Sheila, Daniel, Terry, Nutsinee

35.5MHz I/Q optimization, 70.78 degree offset

We injected 105Hz excitation to SHG PZT then adjusted the phase offset while watching I/Q on the SR785. 70.78 deg offset gave a factor of 40dB in ratio and that is now the current setting.

SHG Open-loop gain TF, unity gain frequency ~ 3kHz

We adjusted the common mode board gain until the UGF is ~3kHz. When the SHG crystal was not heated (25C) this gain was 4dB.

Later we changed the crystal temperature to 35C to get green light out of the SHG. The gain since then has been 20dB.

Then we reduced the power going in to the SHG cavity. Was 400mW, now 100 mW. This didn't change the UGF by much so I didn't touch the gain setting (still 20dB).

Here's a snapshot of the final open-loop gain TF as of Friday evening. Once lowered the input power I was only able to drive the PZT at 50mV stably.