Software

Aberrator
Freeware, Version 3.0, that generates star-testing images to show the effects of distortions influencing the quality of a telescope's performance.
http://aberrator.astronomy.net/

ATM Optical Design and Analysis Software
Freeware, Version 7.4, program for designing and analyzing telescope configurations.
http://www.atmos-software.it/

Cell
Public domain mirror cell design program for 9, 18, and 27 point flotation cells.
http://www.davidchandler.com/cell.htm

Java Based Optical Design and Analysis Software
Based on telescope design program MODAS, can design and analyze one mirror and classical two or three mirror telescopes, one mirror catadioptric systems, two mirror catadioptric systems, doublets and triplets, and includes applets.
http://members.kabsi.at/i.krastev/jodas/

Modern Optical Design and Analysis Software
Powerful optical design library, and showing features, slide show, download, and register areas.
http://members.kabsi.at/i.krastev/modas/

StarTrak - Making Setting Circles
Software to plot setting circles for altazimuth mounts (eg Dobsonians) and equatorial mounts.
http://www.startrak.co.uk/MakingSettingCircles.htm