The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N0.2 and N+0.2, where N is a positive integer number.

The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N0.2 and N+0.2, where N is a positive integer number.

The present invention provides a system for measuring concentrations of trace gases in gas mixtures using the absorption spectroscopy method. The system comprising an optical cell containing a gas mixture, a continuous-wave tunable laser, a detector system for measuring an absorption of laser light by the gas in the optical cell, and a processor to conduct an absorption spectroscopy analysis of the gas mixture based on light intensity measured by the detector system at one or more laser frequencies.

The present invention provides a system for measuring concentrations of trace gases in gas mixtures using the absorption spectroscopy method. The system comprising: a resonant optical cavity, a continuous-wave stepwise tunable external cavity laser having a DFB laser as a gain media; a detector system for measuring an 5 absorption of laser light by the gas in the resonant optical cavity, wherein the roundtrip optical cavity length of the external cavity laser are the roundtrip optical cavity length of the resonant cavity are close.

The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N0.2 and N+0.2, where N is a positive integer number.

The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N0.2 and N+0.2, where N is a positive integer number.

The present invention provides a system for measuring concentrations of trace gases in gas mixtures using the absorption spectroscopy method. The system comprising an optical cell containing a gas mixture, a continuous-wave stepwise tunable external cavity laser, a detector system for measuring an absorption of laser light by the gas in the optical cell, and a processor to conduct an absorption spectroscopy analysis of the gas mixture based on light intensity measured by the detector system at one or more laser frequencies.

The invention relates to a method for detecting the presence of ice crystals in an environment, implemented by a detection device in relative motion with respect to said environment, said method comprising at least: an emission step, in which at least one optical radiation is emitted by the detection device into the environment; a reception step, in which at least a portion of the emitted optical radiation is received, a step of calculating a comparison signal, and a step of calculating the noise of the comparison signal, a thresholding step, in which the noise is compared to a defined threshold, a communication step, in which a signal indicating detection of the presence of ice crystals in the environment is transmitted when the noise is greater than the defined threshold.

An arrangement for measuring gas concentrations in a gas absorption method, wherein the arrangement includes a plurality of light sources, a measuring cell, at least one measuring receiver and an evaluation apparatus. The measuring cell has a narrow, longitudinally-extended beam path with an entrance-side opening diameter B and an absorption length L with L>B, wherein the measuring cell has a gas inlet and a gas outlet wherein a plurality of light sources of different wavelength spectra is grouped into a first light source group wherein an optical homogeniser is interposed between the first light source group and the measuring cell, wherein, in particular, the homogeniser is coupled to the light source group directly or via a common optical assembly.

The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N0.2 and N+0.2, where N is a positive integer number.