Critical design review of the metrology camera system

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The metrology camera system (MCS) is one of the PFS subsystems that has been developed by ASIAA (Academia Sinica Institute of Astronomy and Astrophysics) in Taiwan. MCS will be the key component for quick fiber configuration. It is a camera system mounted at the Cassegrain port of the Subaru Telescope looking up the prime focus where the ~2400 science fibers and ~100 fiducial fibers are populated. In the process of fiber configuration, these fibers are “back-illuminated”: In other words the fiber tips at the side of spectrograph system are illuminated so that the other ends at the prime focus are lit. MCS will then take the images of these back-lit fiber tips so that one can measure their positions on the focal plane, see how far away they are currently located from the requested positions, and send commands to the fiber positioner system accordingly. MCS has a field of view large enough to image all the fibers at the prime focus by one exposure, which greatly simplifies the process (e.g. no need to stitch a number of images to scan the entire field) and shortens the fiber configuration time.

As design studies are getting completed, we came to a position where the team should have the designs reviewed from independent viewpoints. This time in order to review in particular the mechanical design and Integration & Test (I&T) plan in detail, we invited several experts as reviewers, half from the Subaru observatory and another half from the PFS project but working for the other subsystems. We had this Critical Design Review (CDR) on Sep 22 and 23 at ASIAA with TV connections to a few other places. According to the review report, the team at ASIAA applied further updates to the design and I&T plan and we had another review meeting as a “delta” CDR on Dec 3 where we confirmed improvement and risk mitigation had appropriately been implemented. The team will soon start fabrication aiming at the delivery of MCS to Subaru sometime around the end of 2016.

MCS (MCS mechanical design)