3 is that all of the curves in this family of conic sections have the same radius of curvature r at the origin, and thus have the same paraxial power and the same paraxial chromatic aberration. Substituting this result into eqn. This is the so-called Cartesian oval, which appears in a variety of contexts in visual optics from the prehistoric eyes of trilobites 2 to the study of human corneal topography. 20 Figure 3. Geometrical optics solution to spherical aberration of the reduced eye.
Upper figure traces a ray from object to image space.
The distance from S to paraxial focal point F is a measure of the spherical aberration of the model in image space. Lower figure traces a ray from image to object space. The distance from O to T is a measure of the spherical aberration of the model in object space. Figure 3 illustrates the geometrical optics solution to the problem of quantifying the degree of spherical aberration in the Indiana Eye. To find the distance A S we apply Snell's law to an incident ray parallel to the z-axis.