thomas.vo@LIGO.ORG - posted 12:01, Saturday 20 January 2018 - last comment - 16:51, Saturday 20 January 2018(40209)
Still working on SRC Alignment
Jenne, Sheila, TVo
We spent most of Friday using cameras to get the pointing of SR3 onto SR2 and back down to SRM correctly but it was much more difficult without a sensor to tell if you're actually getting the center of the baffle aperture. We think we were able to eventually get the right beam down to the SRM but it's not obvious how well centered you are on any of the optics (except SR3 since we have the input chain well aligned). We were hoping to get the optics close enough so that an excitation on all three optics would show up all the way back at LSC-POP but unfortunately this didn't work.
The next hopeful resolution is to get into HAM6 and try to align through the Faraday with an IR card.
Re-finding that place where we are hitting SRM and getting some beam back toward SR2, I realized that we hadn't put in any screenshots of the alignment for a while. So, here's an alignment that gets us back toward SR2, although I can adjust the SR mirrors quite a bit and still get this.
In the photo, the beam returning from SRM is at the bottom of the top TV. It's hitting something much lower than the baffle aperture (bottom of cage, or side of ISI or something?). On the lower TV, the smaller circle on the left is where we think the SRM is, and the larger circle on the right is the SR3 baffle aperture. The vertical lines are where we think the cages are for the suspensions, and the dotted line at the bottom is the eye-baffle between HAMs 4 and 5. The top TV has markings for the SR2 baffle, but it's hard to capture. The SRM return beam is directly below the center of the circle part of the SR2 baffle aperture.