Apparatus and method for the remote detection of vibrations of diffuse surfaces

• US 3,952,583 A
• Filed: 01/02/1975
• Issued: 04/27/1976
• Est. Priority Date: 01/02/1975
• Status: Expired due to Term

• Current Assignee: The United States Of America As Represented By The Secretary Of The Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Rosati, Vincent J.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Beauchamp, John P.
• Application Number:
  US05/538,050
• Time in Patent Office: 481 Days
• Field of Search: 73/71.3, 356/109, 356/196, 356/209, 356/256, 356/5, 340/261
• US Class Current: 73/655
• CPC Class Codes: G01H 9/00 Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means

Abstract

Apparatus and method for the remote detection of vibrations of diffuse surfaces. 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.

Claims

1. Apparatus for the remote detection of vibrations of a diffuse surface having randomly distributed points comprising:

means for providing a source of coherent radiation;

means for projecting a beam of said coherent radiation onto said diffuse surface; and

means, separate and independent of said source, for detecting a reflected time-varying intensity distribution resulting from a scattering of the photons of said beam of coherent radiation by said randomly distributed points on said surface as said surface vibrates and producing corresponding electrical signals.

2. The apparatus according to claim 1 wherein said source of coherent radiation comprises a laser.

3. The apparatus according to claim 1 wherein said source of coherent radiation comprises a filtered arc lamp.

4. The apparatus according to claim 1 wherein said projecting means further comprises means for producing parallel rays of said beam of coherent radiation.

5. The apparatus according to claim 1 wherein said detecting means comprises:

means for collecting and focusing said time-varying intensity.

6. The apparatus according to claim 5 wherein said detecting means comprises:

means for translating said electrical signals into sensorially perceivable signals.

7. The apparatus according to claim 6 wherein said translating means comprises an audible display device.

8. The apparatus according to claim 7 wherein said audible display device is a loudspeaker.

9. The apparatus according to claim 6 wherein said translating means comprises a visual display device.

10. The apparatus according to claim 9 wherein said visual display device is an oscilloscope.

11. A method for the remote detection of vibrations of diffuse surfaces comprising the steps of:

projecting a beam of coherent radiation from a coherent light source onto said diffuse surface; and

detecting, separately and independently of said source, a reflected time-varying intensity distribution resulting from a scattering of the photons of said beam of coherent radiation by said diffuse surface as said surface vibrates and producing corresponding electrical signals.

12. The method according to claim 11 wherein said beam of coherent radiation is produced by a laser.

13. The method according to claim 11 wherein the detecting step comprises

collecting and focusing said time-varying intensity distribution.

14. The method according to claim 13 wherein said detecting step comprises

translating said electrical signals into sensorially perceivable signals.