SOFIA Telescope
The SOFIA telescope is designed using two types of mirrors, a
parabolic 2.7m primary, and a hyperbolic secondary in a bent Cassegrain
configuration.
The secondary mirror of the SOFIA is attached to a chopping mechanism
which provides chop amplitudes of up to plus or minus 5 arc minutes at chop
frequencies between 0 and 20 Hz. Its programmable by either a user supplied
analogue or TTL curve or by the telescope control electronics.
An IR beam is reflected into the infrared Nasmyth focus from a flat
tertiary mirror, 300mm behind the instrument flange. The transmitted optical
light is reflected by a secondary tertiary, when the fully reflecting
tertiary is replaced with a dichroic mirror. There it is sent into the Focal
Plane Imager of the SOFIA, an optical focal plane guiding camera system.
Attached to the front ring of the telescope are two other imaging and
guiding cameras the Wide Field Imager and the Fine Field Imager.
