Position and displacement sensing with Shack-Hartmann wave-front sensors

The use of a Shack-Hartmann wave-front sensor as a position-sensing device is proposed and demonstrated. The coordinates of a pointlike object are determined from the modal Zernike coefficients of the wave fronts emitted by the object and detected by the sensor. The position of the luminous centroid of a moderately extended incoherent flat object can also be measured with this device. Experimental results with off-the-shelf CCD cameras and conventional relay optics as well as inexpensive diffractive microlens arrays show that axial positioning accuracies of 74 mu m rms at 300 mm and angular accuracies of 4.3 mu rad rms can easily be achieved. (C) 2000 Optical Society of America.