Compact structured-light projector for 3D surface profiling

We present a highly compact projector using a diffractive optical element (DOE) and a collimated laser beam to project light patterns on to a three-dimensional (3D) surface as used in structured-light 3D surface profilers. The compact device has been designed to work in a far-field range from 4 mm to 40 mm with the pattern size of 5 mm× 5 mm at 10 mm distance, yielding a projection angle of 28°. A first prototype successfully demonstrated projection of stripe patterns over this large depth-of-focus range with a very short image plane distance of 4 mm.