Yesterday we basically tried to align the beam better, since we found out it is a bit low on the small window near the central room, also some problems in the horizontal direction. Now we are at a pretty good position in vertical position in the windows and the second target, we can use this height to align the first target again to the right height. In the horizontal direction we managed to align the beam more or less in the center in the windows and the second target, but then we found out it was far away from(left side) the center of the first target, it seems a little bit strange, but we decided to work with this situation. There is some construction work going on outside TAMA, we cannot adjust the beam in the daytime while they are working, because the beam in the central room does not go into to the vacuum yet, it is affected a lot by the seismic motion.
Also the SHG cavity had high frequency oscillation when it went around the resonance, so we changed the low pass filter frequency to 3Hz and the gain to 200.
The other problem we found out yesterday is that the optimal temperature of the SHG has been changed, before the thermal controller was set with the resistance of 3.270 where we can get the maximum power of green. But yesterday we found out the green beam power is too low, but the mode matching seems not bad, so we tried to change the temperature, and now the maximum green power was at 3.230, there we have the power about 20mW, it is still lower than before. One of the possibility is that the environment temperature in TAMA increased recently, so the radiator may not work as good as before.
And also now TAMA air conditioner is working at winter mode, when we tried to change it to summer mode, we found out the green beam shaked a lot. It may caused by the air flow between different temperature, since TAMA is quiet large, maybe it will take a long time for the temperature to get stable, so we planned to set the air conditioner to summer mode after we finish work this Friday, let it adjusts along all the weekend, hope on Monday it is stable enough for us to work on.