What is an oblate ellipsoid mentioned in the Surface Types chapter under the Standard surface?
In geometry, it is a surface of revolution formed by rotating an ellipse about its minor axis, producing a squashed spheroid with the locus of foci forming a circle. In ZEMAX it is a rotationally symmetric surface described by the standard surface sag equation with a conic constant greater than 0. Spheres, hyperbolas, parabolas, and ellipses are used more commonly; all defined by conic constants less than or equal to zero.
