Applied Technique Study On Improving Measurement Precision Of Phase Measuring Profilometry

Phase measuring profilometry is the technique of the measuring 3-D profile using optical method with structured illumination, which is fast-speed, non-contact and high-precision. A variety of applications of 3-D shape measurement include control for intelligent robots, obstacle detection for vehicle guidance, dimension measurement for die development, stamping panel geometry checking, and accurate stress and vibration measurement.However, the CCD non-linear, the intensity of projecting fringes non-sinusoidal and error-transferring when the wrapped phase is unwrapping and shadow and fringe- discontinuing have a great affect on the measuring precision of phase measuring profilometry. This dissertation focuses on improving measurement precision of phase measuring profilometry. The main results obtained can be summarized as follows:1. Profilometry for phase measurement with non-integral times twin-frequency grating is proposed, lowering the errors transferring during phase-unwrapping. The simulating experiment compared with integral times twin-frequency grating shows that the measuring precision is improved.2. The sign mosaics method in phase measuring profilometry is proposed. By measuring the measured object two times in PMP when the measured object is rotated in the reference plane at 0 and 180 degree ,and fusing the two measuing results through some of planed signs. The 3-D profile of the measured object was reconstructed accurately from the measured credible height information with a simple measurement system.3. The temporal phase unwrapping method is discussed. In the lease common multiple region we carried out the temporal phase unwrapping by computer simulation and experiment.