SAGA Timing (changing energy)

We can vary the amount of energy that is extracted in the final amplifier by changing the timing of the SAGAs.

Look at this timing diagram for guidance:

Figure 1: S20 Laser timing diagram. Note that A and E are now 181 450 ns and 181 190 ns instead of 6xx xxx ns.

The relevant channels to change are DG645 upper (trigger box), channels A and E (flash lamp start for SAGA#2 and #1 respectively).

This will keep the pump energy the same but will change the relative arrival time of the IR pulse and the green pulse.

When changing Q-switch start (channels C and G) we change the arrival time and the green energy at the same time, which is not ideal.

In theory, the advantage of changing the timing rather than the pump energy is that most thermal properties of the system remain the same.

There was some mention of a change due to the difference in extracted energy from the crystal, but this is being investigated.

Examples of energy levels (using flash lamp timing)

Early flash lamps (green arrives before IR), only using data points with equal delay on both SAGAs:

Late flash lamps (green arrives after IR), only using data points with equal delay on both SAGAs:

Note the shorter time window when delaying the flash lamps.

We probably want to use the early flash lamp timing. Within the first microsecond we have almost linear scaling.

Some of this might change after fixing the SAGAs and the polarisation issue.

Based on:

Note that output energies vary a bit based on the pointing/profile distribution on S20Launch.