Meade EXT90 - Appendix F; Maksutov-Cassegrain Optical System

MAKSUTOV-CASSEGRAIN OPTICAL SYSTEM
APPENDIX F:
In the optical design of the ETX90, light enters from the
right through a multi-coated meniscus lens, proceeds to
an f/2.2 primary mirror, and then to a convex secondary
mirror that multiplies effective focal length by a factor of
6.3. The secondary mirror light bafe, in combination
with the anti-reection threads inside the primary mirror
bafe, produces extremely high contrast astronomical
images at the focal plane. The oversize 96mm-diameter
primary mirror results in a fully-illuminated (unvignetted)
eld of view signicantly wider than can be obtained
with Maksutov optics incorporating primary mirrors of
the same apertures as their correcting lenses.
OPTICAL SYSTEMS
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