Infrared analyser

摘要

An infrared analyser, which serves for the determination of the concentration of a gas, makes use of a broad-band radiation source (1), whose light is reflected by two concave mirrors (13, 18) in such a way, that the light bundles (14, 19) pass at different angles through an interference filter (16) to a detector (15). The transmission wavelength ranges of the interference filter (16) assigned to the two directions of incidence are so selected, that one of them lies in a stronger absorption band and the other in a weaker absorption band and correspondingly lower and higher gas concentrations can be determined. The signal separation of the two wavelength regions is carried out with the aid of a periodically acting beam interrupter (5), which in each case allows only the light from a mirror (13, 18) to fall onto the detector (15) and, in an intermediate position, interrupts the light from both mirrors (13, 18) for the determination of background. The signal processing system (9, 22-29) is coupled to this beam interrupter (5). <IMAGE>