Abstract: The invention relates to a dual-beam spectrometer in which a measuring beam, after passage through a measuring cell, and a reference beam each travel through an entrance slit into a spectrometer. Both beams are spectrally separated by means of an optical grating. The spectrometer is intended to operate with a single photodiode array. According to the invention, the two entrance slits, the center of the grating and the measuring and reference spectra lie in one plane; both spectra are recorded on a single detector array, with the spectrum of the measuring beam of the +1 order directly following the spectrum of the reference beam of the -1 order.

Abstract: A method for spectroscopically measuring a concentration of component gases in a gas mixture, wherein at least one component gas A has an absorption line spectrum and wherein the concentration of the gas A in the gas mixture exceeds the concentration of other component gases of the gas mixture to such an extent that measurement of the concentration of the other component gases would normally be interfered with by the gas A.