this morning, with Daniele, we took some images of the M1 mirror HR surface :
1- large image span of the mirror surface (~center) before being cleaned :
one can see a lot of spots
2- zoom in on some spots in the middle of the mirror.
Daniele saw 2 suspicious spots among many.
difficult to be sure if it's only some dust or if it's some damage
3- large image span of the mirror surface after being cleaned with the spin coater machine
only the 2 suspicious spots remain, all others have been washed.
4- zoom in on the 2 suspicious spots
if one compares with the image before cleaning, one can see the spots are much larger
5&6- zoom in on the 2 suspicious spots separately after a 2nd cleaning process with the spin coater,
it seems the spots are even a bit larger than before
conclusion : it seems that these spots are presently showing some damage on the mirror surface.
it is strange that there are 2 in the same time.
one possible explanation is that, as we had to move the z-axis motor before, and we know that the mechanics are rusty, it's possible that it released some metallic particles on the mirror surface.
and 2 were in the beam area....
| Ronic Chiche wrote: |
|
after trying to increase the power and after moving S3 to try to change the size of the beam on the mirrors, the FPC power suddenly droped.
so, we need to remove M1 to check if it has been damaged.
we placed an iris in reflection of the FPC to keep the alignment for the new mirror M1.
the alignment has been done with an iris and the amplifier at 10% (to get a quite round beam) and the beam profiler.
once the iris is almost closed, the alignment is good, using the diffractions rings.
|
|