Method for accurate focal length measurement of optical imaging system based on moon imaging

Abstract

The invention discloses a method for accurate focal length measurement of an optical imaging system based on moon imaging. The method for accurate focal length measurement of the optical imaging system based on moon imaging comprises the steps that a moon image is obtained through the optical imaging system, the edge of the moon image is extracted based on the sub pixel edge detection algorithm, primary fitting is conducted by means of extracted edge information to enable a primary rough fitting disc to be obtained, fitting is conducted on the moon disc with the least square method and progressive optimization is conducted based on distance constraint to enable a high-precision sub-pixel-level moon disc to be obtained, and the focal length of the optical imaging system is calculated by means of the relative position geometrical relationship. Compared with the prior art, the method for accurate focal length measurement of the optical imaging system based on moon imaging has the advantages that the problems that during ground development, the measurement cost of a large-focal-length optical imaging system is high, a measurement device is complicated, the difficulty of focal length measurement of the optical imaging system is high during in-orbit operation, and the precision is limited are solved, the moon is fully used for imaging, the diameter of the moon disc is obtained through sub pixel extraction with the least square method, both a 'full moon' and a 'waning moon' can be used for focal length measurement, and the method is an economical and reliable focal length measurement method for large-focal-length optical imaging systems.

Description

technical field [0001] The invention relates to a method for accurately measuring the focal length of an optical imaging system based on lunar imaging, which belongs to the technical field of optical imaging system measurement, and is particularly suitable for the precise measurement of the focal length of an optical imaging system operating on the ground and in orbit. Background technique [0002] In order to meet the task requirements of high-resolution observation and imaging, it is increasingly necessary to use long-focus optical imaging systems, for example, QuickBird-2 has a resolution of 0.61m and a focal length of 8.8m, and GeoEye-1 has a panchromatic resolution of 0.41m and a focal length of 13.3m. The long-focus optical imaging system used in the Hubble Space Telescope system has a focal length of 57.6m. [0003] For optical imaging systems, whether it is the ground development process or the orbital operation stage, it is necessary to use the corresponding focal l...

AI Technical Summary

Problems solved by technology

[0004] The technical problem of the present invention is: to overcome the deficiencies of the prior art, to provide a method for accurately measuring the focal length of an optical imaging system based on lunar imaging, to use the imaging of the moon, to propose sub-pixel extraction, and to obtain the lunar circle through least squares fitting The diameter of the disk makes it possible to measure the focal length regardless of the "full moon" or "waning moon", which solves the problem of the high cost of measuring the focal length of the optical imaging system during the ground development process, especially the long focal length optical imaging system, the difficulty of device development, and the difficulty in developing the device during orbital operation. The focal length measurement of the optical imaging system depends on the ground calibration site, which brings about complex means and high cost. It is an economical and feasible method for measuring the focal length of the optical imaging system with a long focal length.

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