For atmospheric research, temperature distribution, wind and aerosols in the middle atmosphere from 10 km to 100 km are of particular interest because of scarce data and unresolved discrepancies between measurements and simulations. One approach to gain such data is the use of Doppler-Mie (aerosols), -Rayleigh (air molecules) and -resonance lidar systems for the different altitudes in a single general purpose lidar system [1]. For Doppler resonance fluorescence, metal resonance lines of, e. g., potassium (770 nm) and iron (386 nm) are addressed. The Doppler-broadened and -shifted metal resonance line is scanned, which requires a linewidth of the laser below 30 MHz and consequently a laser in single longitudinal mode (SLM) operation.