YuefanGuo - 23:08, Monday 17 April 2017 (456)
Check and align the beam
Today we checked the beam at several different place and tried to find where the astigmatism came from.
First in the situation as last Friday, we checked the reflected beam from the window, it was almost like before, very obvious elongated in horizontal direction, and also checked after the window, it seems even worse than before, it used to be about circular.
Then we tried to turn the dichroic mirror in the PR chamber to reflect the infrared beam enough far(into the west arm,PI) to look at the shape, it is more or less round beam.
The third beam is the transmitted of BS1, we checked across the table(P1), it is elliptical.
Next one we checked the transmitted beam of M2, luckily this beam pass successfully through the about 5cm gap between two tubes.We had enough distance to check it(P2), this beam is already started to be longer in horizontal.
Then the last check we put another mirror between L1 and M2(MT) to reflect the beam,checked with almost the same distance with P1, it is not a perfect round beam from my sight. But then we put the beam profiler at the edge of the bench, try to get the shape with it. Actually from the profiler, it seems a pretty good beam.
Then since we already finished all the picomotors, and I finished to make the cover of the extended wire today, so then we tested the extended cable again in case that I broke some during making the cover. All of them works well. But when we tried to move the picomotors of PR chamber, there is one layer of dirvers did not work. So now we have one problem is that we do not have enough drivers for the end room.
After fixed all the problems of picomotor, then we tried to re-align the beam. We recovered the last mirror on the bench for green first(M4), since we set the position with the target, it was not very hard to do it. But then we found out that the green beam on both the turning mirror and the dichroic mirror are both not very centered, I am not sure about the situation after the middle part of the chamber put back, but since we did not change M4 in horizontal, so we keep working with that. The we realign all the beam until the BS suspension mirror.
We took the 2cm shift into consideration(Logbook entry 450), and found out the beam is a little bit right on the mirror, left on the 10m target. So the dash line shows the situation now. So then we will move the PR and BS suspension mirror together to send the beam straight, after centered it on the window and the 10m target, we will try to center it on the 290m target.
First in the situation as last Friday, we checked the reflected beam from the window, it was almost like before, very obvious elongated in horizontal direction, and also checked after the window, it seems even worse than before, it used to be about circular.
Then we tried to turn the dichroic mirror in the PR chamber to reflect the infrared beam enough far(into the west arm,PI) to look at the shape, it is more or less round beam.
The third beam is the transmitted of BS1, we checked across the table(P1), it is elliptical.
Next one we checked the transmitted beam of M2, luckily this beam pass successfully through the about 5cm gap between two tubes.We had enough distance to check it(P2), this beam is already started to be longer in horizontal.
Then the last check we put another mirror between L1 and M2(MT) to reflect the beam,checked with almost the same distance with P1, it is not a perfect round beam from my sight. But then we put the beam profiler at the edge of the bench, try to get the shape with it. Actually from the profiler, it seems a pretty good beam.
Then since we already finished all the picomotors, and I finished to make the cover of the extended wire today, so then we tested the extended cable again in case that I broke some during making the cover. All of them works well. But when we tried to move the picomotors of PR chamber, there is one layer of dirvers did not work. So now we have one problem is that we do not have enough drivers for the end room.
After fixed all the problems of picomotor, then we tried to re-align the beam. We recovered the last mirror on the bench for green first(M4), since we set the position with the target, it was not very hard to do it. But then we found out that the green beam on both the turning mirror and the dichroic mirror are both not very centered, I am not sure about the situation after the middle part of the chamber put back, but since we did not change M4 in horizontal, so we keep working with that. The we realign all the beam until the BS suspension mirror.
We took the 2cm shift into consideration(Logbook entry 450), and found out the beam is a little bit right on the mirror, left on the 10m target. So the dash line shows the situation now. So then we will move the PR and BS suspension mirror together to send the beam straight, after centered it on the window and the 10m target, we will try to center it on the 290m target.
Images attached to this report
