Patent ID: 8072609
Filing Date: 2011-12-06
Classification: G01D,G01H

Abstract:
1. A laser vibrometer capable of detecting and displaying pressure waves from acoustic signals comprising: means for propagating a beam of monochromatic light; means for splitting said beam of monochromatic light into a reference beam and a sensing beam, said reference beam being directed to a photosensor; a pressure-sensing diaphragm having a first side which when impacted by the pressure waves responsively vibrates; said pressure-sensing diaphragm having a second side, which has a mirror-like surface finish; said sensing beam being directed against said second side of said pressure sensing diaphragm, said sensing beam being reflected therefrom to a reflective mirror assembly, which mirror assembly is sized and curved to re-reflect said sensing beam back against said pressure sensing diaphragm three or more times; said sensing beam is then directed to said photosensor, wherein said photosensor is a photo-EMF sensor, which heterodynes this the sensing beam with the reference beam to output an analog signal whose phase modulation is proportional to the displacement of the diaphragm caused by the incident pressure wave, wherein a displacement of the diaphragm as small as approximately 4 picometers or less can be detected; means whereby said analog signal is displayed.