Accession Number : ADD003070

Title :   Apparatus and Method for the Remote Detection of Vibrations of Diffuse Surfaces.

Descriptive Note : Patent,

Corporate Author : DEPARTMENT OF THE ARMY WASHINGTON D C

Personal Author(s) : Rosati,Vincent J

Report Date : 27 Apr 1976

Pagination or Media Count : 4

Abstract : Apparatus and method for the remote detection of vibrations of diffuse surfaces is described. A beam of coherent light incident on a vibrating diffuse surface is scattered. A photodetector sees the scattering as a time-varying intensity distribution related to the vibration frequency of the surface. The detected time-varying intensity distribution is converted into time-varying electrical currents which can be rendered audible by using a loudspeaker or visual by using an oscilloscope. The invention provides a novel method and apparatus for the covert surveillance of distant conversations, movements of people, movements of vehicles, and the like. This is accomplished by the remote detection of vibrations of a diffuse surface of which some examples are windows, window shades, door panels, walls and trees.

Descriptors :   *Remote detectors, *Vibration, *Patents, Covert operations, Optical detectors, Coherent radiation, Laser beams, Photodetectors, Warning systems, Acoustic detectors

Subject Categories : Optical Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE