Abstract: An apparatus for determining the paramagnetic characteristics of substances such as oxygen includes a cuvette rotating in a magnetic field. The cuvette includes measuring chambers and reference chambers and an alternating voltage is induced in the measuring field coils by the rotation of the cuvette along the magnetic field. A base signal disturbing the measuring signal is also generated. This base signal is caused primarily by changes in the thickness of the material in the reference chambers and the measuring chambers and/or by material thickness changes of the cuvette. To eliminate this base signal, the cuvette includes a magnetic compensating device. This device is mounted at such a position that it generates a compensating magnetic field during its rotation through the magnetic field. This compensating field generates a compensating voltage which has the same amplitude as the base signal but has a signal waveform which is opposite in phase to the base signal.

Abstract: The invention is directed to a method of operating a laser diode in a measuring system for spectroscopically measuring the concentration of a gaseous component in a gas sample. This method is improved in that the mode jumps of the laser diode are easily recognized when adjusting the temperature-current operating point of the laser diode. An optical filter is placed in the beam path for adjusting the temperature-current operating point of the laser diode and, by changing the temperature T and the operating current I of the laser diode while simultaneously receiving the output signal supplied by an evaluation unit, the spectral positions of the mode jumps of the laser diode are determined which are included in the absorption lines of the gas sample. Thereafter, the temperature-current operating point is adjusted so that the distance of this operating point to the positions of the mode jumps is not less than a fixed spacing.

Abstract: The invention is directed to an apparatus for determining the proportion of substances having paramagnetic characteristics, such as oxygen, in a mixture of substances. The apparatus has a housing and the mixture of substances is passed along an arrangement of four magnetic field sources by a rotatable cuvette arrangement mounted in the housing. The apparatus is improved in that the effect of external disturbing influences on the penetration of the cuvette by the magnetic field is reduced and so that the measuring characteristics are independent of the position of the plurality of magnetic field generating units. For this purpose, the arrangement of the magnetic field sources is simply disposed at one side of the housing lying opposite to the rotating surface of the cuvette arrangement facing toward the drive shaft. The arrangement of magnetic field sources includes a carrier plate on which the magnetic field sources are accommodated and carry respective measuring field coils.

Abstract: The invention is directed to a sensor for making capacitive measurements of the pressure in gases and contains two measuring electrodes conjointly defining a capacitor and arranged in spaced relationship to each other. This sensor is improved such that a pressure measurement is possible without deformable parts. Long-term drift free measurements can be carried out with even the smallest electrode spacing being realized so that miniature sensors can be provided. The intermediate space between the electrodes is accessible to the gas to be investigated and has electrically insulating spacers between the electrodes. The spacers determine the spacing between the electrodes and maintains the electrode spacing during the measurement.