ONLINE OR IN SITU MEASURING DEVICE FOR MEASURING THE CONCENTRATION OF A GAS

The invention relates to an online or in situ measuring device (10) for measuring the concentration and/or quantitatively analyzing the concentration of a gas (22) or a gas mixture (24) using Raman spectroscopy. The measuring device (10) comprises at least one gas measuring chamber (20, 56) for the gas (22) or the gas mixture (24), said chamber having one or more optical entrances (28) and one or more optical exits (30). A high-power laser (14), in particular a laser diode (16), is provided which illuminates the gas (22) or the gas mixture (24) in the at least one gas measuring chamber (20, 56) in a focused manner in the visual spectral range and supplies Raman-scattered light (34, 62) from the focused illuminated gas (22) or gas mixture (24) to a spectral analysis unit (38) through an optical system (36) that amplifies the physical Raman scatter intensity of the Raman-scattered light (34, 62) and comprises filters and diaphragms. The invention additionally relates to a method for measuring the concentration of a gas (22) or a gas mixture (24) and to the use of the measuring device (10) and the method.