Abstract: 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.