2.1

The oscillator

The pumping head is composed by a Nd : KGW rod longitudinally pumped by an autostack. The main advantage of the autostack is its very high brightness. It provides a peak power of 1 kW for a 100 μs pulse duration. The very high spectral acceptance of the Nd : KGW rod provides very small absorption variations over wide temperature ranges. This allows both the diode and the rod to be conductively cooled and run on the large temperature variations of the mission.

Fig. 1 shows the oscillator energy versus the autostack temperature measured on a table top prototype. For a diode temperature range as large as 25°C, the energy decrease is less than 20%.

Fig. 1

Oscillator energy versus autostack temperature

The oscillator is linear and composed of the pumping structure and two mirrors. A polarizer, wave-plate and pockels cell Q-switch the cavity. Fig. 2 shows a mechanical drawing of the oscillator. It should provide an output energy of 13mJ with a pulse duration < 10ns, and a quality factor < 3.

Fig. 2:

Mechanical drawing of the oscillator

Due to the mission constraints, compactness and weight were two driving factors of the mechanical design, keeping the necessary ruggedness at the same time. Oscillator dimensions are about ϕ50 x 200 mm, and weight is about 300 g

2.2

The amplifier

The pumping head for the amplifier is identical to the oscillator one. The laser beam emitted by the oscillator enlarged by a telescope travels twice the amplifier, in order to increase the extraction efficiency.

Fig. 3:

Mechanical drawing of the amplifier

An output energy in excess of 30 mJ should be obtained at the system output, with a M² factor < 3.