Optical stripe phase spatial domain demodulation method

Abstract

The invention discloses an optical stripe phase spatial domain demodulation method. The demodulation method comprises the following steps: (1) demodulation is carried out on phases of single-row image signals, and phase values of all pixel points of the row are obtained; (2) phases of signals of images of all rows in a two-dimensional optical stripe are demodulated according to the method in the first step, and the phase values of all pixel points of the entire optical stripe graph are obtained. The method is characterized in that the specific demodulation method in the first step is that a formula as described in the specification is adopted for carrying out demodulation on the phase phi(Xm) of the Xm point; and in the formula, Im1, Im2, Im3, and Im4 are total values of light intensity of four adjacent sub regions. Compared with the prior phase demodulation technology, the method of the invention only operates in the spatial domain, locality of the spatial domain is smaller than two stripe periods, and the highest can reach four pixels. The locality is poorer than the time domain phase shift technology but higher than the windowed Fourier transform technology and the wavelet transformation technology. only one stripe graph is needed for the phase, and the method is suitable for dynamic measurement.

Description

technical field [0001] The invention relates to the technical field of optical measurement, in particular to an optical fringe phase demodulation method in optical fringe-based measurement. Background technique [0002] Optical precision measurement based on optical fringes (such as interference fringes, projected fringes, Moiré fringes) is a widely used technique. Automatic analysis of optical fringes is key to the technology. Optical fringe phase demodulation technology is a widely used automatic optical fringe analysis technology. Optical fringes are expressed in the form of phase modulation signals: i(x)=a(x)+b(x)cos[2πf 0 x+φ(x)], where i(x) is the light intensity distribution of a column of signals in an optical fringe pattern (the stripe direction is the row direction), x is the column coordinate of the optical fringe pattern, and a(x) is the background light intensity, b(x) is the modulation amplitude, f 0 is the carrier frequency, φ(x) is the modulation phase. ...

AI Technical Summary

Problems solved by technology

However, the process of solving the instantaneous frequency distribution of the fringe pattern is relatively complicated. Generally, the wavelet transform is used to solve the instantaneous frequency distribution. The solution takes a long time, which is not suitable for fast and real-time measurement, and the accuracy of the instantaneous frequency will affect the phase demodulation accuracy of the fringe. and the locality of the phase demodulation algorithm

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