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We present a high-bandwidth Hartmann-Shack sensor for adaptive optics implemented in a standard 0.35 /spl mu/m CMOS process technology. Hartmann-Shack sensors reconstruct an optical wavefront from the displacement of focal points as imaged by a microlens array. This image is usually captured by CCD cameras and then processed by software, limiting the wavefront bandwidth to a few hertz. The presented CMOS-based sensors achieves a frame rate of up to 4 kHz by analog image processing on the focal plane. The implemented position sensitive detectors consist of a resistive-ring network of Winner-Take-All circuits with reduced sensitivity to transistor mismatch and fixed-pattern noise. This CMOS-based wavefront sensor allowed the first high-bandwidth wavefront measurements at the human eye.

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 /spl plusmn/1 diopters at an accuracy of /spl plusmn/0.15 diopters. The incident power of 1 nW per focal point thereby allows integration periods of 1 ms for position detection.