High-speed CMOS wavefront sensor with resistive-ring networks of winner-take-all circuits

We present a high-bandwidth Hartmann-Shack sensor for adaptive optics implemented in a standard 0.35 μm 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.