Abstract: An apparatus and method for noncontact and nondestructive test of a photodiode array are given. Such apparatus comprises a Surface Acoustic Wave (SAW) device having one or more sets of interdigital finger pairs placed on each end of the device, separated by slotted waveguide which confines the SAW test probe test signal to a row of diodes to be tested and which is positioned immediately above the waveguide. The SAW device is coupled to signal processing electronics from which individual detector properties, such as the zero voltage bias resistance of each detector, may be calculated.

Abstract: A wavefront sensor for detecting the slope of an input wavefront. A surface acoustic wave reflective diffraction grating is positioned at a focal point of the wavefront, and generates surface acoustic waves at two primary frequencies f.sub.1 and f.sub.2. The reflective diffraction grating produces a first AC shearing interferogram between two like diffraction orders generated by the f.sub.1 and f.sub.2 surface acoustic waves. A photodetector array is positioned to detect the shearing interferogram at a two dimensional array of zones, and the phase of the output signal for each zone is representative of the local slope of the wavefront in the direction of shearing, thus producing the slope in one direction. Complete two dimensional wavefront slope information is obtained by shearing the wavefront in a second orthogonal direction in substantially the same manner utilizing a second surface acoustic wave diffraction grating and a second photodetector array.