Optical measurements of structural intensity distributions
Abstract
The distribution of acoustic intensity in a 40 x 15 x 0.625-cm Al plate bolted at one end to a vibration-isolation table and excited by a sine-wave-driven electromagnetic shaker mounted near the free end is investigated experimentally using phase-resolved holographic interferometry. Light from a 4-W Ar-ion laser is fed through an acoustooptic modulator and pinhole (to permit pulsed illumination of the plate) and used to create holograms on a thermoplastic recorder. The vibrating plate is viewed with either steady or pulsed illumination through a hologram obtained with the plate at rest in steady illumination, and the resulting interference fringes are analyzed. It is shown that when the illumination is pulsed at a rate near one-fourth the period of vibration (i.e., near quadrature) the traveling-wave component of the plate motion becomes visible and can be used to derive the structural intensity distribution.
- Publication:
-
2nd International Congress on Acoustic Intensity Measurement
- Pub Date:
- December 1985
- Bibcode:
- 1985aimm.cong..171C
- Keywords:
-
- Optical Measuring Instruments;
- Sound Intensity;
- Structural Vibration;
- Vibration Measurement;
- Displacement;
- Holography;
- Laser Applications;
- Point Sources;
- Quadratures;
- Instrumentation and Photography