Automatically focusing method and application thereof

Abstract

The present invention is an auto-focus method and its application, mainly providing an image capture device based on a multi-stage search rule and a focus function, with coarse search for different sizes of focus positions, wave packet area search and optimal focus position. Focusing in three stages of fine search. Among them, the wavelength of the incident light beam of the image capture device is taken as the search step by an integer multiple of half, and the maximum value of the focus function is searched in the wave packet area, and the focus position corresponding to the maximum value of the focus function is defined as the best The focus position is used to quickly and effectively obtain the best focus position.

Description

technical field [0001] The present invention relates to an automatic focus method and its application, in particular to a focus judgment method for an image capture device, which is used to achieve the focus operation of the image capture device for image capture of an object under test. Background technique [0002] The autofocus method used in the existing image capture system is to provide the control needed to adjust the focusing distance of the optical lens group during image capture, so as to obtain clear and correct image information. Usually in this type of technology, for passive imaging systems, the focus function curve is a single-peak curve that changes along the position of the focus axis of the optical lens group, so that the maximum value of this function is the best focus defined by the system Location. However, for the focus function curve of the interferometric system, the focus function is a signal formed by the superposition of a unimodal curve and an in...

AI Technical Summary

Problems solved by technology

It usually has some disadvantages, including that even if the search position has entered the wave envelope area, it still needs to search back and forth to determine the boundary of the wave envelope area, so it is quite time-consuming in the automatic intersecting process, and it can only search near the wave envelope area, thus only suitable for small search ranges

Furthermore, this type of technology sets the intensity threshold as the threshold of the best focus position, but the intensity threshold will change due to the different surface properties of the measured object, or the interference objective lens will cause the maximum intensity and zero light due to chromatic aberration. If the distance difference positions are not coincident, the algorithm will not be able to find the best focus point

[0004] In addition, some existing technologies still need to use other hardware assistance to achieve the purpose of autofocus, so the interference system must have more hardware configurations

Or it must have complete wave packet area information to perform focusing actions, so the process is time-consuming and not suitable for large-scanning range auto-focusing

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