Pupil Aberration

Shows entrance pupil distortion as a function of pupil coordinate.

The options are identical to those for ray aberration fans, except the only option for "Tangential" and "Sagittal" is pupil aberration, since pupil aberration is a scalar quantity. The "Surface" only allows "Image" because this data is always computed at the stop surface.

Discussion Entrance pupil aberration is defined as the difference between the real ray intercept on the stop surface and the on axis primary wavelength paraxial ray intercept as a percentage of the paraxial stop radius. If the maximum aberration exceeds a few percent, ray aiming (see "Ray Aiming") may be required to get the rays in object space to correctly fill the stop surface. If ray aiming is switched on, the entrance pupil aberration will appear to be zero (or a very small residual value), because the distortion is accounted for by the ray tracing algorithm. This is used as a check that ray aiming is working correctly. The definition used here for pupil aberration is not intended to be complete or in agreement with other definitions. The sole purpose of this feature is to provide guidance as to whether or not ray aiming is required.

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• Field Curvature and Distortion