Optical performance of the 6.5-m off-axis new planetary telescope

We describe an off-axis design for a 6.5-m astronomical telescope optimized for law scattered light and low emissivity. This is part of a new concept for an instrument that we call the New Planetary Telescope. We shaw how the geometric optical performance can equal that of an an-axis conventional te lescope while the diffractive performance fundamentally surpasses conventio nal telescopes because of the absence of pupil obstruction. The decentered concept also allows wide-field and versatile instrumentation cofigurations that are not possible with more-conventional designs. (C) 2000 Optical Soci ety of America OCIS code: 110.6770, 350.1260, 220.4830.