Vibration modal analysis using all-optical photorefractive processing
A new experimental method for vibration modal analysis based on all- optical photorefractive processing is presented. The method utilizes an optical lock-in approach to measure phase variations in light scattered from optically rough, continuously vibrating surfaces. In this four-wave mixing technique, all-optical processing refers to mixing the object beam containing the frequency modulation due to vibration with a single frequency modulated pump beam in the photorefractive medium that processes the modulated signals. This allows for simple detection of the conjugate wavefront image at a CCD. The conjugate intensity is shown to be a function of the first-order ordinary Bessel function and linearly dependent on the vibration displacement induced phase. Furthermore, the results demonstrate the unique capabilities of the optical lock-in vibration detection technique to measure vibration signals with very narrow bandwidth (< 1 Hz) and high displacement sensitivity (sub-Angstrom). This narrow bandwidth detection can be achieved over a wide frequency range from the photorefractive response limit to the reciprocal of the photoinduced carrier recombination time. The technique is applied to determine the modal characteristics of a rigidly clamped circular disc from 10 kHz to 100 kHz.
- Research Organization:
- Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Human Resources and Administration, Washington, DC (United States)
- DOE Contract Number:
- AC07-94ID13223
- OSTI ID:
- 439001
- Report Number(s):
- INEL-96/00140; CONF-960848-38; ON: DE97050834
- Resource Relation:
- Conference: Denver `96: 1. conference on space processing of materials, at SPIE International Society for Optical Engineering (SPIE) annual international symposium on optical science, engineering, and instrumentation, Denver, CO (United States), 4-9 Aug 1996; Other Information: PBD: [1996]
- Country of Publication:
- United States
- Language:
- English
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