Abstract: A system for determining a surface shape of a test object includes a pattern having a plurality of first elements dispose about a central axis and defining an aperture containing the central axis. The first elements includes a plurality of common elements having a common form and a reference element having a reference form that is different than the common form. The system further comprises a detector array and an optical system. The optical system is adapted to provide an image of the first elements when light reflects off a surface of a test object, passes through the aperture, and is received by the detector array. The reference form may be configured to facilitate an association between the common elements and the spot images of the common elements.

Abstract: A phase diversity wavefront sensor includes an optical system including at least one optical element for receiving a light beam; a diffractive optical element having a diffractive pattern defining a filter function, the diffractive optical element being arranged to produce, in conjunction with the optical system, images from the light beam associated with at least two diffraction orders; and a detector for detecting the images and outputting image data corresponding to the detected images. In one embodiment, the optical system, diffractive optical element, and detector are arranged to provide telecentric, pupil plane images of the light beam. A processor receives the image data from the detector, and executes a Gerchberg-Saxton phase retrieval algorithm to measure the wavefront of the light beam.