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Optimization of 3-D topography measurement based on Moiré technique

To provide a non-contact, simple, high speed and high accuracy measuring technique for industry measurement, the advanced Moiré fringe method is developed in this paper. Based on virtual grating, fringe doubling, spatial filtering and phase shifting technique, a three-dimensional topography is measured. The virtual grating, spatial filtering and phase shifting technique are used to eliminate the phase shifting errors. Four step phase shifting virtual gratings, generated by computer, are superposited with testing grating and Moiré fringe patterns are formed. Four phase-shifting patterns can be gained by filtering four Moiré fringe patterns. An experiment equipment is designed and built. With the fo spatial filtering, phase shifting technique and phase unwrapped of virtual grating, the three-dimensional topography is measured, and the measuring accuracy is also evaluated. The obtained result shows that the improvement of the phase-shifting topography measurement methods is suitable for testing industrial product topography featuring non-contact, simplicity, high speed and high-precision.