Digital Phase-Shifting Technique For Phase Measurement Profilometry And Its Application

An optical measuring method with high precision, high speed and simple configuration is introduced .The surface profile of a 3-D diffuse object is obtained by measuring the phase of the intensity distribution which is deformed by the phase .The phase-shift technique is used with a computer,and a CCD is used to detect the distorted image and a micro-computer to process the data . The deformed grating pattern is dealt with by phase-shift method and digital image processing technique. The technique is set up by 2-D digital image processing of the grating projected on 3-D surface , by means of program design .automatic measurement of 3-D object shape is achieved .Experiments are designed to verify the novel highly sensitive of method. Further, all errors of the method and their origins are analyzed theoretically in detail. Some method to eliminate and restrict these errors are proposed . Based on the precision analysis, the method has been successfully applied to measure the surface of 3-D object .For discontinuous measured objects, spatial phase unwrapping method can not get the unwrapped phase correctly. In this dissertation, a noise-immune phase unwrapping algorithm based detection of poles and mask is proposed to solve this problem. With respect to the measurement, by using the relationship and unwrapped phase of measured object, the height of measured object is calculated. The result coming from experiment show the method is very easy and comprehensive , what is more ,this method is fastish and goodish .