Self-oscillating, optical resonant sensor

Claim 2

Apparatus to drive a mechanical resonator from a source of optical power, comprising: (a) means for communicating said optical power to the mechanical resonator; (and) (b) optical interferometric means for conversion of the optical power to (vibration) vibratory motion of the resonator(.); and (c) resonator means for modulation of said optical power.

Claim 3

Apparatus as in claim 1 wherein the product of the source-to-modulated light gain G1 and the modulated light-to-mechanical motion gain G2 of said conversion multiplied by the incident optical power I 0 is at least one.

Claim 4

The apparatus of claim 1 in which there is a power threshold for sustained oscillation of the resonator and this threshold is reached or exceeded.

Claim 5

The apparatus of claim 3 in which the resonator sustained oscillation threshold is preferably exceeded by a factor greater than 2.

Claim 6

The apparatus of claim 1 in which the resonator is located in a vacuum.

Claim 7

The apparatus of claim 1 in which the vibrating resonator modulates the light.

Claim 8

An optically-powered mechanically resonant apparatus for sensing a physical parameter, or measurand, at a measurement site, comprising: (a) source means of optical power; (b) optical pathway means for communicating said optical power to said measurement site; (c) vibratable resonator means having a resonant frequency of vibration and being coupled to the measurand; (d) means for relating changes in the resonant frequency of the resonator to a changing measurand; (e) means for converting said at least a portion of said optical power into mechanical vibratory motion of said resonator; (f) optical interferometric means for modulating at least a portion of said optical power by motion of said resonator means; (g) detection means for converting a portion of said modulated optical power into signals related to the measurand; and (h) means for returning said signal portion of said modulated optical power to said detection means.

Claim 9

An optically-powered mechanically resonant apparatus for sensing a physical parameter, or measurand, at a measurement site, comprising: (a) source means of optical power; (b) optical pathway means for communicating said optical power to said measurement site; (c) vibratable resonator means having a resonant frequency of vibration and being coupled to the measurand; (d) means for relating changes in the resonant frequency of the resonator to a changing measurand; (e) means for converting said at least a portion of said optical power into mechanical vibratory motion of said resonator; (f) optical interferometric means for modulating at least a portion of said optical power by motion of said resonator means; (g) detection means for converting a portion of said modulated optical power into signals related to the measurand; and (h) means for returning said signal portion of said modulated optical power to said detection means.

Claim 10

Apparatus as in claim 7 wherein said resonator means includes a resonant ribbon.

Claim 11

Apparatus as in claim 7 wherein said resonator includes at least one mechanical beam element.

Claim 12

Apparatus as in claim 7 wherein elements (a) and (g) are located at a first location and elements (c), (d), (e), and (f) are located at a separate second location.

Claim 13

Apparatus as in claim 10 wherein said source optical power is communicated to the second location and said modulated optical power is communicated to the first location along optical fiber pathway means.

Claim 14

Apparatus as in claim 11 wherein said optical pathway means is a single fiber optical pathway.

Claim 15

Apparatus as in claim 7 wherein said optical interferometric means includes a Fabry-Perot cavity.

Claim 16

Apparatus as in claim 13 further including thin film coatings used to enhance the finesse of the Fabry-Perot optical cavity.

Claim 17

Apparatus as in claim 13 wherein partially absorbing thin film coatings in the Fabry-Perot optical cavity are used to directly convert optical power to resonator motion (through the photothermal effect).

Claim 18

Apparatus as in claim 13 wherein the Fabry-Perot cavity is wedge shaped.

Claim 19

Apparatus as in claim 13 wherein the Fabry-Perot cavity space is adjacent the zero or low order of interference so that non-monochromatic light and multimode optical fibers may be employed.

Claim 20

Apparatus as in claim 7 wherein the Fabry-Perot cavity is integral with the vibratable resonator.

Claim 21

Apparatus as in claim 7 wherein said optical interferometric means includes a Michelson interferometer.

Claim 22

Apparatus as in claim 19 wherein said optical interferometric means is a convergent beam Michelson interferometer.

Claim 23

Apparatus as in claim 7 wherein said means for converting said modulated optical power into mechanical energy includes means for conversion of optical power to thermal energy.

Claim 24

Apparatus as in claim 7 wherein said means for converting said modulated optical power into mechanical energy includes means for conversion of optical power to electrical power.

Claim 25

An optically-powered resonant apparatus for sensing a physical parameter, or measurand, at a measurement site, comprising: (a) source means of optical power; (b) optical pathway means communicating said optical power to said measurement site; (c) vibratable resonator means coupled to the measurand; (d) means for relating the frequency of the resonator to the measurand; (e) Michelson interferometric means for modulating at least a portion of said optical power by motion of said resonator means; (f) means for producing amplitude divided interferometer beams and for directing at least one of the amplitude divided interferometer beams to the resonator and to recombine said beams to produce modulated optical power; (g) means for converting at least a portion of said modulated optical power into mechanical energy of said resonator; (h) detection means for converting a portion of the modulated optical power into signals; and (i) means for returning a portion of said signal modulated optical power to said detection means.

Claim 26

An optically-powered resonant apparatus for sensing a physical parameter, or measurand, at a measurement site, comprising: (a) source means of optical power; (b) optical pathway means communicating said optical power to said measurement site; (c) vibratable resonator means coupled to the measurand; (d) means for relating the frequency of the resonator to the measurand; (e) Michelson interferometric means for modulating at least a portion of said optical power by motion of said resonator means; (f) means for producing amplitude divided interferometer beams and for directing at least one of the amplitude divided interferometer beams to the resonator and to recombine said beams to produce modulated optical power; (g) means for converting at least a portion of said modulated optical power into mechanical energy of said resonator; (h) detection means for converting a portion of the modulated optical power into signals; and (i) means for returning a portion of said signal modulated optical power to said detection means.

Claim 27

Apparatus as in claim 23 which is selectively sensitive to the desired mode of resonator vibration.

Claim 28

Apparatus as in claim 23 wherein said Michelson optical interferometric means is a convergent beam Michelson interferometer.

Claim 29

Apparatus as in claim 23 wherein said means for producing amplitude divided optical power to the resonator includes beamsplitter means such that said resonant apparatus is less sensitive to undesired motion between the resonator, beamsplitter, and beamsplitter mounting means.

Claim 32

The method of claim 27 wherein said generation of source optical power occurs at a first location separated from the measurement site, further including the step of returning at least a portion of the modulated optical power to said first location.

Claim 33

The method of claim 28 wherein the source optical power is communicated to the measurement site by optical fiber pathway means and the modulated optical power is communicated to the first location via optical fiber pathways.

Claim 34

The method of claim 29 wherein said optical fiber pathway means is a single fiber optic pathway.