Laser speckle applied in research on vibrational characteristics
Abstract
The laser speckle effect is applied to the determination of the vibration characteristics of compressor blades. The speckle pattern is produced by the light from a helium-neon laser which has been expanded by a microscope lens and passed through a diffuser and is incident at an angle of 45 deg on the blade. As the blade resonantly vibrates, nodal lines become visible as areas where speckling is apparent. The pattern is recorded photographically at an exposure time chosen so that the average illumination produces the maximum optical density. Photographs of the speckle patterns are compared with holographic interference patterns of the same vibration modes recorded by averaging. It is pointed out that the speckle method is sensitive to a wider range of vibrations than holographic interferometry and does not require excessive degrees of vibration isolation and film resolution.
- Publication:
-
Problemy Prochnosti
- Pub Date:
- June 1979
- Bibcode:
- 1979PrPro..10..111S
- Keywords:
-
- Helium-Neon Lasers;
- Laser Applications;
- Speckle Patterns;
- Structural Vibration;
- Diffraction Patterns;
- Laser Outputs;
- Resonant Frequencies;
- Instrumentation and Photography