Apparatus for Simultaneous Generation and Detection of The Optical Diffraction Pattern for Vibration Monitoring
The invention relates to the field of opto-electronics in general, with particular emphasis in the area concerned with optical techniques for vibration monitoring; and more specifically in the field of opto-electronic devices for monitoring remote sound, and, or mechanical vibrations.
The invention elucidates an innovative method and apparatus for the simultaneous generation and detection of optical diffraction interference pattern on a photo detector. The vibration monitoring device discussed herein comprises of a (any) continuous wave coherent collimated beam of light (or a laser) falling on an (any) optically reflective coating on the surface of the body with inherent vibrations, or with manifest vibrations induced from another source through any medium where the said light is reflected, and then received on the surface of a (any) photo detector in such a way that the received light falls partially on the sensing area, and partially on the outer perimeter of the active sensing area(annular ring surrounding the perimeter of the active sensing area) of the said photo detector.
The spatial intensity pattern produced on the photo detector due to the interference between the directly incident light and the optically diffracted light, changes, if the incident light emanating from the reflecting surface undergoes changes in its path length as a result of vibrations felt on the reflecting surface. The photo detector records the precise time varying optical diffraction interference pattern, corresponding to the time varying vibrations experienced by the optical reflector. The output signals from the photo detector are recorded and compared with the vibrations fed on to the reflecting surface to demonstrate the efficacy of this method.