Vibrometer, Torsional, Laser
Wednesday, September 20, 2006
A Laser Torsional Vibrometer has been designed and developed that can measure the fluctuating rotational speed of a component. Measurements are made by pointing two low-power laser light beams at the test sample.
The Vibrometer is insensitive to solid body vibrations of the rotating component by the use of parallel Laser light beams. The Vibrometer can operate on any cross section of a shaft by allowing gears of irregular shape to be a moving target.
The Vibrometer tracks the change in light beam frequency produced by the Doppler effect of scattered light from a moving target. A Laser light beam (HeNe , 2 mW) is divided into two equal parallel beams. The Doppler shifted Laser light back scattered from one point is mixed with Laser light from another point on the receiver photodetector. The photodetector output current is modulated at the difference frequency or beat frequency. This frequency is insensitive to whole body, radial or axial, shaft or Vibrometer movement.
Source: Dr.Neil Halliwell, Institute of Sound and Vibration Research, University of Southampton, UK
Bruel and Kjaer, A/S Naerum, Denmark
Loughborough University of Technology
posted by JD52 @ 8:59 PM,