J. Kissel, A. Pele, K. Izumi, T. Sadecki

After Bartlett had completed repairs on SR3, we wanted to get PSL IR light into the output arm in order to confirm that alignment had been restored after finding it pitched down after HWS work last week (see LHO aLOGs 12599 and 12609). However, we immediately found no light coming from the input chain. After confirming that all suspensions were in the same location as the last time this temporary bypass path was aligned (circa June 26th 2014), upon going into HAM2 to investigate we found the by-passed IMC beam clipping after IM1, and not making it through the Input Faraday Isolator. 

Suspecting that the temporary by-pass optics had been bumped (they're right on the edge of the table -- see attached layout), we elected to restore the main IMC trans path alignment to check if the bypass path was still co-linear. The trans path alignment had not yet been restored into flashing again after the 2 [mm] move. Thankfully, with the help of the irises on the table, restoring the IMC flashing required no more than a ~900 [urad] adjustment in Yaw. No change in PSL PZT or MC1 was required; unblocking MC1 revealed that we hit the first (in HAM2 just beyond MC1) and 2nd (in HAM3 just in front of MC2) irises, and were only off by an iris radius in yaw. Nice work pusher team!

Once IMC trans path was restored and flashes found, we confirmed that this path was still centered on IMs 1-4, to ensure a good reference path alignment against which to compare the by-pass. Indeed, with the trans path aligned, we found the bypass path was no longer co-linear.

We spent the rest of the evening re-aligning the by-pass path, and the main beam now is re-aligned up to PR3 (beam hits PR3, but PR2 alignment still needs tweaking to be centered on PR3). 

We've confirmed our alignment with the following:
- By-pass beam is co-linear with IMC trans beam up to IM2
- By-pass beam hits reference spot on the wall
- By-pass beam shows up on IM4 trans QPD
- By-pass beam is centered (by eye) on PR2

In order to help see the spot on PR3, we've turned OFF PR3 optical lever (though left the HAM2 ISI oplev ON). We've elected to leave it OFF, such that we can resume where we left off tomorrow morning. MC1 remains *unblocked,* but MC3 has its metal protective shield on to block the main IMC trans path.

Details for the record:
IM4 Trans QPD SUM values:
    ~4 [ct] BLOCKED
   ~50 [ct] UNBLOCKED

Suspended optics alignment values (in [urad]):
     MC1     MC2     MC3    IM1    IM2     IM3     IM4     PRM     PR2    PR3
P   +1254   +542    -550     0    +35849  +14057  -30000 -540.1  -2000  -245.5
Y   -2366   -550   -2557  3786    +5154.7  +5464  -8737  -244.1  +1000  -250.9