Photo-acoustic, multi-band, multi-cavity gas detection system
AssigneeHoneywell International Inc.
InventorSteven P. Gautieri
Life of this patent
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Abstract
A single gas detector combines a dual cavity photo-acoustic gas sensor with a common microphone and common source. Electrical outputs from the microphone can be analyzed to determine an analyte gas concentration in the local region being monitored. Radiant energy from the common source can be directed into both cavities simultaneously. Alternately, the sensor can be used with two microphones to establish a concentration of each of two different gasses, or a gas and water vapor.
Claims16
A photo-acoustic gas detector comprising:
- a sensor having first and second, spaced apart gas absorption cavities;
- at least one microphone coupled acoustically to at least one of the cavities;
- a common source of radiant energy coupled optically to the two cavities, and which injects radiant energy into both of the cavities;
- and
- control circuits coupled to the microphone to establish at least one gas concentration, associated with at least one of the cavities,
- wherein different acoustic signals from each cavity are combined together to form a composite acoustic signal before the composite acoustic signal is coupled to the microphone for measurement,
- wherein the control circuits establish the gas concentration in response to the measurement of the composite acoustic signal by the microphone, and
- wherein the composite acoustic signal is stronger than a sum of the different acoustic signals from each cavity.
A method of determining concentration of a sample comprising:
- generating a first audio indicator of absorption of radiant energy by the sample at a first wavelength;
- generating a second audio indicator of absorption of radiant energy by a different sample at a second wavelength;
- combining the first and second audio indicators to form a composite acoustic signal;
- after forming the composite acoustic signal, coupling the composite acoustic signal to a microphone for measurement of the composite acoustic signal;
- and
- responsive to the measurement of the composite acoustic signal, generating an electrical signal indicative of the substance concentration of at least one sample,
- wherein the composite acoustic signal is stronger than a sum of the sensed audio indicators.
A dual channel photo-acoustic gas detector comprising:
- first and second gas sensing cavities;
- a common microphone to measure acoustic signals;
- and
- a common source of radiant energy which can be directed into both cavities,
- wherein the acoustic signals from both cavities are combined to form a composite acoustic signal before the composite acoustic signal is coupled to the microphone for measurement,
- wherein electrical outputs from the microphone are analyzed to determine a gas concentration in the cavities, and
- wherein the composite acoustic signal is stronger than a sum of the acoustic signals from both cavities.
Dependencies are inferred from the claim text.