Optical systems for sensing temperature and other physical parameters
OwnerMarcos Y. Kleinermaninventor
Life of this patent
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Abstract
Optical sensors for physical parameters use a parameter-dependent relative distribution of the intensity of interrogating light of wavelengths .lambda..sub.1 between two light-guiding regions of a light-guiding probe. The relative distribution can be determined by a plurality of means including the spatial separation of the lights carried by the two light-guiding regions, and/or the conversion of one of the lights into light of wavelengths .lambda..sub.2 different and easily separable from light of wavelength .lambda..sub.1. The sensors can be adapted to measure diverse physical parameters, including but not limited to temperature, and to measure infrared radiation by measuring its heating effect on the sensing probes.
Claims19
An optical fiber comprising a core having an index of refraction n.sub.1 and at least one light-guiding region including a light-absorbing organic material, said material capable of absorbing light of pre-selected wavelengths .lambda..sub.1 to which the core is substantially transparent.
A device for sensing temperature changes, including:
- (a) an optical fiber probe having a first end and a second end and comprising a core having an index of refraction n.sub.1, a first cladding around said core having an index of refraction n.sub.2 lower than n.sub.1, and a second cladding around said first cladding having an index of refraction n.sub.3 lower than n.sub.2, the value of n.sub.2 decreasing in a known manner with an increase in temperature at a greater rate than the decrease in the value of n.sub.1 for the same temperature change;
- (b) light source means for injecting interrogating light into said core and said first cladding at said first end of said fiber probe, the intensity of said interrogating light being distributed between said core and said first cladding, the relative distribution varying in a known manner with the probe temperature;
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- (c) optical means located at or near said second fiber end including photodetector and associated means for measuring the relative distribution of the intensity of said interrogating light between said core and said first cladding.
A method for sensing temperature changes in an object or environment, including the steps of:
- (a) placing an optical fiber probe having a proximal end and a distal end in thermal communication with said object or environment, said fiber probe comprising a core having an index of refraction n.sub.1, a first cladding around said core having an index of refraction n.sub.2 lower than n.sub.1, and a second cladding around said first cladding having an index of refraction n.sub.3 lower than n.sub.2, the value of n.sub.2 decreasing in a known manner with an increase in temperature at a greater rate than the decrease in the value of n.sub.1 for the same temperature change;
- (b) injecting interrogating light into said core and said first cladding at the proximal end of said fiber probe, the intensity of said interrogating light being distributed between said core and said first cladding, the relative distribution varying in a known manner with the probe temperature;
- (c) selectively directing light propagating along said first cladding to photodetector means;
- and
- (d) measuring the intensity of said light propagating along said first cladding to said photodetector means.
An optical fiber probe having a first end and a second end and comprising a core having an index of refraction n.sub.1, a first cladding around said core having an index of refraction n.sub.2 lower than n.sub.1, and a second cladding around said first cladding having an index of refraction n.sub.3 lower than n.sub.2, the value of n.sub.2 decreasing in a known manner with an increase in temperature at a greater rate than the decrease in the value of n.sub.1 for the same temperature change.
Dependencies are inferred from the claim text.