Phase stabilizing method based on PTAC for fiber-optic interference fringe projection profilometry

Fiber-optic interference fringe projection profilometry for high-precision 3D (Three-dimensional) shape reconstruction which is insensitive to external electromagnetic disturbances. We designed a system which takes advantage of Mach–Zehnder interferometer structure and Young’s double pinhole interference principle to realize fringe projection, while utilizing Fresnel reflection on fiber end face and interference to constitute close-loop feedback model, achieving precise control of the projected fringe phase with PTAC (AC Phase Tracking). A root-mean-square phase stability of 4 mrad. The spin filter is used for eliminating the noise, meanwhile preserving details of the fringes; finally we realized real-time 3D shape retrieving through Fourier transformation profilometry, the measuring time of the whole system is less than 250 ms.

► We use fiber-optic interferometer to build a high-precision 3D measuring system.
► Building mathematical model of interference fringe projection 3D shape measurement.
► Building nonequilibrium feedback model to realize stable control for interferometer.
► Enhancing the interference fringe images resolution and stability by PTAC.
► We use Discrete Cosine Transform least square algorithm to achieve phase unwrapping.