Mechancial design of the LSST telescope and enclosure

The three mirror optical system being developed for the LSST presents some interesting mechanical challenges. The optical support structure must hold three large mirrors (8.4, 3.5 and 4.2 m diameter) in accurate alignment, and allow for their periodic recoating. The telescope must be agile, with no more than 5 seconds allowed to repoint by 3 degrees and settle at a new field. To achieve such high performance drives we have adopted a mechanical concept based on the C-ring support of the LBT. Preliminary designs achieve a lowest resonant frequency over 7 Hz, and 10 Hz should be achievable, higher than is realized for conventional 8 m telescope designs. This should provide exceptional performance. The building concept places the telescope and handling crane in a co-rotating housing above a large, stationary service building, with access via a trap door. Relatively small building size and efficient handling of optics will make for a low cost, high performance observatory.