Continuously-Variable Ultrasonic-Optical Delay Line

Experimental results are reported on a continuously-variable delay line using acoustic waves to diffract and frequency-shift a portion of an argon ion laser beam. Data was obtained from 300 to 700 MHz utilizing thin-film CdS transducers deposited on a single-crystal Z-cut quartz rod placed within the laser cavity. The diffracted, frequency-shifted beam was optically heterodyned on a PIN detector. Variable delays of the order of 10 μsec were obtained by varying the distance from the CdS transducer to the beams' intercept point. A novel folded-acoustic path configuration is also described.