Detection and Exploitation of Vibration Induced Optical Amplitude Modulation
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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The remote sensing of surface vibrations on an object via optical methods has many applications. Current techniques use phase coherent methods which are difficult to apply against a noncooperative target, or one at great distances. A simple method of exploiting the apparent amplitude modulation imposed on a light beam reflecting from a vibrating surface is explored. This method requires no phase reference between source and detector, and can use reflected sunlight as its sensor beam. The design and construction of an experimental receiver is presented, and its sensitivity against targets of varying reflectivity, specularity, and mechanical compliance is tested. Impact detection at a distance using this technique is demonstrated, as is identification of the impacted object from its recovered acoustic spectrum. Theoretical range curves are developed, and suggestions for additional uses of the technology are discussed.
- Optical Detection and Detectors