Tried to measure NLG (following 76542) at different ISS setpoints (by changing the SHG waveplate to adjust how much power is incident on the AOM), with the same OPO TRANS power. Because in 86363 we were confused that the NLG increased significantly when we realigned Pump fiber, with the same OPO Trans setpoint.
This was confusing and I'd like to repeat next week. I initially thought we were getting pump depletion so decreased the seed power, but later noticed the ISS was just unable to keep up and the control voltage was dropping to -5 for the low values of ISS setpoint, see attached, it could hold in LOCKED_CLF_DUAL with 80uW OPO_TRANS fine but not with the SEED beam.
| OPO Setpoint | ISS Setpoint when locked on | Amplified | Unamplified | NLG | Notes | |||
| CLF DUAL | SEED | Max | Min | UnAmp | Dark | |||
| 80 | 4.9 | 3.2 | 0.192924 | 0.002389 | 0.0079612 | -2.1e-5 | 24.2 | |
| 80 | 2.9 | 2.9 | 0.045037 | -2.2e-5 | 39 ?(using below unamp) | Pump deplation? Reduced SEED power from 0.7 to 0.3 to keep it locked on SEED (still didn't work first time). | ||
| 80 | 6.3 | 6.3 | 0.0430464 | 0.000546 | 0.0011063 | -2.2e-5 | 38 ? | Unamp signal decreased from SEED power change. |
| 80 | 4.8 | 4.7 | 0.0454944 | 0.0005378 | 0.0018533 | -2.7e-5 | 24.2 | |
| 80 | 2.9 | -5 ? | Noticed ISS Controlmon at -5. | |||||
| 80 | 3.5 | 3.5 | 0.0452317 | 0.00054049 | 0.0018636 | -2.4e-5 | 24.0 | |
| 80 | 4.95 | 0.04523 | 24.0 | Leaving here. | ||||
Repeated while Corey was relocking today. We had one strange measurement when the ISS setpoint at 3.3V where the un-amplified signal was much lower but when later repeating at 3.1V, we didn't see this.
| OPO Setpoint | ISS Setpoint when locked on | Amplified | Unamplified | NLG | |||
| CLF DUAL | SEED | Max | Min | UnAmp | Dark | ||
| 80 | 5.0 | 5.0 | 0.042961 | 0.00051437 | 0.00176935 | -2.1e-5 | 24.0 |
| 80 | 2.8 | ISS Setpoint dropped to -5, so OPO TRANS not at 80uW | |||||
| 80 | 3.3 | 3.2 | 0.043273 | 0.0005247 | 0.00106713 | -2.1e-5 | 39.7 |
| 80 | 6.2 | 6.2 | 0.041031 | 0.00051677 | 0.0017658 | -2.1e-5 | 23.0 |
| 80 | 6.5 | 6.4 | 0.0409285 | 0.00051425 | 0.00175578 | -2.1e-5 | 23.0 |
| 80 | 3.6 | 3.5 | 0.0429806 | 0.00051216 | 0.00175932 | -2.7e-5 | 24.1 |
| 80 | 3.1 | 3.0 | 0.0431685 | 0.000516166 | 0.0017296 | -2.7e-5 | 24.5 |
| 80 | 2.8 | ISS Setpoint dropped to -5, so OPO TRANS not at 80uW | |||||
| 80 | 4.9 | 4.8 | 0.0429243 | 0.0005134 | 0.0017627 | -2.7e-7 | 24.0 |