Keita, Camilla, Jim, Gerardo, Sheila
I will let others alog about the work of routing the fibers in chamber, but we connected the 532 diamond fiber for the filter cavity green sensing and the IR fiber for the seed and CLF that was uninstalled from HAM6 in November 2020.
We inspected each fiber end with the fiber microscope before connecting them, but didn't disconnect the fibers inside SQZT0 to inspect them. The long IR fiber had large specs of dust, which came off with a vectra alpha wipe. The in vaccum IR fiber also had several specs of dust, we tried vectra alpha wipes (in an S pattern) and the fiber cleaning tool recomended by diamond. There was still one piece of visible dust after that, Camilla has a photo.
The diamond fiber for the filter cavity green has what looks like a scratch on the cladding on the side that goes to the collimator in HAM7. Camilla also has a photo of that.
We used the seed beam to check transmission of the IR fiber, the coupling of the seed on SQZT0 is only 47%, the long fiber transmission is close to 100%, and the feedthrough + in vac fiber transmission is 79%. The total transmission from fiber port to in chamber is 39%.
The filter cavity green sensing is also not well coupled on SQZT0, wit 21% of the power incident on the fiber port measured at the outside of the table feedthrough. After that the transmission is good, 89% through the long in air fiber, and 88% for the feedthrough to the collimator in HAM7. The total tranmission of this chain is 16%, we have 1.33mW incident on the fiber. We can attempt to improve the coupling on SQZT0 when we are not using this for work inside HAM7.
IR and FCGS in-chamber fibers were installed. Pump fiber will be done tomorrow.
It was nerve-wracking, knowing that one wrong move could damage these fibers.
For FCGS (green) fiber, even a seemingly simple act of attaching the feedthrough to the chamber was overly complicated because we had to thread the fiber through the copper gasket, then through the reducer flange on the chamber, which was at least 3-persons' job (we ended up using four persons).
The 1st and the 2nd picture show how the fibers are routed from the feedthrough to the bottom of the ISI.
Risk 1: A year or two from now, when somebody who doesn't know anything about these fibers will work on the CPS or whatever in this corner of the ISI, or worse, step on the bottom platform, these fibers could be damaged.
Since there's no official way for strain releaf from the OPO breadboard to the ISI surface, and since the blade spring towers are already crowded by thermistor/PZT/picomotor/OSEM cables, we had to improvise. Third/fourth/fifth pictures show that we used a PEEK cable clamp attached to an ISC pole for strain relieving the IR fiber (black jacket) while we used another PEEK cable clamp close to the edge of the ISI table for the green FCGS fiber (no jacket).
Risk 2: If somebody leans on where the fibers are touching the edge of the ISI table, the fibers will be damaged. It would be good if we have some kind of guard. Even a sheet metal structure would be better than nothing.
I wasn't super happy and neither was Jim, but we did what we could.
Systems, we could use your help. We need to think about something for future at least, but I prefer to have something that we can use now.
Details of fibers when disconnected in optics lab is in alog 59707. We are using IR F:COL1: D1700396-V1-S1800707-0007; FCGS H:COL1: DIAMOND9708433--00-2135431V005; Pump G:COL1: DIAMOND9708433--00-2135431V003.
Attached are images using the fiber microscope of in-vac H:COL1 (same as prev in alog 59707), in-air IR fiber, feedthru side of F-COL1, collimator side of F:COL1 before and after cleaning. Still had a small white dot we coudln't remove.
Also attached is 2 photos of the fiber routing.
Green fibers swapped 5th Oct 2021 - alog 60148. Now FCGS H:COL1:DIAMOND9708433--00-2135431V003; Pump G:COL1:DIAMOND9708433--00-2135431V005