As we said, after glow discharge and spin coater we recovered a low power finesse ~23000 (aligning away from the M1 crater).
Today, we have made some power up to 48kW (3A on 3rd stage). At this power, there was no important effect on the transmission which can be compared with the coupling (see image "3A_136mWtrans"). We waited ~20min without aligning and the power dropped slowly (misalignment) to 39kW.
Then we increased the amplifier power to 4A and the power went up to 44kW. At this moment, the strange transmission behavior that we observed before mirror crater, appeared again (see image "4A_126mWtrans"). We also observed a mode deformation with the camera, see image "mode_strange". This shape was not depend of the camera/filter rotation angle and still appear with another camera.
| Loïc Amoudry wrote: |
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The mirrors went in the cavity the 28th of november (We did several power up to 30kW stored and only one to 40kW then the power went down to 2kW during the run).
Microscope study shows that mirrors get some dust during the handling [travel from microscope to SBOX --> installation --> in SBOX for +1month and power up --> travel to microscope].
Almost all of these dusts can be removed with cleaning.
There is only one important difference between 28th of november and today, a large spot on M1.
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