We describe here an off-axis design for a 4.0-m astronomical telescope. We show that the geometric optical performance of this configuration can equal that of an on-axis conventional configuration while the diffractive performance fundamentally surpasses conventional telescopes because of the absence of pupil obstruction. The specific optical design described here uses a single off-axis primary mirror to obtain three distinct final focus ports: an <i>f</i>/10 port (with corrector) for wide-field imaging and spectroscopy with a field of view (FOV) of 15 arc min; a small-field, 2-reflection <i>f</i>/10 port suitable for polarimetry and coronagraphy; and a slower, <i>f</i>/16(3-reflection) port with a 7 arc min FOV. For general astronomical observations requiring high optical throughput and low scattered light, this design is superior to conventional Ritchey–Chretien optical configurations.
© 1998 Optical Society of America
(120.1680) Instrumentation, measurement, and metrology : Collimation
(120.3620) Instrumentation, measurement, and metrology : Lens system design
(120.4570) Instrumentation, measurement, and metrology : Optical design of instruments
(120.4640) Instrumentation, measurement, and metrology : Optical instruments
Gilberto Moretto and Jeff R. Kuhn, "Off-Axis Systems for 4-M Class Telescopes," Appl. Opt. 37, 3539-3546 (1998)