IDEA #39ZJ9D Method of calibrating a wavelength-modulation spectroscopy apparatus using a first, second, and third gas to determine temperature values to calculate concentrations of an analyte in a gas

Several methods of calibrating a wavelength-modulation spectroscopy apparatus configured to measure a concentration of an analyte in a sample gas are disclosed. Each of the methods allows for calibration and recalibration using a relatively safe gas regardless of whether the sample gas for which the concentration of the analyte can be determined is a hazardous gas. In one embodiment of the invention, calibration that is sample-gas specific is accomplished by determining a first slope coefficient and calibration function for the sample gas, after which a scaling factor can be determined based on the first slope coefficient and a second slope coefficient for the same or a different sample gas and used in a subsequent calibration (or recalibration) to scale the calibration function. In other embodiments of the invention, calibration that is not sample-gas specific is accomplished to allow for the determination of the analyte concentration in variable gas compositions and constant gas compositions. https://app.acclaimip.com/pdf/C7OAON2ulDFQs4BdOK6UPTt_uVObukd8EOku7go/US8217376B2