Dr Dennis Crabtree (DAO, Canada)

Canadian Very Large Optical Telescope Studies - Dr Dennis Crabtree Colloquium

ATNF Marsfield Lecture Theatre

Abstract

As part of our Long Range Plan for Astronomy, Canada has started
studies of a Very Large Optical Telescope (VLOT). The goal is to have the
telescope operational by early in the next decade to complement the science
discoveries of the NGST and ALMA. This design is suitable for location on
the Mauna Kea summit ridge, and could replace the current 3.6 m CFHT
telescope. The telescope structure provides room for two vertically oriented
Nasmyth instruments, implements a very stiff monocoque mirror cell, and
offers a short and direct load path to the telescope mount. A Calotte style
dome structure offers many advantages over current designs including lower
and more even power requirements, and a circular aperture that will better
protect the telescope structure from wind buffeting. The science
requirements are presented, and the telescope optical design, primary mirror
pupil segmentation options, including hexagonal segments and a radial
segment design with a central 8 m mirror, are considered. Point spread
function plots and encircled energy calculations show that there is no
significant diffraction performance difference between the options except
that hexagonal segments in the 1 m point-to-point range appear to deliver
poorer PSF's as compared to 2 m and larger segments. Plans for
implementation of a Matlab based integrated telescope model are discussed.