Acousto-optic spectrum and Fourier analysis techniques

The paper examines two major classes of acousto-optic analog processors for implementation of the Fourier transform. Attention is given to the first, termed space integrating processors, which relies on dispersive spatial frequency characteristics of free space propagation combined with lenses as space quadratic phase multipliers, noting that in this case the spatial integration is the diffraction integral. Further, the second class, termed time-integrating processors, is shown to implement the Fourier transform by integration in time of data located at specific points in space relayed by optical imaging. It is concluded that the processors can generally be shown to be implementations of chirp transform algorithms for the Fourier transform in space and time, respectively.