William Knox Cadwallender

US Patent:

50338277, Jul 23, 1991

Filed:

Jul 19, 1990

Appl. No.:

7/554757

Inventors:

Gary C. Vezzoli - Newton NJ
William C. Cadwallender - Parsippany NJ

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

G02F 111
G02F 133
H03B 512
H01J 4014

US Classification:

350358

Abstract:

An optical oscillator uses a monochromatic light beam passing through a poelectric crystal subjected to acoustic vibrations which cause the emission of a diffracted light beam. The undiffracted beam is detected by photodetecting means and generates a first voltage signal. The diffracted beam is passed through a unit for delaying the passage of the beam, e. g. a fiber optics loop, and detected by photodetecting means to generate a second voltage signal. The signals are combined and fed to a control unit which allows a radio frequency signal to reach the piezoelectric crystal, causing acoustic vibrations. The time delay and voltage output relationships in the loop associated with the diffracted beam cause oscillation and control the frequency of such oscillations. The oscillations can be amplitude and frequency modulated by variation of appropriate circuit parameters. The oscillator of this invention is useful as an extremely sensitive optical and acoustic sensing and alarm device for intruders into critical areas.