture subaperture array is composed of seven paths of subaperture Cassegrain telescope subsystems to realize synthetic imaging, the imaging principle is the Fizeau interference principle, and high-resolution imaging of a target can be directly realized, as shown in figure 2.

The fast reflector 2, the fast reflector 3 and the corner cut reflector 4 are sequentially arranged on the emergent light path of each Cassegrain telescope subsystem 1 and are used for reflecting the imaging light waves of the subsystems and adjusting the phase error of the sparse synthetic aperture;

the emergent light paths of the plurality of corner-cut reflectors 4 sequentially penetrate through the main reflector 5, the circular reflector 6, the CCD camera 7 and the computer 8;

two quick reflectors are arranged at the position of the quick reflector 2, a one-dimensional piezoelectric ceramic displacement platform is arranged behind the quick reflector 3, a two-dimensional deflection piezoelectric ceramic displacement platform is arranged behind the quick reflector 3, imaging light beams are reflected by the quick reflector 2 and the quick reflector 3, and the programming is controllable to adjust the one-dimensional and two-dimensional deflection piezoelectric ceramic displacement platforms of each path, so that the imaging light beams of each sub-aperture are in common phase.

The computer 8 controls the imaging detection system to be responsible for collecting images and processing the collected images in real time on one hand, and controls the phase correction system to output a new voltage control piezoelectric ceramic displacement platform each time on the other hand, so that the rapid correction of the common-phase error is realized.

Taking a seven-aperture imaging system as an example to describe a specific working process, fig. 2 is an array plan view of the seven-aperture imaging system, and a phase correction method of a sparse synthetic aperture imaging system based on seven apertures is shown in fig. 3, and the steps are as follows:

1) after the light waves reflected by the target are imaged by the sparse aperture sub-aperture array, the imaging light waves are reflected by the fast reflector 2 and the fast reflector 3, finally imaged on the CCD camera 7 through the corner cut reflector 4, the main mirror 5 and the circular reflector 6, and the final imaging result is collected through the computer 8;

2) according to image information collected by the CCD camera 7, a known image definition evaluation function is utilized to process a sparse synthetic aperture imaging result collected by a computer, if the evaluation function is not optimal, a blind optimization algorithm is adopted to continue global control, new controller voltage is generated in each iteration, a piezoelectric ceramic displacement platform behind the fast reflector 2 and the fast reflector 3 can be controlled through programming, the inclination error and the translation error of each sub-aperture are corrected, the common phase of each path of light beam is realized, and a high-resolution imaging image can be directly obtained on the CCD camera 7.

The iteration end point of the blind optimization algorithm depends on whether the sharpness evaluation index of the image acquired by the sparse synthetic aperture imaging system is optimal or not, when the index is not optimal, the voltage of the iteration controller is continued, when the index is optimal, the iteration is stopped, and at the moment, the seven-hole synthetic aperture system realizes common phase to obtain a high-resolution image.

The blind optimization algorithm is one of a Simulated Annealing (SA) algorithm, a random parallel gradient descent (SPGD) algorithm, a hill climbing method and a genetic algorithm.

After the phase correction is carried out on the seven-aperture sparse aperture imaging system, the imaging system can clearly image, the resolution is greatly improved compared with a single-aperture imaging system, the high-frequency details of the image can be basically distinguished, and the simulation results of the single-aperture imaging system and the seven-aperture sparse aperture imaging system subjected to the phase correction are shown in fig. 4.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and it should be noted that those skilled in the art should make modifications and variations without departing from the principle of the present invention.