Frequency stable long pulse operation of a self sustained TE CO₂ laser

The development of a frequency stable self sustained low pressure TE CO₂ laser oscillator incorporating an intracavity telescope is reported. The system gives a single mode energy output of up to 40 mJ at 9.25 µm with pulse duration variable from ~35 µs to ~10 µs. Heterodyne measurements show that the intrapulse frequency is constant to within 50 kHz at 20 mJ output level for the first 8 µs of the optical pulse. © 1990.