INTERFEROMETRIC SCANNING ACOUSTOOPTIC SPECTRUM ANALYZER

An interferometric scanning acoustooptic (AO) spectrum analyzer is described. The instantaneous detector array is replaced by an AO Bragg cell driven by a short rf pulse and a single fast photodetector, and the diffracted beam is mixed with a local oscillator. The temporal modulation of the heterodyne signal gives the spectrum of the input signal with linear characteristics. Using this architecture, a dynamic range of 70 dB can be achieved with a large time-bandwidth product (1000) and high speed (50-mu-s/spectrum).