Accession Number : AD0650720

Title :   EXPERIMENTAL TECHNIQUES FOR MEASURING VIBRATIONS USING A LASER INTERFEROMETER.

Descriptive Note : Technical memo.,

Corporate Author : NAVY MARINE ENGINEERING LAB ANNAPOLIS MD

Personal Author(s) : Darby,R. A.

Report Date : MAR 1967

Pagination or Media Count : 54

Abstract : 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)

Descriptors :   (*VIBRATION, MEASUREMENT), (*INTERFEROMETERS, GAS LASERS), TEST METHODS, ACCELEROMETERS

Subject Categories : Test Facilities, Equipment and Methods
      Optics
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE