High-precision Surface Defect Detection Based On Laser Triangulation Method

Laser triangulation is an important method in the field of non-contact measurement. This paper studies for the detection of high precision surface based on laser triangulation method.This paper established a scanning imaging model, established of the object point and the image point between the imaging geometry, according to scan the image sequence, finished on the surface of the object to be measured with high precision measurement.The laser source was vertically incident manner type laser scanning imaging, based on the image information extraction calculation of measured surface morphology. In image processing, this paper adopts the comparative method to choose suitable filter, integrated a variety of laser stripe center lines extraction method, presented a method based on threshold processing with curve fitting centerline extraction method accurately and fastly. In the calibration processing, This paper used the traditional Tsai type two step and transform the effective focal length calibration method. This paper adopted a method of distance transform when calibrated the other System external parameters,using three distance length establishing linear equations and solving. In this paper, horizontal movement direction detection precision can reach0.20mm,vertical direction detection precision can reach0.24mm.This paper measured in the actual situation and analysised of the factors affecting the measuring accuracy. Finally, in order to improve the measurement precision and accuracy, this paper proposes an improved method.