- Today, Daniele and I cleaned the cavity inside, recleaned the M2 and M4 and their mounts, optimized the locking, and the finesse is now about 25,000.
- Although it's lower than the expected 30,000-40,000, we decided to move on to the next step. In addition, the mount of M4 is near the end of the tuning range and may cause instability at high power.
- We adjusted the cavity length to match the repetition rate of the pulsed laser, and the FSR in air is 160.265 MHz.
- Tomorrow, we'll turn on the vacuum and use the pulsed laser to get resonance.
| Xinyi Lu wrote: |
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Today, Daniele and I cleaned mirrors one by one using pure water, alcohol, and the spin coater. Here are the measurements of finesse each time:
1. Initial value: 14,076
2. Clean Mirror 2: 20,606
3. Clean Mirror 4: 18,750
4. Clean Mirror 3: 18,762
5. Clean Mirror 1: 18,563
6. Reclean Mirror 4: 15,226 (unstable lock)
7. Reclean Mirror 4 again: 16,563 (unstable lock)
The finesse reached a maximum of 20,606 but finally was down. For the last two measurements, the locking state was unstable and noisy. Tomorrow we will optimize the locking status and re-measure.
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