(Tanaka, Miyakawa)
Abstract:
This morning, Tanaka-kun and I entered the PSL room and confirmed that the PMC was not broken, and it could be locked to the neoLASE laser with 9A of current. Transmisivity was ~85%, and UGF was ~2kHz.
Detail:
I had trouble with leaking water at the connection between tubes to the neoLASE laser when the chiller started yesterday. I got better connectors from the other neoLASE laser being operated in Toyama Univ. The bad connectors were replaced with good ones this morning, and there was no leakage of water when the chiller started.
Then I turned on the neoLASE laser with very low power (~2A) and checked the PMC status. At first, the beam was out of the frame of the PMC refl camera, and it is consistent that the PMC had been re-aligned with the FB laser since a big misalignment happened during the table bending was recovered. Anyway, I re-aligned the beam of the new laser to hit the PMC relf camera, and some resonance could be seen soon. It means that the mirrors of PMC were not misaligned.
Then Tanaka-kun and I tried to lock PMC. We changed the high-voltage to PZT of PMC, and the transmitted light of PMC also moved. It means that the HV amp and PZT were not broken. In other words, the FB laser without a master on the day before yesterday was totally something wrong. It was not coherent light anymore.
We did the same things as preparation to switch the FB laser to the neoLASE laser as before;
- Re-connecting the modulator.
- Re-connecting DC power monitor.
- Changing the normalizing gain of the DC power monitor.
Then, PMC itself can be locked easily to the neoLASE laser with some higher-order modes sometimes. We aligned the injection beam again, and the transmissivity reached something like ~85% with TEM00 mode. Then we increased the power to ~50W with 9A current. The injecting power to the PMC was ~20W or a little more. We measured the OLTF, and the UGF was ~2kHz.
Then we tried to lock IMC this afternoon. Tanaka-kun will report it.
