Light beam excited piezoelectric vibrator for passive dipole - uses localised incident optical radiant periodically modulated to excite lamina close to resonant frequency

摘要

The resonator consists of a quartz lamina (9) whose principal faces are metallised (7,8) to form electrodes. The lamina is suspended by two metallic rods (10,11) joining the middle of the metallisations to a base (12) having two electrical pins (13,14). The assembly is protected by a glass envelope (15) permeable to radiation. The resonator is excited by an amplitude modulated beam (11) of optical radiation of frequency f. The beam whose source may be a He-Ne laser (1) is modulated by an acousto-optical or electro-optical modulator (2) electrically controlled by a tunable alternating generator (5). A sinusoidal voltage appears at the terminals (13,14) on impact (6) of the light beam with one of the metallisations and when the modulation frequency f approaches the natural resonance frequency of the piezoelectric resonator. The metallisation transforms the optical energy into heat which produces a local dilation of the piezoelectric material.