An ASIC for Hartmann-Shack wavefront detection

An analog VLSI circuit facilitating the focal point position detection in a Hartmann-Shack wavefront sensor for optical wavefront measurements is presented. Detecting the lateral deviation of each focal point of the Hartmann-Shack sensor´s lens array caused by the partial distortion of the aberrated wavefront within the according lens, the phase information of the light beam can be retrieved. With the future aim of measuring optical distortions of the human eye, the ASIC is optimized to process an optical incident power of 1 nW per focal point. To prevent spatial aliasing of the focal point positions due to the eye´s inherent movements during measurement, the signal processing circuits are designed to allow frame repetition rates of wavefront measurement of several hundred hertz. Experimental measurements of optical lenses show the capability of the prototype ASIC of measuring focal point position deviations relating to spherical and cylindrical wavefront aberrations with a dynamic range of ±1 diopters at an accuracy of ±0.15 diopters. The incident power of 1 nW per focal point thereby allows integration periods of 1 ms for position detection