초록 ▼

A method of operating a laser and a gas analyzer to reduce low frequency and high frequency power non-linearity errors passes a laser beam through a sample gas to a detector. Intensity measurements are taken and compared to a reference set of measurements. The reference set of measurements can be ca

A method of operating a laser and a gas analyzer to reduce low frequency and high frequency power non-linearity errors passes a laser beam through a sample gas to a detector. Intensity measurements are taken and compared to a reference set of measurements. The reference set of measurements can be calculated by measuring pressure and temperature of the sample gas. The laser wave number tuning width is locked to tune a high frequency of an absorption path fringe to a predetermined reference value. The analyzer can be operated without taking a reference set of measurements and the analyzer is much smaller than previous analyzers.

대표청구항 ▼

[ I claim:] [1.] A method of reducing low frequency and high frequency power non-linearity errors from components of a spectroscopic absorbance function in operating a laser in a gas analyzer to determine light absorption characteristics of a sample gas, said laser being wavenumber tunable and being

[ I claim:] [1.] A method of reducing low frequency and high frequency power non-linearity errors from components of a spectroscopic absorbance function in operating a laser in a gas analyzer to determine light absorption characteristics of a sample gas, said laser being wavenumber tunable and being oriented to pass a laser beam through said sample gas to a detector, said method comprising:(a) passing said laser beam through said sample gas to said detector, taking intensity measurements and comparing said measurements to a reference set of measurements;(b) controlling a laser wavenumber tuning width to obtain a set of said intensity measurements;(c) correcting said intensity measurements from said detector using a predetermined coefficient to obtain corrected intensity functions;(d) taking the natural log of said corrected intensity functions, folding and averaging said natural logs, normalizing said averages and obtaining absorbance functions;(e) cosine transforming said absorbance functions using orthogonal sets of harmonics;(f) low pass filtering said orthogonal sets of harmonics to reduce said high frequency power non-linearity errors to obtain a sample gas orthogonal set of harmonics;(g) comparing said sample gas orthogonal set of harmonics to a reference set of orthogonal harmonics to obtain a set of harmonic ratios; and(h) correcting said set of harmonic ratios using a predetermined coefficient thereby reducing said low frequency laser power non-linearity errors.