The structure of the program is divided into two tasks. The first program, PUPIL, generates a beginning pupil function. Typically, this pupil function file is calculated to represent a focused and unobstructed telescope. It also possesses a standard aberration value, such as 1 wavelength RMS. This file is then fed to the diffraction pattern program ASYMM. One applies additional obstruction and defocusing on the pupil function and an aberration multiplier as well. ASYMM then generates the image intensity file.
Because ASYMM was designed to do the tedious direct integration of Eq. B.3, it was written with a 32-bit FORTRAN optimizing compiler and uses a DOS extender during execution. It runs in 9.6 hours on a 25 MHz 386/7 and 2.3 hours on a 486DX50.4
The modulation transfer function is calculated from the pupil function file using a separate routine named MTF. It generates a file with the OTF's of the three bar directions in sequence. The MTF is readily derived from these complex values.
The longitudinal slice patterns through focus are calculated with a variation of ASYMM.
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