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optical design - ritchey-chretien max reason

ritchey-chretien optical system
This page describes a 10" f/6 ritchey-chretien optical system.

Most large observatory telescopes have ritchey-chretien optical systems.  The primary advantage of this optical configuration is a complete lack of coma.  To reliably determine the position of an image can be very difficult in images with significant coma.  Therefore, even though ritchey-chretien optical systems have significant astigmatism at moderate field-angles, the positions of stars, asteroids and other objects can be more accurately determined.  Flat-field ritchey-chretiens are easy to design, but they unavoidably have large secondary mirrors and central obstructions.  The focal surface of the design on this page is curved to give best performance.  Field flatteners can flatten the field with minor introduction of other aberrations.

The primary mirror is a weak hyperbola, while the secondary mirror is a moderately strong hyperbola.

-----   design specifications   -----

ritchey_data.gif (13583 bytes)

-----   design layout   -----

ritchey_design.gif (9453 bytes)

-----   image quality   -----
               spot image                                        wavefront-interference image

ritchey_spots.gif (8479 bytes) ritchey_waves.jpg (35389 bytes)

-----   aberrations   -----

ritchey_aberrations.gif (15236 bytes)

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