Method and apparatus for enhanced evanescent field exposure in an optical fiber resonator for spectroscopic detection and measurement of trace species
First Claim
1. An apparatus for detection and measurement of trace species in at least one of a sample gas and a sample liquid comprising:
- a passive optical fiber;
at least one sensor in line with the optical fiber, the at least one sensor having a portion thereof exposed to the sample gas or sample liquid;
a coherent source of radiation;
coupling means for i) introducing a portion of the radiation emitted by the coherent source to the passive fiber optic ring and ii) receiving a portion of the radiation resonant in the passive fiber optic ring;
a detector for detecting a level of the radiation received by the coupling means and generating a signal responsive thereto; and
a processor coupled to the detector for determining a level of the trace species in the gas sample or liquid sample based on the signal generated by the detector.
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Accused Products
Abstract
An apparatus for detection and measurement of trace species in a gas or liquid sample. A sensor of a ring down cell formed from an optical fiber is exposed to the sample gas or liquid. A coherent source emits radiation into the optical fiber loop, which in turn is received at an output coupler. The fiber optic ring is coupled to a sensor which has a portion thereof, between the input and output, exposed to the sample gas or sample liquid. The sensor has an enhanced evanescent region. A processor is coupled to the receiver and determines the level of trace species in the gas or liquid sample based on the rate of decay of the radiation within the fiber optic ring.
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Citations
71 Claims
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1. An apparatus for detection and measurement of trace species in at least one of a sample gas and a sample liquid comprising:
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a passive optical fiber;
at least one sensor in line with the optical fiber, the at least one sensor having a portion thereof exposed to the sample gas or sample liquid;
a coherent source of radiation;
coupling means for i) introducing a portion of the radiation emitted by the coherent source to the passive fiber optic ring and ii) receiving a portion of the radiation resonant in the passive fiber optic ring;
a detector for detecting a level of the radiation received by the coupling means and generating a signal responsive thereto; and
a processor coupled to the detector for determining a level of the trace species in the gas sample or liquid sample based on the signal generated by the detector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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50. An apparatus for detection and measurement of trace species in at least one of a sample gas and a sample liquid comprising:
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a passive resonant fiber optic ring;
at least one sensor in line with the fiber optic ring, each of the at least one sensor having a tapered portion thereof exposed to the sample gas or sample liquid;
a coherent source emitting radiation;
a first optical coupler to provide at least a portion of the radiation emitted by the coherent source to a first section of the passive resonant fiber ring;
a second optical coupler for receiving a portion of the radiation in the passive resonant fiber ring from a second section of the resonant fiber ring; and
a processor coupled to the second optical coupler for determining a level of the trace species in the gas or liquid sample based on a rate of decay of the radiation received by the second optical coupler. - View Dependent Claims (51, 52, 53, 54, 55)
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56. An apparatus for detection and measurement of trace species in at least one of a sample gas and a sample liquid comprising:
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a passive resonant fiber optic ring;
at least one sensor in line with the fiber optic, the at least one sensor having a “
D”
shaped cross section portion thereof exposed to the sample gas or sample liquid;
a coherent source emitting radiation;
a first optical coupler to provide at least a portion of the radiation emitted by the coherent source to a first section of the passive resonant fiber ring;
a second optical coupler for receiving a portion of the radiation in the passive resonant fiber ring from a second section of the resonant fiber ring; and
a processor coupled to the second optical coupler for determining a level of the trace species in the gas or liquid sample based on a rate of decay of the radiation received by the second optical coupler. - View Dependent Claims (57)
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58. A method for detecting and measuring a trace species in at least one of a sample gas and a sample liquid, the method comprising:
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forming a sensor from an optical fiber by tapering a portion the optical fiber;
exposing the tapered portion of the optic fiber to the sample gas or sample liquid;
emitting radiation from a coherent source;
coupling at least a portion of the radiation emitted from the coherent source into the fiber optic ring;
receiving a portion of the radiation travelling in the fiber optic ring; and
determining the level of trace species in the gas or liquid sample based on a rate of decay of the radiation within the fiber optic ring. - View Dependent Claims (59, 60, 61)
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62. A method for detecting and measuring a trace species in at least one of a sample gas and a sample liquid, the method comprising:
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forming a sensor from an optical fiber by removing a portion of a cladding of the optical fiber to form a “
D”
shaped cross section;
exposing the “
D”
shaped cross section portion of the optic fiber to the sample gas or sample liquid;
emitting radiation from a coherent source;
coupling at least a portion of the radiation emitted from the coherent source into the fiber optic ring;
receiving a portion of the radiation travelling in the fiber optic ring; and
determining the level of trace species in the gas or liquid sample based on a rate of decay of the radiation within the fiber optic ring. - View Dependent Claims (63, 64, 65)
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66. A sensor for detection of trace species in at least one of a sample gas and a sample liquid, for use in cavity ring down spectroscopy comprising, the sensor comprising:
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a passive optical fiber having an first inner core and a cladding with respective first diameters;
a tapered portion formed from and in line with the optical fiber, the tapered portion having a second inner core and cladding with respective second diameters, wherein the diameter the second inner core is less that the diameter of the first inner core, the diameter of the second cladding is less than a diameter of the first cladding, and the tapered portion is exposed to the at least one sample liquid and sample gas to detect the trace species. - View Dependent Claims (67)
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68. A sensor for detection of trace species in at least one of a sample gas and a sample liquid, for use in cavity ring down spectroscopy comprising, the sensor comprising:
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a passive optical fiber having an inner core and a first cladding with respective first diameters;
an abraded portion formed from and in line with the optical fiber, the abraded portion having a cladding with a substantially “
D”
shaped cross section,wherein the abraded portion is exposed to the at least one sample liquid and sample gas to detect the trace species. - View Dependent Claims (69)
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70. A sensor for detection of trace species in at least one of a sample gas and a sample liquid, for use in cavity ring down spectroscopy comprising, the sensor comprising:
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a passive optical fiber having an inner core and a first cladding with respective first diameters;
a tapered portion formed from and in line with the optical fiber, the tapered portion having the inner core and a second cladding, the second cladding having a diameter less than the diameter of the first cladding, wherein the tapered portion is exposed to the at least one sample liquid and sample gas to detect the trace species. - View Dependent Claims (71)
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Specification