[Alexa and Kiwamu]
As a preparation for the upcoming HAM1 installation work, we applied some modifications on ISCT1. ISCT1 is now ready for the HAM1 in-vacuum work.
Replacement of a top periscope mirror with a dual-wavelength mirror
We replaced the upper mirror of the middle periscope by a 2" dual-wavelength mirror so that it reflects both 1064 and 532 nm at once. Note that we had three periscopes on ISCT1 (see D1201103-v13 for the diagram) and the one we modified today is the middle one which used to reflect only green light. The mirror we newly put is E1000425-v3 which we took out of the LSB clean room.
Installation of an infrared bottom periscope mirror
We installed a 2" infrared high reflector. This will take care of the PSL doubling infrared light directed by the upper mirror of the middle periscope. Unlike the usual bottom periscope mirror this one simply stands on the optical table instead of being attached on the periscope structure. We stole one of the 2" infrared mirrors from the rightmost periscope and then mounted it for this bottom mirror. Note that we are not going to use the rightmost periscope mirror any more for steering the PSL doubling light and therefore we removed it (see below).
Removal of the rightmost periscope
We removed the rightmost periscope which had been taking care of the PSL doubling light. The periscope is now put nearby the entrance of the squeezer bay.
Removal of a light pipe
We removed the light pipe which was for the lower right viewport of HAM1 since we are not going to use this port any more. The yellow cover and the lexan guillotine were put back to protect the viewport.
Removal of lexan protection plates (a.k.a. guillotines)
During the removal of the rightmost light pipe, we noticed that the rest of two light pipes somehow still had the lexan guillotine in. This is not great because we know the lexan plate does something bad (see for example alog 6073). We are not sure if they had been there all the time during HIFO-Y. We took them out and put the metal cover on the slot because there is no point to keep them in there.