Studies And Applications Of Phase Measurement Profilometry

With the development of the technology and the manufacture, the demands to the measurement of the surface profile geometry dimension, moulds and bend surface become go up, and the precision becomes higher and higher. Because the traditional mechanical contact profilometry has many limitations, for example,the measurement speed is low, it exists measuring power and need compensate the size of the probe, it can't measure the soft material. Therefor, the people seek a better kind of profilometry which is able to overcome these limitations, nocontact optical profilometry based on light pattern projection is such an profilometry.Nocontact optical profilometry based on light pattern projection has many types. One is grating projection phase measurement method. It has many advantages such as nocontact, high speed, high precision, more data. It also isn't affected by the electromagnetic wave in the surrounding environment, it can measure the nonmetal object and soft material. Phase measurement method is becoming more and more important for his advantages.Phase measurement method is primarily applied on the shape measurement of the diffuse objects. Its fundamental is triangulation. Phase measurement method includes moire contouring profilometry, time-domain phase measurement profilometry, space domain phase measurment profilometry and Fourier transform profilometry. The projection system often uses face structure light.The all tasks focus on the time-domain phase measurement profilometry and Fourier transform profilometry, the main research works and fruits are composed of theory analysis and its applications.Firstly, the basic principles of the time-domain phase measurement profilometry and Fourier transform profilometry are analyzed in detail includes the error theory. Based on the above work, we also finish these new works:1) On phase unwrapping, a new method based on derivative is proposed, and applied both on phase shifting and Fourier transform technique successfully. To eliminate the shadow bug in the unwrapping process, a new idea based on a object's gray image is proposed, the experiment proves it.2) In Fourier transform profilometry, there are frequency leakage, frequency aliasing and frequency railing. In order to eliminate the frequency leakage effect, a kaiser-bessl window is proposed , the simulations show that this method is effective; then, the nonlinear effect of the CCD' response and the CCD's integral sampling characteristics effect on the Fourier transform profilometry are investigated, some proposes are put forward to clear up these error; lastly, denoiseing using wavelet is firstly taken forward, simulations prove that the denoiseing using wavelet is better the denoiseing in the frequency domain.3) We analyze the feasibility of using the time-domain phase measurement profilometry to measure the profile of shadowmask. A measurement system is set up, a arithmetic used to seamless joining two or more pieces in big object is finished, then we apply the system to measure a standard object and the shadowmask. The measurement results are successfully basically. At the end of the paper, we analyze the error and bring forward some steps to remove these errors.