Advanced carrier squeezing interferometry: a technique to suppress gamma distortion in fringe projection profilometry

An advanced carrier squeezing interferometry (CSI) technique is proposed to suppress gamma distortion in fringe projection profilometry. CSI combines phase-shifted fringes into a single spatial-temporal fringe and then extracts the phase from its frequency spectrum. Although it has the property of rejecting high-order harmonics, the traditional CSI technique uses an approximate model that generates extra disturbance lobes in the process of phase extraction from the frequency domain. Therefore, the filter window used to extract the phase has to be very narrow, which results in the extra loss of high-frequency information. In this paper, we improve the approximate model by introducing a phase-correction term and encoding it into the projected standard fringes. Then, there are no extra disturbance lobes in the spectrum, and the acceptable filter window to reject high-order harmonics can be much wider. Thus, it is possible to preserve more high-frequency information in the retrieved phase. We performed simulations and experiments to validate the ability of this method to suppress gamma distortion and preserve high-frequency information as compared to the traditional CSI method.