Diffractive optical element-based profilometer for surface inspection

We introduce a new 3-D sensor based on a diffractive optical element (DOE). Structured light is obtained by the interference of two beams. The design of the projection unit has the following features: the system is very simple, small and cheap and the fringe spacing is easily adjustable. Fringes generated by the DOE interferometer are analyzed by Fast Fourier Transform (FFT) method, which produced a 3-D perspective plot. The technique and the experimental results of real surface profiles are given