YuefanGuo - 00:51, Saturday 22 April 2017 (460)
Several work has been done
From yesterday we started to reflect some beam in the PR chamber out of the chamber, then we can mark the position for reference in case if we lose the alignment. Then we chose the four beams shows in the first picture, two are green and two are infrared. So from the picture, G2 and IR2 are used to set the alignment of the bench, and IR1 for the path of infrared, G1 to set the position of the dichroic. There is also a green beam transmit from the turning mirror, which hit one of the tube of the chamber, if we need to use that one, we just need to change that port to a window.
Then after we put the mirror like the type for the local control,working well in vacuum, to reflect the beams come out all from one window, on the right side of the input window of PR if you face the optical bench. Then we use a plastic sheet to put some cross on the position of the beam,and fixed them near the window( Pic 2), we use this kind of mount then if we need we can remove the plastic and then put them back again on the right position.
Yesterday we suddenly lost the infrared alignment, the beam went into the chamber but missed the first mirror. We checked the beam on the bench, there are totally three mirror to turning the beam into the chamber. Between the 1st and 2nd, we check with the target, it is fine. Then we wanted to know the reason why suddenly we lost the alignment, so we try to push a little bit at the edge of the 2nd and 3rd mirror, it seems the 2nd mirror fixed very good on the mount, but the third one does not. Also the beam is near the left edge of the 3rd mirror, and also we missed the 1st mirror in the chamber with the beam on the left side. If we wanted to move the beam on to the 1st mirror in the chamber, we need go more left on the 3rd mirror, then we will go out of this one. So we decided to move only the third mirror. Luckily, we got the alignment back with only moving this one.
Also we put another mirror after the dichroic mirror to check the reflect infrared beam can go to the right point on the bench or not. So it seems the alignment is very good, the infrared go back through the Faraday and reach good position.
We finished everything of the PR chamber, so in the afternoon we moved the clean booth to the BS chamber and closed the PR.(pic 3)
Today we also work a little bit on the astigmatism. At first we only want to put some aperture to set the beam position on the bench for re-align easier in the future. Then we found out if we make the beam on the bench through the aperture to make them round (pic 4), the beam after the telescope looks pretty good.(pic 5). So this time we were sure that the astigmatism is not from the things in chamber. Then we tried to put another aperture after the lens on the bench, the large beam looks very good as well， then put it before the lens, it seems the beam got worse, but since the beam before the lens is very small, it was hard to say the lens is the only reason for that.
Then after we put the mirror like the type for the local control,working well in vacuum, to reflect the beams come out all from one window, on the right side of the input window of PR if you face the optical bench. Then we use a plastic sheet to put some cross on the position of the beam,and fixed them near the window( Pic 2), we use this kind of mount then if we need we can remove the plastic and then put them back again on the right position.
Yesterday we suddenly lost the infrared alignment, the beam went into the chamber but missed the first mirror. We checked the beam on the bench, there are totally three mirror to turning the beam into the chamber. Between the 1st and 2nd, we check with the target, it is fine. Then we wanted to know the reason why suddenly we lost the alignment, so we try to push a little bit at the edge of the 2nd and 3rd mirror, it seems the 2nd mirror fixed very good on the mount, but the third one does not. Also the beam is near the left edge of the 3rd mirror, and also we missed the 1st mirror in the chamber with the beam on the left side. If we wanted to move the beam on to the 1st mirror in the chamber, we need go more left on the 3rd mirror, then we will go out of this one. So we decided to move only the third mirror. Luckily, we got the alignment back with only moving this one.
Also we put another mirror after the dichroic mirror to check the reflect infrared beam can go to the right point on the bench or not. So it seems the alignment is very good, the infrared go back through the Faraday and reach good position.
We finished everything of the PR chamber, so in the afternoon we moved the clean booth to the BS chamber and closed the PR.(pic 3)
Today we also work a little bit on the astigmatism. At first we only want to put some aperture to set the beam position on the bench for re-align easier in the future. Then we found out if we make the beam on the bench through the aperture to make them round (pic 4), the beam after the telescope looks pretty good.(pic 5). So this time we were sure that the astigmatism is not from the things in chamber. Then we tried to put another aperture after the lens on the bench, the large beam looks very good as well， then put it before the lens, it seems the beam got worse, but since the beam before the lens is very small, it was hard to say the lens is the only reason for that.
Images attached to this report
Comments related to this report
Pictures of the opened PR chamber.
3 mirrors have been added to obtain the IR and green references.
G1 is the green beam reflected by the dichroic
IR 1 is the IR beam after the Faraday Isolator and a folding mirror
GR2 and IR2 are reflected by the same mirror ( between the green folding mirror and the dichroic and between the 2 metallical structures).
They can be seen on the "PR references" picture.
I will try to upload a more precise optical scheme of this chamber