Opto-mechanical design of SCUBA-2

Abstract

This paper describes the opto-mechanical design of a large instrument for sub-mm, SCUBA-2, to be commissioned at JCMT. The scientific requirements, specially the large fov and the constraints of the telescope mechanical structure, lead to a complex optical design using freeform aluminium mirrors . The mechanical design is also challenging with large modules to be mounted and aligned in the telescope as well as the cryogenic instrument containing the mirrors, the filters, the dichroics and the detector modules. The cryogenic isostatic mounting, the structural and thermal designs are presented. This includes details of the fabrication of the structure and design of a shutter mechanism for operation at 4K. The results of the first AIV cool-down are also presented.

SCUBA-2: a 10,000-pixel submillimeter camera for the James Clerk Maxwell Telescope

“…The instrument opto-mechanical design 2,3 is driven by two principal requirements, the large field-of-view of 50 sqarcmins, and a detector operating temperature in the 100mK regime. The large field-of-view results in extremely large mirrors (up to 1.2m across), the last 3 of which must be cooled to temperatures below 10K, in order to minimise the thermal background on the arrays.…”