Study for phase retrieval based on dual frequency grating projection

The dual frequency grating projection based on structured light is very important in the phase retrieval for the fusing of the advantages of dual frequency grating, it must satisfy a basic condition to better obtain the phase information. Firstly, the relationship between phase information and height information of object measured is given, and the basic principle of phase retrieval based on dual frequency grating projection is analyzed in detailed. Secondly, the corresponding phase retrieval condition is proposed, that is to say, the high frequency must be at least twice as large as the low frequency to satisfy the spectra separation between the two frequencies, the maximal allowable phase error of low frequency unwrapped phase must be less than pi /2. Finally, to demonstrate the validity and correctness of the proposed basic principle, both of simulation and experiment are carried out, the expected results are obtained, when the phase recovery condition is satisfied, the phase errors are smaller, and vice versa.