Fiber-optic vibration sensor based on frequency modulation of light-excited oscillators
March 30, 2019. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesFiber optical devices for measuring physical phenomenon Combined force transducer and temperature sensor Mechanical resonance, silicon accelerometer Vibrating sensor Opto-electro-mechanical device or filter, process for making, and sensors made therefrom Remote activity sensing system Fiber optic self-multiplexing amplified ring transducer and force transfer sensor with pressure compensation Fiber optic self-multiplexing amplified ring transducer and force transfer sensor with pressure compensation 5808210 Integrated released beam, thermo-mechanical sensor for sensing temperature variations and associated methods Patent #: 5917226 InventorsAssigneeApplicationNo. 09/281388 filed on 03/30/1999US Classes:367/140SIGNAL TRANSDUCERSExaminersPrimary: Pihulic, Daniel T.Attorney, Agent or FirmInternational ClassesG01P 15/097 (20060101)G01P 15/08 (20060101) G01P 15/10 (20060101) AbstractA sensor device for detecting vibration, including a light source for providing a laser light, a first optical fiber connected to the source for transmitting the laser light, an oscillator positioned to receive the transmitted laser light and adapted to reflect the light as a frequency modulated light; a second optical fiber positioned to capture the frequency modulated light to transmit the frequency modulated light; and a frequency modulated discriminator for receiving the frequency modulated light from the second optical fiber and producing a signal responsive of vibration of the oscillator. In a preferred embodiment, the frequency modulated discriminator further includes a frequency meter for determining the average number of cycles per unit time to provide a second signal responsive of the temperature of the oscillator. The optical fibers may be a pair of different fibers positioned for transmitting the laser light and the frequency modulated light respectively, or the same fiber positioned for transmitting both the laser light and the frequency modulated light. In this latter embodiment, the device further includes a beam splitter to direct the frequency modulated light to the discriminator. The preferred oscillator includes a microchip having a microbeam mounted on a thin silicon cantilever such that deflection of the beam perpendicular to the plane of the microchip changes the tension in the microbeam to change its resonant frequency. Also preferred is a microbeam including a thin metal deposit to create a bimorph structure.Other References
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