Betsy, Robert

When the IFO broke lock around 11am, it was decided that we should go clean the viewport window on the South side of the HAM1 chamber which the PSL beam enters (see pix of inspection prompting this at alog 30867).  Travis lowered the power of the PSL via the rotation stage to 0.0 and we also locked out the rotation stage and the light pipe out on the floor.  We then decoupled the light pipe from the HAM1 port and slid the unit back about a foot.  We then proceeded to do a spray-on First Contact cleaning using the "canning cone" as described in procedure E1600263.  We let it dry ~30 mins before pulling the sheet off, however 2 small fragments of FC tore off and remained on the window just below center.  A second sheet was applied, but it again left a small fragment near the bottom of the window.  This time I just painted a stripe across the fragment and pulled it in a 3rd attempt - Robert and I reconciled that this was low enough to be well out of the beam path if I left a streak.  Lighting was poor and with laser goggles made for a difficult cleaning.  Otherwise, the cone and procedure worked well.  I'll add to spray more than 3 layers next time as this may have made for a more sucessful first pull.

Pix are of the 1st and 2nd FC sheet followed by the 3rd little stripe pull.  The last picture is the PSL beam centering on the viewport.  The beam goes through the viewport just below center, and we see a visible improvement of the scatter points in that area due to the cleaning(s).  Note, there is ring of particulate outsid eof the FC sheet pull area, but this is covered by the lightpipe mounting plate which reduced the beam view to the window.