Abstract: In a process for the quantitative detection of a given gas and in a device for the quantitative detection of a given gas, a gas sample (3), which may contain the given gas as a component, is irradiated with a diode laser (1) operating in a single mode and free of mode jumps, the wavelength of which being continuously tuned by varying the laser control current. The laser control current is varied by superimposing a sinus modulation current of a predetermined frequency to a periodically varied d.c. component so that a laser wavelength range is scanned in the area of the absorption line of the given gas. The intensity of the laser radiation after passing through the gas sample is measured by means of a detector. The d.c. component of the detector signal and the second harmonic of the detector signal corresponding to the doubled frequency of the sinus modulation current are determined.

Abstract: The invention is directed to a sensor arrangement for optically measuring the components of a gas. The sensor arrangement includes a housing containing a transmitter, a receiver device, a heatable holder for a measuring cuvette and optical devices for establishing the beam path. The sensor arrangement is improved by limiting the heating of the cuvette walls to those areas which lie in the beam path without the pass-through area of the optical devices being narrowed by the heating device. Also, the cuvette walls are heated in the manner described above without electrical contacts being disposed on the cuvette or on the sensor. The heatable cuvette holder includes one window disposed in the beam path which is transmissive for the measuring radiation. When the cuvette is seated in the cuvette holder, this window lies in virtual contact engagement with the cuvette and has a surface facing away from the cuvette.