An improved method and arrangement for measuring the optical absorptions of gaseous mixtures.

摘要

A gas analyzer arrangement for detecting the presence or quantity of a gas of interest includes a source of electromagnetic radiation (52) for directing a light beam through a light conditioning device (54) such that the light beam is collimated into a parallel beam of light. The conditioned light beam is then directed through a gas sample cell (58) which contains a sample of the gas of interest. The gas of interest has associated therewith, vibrational rotational absorption lines specific to that gas and which are effective for altering the light beam according to the absorption characteristics thereof. The altered light beam is then directed to a birefringent etalon device (64) which has been sized specifically to match those absorption lines of the gas of interest. An electro-optical modulator device (68) associated with the birefringent etalon modulates the absorption lines between the transmission spectra maxima and a point between the transmission spectra maxima so that an absorption ratio can be utilized to determine the presence or quantity of the gas of interest.