Closed-loop adaptive optics using a CMOS image quality metric sensor

When compared to the Shack-Hartmann sensor, the image sharpness feedback method has the advantage of easy implementation in a closed-loop adaptive optics system. It also has the potential to be implemented as a smart sensor using VLSI technology. In this paper, we present a novel adaptive optics testbed that uses a CMOS sharpness imager built in the New Mexico State University (NMSU) Electro-optics Research Laboratory (EORL). The adaptive optics testbed, which includes a CMOS image sharpness imager as a wavefront sensor and a 37-channel deformable mirror, has the capability to rapidly compensate the high order phase aberration. An experimental performance comparison of the pinhole image sharpness feedback method and the CMOS imager is presented. The experimental data shows that the CMOS sharpness imager works well in a closed-loop adaptive optics system. Its overall performance is better than that of the pinhole method, and it has a fast response time.