The classic Cassegrain telescope has a parabolic primary mirror and a hyperbolic secondary mirror

Gallery
Tutorial
TRAIL: Webel SysML Parsing Analysis example: Optical telescopes from Wikipedia: Structure and port-based light flow model
Section
Topic level
INTERMEDIATE
UML keywords
Generalization
Property::redefinedProperty
Property::subsettedProperty
SysML keywords
Block
Keywords
Slide kind
SysML Block Definition Diagram (BDD)
The target snippet are:
Wikipedia: 'The cassegrain telescope (sometimes called the "Classic Cassegrain") ... has a parabolic primary mirror, and a hyperbolic secondary mirror that reflects the light back down through a hole in the primary.'
Wikipedia: 'The Ritchey–Chrétien telescope ... is a specialized Cassegrain reflector which has two hyperbolic mirrors (instead of a parabolic primary).'
Click on the image to view it full size
The diagram also includes an embedded captioned figure:
Wikipedia: 'Light path in a Cassegrain telescope.'
Image author: Krishnavedala; Copyright licence: Creative Commons CC BY-SA 4.0

Any CassegrainReflector is characterised by having a ConvexHyperbolicMirror as its secondary.

(Inadvertently, the model has ended up so far with a convention that only convex variants of mirrors have 'Convex' explicitly prefixed in the name.)

The ClassicCassegrainReflector has a concave HoledParabolicMirror as its primary.

A RitcheyChrétienReflector has a concave HoledHyperbolicMirror as its primary. We are told also:

Wikipedia: 'It is free of coma and spherical aberration at a nearly flat focal plane if the primary and secondary curvature are properly figured.'

It is beyond the scope of this trail to model coma and spherical aberration in detail, but they can be represented for now by the ValueTypes ComaMeasure and SphericalAberrationMeasure, used to type value properties in any OpticalTelescope.

Up next
Comparison of reflecting telescopes so far
Notes
[CAPABILITY, FEATURE, TOOL]{INFORMATIVE} MagicDraw/Cameo supports embedding images in diagrams
[DISPLAY, STYLE, TIP]{SUGGESTED} Webel Parsing Analysis: If the dashed-line "anchors" from your «snippet» ElementGroup symbols to elicited elements make a «pa» Parsing Analysis Diagram (PAD) too hard to read, try making them light grey using symbol properties.
[POLICY, STYLE]{STRICT} Webel «pa» Parsing Analysis Diagrams (PADs) are "scratchpads" used to elicit model elements traceably from text Snippets (extracts from source Documents). While BDDs are a good initial choice, most types of SysML diagram can be used as a «pa» diagram.
[POLICY, STYLE]{STRICT} Webel Parsing Analysis «pa» diagrams are NOT intended as final presentation diagrams! They serve merely to traceably elicit model elements, which may then be shown in other (typically much tidier) presentation diagrams elsewhere.
Snippets (quotes/extracts)
 The cassegrain telescope (sometimes called the "Classic Cassegrain") ... has a parabolic primary mirror, and a hyperbolic secondary mirror that reflects the light back down through a hole in the primary.
 The Ritchey–Chrétien telescope ... is a specialized Cassegrain reflector which has two hyperbolic mirrors (instead of a parabolic primary).
 It is free of coma and spherical aberration at a nearly flat focal plane if the primary and secondary curvature are properly figured.
 Light path in a Cassegrain telescope.
Visit also
Visit also (backlinks)
Related slides (includes other tutorials)
Related slides (backlinks, includes other tutorials)