betsy.weaver@LIGO.ORG - posted 16:23, Thursday 26 February 2026 - last comment - 20:21, Friday 27 February 2026(89289)
HAM1 JAC Viewport window re-FirstContact cleaning
Jordan and Camilla pulled the FirstContact from the JAC viewport in prep to install it on the -Y door. Unfortunately the inner glass surface was still showing many dots of particulate so we decided to re-FirstContact clean it. I poured on a new sheet and we are now letting it dry overnight. Install will need to happen tomorrow after we pull the sheet and hopefully have better results. This seems to be typical of FirstContact these days - needing to reapply a second time on numerous optics...
The second application of FirstContact was peeled from the vacuum-side of the viewport this morning. During the peel, the TopGun N2 ionizer output was at ~10 psi, with a follow-up TopGun pass at ~30 psi. I observed no macroscopic particulate within the ~2.5 inch diameter of the FC coverage after removal. At the edges of the FC sheet (the ~2.5 inch diameter centered on the viewport optic), I noted two "smudges" of FC film. I removed these smudges with a small Contec swab dipped in reagent grade acetone. Another ~1 mm droplet of FC was noted at the optic/mounting ring interface. I also attempted to remove this with a swab/acetone wipe, but since it was in an interior corner, some FC remained where it had wicked into the interface.
The viewport was then installed on the HAM1 -Y door A2F3 flange. Torquing of the CF flange and and installation of the guillotine assembly went without a hitch. We didn't do any cleaning to the in-air side of the viewport post-installation.