Analizzatore di spettro acusto-ottico in tempo reale ad onde acustiche superficiali

The acousto-optical spectrum analizer is a very simple optical processor, that performs real time Fourier transform of an electrical signal. It is substantially based on four components alone: they are a laser source, an acousto-optical cell, a lens and photodiode array. The processing operation of an analyzer is here described, where the acousto-optical cell is based on light - surface acoustic waves interaction and both the cases of guided and unguided light are considered. Results are reported relative to an experimental device that uses side entry internal reflection geometry of interaction and has 50 MHz bandwidth, 300 kHz resolution and 27 dB dynamic range.