Holographic interferometry and the moire speckle-effect method
Abstract
Two methods for studying the vibrations of thin plates, one based on holographic interferometry and the other on the moire speckle effect observed in optical systems, are compared. Holographic interferometry techniques which permit the recording of vibrations having a wide range of amplitudes are reviewed; difficulties in obtaining suitable conditions for holographic testing in industrial environments are also mentioned. A theoretical treatment of the speckle effect is given, and the filtering and laser systems used to obtain moire images of vibrating plates are described. Experiments involving a thin steel plate or the membrane of an electroacoustic transducer are discussed. It is concluded that the holographic method has the advantage of recording very small vibratory amplitudes, while the speckle-effect technique provides a simpler and more rapid means of obtaining estimates of the geometry of vibrations, and can be used to study nonplanar displacements.
- Publication:
-
Revue Francaise de Mecanique Quarterly
- Pub Date:
- December 1976
- Bibcode:
- 1976RFrMQ.......73M
- Keywords:
-
- Holographic Interferometry;
- Moire Effects;
- Speckle Patterns;
- Structural Vibration;
- Thin Plates;
- Vibration Measurement;
- Electroacoustic Transducers;
- Hologrammetry;
- Imaging Techniques;
- Vibration Mode;
- Wave Front Reconstruction;
- Instrumentation and Photography