The master oscillator operates using comprehensive cavity Q-control which provides mode locking at feedback prelase stabilization, Q-switching and selection of the single optical ultrashort pulse from the master oscillator cavity. Pulse formation at feedback stabilized prelasing provides highly reproducible generation of 70 ps pulses.

The triggering of the flash lamps and all Q-control events in the laser (mode locking rf-pulse, Q-switching and cavity dumping) are monitored by the control unit with a multichannel timing circuit phase locked to the signal of the reference oscillator. This keeps system time in the cavity roundtrip units. The use of such timing circuit allows new possibilities for the optical pulse synchronization to external devices:

- TTL output sync pulse either forthcoming or delayed relative to an optical pulse in the range ±120?s with a 1 ns resolution and timing jitter of less than 200ps;

- Laser triggering by external TTL sync pulse with the optical pulse delay is in the range 110-140 ?s with timing jitter of ±10ns;

- Two LS-2151 lasers synchronization to an accuracy about of ±15 ps.

The LS-2151 has built in photo-detectors monitoring the energies of the MO, PA and SH output pulses. Energy values are indicated in the laser control window of the remote control PC.

Independent discharge circuits for MO and PA flash lamps allow ajustment of the output energy of laser system to optimize for the application requirements.