Beam intensity detection in a cavity ring down sensor
First Claim
1. A gas sensor comprising:
- an electromagnetic radiation source configured to emit an input beam of light;
an optical cavity for receiving a gas to be detected, the optical cavity defined by one or more optical segments separating at least two mirrors, wherein the at least two mirrors are configured to reflect an internal beam of light through the one or more optical segments;
an optical element disposed in at least one of the one or more optical segments, wherein the optical element is configured to reflect a portion of the internal beam of light when the input beam of light emitted by the electromagnetic radiation source is selectively allowed to enter the optical cavity;
a first detector positioned to detect the portion of the internal beam of light reflected by the optical element, wherein the first detector is configured to produce a signal that is related to the intensity of the internal beam of light present in the optical cavity; and
a controller coupled to the first detector, the controller is configured to receive the signal from the first detector and, when the controller determines that the intensity of the internal beam of light in the optical cavity has reached a threshold level, the controller is configured to cause the input beam of light emitted from the electromagnetic radiation source to be prevented from entering the optical cavity.
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Accused Products
Abstract
A cavity ring down gas sensor may include a radiation source emits an input beam of light having a wavelength corresponding to an absorption line of a gas to be detected. The input beam of light is coupled into an optical cavity to amplify an internal beam of light that is reflected about the optical cavity. An optical element is disposed in the optical cavity at an angle close to, but not at, the Brewster'"'"'s angle to reflect a relatively small portion of the internal beam of light to a detector. When a specified light intensity is reached in the optical cavity, the input beam of light may be prevented from entering the optical cavity, and a cavity ring down time decay may be measured. The cavity ring down time decay may be related to the gas concentration of a gas to be detected in the optical cavity.
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Citations
20 Claims
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1. A gas sensor comprising:
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an electromagnetic radiation source configured to emit an input beam of light; an optical cavity for receiving a gas to be detected, the optical cavity defined by one or more optical segments separating at least two mirrors, wherein the at least two mirrors are configured to reflect an internal beam of light through the one or more optical segments; an optical element disposed in at least one of the one or more optical segments, wherein the optical element is configured to reflect a portion of the internal beam of light when the input beam of light emitted by the electromagnetic radiation source is selectively allowed to enter the optical cavity; a first detector positioned to detect the portion of the internal beam of light reflected by the optical element, wherein the first detector is configured to produce a signal that is related to the intensity of the internal beam of light present in the optical cavity; and a controller coupled to the first detector, the controller is configured to receive the signal from the first detector and, when the controller determines that the intensity of the internal beam of light in the optical cavity has reached a threshold level, the controller is configured to cause the input beam of light emitted from the electromagnetic radiation source to be prevented from entering the optical cavity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A gas sensor comprising:
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an electromagnetic radiation source configured to emit an input beam of light having a wavelength corresponding to an absorption wavelength of a gas to be detected; an optical cavity including at least three mirrors separated by one or more optical segments, wherein the at least three mirrors are configured to reflect an internal beam of light through the one or more optical segments, wherein one of the at least three mirrors couples the input beam of light into the optical cavity; an optical element disposed in at least one of the one or more optical segments, the optical element configured to reflect a portion of the internal beam of light in the optical cavity; a first detector configured to detect the portion of the internal beam of light reflected by the optical element and produce a signal that is related to the intensity of the internal beam of light in the optical cavity; a second detector for detecting a cavity ring down time of the internal beam of light in the optical cavity; and a controller for configured to receive the signal from the first detector and, when the controller determines that the intensity of the internal beam of light in the optical cavity has reached a threshold level, the controller is configured to cause the electromagnetic radiation source to stop providing the input beam of light. - View Dependent Claims (14, 15, 16)
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17. A method of detecting a gas, the method comprising:
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transmitting an input beam of light from an electromagnetic radiation source into an optical cavity, wherein the optical cavity includes the at least two mirrors separated by one or more optical segments, and wherein the at least two mirrors reflect an internal beam of light around the optical cavity, the input beam of light having a wavelength that corresponds to an absorption line of a gas to be detected and contributes to the internal beam of light; reflecting a portion of the internal beam of light off an optical element in the optical cavity; determining a measure related to the intensity of the internal beam of light in the optical cavity from the reflected portion of the internal beam of light; and stopping the input beam of light from entering the optical cavity and contributing to the internal beam of light when the measure related to the intensity of the internal beam of light in the optical cavity indicates that the intensity of the internal beam of light in the optical cavity has reached a threshold intensity. - View Dependent Claims (18, 19, 20)
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Specification