Abstract: This invention relates to a method that makes the measurement of a trace gas concentration invariant or at least less affected to pressure variations in the gas and atmospheric pressure changes. This method neither requires a pressure sensor nor a pressure calibration routine. Furthermore, the method can be applied to other gas species present in the background gas or to the background gas itself that cross-interfere with the target gas of interest. This allows removing any pressure dependency of cross-interference parameters of other gas species and/or the background gas. The new method for accurately measuring a gas concentration is based on optimizing the wavelength modulation amplitude of the laser to minimum pressure dependency.

Abstract: Laser unit, preferably for gas detection, with a semiconductor laser chip comprising an output mirror with an exit zone for a laser beam and an optical element that reduces self-mixing which is arranged at the exit zone, wherein optical element and laser chip are connected with each other with direct physical contact over an entire surface, at least in the exit zone. Said optical element is connected to the laser chip positively or by means of an optical medium. Thereby optionally a beam-shaping element may be arranged on the optical element that is connected positively or by means of an optical medium with the optical element. Preferably beam-shaping element and optical element have similar or identical refractory indices and are connected with each other and with the laser chip by adhesive agents having corresponding refractory indices.

Abstract: Process and measuring equipment for improving the signal resolution in gas absorption spectroscopy, wherein the measuring equipment includes a laser light source, a light detector and a measuring chamber arranged in between, and furthermore a light source control unit and a light detector evaluation unit. To improve the signal resolution, the noise intensity of the measuring equipment is reduced by averaging over time the interfering signal portions caused by back-reflections, etalons respectively self-mixing effects. This is accomplished by a light modulator arranged downstream the laser light source that continuously periodically influences the optical path length of the light beam. Thereto the light modulator includes an optical element with an adjustable refractory index that continuously cyclically alters the phase of the laser light of the light beam.

Abstract: This invention relates to a method that makes the measurement of a trace gas concentration invariant or at least less affected to pressure variations in the gas and atmospheric pressure changes. This method neither requires a pressure sensor nor a pressure calibration routine. Furthermore, the method can be applied to other gas species present in the background gas or to the background gas itself that cross-interfere with the target gas of interest. This allows removing any pressure dependency of cross-interference parameters of other gas species and/or the background gas. The new method for accurately measuring a gas concentration is based on optimizing the wavelength modulation amplitude of the laser to minimum pressure dependency.