A Shack-Hartmann sensor is an optical device used to measure the wavefront of a light beam. It consists of a lenslet array that divides the incoming wavefront into smaller sub-apertures, each of which focuses light onto a detector. By analyzing the positions of these focal spots, the sensor can determine the local slopes of the wavefront, allowing for the reconstruction of the wavefront shape. This is commonly used in adaptive optics systems to correct for optical aberrations in real-time.
