J. Oberling, P. King, R. Savage.

We spent a little time attempting to get the DBB up and running for a mode scan to try to see the higher-order mode content of the 70W amp beam.  The beam was aligned into the DBB and the mode matching lenses tweaked to a point where things looked good to us.  We took a 1 minute duration DBB mode scan and it reported a higher-order mode content of ~80%.  This can't be right as we're transmitting almost 80% of the incident light through the PMC, so something still isn't quite right.

After that we spent some time carefully tweaking the alignment through the 70W amplifier.  The goal was, as always, the best beam quality we could find at the highest power.  After some careful tweaking I was able to get a good portion of our halo to disappear.  Peter then tweaked it further, and we now have a beam out of the 70W amp that looks pretty good; see the attached picture.  While there is still a bit of a halo, it is much smaller than it was when we started.  In addition, the Gaussian fit from the WinCAM software is the highest we've seen yet.  The 70W amplifier is outputting 70.5W in this configuration.  Peter and I then aligned the beam to the PMC and locked it and the FSS.  We didn't spend much time with the PMC alignment, so there is definitely some tweaking to do there; the PMC is currently outputting 51.5W with the ISS OFF.

This completed the PSL work for today, so Cheryl and myself then began aligning the IMC for tomorrow's HAM1 work.  She will alog those results.