Surface Apertures

Surface apertures include circular, rectangular, elliptical, and spider shaped apertures which can vignette rays. There are also user defined shapes for surface apertures and obscurations; and a "floating" aperture that is based upon the current clear semi-diameter or semi-diameter value. Surface apertures do not affect ray launching or tracing, except for the termination of a ray if it does not pass the surface aperture. Surface apertures have no effect on the system aperture.

For more information, see the Aperture section of the Surface Properties