  This paper describes a package for analytical ray tracing of relatively
simple optical systems. AESOP (An Extensible Symbolic Optics Package) enables
analysis of the effects of small optical element misalignments or other
perturbations. (It is possible to include two or more simultaneous independent
perturbations.) Wavefront aberrations and optical path variations can be
studied as functions of the perturbation parameters. The power of this approach
lies in the fact that the results can be manipulated algebraically, allowing
determination of misalignment tolerances as well as developing physical
intuition, especially in the picometer regime of optical path length
variations.
