Phase extraction method of optical fiber interference fringe image based on Hilbert transform

Abstract

The invention discloses a phase extraction method of an optical fiber interference fringe image based on a Hilbert transform. According to the phase extraction method of the optical fiber interferencefringe image based on the Hilbert transform, fast and accurate phase extraction can be realized only by capturing a fringe image, and the phase information extraction speed and precision are effectively improved compared with the existing method. The method comprises the following steps of: (1) capturing a fringe structured light image projected by the optical fiber interferometer through an areaarray camera and a deformed fringe image modulated by the measured object; (2) performing a first Hilbert transform after the gradation transformation process to obtain a new image that filters out adirect current component and is in an orthogonal relationship with the image before transformation; (3) performing a second Hilbert transform process on the new image to obtain a final image in an orthogonal relationship with the first transformed image; (4) constructing an analytic signal according to the sine component and the cosine component of the image obtained by the two transformations; and (5) obtaining phase information of the interference fringe image based on the analytic signal.

Description

technical field [0001] The invention belongs to the technical field of optical image processing; it relates to a method for extracting phase information of an optical fiber interference fringe image based on Hilbert transform; it can be used for the phase information of an interference fringe image based on optical fiber interference projection in a small field of view collected by an area array camera quick extraction. Background technique [0002] With the continuous innovation and rapid development of optical measurement and machine vision technology, the measurement accuracy and speed in the field of three-dimensional dimension information measurement have been continuously improved. At present, the application of non-contact three-dimensional measurement of small-sized objects in industrial production is becoming more and more The more extensive, such as the detection of fine pits on bearings, the detection of small deformation of springs, the detection of surface defec...

AI Technical Summary

Problems solved by technology

Among them, the height (depth) information extraction of all positions on the surface of the object to be measured is the key technical link of this method. Structural parameters, to achieve the height (depth) measurement of any point on the surface of the measured object; however, the existing algorithms have certain limitations in the extraction of bit information from the interference fringe image, especially in terms of accuracy and speed.

At present, the commonly used phase information extraction methods mainly include phase shift method and Fourier transform method. Among them, the phase shift method needs to collect multiple interference fringe images for stationary objects and also requires a precise phase shift device. Therefore, there are certain limitations in the measurement of dynamic objects. However, the Fourier transform method only needs to collect one image to realize the extraction of phase information, but in this method, the DC component and the fundamental frequency component of the interference fringe image are prone to spectrum aliasing, thereby reducing the measurement accuracy, so the developed A set of fast and high-precision extraction methods for the phase information of optical fiber interference fringes in a small field of view is difficult

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