On the Shape Measurement Based on Shadow Moire and Temporal Phase Analysis Techniques
基于时域位相分析的云纹法形貌测量技术研究

Shape measuring techniques are discussed in this paper based on shadow moiré and temporal phase analysis. A high precision rotary stage was designed and manufactured to enable the spatial frequency of grating to vary linearly. In this way, the height of object surface becomes a function of the grayscale variation frequency. Fast Fourier Transform was used to identify this frequency in the sequential images. Zeroes were added to the grayscale array prior to the FFT to improve the precision of the measurement. It was found that when the length of zeros was 128 times of the original data, the precision of the height measurement can reach 0.02 mm with a grating whose spatial frequency is 5 lines/mm. Calibration test and a practical application to measure the human incisor grooves growth are presented in this paper, which indicates the potential applications to determine tooth shape in dental restoration. Detailed measurement process is illustrated to show that this new measuring technique is easy to achieve high precision.