Digital Image Processing Applied Research, In The Optical Detection

The technology of optical detection is of noncontact, nondestructive, high precision, whole fields, etc. It has been used in the fields of aerospace, industrial inspecting, automobile technics, road-bridge engineering, etc. Therefore, more and more scholars attach importance to optical detection and it is being one of front line researching direction and studying fields of nondestructive testing (NDT).In this paper, firstly, it summarizes detailedly the development of the technology of NDT and speckle interferometry and optical holography, and discusses the principles and realization scheme of digital shearography detection. At the same time, it compares and analyzes all kinds of realization schemes.Secondly, it simulates the detecting system for micro-displacement off surface by the programming technology of VC++. After speckle interferometric images of the object and taking distortion object are obtained, demodulate phase distributing by different temporal phase-stepping methods. Synthesizing to compare the results of different methods, ideal demodulation method is three phase-stepping. Furthermore, it integrates experimental images and particularly analyzes the physical meaning of digital shearography interferometric stripes.Thirdly, the paper presents a scheme based on the skeleton of digital shearography interferometric stripes, which can calculate micro-displacement off surface field. It simulates displacement off surface calculating system with computer, and introduces minutely the methods of computer image processing in every part of the system. At last, the system gains displacement off surface distributing along the shearing direction on x-axis. When the CCD resolution is 512x512, the detecting size of displacemen off surface is the order of 10^-2mm, and the detecting relative error is less than 2% at the position of maximal displacement off surface. According to the error analysis of the result, it shows the feasibility and high precision of displacement off surface calculating system, and it can meet the demand of engineering testing. In addition, carefully discussed the difference between experimental images of digital shearography interferometric stripes and simulating results, relevant digital image processing arithmetics are improved. At last, we obtaindigital shearography interfere metric stripes which can be used for calculating micro-displacement off surface fi, id.Finally, the application of digital image processing in digital holography testing was probed into. Distribution of phase difference was stirnulanted by thrice curve; and it expressed the image data detected by CCD. With single image processing, it is possible to gain distribution of complex amplitude of object light which arrived a CCD.With the appearance of the technology of digital image processing, a ne'w research direction is inaugurated for the technology of optical detection which was applied in the NDT field.