ABSTRACT
This chapter intends to provide the tools necessary to determine the ideal localization, size and orientation of the image formed by an optical system. It reviews several paraxial ray tracing methods. The paraxial optics version of every optical system represents its behavior as a Perfect Optical System. Such "perfect" systems constitute both the first step in the optical design process and the target that the real optical system seeks to reach as the optimization process progresses. Optical engineers have developed powerful ray tracing methods to analyze complex optical systems in order to determine their basic first-order properties and to evaluate the aberrations present in the system. Rays propagate in rectilinear fashion through homogeneous isotropic media, changing their height from one reference plane to another but keeping their propagation angle. Matrix methods can also be used to determine which surface actually acts as the aperture stop within a diaphragm-free optical system.
