Optical sensing system with separable spectrally overlapping sensor responses
AssigneeIntelligent Fiber Optic Systems, Inc.
InventorsBehzad Moslehi, Mehrdad Moslehi
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Abstract
An optical sensing system including an optical interrogator is operative with an array of reflective sensors, each sensor providing a separable reflected spectral response parameter such as a unique Gaussian standard deviation or reflected response compared to other sensors in the same operating wavelength range. The optical interrogator provides narrowband swept or broadband continuous optical power source to the array of FBG sensors, and an optical interrogator generates a g(x) representation of power vs wavelength of the reflected optical power and decomposes the representation into the wavelength of the individual sensors, thereby allowing operation of two or more FBG sensors in the same operating wavelength range.
Claims17
A measurement system comprising a plurality of fiber Bragg grating (FBG) sensors arranged on a single optical fiber, the plurality of FBGs operating in a shared range of wavelengths such that at least one FBG sensor reflects optical energy at a same wavelength as another FBG sensor, the plurality of FBGs receiving optical power from an optical interrogator;
- each FBG of the plurality of FBGs having a unique full width half max (FWHM) bandwidth, each of the plurality of gratings reflecting less than 10% of an incoming optical power;
- the optical interrogator receiving reflected optical power, the optical interrogator having at least one optical detector operative to measure reflected optical power at a plurality of wavelengths;
- the optical interrogator operative to generate a representation of response power vs wavelength;
- the optical interrogator operative to identify for a peak response, at least one of:
- a standard deviation, a Full Width Half Maximum (FWHM) value, or a bandwidth;
- the optical interrogator subtracting a response corresponding to a closest match response of the representation and associating a wavelength to the subtracted response.
A sensor system comprising:
- a plurality n of Fiber Bragg Gratings (FBG) arranged on a single optical fiber, each FBG having a unique standard deviation σ;
- a tunable laser coupling optical energy into the plurality of FBGs;
- a detector operative to measure reflected optical power from the plurality of FBGs;
- a controller operative to generate a response plot g(x) of power vs wavelength, the power measured by the detector and the wavelength varied by the tunable laser to form the response plot;
- the controller operative to iteratively identify a peak response and subtract a proposed FBG response from the response plot to generate a residue;
- the controller continuing to iteratively identify a peak response and subtract a proposed FBG response until the residue is below a threshold, or a number n of iterations have been performed;
- where the tunable laser has a bandwidth which is narrower than a narrowest bandwidth of a sensor FBG by a factor of at least 4.
A measurement sensor comprising a plurality of fiber Bragg gratings (FBGs) arranged in sequence on a single optical fiber, the FBGs operating in a shared range of wavelengths such that at least one FBG sensor reflects optical energy at a same wavelength as another FBG sensor, the plurality of FBGs receiving optical power from an optical interrogator;
- each of the plurality of gratings having a unique full width half max (FWHM) bandwidth, each of the plurality of gratings reflecting less than 10% of incoming optical power;
- the optical interrogator configured to associate a wavelength to each FBG according to a measured unique FWHM bandwidth.
Dependencies are inferred from the claim text.