CN114815133B - Automatic confocal method of optical multi-aperture imaging system - Google Patents

Abstract

The invention discloses an automatic confocal method for an optical multi-aperture imaging system, which can be used for the pre-calibration of the sub-aperture orientation of the optical multi-aperture imaging system. This method uses the centroid extraction algorithm of multi-connected regions and the binarized area method to calculate the distance between multi-spot and common focus and the total area of the spot, and constructs an evaluation function based on this, and adjusts the distance and the focal plane adaptively by combining the current moment and the previous moment of focal plane information. The weight of the area, through the optimization algorithm to automatically control the pointing actuator, to realize the automatic coincidence of the focal plane spot of the multi-aperture system. This method can achieve multi-aperture spot confocal with one click for the complex initial state of the spot, without the need for sequential shutter modulation and additional optical components, and is less limited by the aperture arrangement, number of apertures, optical path structure, and system parameters.

Description

An automatic confocal method for an optical multi-aperture imaging system

technical field

The invention belongs to the field of optical multi-aperture imaging, in particular to an automatic confocal method for an optical multi-aperture imaging system.

Background technique

Large-scale photoelectric telescope systems are widely used in many important fields such as environmental monitoring, astronomical observation, and remote sensing imaging, and are playing an increasingly important role in national security, space research, and human life. The demand for high-quality detection with high noise suppression, high resolution accuracy, and high detection efficiency is increasing day by day. Theoretically speaking, the larger the aperture of the telescope, the stronger its light-gathering ability and the higher the resolution. However, with the existing technical process, a single primary mirror cannot achieve the required caliber. Until the 1970s, with the maturation of optical multi-aperture imaging theory and the gradual accumulation of telescope manufacturing technology, optical multi-aperture imaging technology provided a new idea for breaking through the limitation of system aperture.

Optical multi-aperture needs to improve the resolution through the confocal and common phase between the sub-aperture systems, otherwise it will not work. In multi-aperture imaging, confocal is a prerequisite. Especially in the initial state, there are obvious pointing differences between the sub-apertures, resulting in interlaced images of each sub-aperture, which requires confocal calibration. When the multiple spots are completely separated from each other, although the centroid of the sub-aperture spot can be extracted, it is difficult to identify the corresponding relationship between the spot and the aperture; when multiple spots overlap, the extraction of the centroid of the sub-aperture spot also becomes difficult.

Therefore, in engineering, the decoupling of each sub-aperture spot is often achieved by means of sequential shutter modulation or a special spot separation module. The James Webb telescope uses sequential shutter modulation to traverse all the sub-mirrors through two-by-two calibration to achieve confocality of the primary mirror. ;The STAR-9 telescope array developed by Lockheed Martin also uses timing shutter modulation to achieve 9-aperture confocal; the three-aperture telescope array developed by the National Astronomical Observatory of the Chinese Academy of Sciences divides three sub-aperture spots through a spot separation module composed of multiple prisms . Sequential shutter modulation will significantly increase the complexity of calibration and reduce engineering reliability as the number of apertures increases. The specially designed spot separation module will undoubtedly increase the complexity of the system, and is limited by the aperture arrangement, aperture number, optical path structure, and system parameters, so the universality and portability are poor.

Contents of the invention

In order to overcome the problems and limitations of existing methods, the present invention provides an automatic confocal method for optical multi-aperture imaging systems, which does not require complex spot separation modules and tedious timing calibration, and is suitable for optical multi-aperture imaging systems of various structures .

The technical scheme adopted in the present invention is: an automatic confocal method for an optical multi-aperture imaging system, during the confocal process, the focal plane point spread function image is collected; the multi-connected region centroid extraction algorithm is used to calculate the distance between the multi-spot and the confocal point, The binarized area method calculates the total area of the spot, and constructs an evaluation function based on the distance and area; combines the focal plane information at the current moment and the previous moment to adaptively adjust the weight of the distance and area in the evaluation function; controls the pointing actuator through an optimization algorithm, so that The evaluation function is optimal, so as to realize the automatic confocal of the multi-aperture imaging system.

Among them, the multi-connected area centroid extraction algorithm is used to obtain the centroid position of the multi-spot area in real time from the image collected by the detector, without the need for each sub-aperture spot to be in a separated or incoherent state.

Among them, the evaluation function comprehensively utilizes the distance and area information to avoid the problem of gradient disappearance.

Among them, the evaluation function uses the focal plane information of the current moment and the previous moment at the same time, which reduces the local extremum in the optimization process.

Wherein, the initial state should ensure that all sub-aperture spots are within the field of view of the detector.

Among them, the specific steps are as follows:

Step 1), performing imaging detection on the converging light beam after the imaging primary mirror of the n-aperture telescope array, wherein n≥2;

Step 2), place the detector on the focal plane of the optical multi-aperture imaging, and select a point (x0, y0) on the focal plane as the spot confocal point;

Step 3), extract multi-region centroids through the multi-connected region centroid extraction algorithm, the number of centroids m≥n, and obtain the centroid positions (x1, y1), ..., (xm, ym), thereby calculating the distance information with the common focus;

Step 4), the total area S of the spot is obtained by the binarized area method, and Smax is the area when the spot is completely separated and there is no overlapping area;

Step 5), use the distance and area to construct the evaluation function, perform optimization iterations, drive the high-precision deflection mirror through the servo control module to perform confocal, and at the same time adjust the area in the evaluation function adaptively through the distance and area information at the current moment and the previous moment And the weight of the distance, and finally realize the automatic confocal closed loop of the n-aperture telescope array, after the closed loop, the spot coincides with the confocal point.

