It was April 2018 that the first fiber module was shipped from Caltech, US to Taiwan. Two years later, now we have completed delivering all the modules to Taiwan.
PFS is an instrument to observe celestial objects using optical fibers. Actuators nicknamed “Cobras” are used to position fibers to the targets, and “Cobra” modules consisting of the “Cobras” and fibers are produced by Caltech (USA) and Laboratório Nacional de Astrofísica (Brazil).
Let us introduce several numbers featuring “Cobras”. “Cobras” are about 8mm in diameter, and about 10cm long, so they are 2-axis motors as small as pens. 6-meter long, 200-micron thick fibers are attached to this small delicate devices. One “Cobra” module consists of 57 “Cobras” in a pitch of 8mm. That is, “Cobras” are lined up in two lines with little gap. By paving 42 “Cobra” modules on the focal plane of Subaru telescope, we can observe 2394 celestial objects.
Looking these numbers, you may feel how delicate it is to assemble “Cobra” modules. Indeed, it was very delicate process. Caltech team assembled 44 “Cobra” modules including spares manually one by one. During production, whenever they found issues with production process or module performance, we discussed their report, corrective actions, impacts on instrument performance, and so on.
Caltech finished assembly several months ago, after which we tested “Cobra” modules to check if “Cobras” goes to targeted positions. We also picked up “Cobras” to pay attention in later phase, where “Cobra” modules will be integrated to Prime Focus Instrument in Taiwan. Although we also finished testing all “Cobra” modules and shipped most of them, we suspended shipping the last 5 modules due to difficult situation with COVID-19.
However, in May 2020, Caltech team made a plan to ship the last modules keeping the members’ safety. The last modules were shipped and delivered to Taiwan, where Taiwan team are carrying out tests and preparatory work to install Prime Focus Instrument.
Thank you for great job, Caltech!
