Michimura, Akutsu
Abstract
We have installed two QPDs in the IR beam path for TMSY, even though we did not have the IR transmitting beam itself there today. We laid cables to connect the IR QPDs with the digital system, and roughly confirmed they provided signals. We also moved a "whitening filter with DC" used for green QPDs from the EY0 rack to the TMSY rack.
Details
IR QPDs
- We brought two QPDs (S/N# 023 and 037), and set them on the optical table in the TMSY clean booth for the IR beam path (Fig 3). As we did not have the IR transmitting beam there, we just put those according to the Nagano-kun's layout.
- We connected the QPDs to the digital system. For this purpose, two new 15-pin Dsub cables were added and laid from the clean booth to digital racks. There have been already whitening filters (see 9116), and we connected the cables to one of them (8658); see Fig 1. Then the outputs from the whitening filter were connected with two 9-pin Dsub cables to an AA chassis (IR QPD 1 -> "IN17-20", IR QPD2 -> "IN21-24"... I don't know the jgwdoc number of the AA; I know the AA is the same one as the Gr signals are connected) already installed in the EY0 rack; see Fig 2.
- Then we illuminated each of the QPDs one by one using my iPhone's light, and roughly confirmed that their outputs were read by the digital system. (By the way, we also checked Gr QPDs as well.)
Re-arrangement of the racks (for Gr QPDs)
In order to re-arrange the racks EY0 and TMSY, we moved a whitening filter (8107) from the EY0 rack to the TMSY rack (also see Fig 1). The whitening filter's function were unchanged; it has been taking care of the Gr QPDs for TMSY.
To do's
- Those whitening filters at the TMSY racks (8107, 8658, and 8087) need to be replaced with those properly inspected having data of measured transfer functions, the noise, and so on. Also note that the 8087 was not yet used but reserved for oplev of TMSY-VIS.
- At least the IR QPDs did not have proper interface screws to accept connectors of the cables. It would be a tiny thing at a glance, but indeed important, so need to be taken care of.
- Once we get the IR transmitting beam at Yend, we need to align those optics including the IR QPDs again. Probably we will start with measuring the beam profiles.
