Orthogonal grating phase shift method for three-dimensional surface shape measurement

Abstract

The invention discloses an orthogonal grating phase shift method. In the conventional orthogonal grating phase shift method, phase shift is generally required to be performed on stripes in two orthogonal directions (namely horizontal direction and vertical direction) respectively in order to demodulate phase information on the two orthogonal directions, so that respective phase distribution can be obtained with 2N (N is greater than or equal to 3) frames of images; when phase shift is performed by using a mechanical device, a two-dimensional translation mechanism is required to be adopted. According to the method, the phase shift is performed on an orthogonal grating according to a specific direction, so phase shift magnitudes of the stripe in the horizontal direction and the stipe in the vertical direction have integer multiple relation; thus synchronous phase shift of the stripes in the two orthogonal directions is realized, and the phase distribution of each direction can be calculated through N frames of phase shift images. According to the method, the phase shift of the stripes in the two orthogonal directions can be simultaneously performed; when the mechanical device is adopted, only the one-dimensional translation mechanism is required; the method is particularly suitable for a three-dimensional surface shape measurement system of the 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...

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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

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