EXPERIMENTAL TECHNIQUES FOR MEASURING VIBRATIONS USING A LASER INTERFEROMETER.
NAVY MARINE ENGINEERING LAB ANNAPOLIS MD
Pagination or Media Count:
Existing and some apparently novel experimental techniques for measuring vibrations by use of a HeNe gas laser interferometer are evaluated. Schemes for obtaining accurate, absolute measurements of displacements less than 100 A, such as used in calibrating accelerometers, are considered as well as are methods of scanning a vibrating surface in order to obtain its dynamic displacement profile, as is often desired in acoustic radiation studies. The effect of intensity fluctuations of the light source, variations of the medium in the optical paths, background vibrational noise, and other phenomena are evaluated by comparison of the theory with measurements made on both a vibrating elastic plate and a vibration shake table. It is shown that experimental measurements at low displacements 1938 A can be compared with theory without resorting to statistical evaluations of instrument error and undesired time-variant parameters. Author
- Test Facilities, Equipment and Methods