Telescope adjusted

With the data measured at the end of the bench, we found the beam waist and position. Then we did the simulation with the 2-inch mirror, PR suspension, input and output mirror. The position and the focal length of these mirrors are as below:(The origin is set as the steering mirror which is 85cm from the end of the bench)

2-inch mirror: f=-30cm z=4.51m
PR suspension: f=3m z=7.235m
Input mirror: f=-218.35m z=12.135m
End mirror: f=-218.35m z=312.135m

With these values, the simulation result shows that the beam will keep diverging in the arm which is not what we want(pic1). So I did some calculation, we need to move the 2-inch 3.9cm backward to get the beam waist around 150m inside the arm. (pic2)

The other reason why we should move 2-inch mirror is after we installed the real input mirror, we got green reflect back from the from surface of that mirror. But it seems the reflected beam is much larger the original one.

Before moving the mirror, we set two reference point, one is the position of the beam in front of the input mirror, the other is the beam reflected back to the bench. Also after the input mirror we put two aluminum mirror to reflect the beam into the corridor to check the beam propagation. At first we only tried to move the picomotor of the 2-inch, but even we when we finished all the range, nothing changed. So we moved by hand little by little. Every time we moved, we recovered the beam with pitch and yaw of the 2-inch on two reference point and check the beam size at the entrance of the corridor and bench. After moving about 3cm, the reflected beam size seems fine, so we followed the beam inside the corridor, found it has beam waist around 150m, and the size is from 1cm to 2cm which is acceptable.

Then we took the reference of the BS chamber like what we did to the PR, with two aluminum mirror, the beam transmitted by the 2-inch and the BS suspension have been reflect out of the chamber.