Study On The Measurement System Of Transparence Surface Topography With Sodium Light Interference

The 3D-profile measurement is an interdisciplinary among optical physics, experimental mechanic, machinery, electronics, material physics, topology, computer and digital image processing, and its potential can be seen from its widely applications which can be found in fields of products quality inspection, process automation, CAD, mechanical vision, etc. In the thesis we will focus on the 3D-profile measurement of transparence which based on the method of equal thickness interference phase-shifting. Practically, several topics have been considered and carried out, including:the method of automatic detecting phase period based on image similarity, repeatability validation and improvement of phase shifter, the application of sodium light interference in the 3D-profile measurement, the designing and making of digital PZT power, the integration of hardware and software in the 3D-profile measurement. And in the thesis, topics have been arranged in the following form:1. The method of automatic detecting phase period based on image similarity. In the period of phase shifting, interference images haven been collected uninterrupted. The curve of similarity can be obtained according to the difference of every image to the first one, and theoretically the phase period can be determined from the analysis of the curve. In our experiment, two possible algorithms have been simulated and compared with each other.2. Repeatability validation and improvement of phase shifter. In our experiment, curves of signal-to-noise ratio (SNR is called for short) have been compared several times to figure out the repeatability of the phase shifter. With the obtained information, the reason of bad behavior on the repeatability has been found out, and improvement has been taken, which are believed to improve the ability greatly.3. The application of sodium light interference in the 3D-profile measurement. In our experiment, the traditional light has been substituted with the sodium light, which could minimize the error from the speckle of laser in the measurement. We have compared the sodium-light and laser-light, with the result showing the advantage of sodium-light.4. Design and production of a 3D-profile measurement of transparence. In the system, CCD, microscope, light source, phase shifter, PZT power system and software are included. Particularly, among them, we have designed and produced the phase shifter and the digital PZT power system, and software is developed in the C++ programming language, which is easy to port and use.