Device (1) for determining a pressure, a temperature and / or a particle density of a gas or gas mixture (G), comprising • a laser device (3) which is set up to emit a laser beam (5), • a measuring unit (40), which is set up to measure absorption values of a gas or gas mixture (G), the laser device (3) and the measuring unit (40) being arranged in such a way that the laser beam (5) can traverse at least part of the gas or gas mixture (G) and can be directed to the measuring unit (40) so that the absorption values of the gas or gas mixture (G) can be measured by means of the measuring unit (40), characterized by an analysis device (41) which is set up to measure the pressure, the temperature and / or derive the particle density of the gas or gas mixture (G) from the absorption values.