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

1) The present invention utilizes focal plane information optimization technology to realize automatic confocal without additional optical elements and cumbersome timing shutter calibration, which improves the engineering applicability and reliability of the optical multi-aperture imaging system.

2) The present invention is less limited by aperture arrangement, aperture quantity, optical path structure and system parameters, etc., has strong universality and portability, and can be used for automatic co-location of optical multi-aperture imaging systems with various structures Jiao standard school.

Description of drawings

Figure 1 is a schematic diagram of the centroid extraction effect of the multi-connected region centroid extraction algorithm when the light spots overlap.

Fig. 2 is a schematic diagram of obtaining the total area of the light spot by the binarized area method.

Fig. 3 is a schematic diagram of the result of automatic confocal realization by the eight-aperture imaging system using the method of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The present invention is an automatic confocal method for an optical multi-aperture imaging system, using a multi-connected area centroid extraction algorithm and a binarized area method to construct an evaluation function, and adaptively adjusting the area and the area in the evaluation function according to the focal plane information at the current moment and the previous moment The distance is weighted, the local extremum is eliminated, and the confocal process is completed by optimizing the iterative control pointing execution structure.

The embodiment of the present invention is an eight-aperture imaging system, and the specific implementation steps are as follows:

1) The eight-aperture imaging system converges the beam;

2) Place the detector on the imaging focal plane of the system, and select the center point (x0, y0) of the focal plane image as the spot confocal point;

3) Use the multi-connected region centroid extraction algorithm to extract multi-region centroids, as shown in Figure 2, m≥8; obtain the centroid positions (x1, y1), ..., (xm, ym), and calculate the distance between these positions and the confocal points distance;

4) Obtain the total area S of the light spot by using the binarized area method, as shown in Figure 2, Smax is the area when the light spots are completely separated and do not overlap;

5) Taking the distance and area as the evaluation index, carry out SPGD optimization iteration, drive the high-precision deflection mirror through the servo control module to perform confocal, and combine the information of the current moment and the previous moment, and make the ratio and integration of the two frames of information based on the time sequence The adaptive factor is obtained by iterative operation, and the weight of the area and distance in the evaluation function is adjusted. The evaluation function adaptively changes to eliminate the local extremum, and realizes the automatic confocal closed-loop of the eight-aperture imaging system. shown.

The above descriptions are only specific implementation methods in the present invention, but the protection scope of the present invention is not limited thereto. As long as the time-varying area and distance information is used to construct the evaluation function, the automatic confocal method, algorithm and device for adaptive optimization of the focal plane image of the optical multi-aperture system all belong to the protection scope of the present invention.

Claims (5)

1. An automatic confocal method of an optical multi-aperture imaging system is characterized in that: in the confocal process, collecting a focal plane point spread function image; calculating the distance between multiple light spots and a common focus by using a multi-connected region centroid extraction algorithm, calculating the total area of the light spots by using a binarization area method, and constructing an evaluation function based on the distance and the area; the focal plane information at the current moment and the previous moment is combined to adaptively adjust the weights of the distance and the area in the evaluation function; the pointing execution mechanism is controlled through an optimization algorithm to optimize an evaluation function, so that automatic confocal of the multi-aperture imaging system is realized;

the method comprises the following specific steps:

step 1), carrying out imaging detection on a converged light beam after an n-hole telescope array imaging main mirror, wherein n is more than or equal to 2;

step 2), placing the detector in an optical multi-aperture imaging focal plane, and selecting a point (x 0, y 0) in the focal plane as a light spot confocal point;

step 3), extracting multi-region centroids through a multi-connected region centroid extraction algorithm, wherein the number m of the centroids is more than or equal to n, and obtaining centroid positions (x 1, y 1), …, (xm, ym) so as to calculate and obtain distance information with a confocal point;

step 4), obtaining the total area S of the light spots by a binarization area method, wherein Smax is the area of the light spots which are completely separated and have no overlapped area;

and 5) constructing an evaluation function by using the distance and the area, optimizing and iterating, driving the high-precision deflection mirror to perform confocal through the servo control module, and adaptively adjusting the weight of the area and the distance in the evaluation function according to the distance and the area information at the current moment and the previous moment to finally realize the automatic confocal closed loop of the n-hole telescope array, wherein the light spot is coincided with the light spot confocal point after the closed loop.

2. An optical multi-aperture imaging system auto-confocal method according to claim 1, wherein: the centroid position of the multi-spot area is obtained in real time from the image collected by the detector through a multi-connected area centroid extraction algorithm, and each sub-aperture spot is not required to be in a separated or incoherent state.

3. An optical multi-aperture imaging system auto-confocal method according to claim 1, wherein: the evaluation function comprehensively utilizes distance and area information, and avoids the problem of gradient disappearance.

4. An optical multi-aperture imaging system auto-confocal method according to claim 1, wherein: the evaluation function simultaneously utilizes the focal plane information of the current moment and the previous moment, and the local extreme value in the optimization process is reduced.

5. An optical multi-aperture imaging system auto-confocal method according to claim 1, wherein: the initial state is to ensure that all sub-aperture spots are within the detector field of view.

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