Self-oscillating, optical resonant sensor
AssigneeThe Foxboro Company
InventorAnthony C. Gilby
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Abstract
Light from a source is communicated to a measurand site. Interferometric means located at the measurand site modulates the light by means of a resonator, the frequency of which is related to the measurand value, said resonator being driven by the modulated light to provide localized oscillator loop closure at the measurand site. Embodiments are disclosed using modified Fabry-Perot and Michelson interferometer designs.
Claims30
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.
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.
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.
The method of sensing a physical parameter, or measurand, by a vibratable resonator at a measurement site, comprising the steps of:
- (a) generating a beam of optical power;
- (b) communicating said optical power to said measurement site;
- (c) relating said measurand to the frequency of the vibratable resonator such that the resonant frequency varies in relation to changes of said measurand;
- (d) modulating at least a portion of the optical power by optical interferometry;
- and
- (e) conversion of said at least a portion of said modulated optical power to mechanical energy of said resonator as (vibration) vibratory motion thereof.
Dependencies are inferred from the claim text.