Design, fabrication, and testing of a Shack–Hartmann sensor with an automatic registration feature

In this research, design, construction, and testing of an innovative Shack–Hartmann sensor are described. As the most critical component, a polymer microlens array is injection molded and mounted on a board-level CMOS camera such that the focal plane of the microlens array is on the camera’s image plane. To allow for automatic registration of the spots of the measured area, a diffusing surface was created at the center of the lens array in the same diamond machining process in an uninterrupted operation. This unique diffusing surface does not generate an image spot. The no-spot feature functions as the reference in the measurement on the camera’s image plane. Using this unique feature, large global tip-tilt error can be detected and eliminated. In this research, both experiments and simulation have shown that the Shack–Hartmann sensor built using low cost components is capable of precision wavefront detection. This research also demonstrated that automatic registration based on the diffusing surface is simple and reliable.