Interferometric Detection of Ultrasound.
Abstract
This report describes the development of an interferometer to measure ultrasonic surface vibrations. The output from a low power helium-neon laser was focused onto the surface to be measured, and the phase of the reflected light was measured. The type of interferometer used was an Optical Heterodyne Interferometer, in which the frequency of the reference beam was shifted by 40 MHz and a phased-locked loop was built to track the 40-MHz signal. The sensitivity, frequency response, and pulse response were measured and compared with those from a PZT transducer. The effects of different surface finishes were also studied, and the sensitivity was compared with theoretical values. The actual sensitivity was 15A on a 10-MHz bandwidth, and 0.02A on a 1-Hz bandwidth. Finally, suggestions are made to improve the sensitivity still further.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1981
- Accession Number
- ADA115930
Entities
People
- Michael J. Rudd
Organizations
- BBN Technologies