Nutsinee Fabrice Sheila Gerardo Daniel
After the vent, the fiber transmission recovered, back up to 6 mW (from about 3mW before the vent). The unit was de-installed and will be shipped back to MIT for diagnostic. The new unit (SN6) was installed.
Power measurements with old fiber after the vent:
- Green launch: 18.5mW (power meter) (and 23.6mW on the green launch PD Epics readout, to be re-calibrated)
- ISCT6 feedtrhough out: 13.2mW (power meter)
- Fiber in-vac output: 5.6mW (power meter)
- In-vac reflected cavity after dichroic: 5.3mW (power meter)
- SQTZ6 periscope downwards between mirrors: 5.3mW (power meter)
Power measurement with new fiber:
- Green launch: 19.5 mW (power meter) to cpl isct6 , (24.5mW green launch PD)
- ISCT6 feedthrough out: 14 mW (power meter) out of ISCT6 into in-air fiber
- Fiber in-air output: 13.3mW (power meter, into HAM6 feedthrough)
- Fiber in-vac output: 5.9 mW (power meter)
-- Fabrice not happy. 5m fiber swapped for a new one. --
Power measurement with new in-air fiber:
- New Fiber in-air output: 14.1mW (power meter, into HAM6 feedthrough)
- Fiber in-vac output: 9.1mW (power meter)
-- Fabrice is less diapointed (transmission was better on the test bench) --
We left the laser on for the night, at lower power (~12mW input) to monitor the health of the power transmission.
Here are trends of the pressure in HAM6, the SHG launched power, the green fiber rejected polarization and the OPO reflection.
During this time Daniel was adjusting the polarization into the fiber, so we need to look at the sum of the rejected polarization and the reflected power. It seems that this recovery isn't happening slowly over the hours between the vent and when we first measured, but it is happening more quickly around the time that we first let light into the fiber (which was also around the time that we went to the chamber to make measurements).