In 1959, Dyson first proposed that a simple concentric arrangement of a planoconvex lens and concave mirror would be free of all Seidel aberrations
at the design wavelength and center of a field imaged at 1:1 magnification .
In addition to calculations for Seidel aberrations
, MODAS offers a thorough mathematical treatment of a variety of optical characteristics--some of them aberrations, others being merely informative, and both sometimes switching roles depending on the design goals.
Features enable users to load and save their own designs, calculate chromatic and seidel aberrations
, identify limiting aperture and field stops, and work in standard and custom CCD formats.