In-orbit focusing method of earth observation satellite-borne visible light transmission camera

Abstract

The present invention discloses an in-orbit focusing method of an earth observation satellite-borne visible light transmission camera. When an optical system of the camera defocuses to a certain extent, an image frequency domain formed by the camera has a zero point; according to a camera image out of focus, a zero point position can be found in the frequency domain; when the zero point position of the frequency domain is known, a radius of a point divergent function caused by defocusing is calculated according to the position of the zero point and a best focal plane position is estimated, and a focusing direction is determined according to the definition of an image formed by different focal plane positions, so as to determine the best focal plane position; and when the image frequency domain has no zero point, the camera is nearby the best focal plane position, the focusing adjustment direction is determined by calculating the definition of the nearby focal plane image, so as to determine the best focal plane position. Through adoption of the method, high-accuracy and efficiency of in-orbit focusing are ensured, and in-orbit imaging performance and image quality of an optical remote sensor are improved.

Description

technical field [0001] The invention relates to an on-orbit focusing method of a space-borne visible light transmission camera for earth observation, belonging to the technical field of aerospace optics and remote sensing. Background technique [0002] Camera defocus is an important factor affecting the quality of satellite imaging. After the satellite is launched, the focal plane position of the camera must be rechecked, and the camera should be adjusted on-orbit if necessary. Therefore, in order to improve the on-orbit imaging quality of satellites, it is necessary to carry out research on the on-orbit focusing method of the camera and the judging method of the focusing effect. [0003] At present, the domestic remote sensing cameras all adopt the focusing method of moving the focal plane. In addition to this method, foreign cameras also adopt other methods, such as SPOT-1, SPOT-4, and SPOT-5, which adopt the dual-camera contrast focusing method. Therefore, it is first ne...

AI Technical Summary

Problems solved by technology

[0005] For linear array CCD cameras that image in push-broom mode, there is no identical part between two consecutive images, and changes in the scene lead to the failure of commonly used focusing algorithms. Generally, only a combination of subjective and objective evaluations can be used to verify whether the current The image formed by the focal plane position has the highest relative clarity

The strong dependence on the subjective evaluation results leads to the poor stability of the combination of subjective and objective focusing methods

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