Single-frame coaxial projection 3D profilometry system using correlation detection of depth-dependent MTF

We propose coaxial 3D measurement system based on depth from defocus of projection system. In this system, the stripe pattern is projected on the object, and it moves on object´s surface generating temporal variation of the light intensity. The projected stripe pattern is defocused depending on its distance from the focal plane. By moving the stripe pattern, defocused spatial frequency component is captured by temporal frequency analysis. We use correlation image sensor (CIS) to capture the temporal frequency component in a single frame. CIS outputs the Fourier coefficients of incident light in each pixel for every frames, and therefore it enables single frame 3D measurement. Evaluation experiments show that projection defocus depends on the distance from the focal plane, and it can be used for 3D measurement.