[Jason, Jenne]

Wednesday and Thursday this week we've made a lot of progress on many smaller things.

After having swapped the cables for the ALS Fiber Distribution Box's external PD (which sits on the PSL table monitoring the power going into the fiber), we confirmed that we're seeing signal in ndscope when we've got beam on it.  (alog 61517 notes that I discovered we chose the wrong cable).

We recalibrated the PD that monitors the power transmitted through the EOM.  It looks from alog 43390 that it was pseudo-calibrated in the past to basically always read out a single-point value, using the offset in a filter bank (in a place that we traditionally just put the dark offset).  Since this former setting was basically hard-coded with a giant offset to always report the same number, we started from scratch and measured the dark offset of the diode and put the negative of that number in the offset.  We then measured the power again with a 10W power meter when we had about 8 W through the EOM, and put the calibration into the filter module 'toWatts'.  A few weeks ago, before we noticed the strange offset, we had put in a temporary gain into the filter bank - this has now been reverted to unity and accepted in SDF, since the calibration is inside the filter module.

We inspected all of the optics in the IO path prior to illuminating them with high power.  Jason did a lot of work cleaning the optics to ensure we have pristine surfaces.  For two of the more stubborn optics (the steering mirror just in front of the EOM, as well as the second main path 2" mode matching lens), Jason removed the optic to do a drag wipe with the optic laying flat on some lens tissue on the table.  The second lens, in particular, had some kind of residue on it that was not coming off with in-situ cleaning.  We didn't think of it before removing and replacing the lens (whos mount never moved, Jason was able to loosen the retaining ring and pull the lens out of the mount, so it pretty much went back to where it came from), but prior to removing the steering mirror, we re-set two of the alignment reference irises to match the beam path after the PZT, now that we've got an aligned IMC.  We then removed the mirror, Jason cleaned it, and we put it back.  We then adjusted the steering of that mirror to get back to our alignment irises.

We slowly increased the power going to the EOM and the rest of the IO path, using the half wave plate just after the PMC.  As this is the first time in several years that these optics have seen more than ~55 W, we were watching the optics with the IR viewer, as well as looking at them without it.  Things all seemed fine the whole way.  During this, the rotation stage was set to allow only minimal power through, so most of the power was dumped on the water cooled dump that is just under the periscope.  According to the PD we had just calibrated, we topped out at just about 101 W through the EOM.  After this, we then turned this waveplate back such that only 1.7 W is going through the EOM to the rotation stage. 

In the afternoon, while the LVEA was laser hazard, I opened the ALS light pipe and confirmed that we're getting light onto the top mirror of the ALS periscope on ISCT1.  This is pretty good for a start, but to get better I'll need a second person so I don't have to go back and forth between ISCT1 and the PSL enclosure.

Finally, we've got the bullseye PD path installed, and the PD plugged in.  Since we're taking the leakage beam through M10 (just after the ISS AOM) and the beam is quite small there, I've got a diverging lens to make the beam a bit larger.  The amount of light is small enough that I don't need an ND filter, but Jason prepped an RG1000 long-pass to block any pump light from the amplifiers from confusing the PD.

With the watchdogs on, and only allowing 1.7 W to go toward the rotation stage, we were done with the PSL enclosure for the evening.  Later, Craig locked and tuned up the alignment of the refcav (alog 61605), and locked and aligned the IMC (which needed some hand alignment since our work of getting back to the alignment irises wasn't perfectly perfect) after we put the PSL in science mode (most fans and the AC off), alog 60617.  To lock the IMC, since we've only got less than 2 W going to the rotation stage, the rotation stage is now set so that it transmits maximum power.  We will likely want to undo this before re-illuminating the IO path with max power.

While we have left the PSL in science mode, Jason did set the ACs so that when we're in there they should go to 23 C, rather than the old setting of 20 C.  We hope that this will better match the ambient temperature when the enclosure is in science mode, so we'll have less of a thermal transient.  This is almost certainly part of the reason that Craig had to touch up the alignment of the ref cav.