Position magnifying sensor using multiple beam shearing interferometry

Full text: A position magnifying sensor is defined here as a device used for detecting the magnified displacement of an image point. Usually position sensors are used to measure the displacement of the point directly. The resolution of a good quality sensor may be several micrometres over a restricted working distance. This may be inappropriate and limiting for some applications. To overcome such limitations we have developed a position magnifying sensor based on Multiple Beam Shearing Interferometry (MBSI). An experimental configuration is illustrated in which the multiple beam transmission fringes produced by a wedged shear plate (with high reflectivity coating on both sides) are imaged on a CCD. The movement of the point source is implemented by the lateral translation of the collimating lens and the resulting amplified movement of the fringes on the CCD is detected. The effective displacement of the point source can be magnified by more than a hundred times over an extensive working distance with this position magnifying sensor. In this paper we will present the theoretical analysis and experimental results obtained with this sensor. Copyright (1999) Australian Optical Society