Projected fringe profilometry for profile measurement of high reflective surface

An improved non-contact optical measuring method,projected fringe profilometry,is proposed to realize the 3-D structure measurement of high reflective surfaces.The reflection characteristics of high reflective surfaces and their effects on phase computation are analyzed,and it is pointed out that the failure reason of the traditional projected fringe profilometry is the mismatch of the range of reflection intensity with the dynamic range of the measuring camera.Then,the techniques of lightdark fringe projection,multi-exposure time image acquisition and image synthesis are introduced to match the measuring range of intensity of camera with the range of reflection intensity.The feasibility and useable range of the method are analyzed.Finally,the processes of fringe projection and image acquisition in the improved profilometry are given.Experimental results indicate that the improved profilometry is able to handle the problems of fringe image saturation and dark images.Moreover,it has obtained 3-D data cloud more than 99.6%,and solve the problem of loss of 3-D data.In conclusions,the improved methodcan measure the 3-D profiles of high reflective surfaces with non-contact methods.