An Orthogonal Grating Phase Shift Method for Three-dimensional Surface Shape Measurement

Abstract

The invention discloses an orthogonal grating phase shift method. In the traditional orthogonal grating phase shift method, in order to demodulate the phase information in two orthogonal directions, it is usually necessary to phase shift the stripes in the two orthogonal directions (that is, the horizontal direction and the vertical direction), so 2N( N≧3) frames of images can obtain their respective phase distributions. When a mechanical device is used for phase shifting, a two-dimensional translation mechanism must be used. The present invention proposes to phase-shift the orthogonal grating along a specific direction, so that the phase shifts of the horizontal stripes and vertical stripes have an integer multiple relationship, so as to realize the synchronous phase shift of the two orthogonal stripes. image, the phase distribution in each direction can be calculated. The present invention can carry out phase shift of fringes in two orthogonal directions at the same time, and only needs a one-dimensional translation mechanism when a mechanical device is used, and is especially suitable for a three-dimensional surface shape measurement system using an orthogonal grating.

Description

technical field [0001] The invention relates to optical three-dimensional sensing technology, in particular to three-dimensional surface shape measurement based on phase measurement method. Background technique [0002] Three-dimensional object surface profile measurement, that is, three-dimensional surface shape measurement, is of great significance in the fields of machine vision, biomedicine, industrial inspection, rapid prototyping, film and television special effects, product quality control and other fields. Optical three-dimensional sensing technology has been greatly developed due to its advantages of non-contact, high precision, and easy automatic control. In the existing optical three-dimensional sensing technology methods, Phase Measuring Profilometry (PMP for short) and Phase Measuring Deflectometry (Phase Measuring Deflectometry for short) based on the phase shift method, the phase of each pixel Values ​​are calculated from a series of phase-shifted images, thu...

AI Technical Summary

Problems solved by technology

For this reason, Canabal et al. proposed to use an orthogonal grating to avoid switching between the horizontal and vertical gratings. This method is used in Moiré deflection surgery, but a two-dimensional translation device is still required to complete the horizontal and vertical phases respectively. When phase shifting in one direction (such as the horizontal direction), the low-intensity area in the grating in the other direction (vertical grating) will reduce the phase measurement accuracy. To improve the measurement accuracy, it is necessary to shift the phase of the vertical grating by half a period. The phase shift is measured again in the horizontal direction, so 2×2×N (N≥3) images are finally required

Images