1. 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) configured to emit a laser beam (5),
   • A measurement unit (40) configured to measure absorption values of a gas or gas mixture (G), wherein the laser device (3) and the measurement unit (40) are arranged such that the laser beam (5) can pass through at least a portion of the gas or gas mixture (G) and be directed toward the measurement unit (40), so that the absorption values of the gas or gas mixture (G) are measurable by the measurement unit (40),
   • Characterized by:
     • An analysis device (41) configured to derive the pressure, the temperature, and/or the particle density of the gas or gas mixture (G) from the absorption values.
2. Device (1) for determining a pressure, a temperature, and/or a particle density of a gas or gas mixture (G) according to claim 1, characterized in that the laser device (3) comprises a distributed Bragg reflector laser diode or a tuning device (30) configured to change the central frequency of the laser beam (5), wherein the tuning device (30) comprises at least one acousto-optic modulator.
3. Device (1) for determining a pressure, a temperature, and/or a particle density of a gas or gas mixture (G) according to claim 1 or 2, characterized in that the device (1) comprises a reflector (6) configured to reflect the laser beam (5), particularly in such a way that the reflected laser beam (5) is measurable by the measurement unit (40).
4. Device (1) for determining a pressure, a temperature, and/or a particle density of a gas or gas mixture (G) according to any of the preceding claims, characterized in that the laser device (3) is configured to emit a laser beam (5) with a central frequency between 3·10¹³ Hz and 4.6·10¹⁴ Hz, particularly between 1.5·10¹⁴ Hz and 4.0·10¹⁴ Hz.
5. Device (1) for determining a pressure, a temperature, and/or a particle density of a gas or gas mixture (G) according to any of the preceding claims, characterized in that the laser device (3), particularly the distributed Bragg reflector laser diode or the tuning device (30), is configured to change the central frequency of the laser beam (5) at a tuning rate of at least 100 Hz, particularly at least 1 kHz, preferably at least 10 kHz.

Note: These patent claims have been translated from German into English.