| The dual frequency heterodyne is widely used for phase unwrapping in fringe projection profilometry. In order to solve the harsh conditions of frequency selection when dual frequency heterodyne unwrapping, a phase unwrapping method based on orthogonal phase shifted multi frequency heterodyne combined with phase encoding is proposed. In this method, five-frame sinusoidal fringe pattern is used to extract the wrapping phase of two frequencies, and a new wrapping phase is obtained by heterodyne between the two wrapping phases. Phase encoding is used to unwrap the wrapped phase obtained after heterodyne, and phase unwrapping is performed according to the unwrapped heterodyne phase. The simulation results show that the phase unwrapping method of multi-frequency heterodyne combined with phase encoding can not only unwrapping the phase correctly, but also can choose the frequency arbitrarily. The projected fringe pattern is less, the speed is faster, and the target object can be measured with high precision. In addition, compared with the existing phase unwrapping methods, it is not necessary to meet the requirement that the heterodyne phase needs to cover the entire field of view. |