Cavity enhanced laser based gas analyzer systems and methods
First Claim
1. A method of measuring cavity loss of a resonant optical cavity over a range of frequencies by exciting one or a plurality of cavity modes of the cavity in a controlled manner, the cavity having at least two cavity mirrors, one of which is a cavity coupling mirror, using a laser that emits continuous wave laser light, wherein the laser is responsive to optical feedback light emerging from the cavity, and wherein a mean optical frequency of the laser is adjustable over a range of frequencies, the method comprising:
- coupling the laser light to the cavity via the cavity coupling mirror using mode matching optics, the cavity having a plurality of optical resonance cavity modes that have frequencies within said range of frequencies of the laser;
applying to the laser a current having a predetermined current profile so as to adjust the mean optical frequency of the laser and to excite cavity modes in an excitation order responsive to a shape of the applied current profile, said excitation order comprising excitation of multiple desired cavity modes in as non-consecutive order; and
detecting dynamics of the intra cavity optical power of light circulating in the cavity after a cavity mode has been excited.
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Accused Products
Abstract
Cavity enhanced absorption spectroscopy systems and methods for detecting trace gases using a resonance optical cavity, which contains a gas mixture to be analyzed, and a laser coupled to the cavity by optical feedback. The cavity has any of a variety of configurations with two or more mirrors, including for example a linear cavity, a v-shaped cavity and a ring optical cavity. The cavity will have multiple cavity resonant modes, or a comb of frequencies spaced apart, as determined by the parameters of the cavity, including the length of the cavity, as is well known. Systems and methods herein also allow for optimization of the cavity modes excited during a scan and/or the repetition rate.
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Citations
38 Claims
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1. A method of measuring cavity loss of a resonant optical cavity over a range of frequencies by exciting one or a plurality of cavity modes of the cavity in a controlled manner, the cavity having at least two cavity mirrors, one of which is a cavity coupling mirror, using a laser that emits continuous wave laser light, wherein the laser is responsive to optical feedback light emerging from the cavity, and wherein a mean optical frequency of the laser is adjustable over a range of frequencies, the method comprising:
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coupling the laser light to the cavity via the cavity coupling mirror using mode matching optics, the cavity having a plurality of optical resonance cavity modes that have frequencies within said range of frequencies of the laser; applying to the laser a current having a predetermined current profile so as to adjust the mean optical frequency of the laser and to excite cavity modes in an excitation order responsive to a shape of the applied current profile, said excitation order comprising excitation of multiple desired cavity modes in as non-consecutive order; and detecting dynamics of the intra cavity optical power of light circulating in the cavity after a cavity mode has been excited. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 37, 38)
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13. A method of measuring cavity loss of a resonant optical cavity over a range of frequencies by exciting one or a plurality of cavity modes of the cavity in a controlled manner, the cavity having at least two cavity mirrors, one of which is a cavity coupling mirror, using a laser that emits continuous wave laser light, wherein the laser is responsive to optical feedback light emerging from the cavity, and wherein a mean optical frequency of the laser is adjustable over a range of frequencies, the method comprising:
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coupling the laser light to the cavity via the cavity coupling mirror using mode matching optics, the cavity having a plurality of optical resonance cavity modes that have frequencies within said range of frequencies of the laser; applying to the laser a current having a predetermined current profile so as to adjust the mean optical frequency of the laser and to excite cavity modes in an excitation order responsive to a shape of the applied current profile, said excitation order comprising excitation of a single desired cavity mode two or more consecutive times and/or excitation of multiple desired cavity modes in a non-consecutive order; and detecting dynamics of the intra cavity optical power of light circulating in the cavity after a cavity mode has been excited, wherein optical feedback light emerges from a second cavity mirror different than the cavity coupling mirror and is redirected to impinge on the laser. - View Dependent Claims (14)
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15. A system for measuring cavity loss of a resonant optical cavity over a range of frequencies by exciting one or a plurality of cavity modes of the cavity, the system comprising:
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a resonant optical cavity having at least two cavity mirrors, one of which is a cavity coupling mirror, the cavity having a plurality of optical resonance cavity modes; a laser that emits continuous wave laser light, wherein the laser is capable of being scanned whereby a mean optical frequency of the laser is adjustable over a range of frequencies, and wherein the laser is responsive to optical feedback light emerging from the cavity, and wherein the modes of the cavity have frequencies within said range of frequencies of the laser; mode matching optics configured to couple the laser light to the cavity via the cavity coupling mirror; a control module coupled with the laser and adapted to apply a current having a predetermined current profile to the laser so as to adjust the mean optical frequency of the laser and to excite cavity modes in an excitation order responsive to a shape of the applied current profile, said excitation order comprising excitation of multiple desired cavity modes in a non-consecutive order; and a first detector configured to measure dynamics of the intra cavity optical power of light circulating in the cavity after a cavity mode has been excited. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for measuring cavity loss of a resonant optical cavity over a range of frequencies by exciting one or a plurality of cavity modes of the cavity, the cavity having at least two cavity mirrors, one of which is a cavity coupling mirror, using a laser that emits continuous wave laser light, wherein the laser is responsive to optical feedback light emerging from the cavity, and wherein a mean optical frequency of the laser is adjustable over a range of frequencies, the method comprising:
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coupling the laser light to the cavity via the cavity coupling mirror using mode matching optics, the cavity having a plurality of optical resonance cavity modes that have frequencies within said range of frequencies of the laser; applying to the laser a current having a predetermined current profile so as to adjust the mean optical frequency of the laser and to excite multiple desired cavity modes in a non-consecutive order as determined based on a shape of the applied current profile; and detecting dynamics of the intra cavity optical power of light circulating in the cavity after a cavity mode has been excited. - View Dependent Claims (25, 26, 27, 28)
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29. A gas analyzer for detecting one or more analyte species present in a gaseous or liquid medium, the gas analyzer comprising:
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a resonant optical cavity containing said medium and having at least two cavity mirrors, one of which is a cavity coupling mirror, the cavity having a plurality of optical resonance cavity modes; a laser that emits continuous wave laser light, wherein the laser is capable of being scanned whereby a mean optical frequency of the laser is adjustable over a range of frequencies, and wherein the laser is responsive to optical feedback light emerging from the cavity, and wherein the modes of the cavity have frequencies within said range of frequencies of the laser; mode matching optics configured to couple the laser light to the cavity via the cavity coupling mirror; a control module coupled with the laser and adapted to apply a current having a predetermined current profile to the laser so as to adjust the mean optical frequency of the laser and to excite cavity modes in an excitation order responsive to a shape of the applied current profile, said excitation order comprising excitation of multiple desired cavity modes in a non-consecutive order; and a first detector configured to measure, and to generate a signal representing, dynamics of the intra cavity optical power of light circulating in the cavity after a cavity mode has been excited. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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Specification