Importance

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Abstract

A motion monitor which produces audible sound representative of motions of a subject or object being monitored, including a carrier, an optical fiber carried by the carrier, a laser source for injecting a laser beam in the optical fiber to produce a speckle light pattern at the output of the optical fiber, a photodetector for producing an output signal representative of modal noise developed in the optical fiber due to physical movement of the fiber, an amplifier for amplifying the output of the photodetector, and a loudspeaker which converts the amplified signals to audible sound representative of the modal noise at the fiber output. Optionally, the signals produced by the photodetector are shifted to a higher frequency range, e.g., the 500-700 Hz range, thereby to enable use of conventional inexpensive electronics and efficient loudspeakers. In one embodiment involving monitoring of a person, the frequency shifted output of the photodetector is transmitted to a remote location for remote monitoring of movements of the person. In another embodiment, the loudspeaker is mounted on the carrier and produces sound mimicking movement of the subject or object to which the carrier is attached.

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First Claim