A phase-space domain demodulation method of optical fringes

Abstract

The invention discloses a method for demodulating optical fringe phase and space domain. The demodulation method is as follows: (1) demodulate the phase of a single row of image signals to obtain the phase values ​​of all pixels in the row; (2) follow step (1) The method demodulates the phases of all column image signals in the two-dimensional optical fringe, thereby obtaining the phase values ​​of all pixels of the entire optical fringe image; it is characterized in that the demodulation method of step (1) is specifically: using the formula to x m point phase demodulation, where, I m1 , I m2 , I m3 , I m4 is the total value of the light intensity of the four adjacent sub-regions. Compared with the existing phase demodulation technology, the present invention only operates in the airspace, and the locality of the airspace is less than two fringe periods, up to 4 pixels. Its locality is worse than that of time-domain phase shift technology, but higher than that of window Fourier transform technology and wavelet transform technology. Only one fringe pattern is needed to solve the phase, which 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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