Fiber grating-based sensing system with interferometric wavelength-shift detection
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsAlan D. Kersey, Timothy A. Berkoff
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Abstract
A system for sensing a measurand field, the system comprising a source of broadband light, a sensor, an unbalanced optical interferometric apparatus, and a signal processor. The sensor produces an optical return signal having a wavelength functionally dependent on the measurand field. The interferometric apparatus produces an electrical interference output signal having a phase shift functionally dependent on the wavelength of the return signal, and the processor develops a processing signal indicative of the measurand field value.
Claims26
A system for sensing a measurand field, the system comprising:
- (a) source means for providing broadband light;
- (b) sensing means responsive to the broadband light for producing an optical return signal having a wavelength functionally dependent on the measurand field and having a coherence length;
- (c) unbalanced optical interferometric means responsive to the return signal for producing an electrical interference output signal having a phase shift functionally dependent on the wavelength of the return signal said interferometric means having optical path difference less than the coherence length of the return signal;
- and
- (d) processing means functionally dependent on the phase shift of the electrical interference output signal for developing a processing signal indicative of the measurand field value.
A method for sensing a measruand field, the method comprising:
- (a) a source step of providing broadband light;
- (b) a sensing step responsive to the broadband light, said sensing step comprising producing an optical return signal having a wavelength functionally dependent on the measurand field and having a coherence length;
- (c) an unbalanced optical interferometric step responsive to the return signal, said interferometric step comprising using an interferometer having optical path difference less than the coherence length of the return signal for producing an electrical interference output signal having a phase shift functionally dependent on the wavelength of the return signal;
- and
- (d) a processing step functionally dependent on the phase shift of the electrical interference output signal, said processing step comprising developing a processing signal indicative of the measurand field value.
A system for sensing a measurand field, the system comprising:
- (a) source means for providing broadband light;
- (b) sensing means responsive to the broadband light for producing an optical return signal having a wavelength functionally dependent on the measurand field and having a coherence length, said sensing means consisting of a grating sensor;
- (c) unbalanced optical interferometric means responsive to the return signal for producing an electrical interference output signal having a phase shift functionally dependent on the wavelength of the return signal, said interferometric means having optical path difference less than the coherence length of the return signal;
- and
- (d) processing means functionally dependent on the phase shift of the electrical interference output signal for developing a processing signal indicative of the measurand field value.
Dependencies are inferred from the claim text.