A Three-dimensional Defect Detection Method For Flat Surfaces Based On Stripe Structured Light

Since 1970 s,automatically product in different industrial fields became more and more prevalent.This leads to the increasing need for different detecting methods on various flaw.3D visual methods become more and more attractive to the industry fields.In this paper,three-dimensional defect detection methods and systems based on striped structured light are studied.The main contributions of the thesis are described as following three points:(1)Different phase demodulation methods and phase reconstruction methods in optical information processing are described.The advantages and disadvantages of different phase demodulation methods are compared,and the spatial phase unwrapping method used in this paper is introduced.(2)The phase demodulation formula of non-equal step four-step phase shift method is deduced,and the non-equal-step phase shift amount is calculated by using the dynamic acquisition image of the reference plate,which is used to measure the directional moving object using three-dimensional measurement technices of structured light.(3)The completion of the automated measurement experimental device hardware structures with industrial camera,projector and stepper motor.Based on the Qt framework,the related application program is programmed to realize the control of the automatic projection fringe coding pattern of the projector,the automatic control of the industrial camera and the precise control of the moving speed and the step size of the stepping motor.The reference plate is placed on the elevator and the measurement of the mapping between the developed phase and the plate height is achieved by moving the measurement up and down several times.