A three-dimensional defect detection method and device for approximately flat surfaces of objects

Abstract

The invention is applied to the technical field of optical measurement, and provides a three-dimensional defect detection method of an approximately flat surface of an object. The three-dimensional defect detection method comprises the steps that S1, a detected object moves in the strip direction of a projection pattern, and every time when the detected object moves to positions which are specified in advance of all parts of the projection pattern, an image of a current moment is acquired; S2, through the combination of characteristic marks, four acquired images are subjected to auxiliary sampling; S3, through the combination of an unequal step phase shifting magnitude sequence which is obtained in advance, according to an unequal step four-step phase shifting formula, the sampled images are subjected to phase reconstruction; S4, through the combination of calibration data of standard slab phase distribution at different heights, height data of the surface of the detected object relative to a reference plane is restored. According to the three-dimensional defect detection method of the approximately flat surface of the object, the detected object which moves directionally can be subjected to three-dimensional defect detection of the approximately flat surface.

Description

technical field [0001] The invention belongs to the technical field of optical measurement, and in particular relates to a method and device for detecting three-dimensional defects on an approximately flat surface of an object. Background technique [0002] The three-dimensional defect detection method of the object's approximate flat surface based on the striped structured light is a non-contact, fast optical three-dimensional digital measurement method. The existing three-dimensional object defect detection method based on stripe structured light is mainly aimed at the measurement of the three-dimensional shape of the static object, that is, the object under test and the measuring device remain relatively stationary, and is not suitable for the object in a directional movement state with an approximately flat surface. Defect detection. [0003] On the one hand, in the measurement of the three-dimensional shape of a static object, the projection pattern is four fringe patt...

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Problems solved by technology

[0005] In addition, for an object in a directional movement state, the moving direction of the object cannot be guaranteed to be exactly the same as the direction of the fringe, and there will always be some deviations. In this way, the four fringe images collected by the camera are not four-step phase shift images with equal steps. The "equal step four-step phase shift method" cannot be used to solve the phase

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