Composition-independent calibration of nondispersive infrared gas sensors

A nondispersive infrared gas detector comprising:

• a sample chamber configured to contain a volume of a sample gas, the sample gas comprising at least a first constituent gas and a second constituent gas;
• a light source configured to emit infrared light through the volume of the sample gas;
• a plurality of gas-specific channels, each gas-specific channel comprising:
• a bandpass optical filter configured to receive light from the light source and selectively block a portion of the light outside a range of wavelengths centered on a wavelength λn different from the wavelength λn of each of the other gas-specific channels;
• and
• a photodetector configured to detect infrared light from the light source that passes through the bandpass optical filter of the gas-specific channel;
• a reference channel comprising:
• a reference bandpass optical filter configured to receive light from the light source and selectively block a portion of the light outside a range of wavelengths centered on a wavelength λref different from the wavelengths λn of all of the gas-specific channels;
• and
• a reference photodetector configured to detect infrared light from the light source that passes through the reference bandpass optical filter;
• and
• processing circuitry configured to calculate:
• a first concentration of the first constituent gas within the sample gas based at least in part on the light detected at the photodetectors of each of the gas-specific channels and the photodetector of the reference channel;
• and
• a second concentration of the second constituent gas within the sample gas based at least in part on the light detected at the photodetectors of each of the gas-specific channels and the photodetector of the reference channel.