A novel technique using an acousto-optic modulator (AOM) as part of a heterodyne interferometer which measures optical path differences between a test signal and a reference signal is disclosed. An array of distinct frequencies are used to drive the AOM, yielding a spatially dispersed array of frequency-shifted subaperture beams of the test signal which are interfered with the wavefront to be measured and then combined with the dispersed reference signal. The frequency shifting of the AOM allows a single detector to collect the beams for signal processing to determine a measurement of the wavefront.
