Phase Reconstruction Of Three-demensional Objects

Due to the wide application of three-dimensional shape measurement and the further translation of shape measurement into phase measurement, the phase reconstruction of objects was discussed from two aspects in this paper. One is to use coherent light, named digital holography method; the other one is to use incoherent light, named projection grating method. Both their related theory and final treatment method were introduced and the results were further proven by simulation and experiments.For the first method, the main principles include Fresnel diffraction and Fourier transform theory. The way to implement was a new proposed single-step phase shift method, which is based on Taylor expansion and the phase shift. For the second one, several common treatment methods including Fourier transform and phase shift methods, and the theoretical knowledge of phase unwrapping were presented. The three-step phase shift and previous proposed single-step phase shift method were used for the final implementation. The theoretical method to remove the noise was also applied in the final experiments.The simulated results showed that the utilized algorithms could well recover the phase of objects. But compared with three-step phase shift, the single-step phase shift could not accurately recover the fringe. But the single-step phase shift is easier during the experiment, because it does not need phase unwrapping. Besides, the experimental results could not be in consistent with the simulated results due to some external factors, which needs further study. In conclusion, although both of those methods could theoretically recover the phase of objects, the experimental procedure of digital holography method is more complicated and stricter experimental conditions are required, like coherent light. While projection grating method could be realized by incoherent light, it has been widely utilized.