Method and device for dispersive, spectrally fully resolved optical gas analysis with suppressed cross-sensitivity

摘要

A device for dispersive optical gas analysis with suppressed cross-sensitivity uses a radiation source (1), a gas cell (4), a monochromator (10), detector means (23 and 25) and evaluation electronics (46). The radiation source (1) emits light consisting of N different frequencies which falls, through the gas cell (4) and the monochromator (10), onto the detector means (23 and 25). In a calibration step, the light beam flows through the pure interfering gas, the middle frequency being selected to be close to the extinction maximum of the measuring gas, so that the extinction of the interfering gas is as small as possible at this middle frequency and that there is a low extinction for the measuring gas at the other frequencies. The N extinction values of the interfering gas lie on a rational integral curve of order N-2. In each measuring step, the measuring cell (4) is filled with the gas mixture to be analysed and the desired extinction value of the pure measuring gas is obtained by means of a subtraction of the interpolated extinction value for the middle frequency, which is obtained by an interpolation with a rational integral function of order N-2 from all the measured extinction values with the exception of the extinction value belonging to the middle frequency, from the measured extinction value of the middle frequency. <IMAGE>