An infinitely thin laser beam is directed into an array of unit cylinders (r=1). The cylinders are either surface mirrored or of transparent (material selectable). The angle of the primary beam (red) can be adjusted directly, or with coarse/fine increments. A secondary beam (blue), slightly offset from the primary, demonstrates the effect of small changes in initial conditions - much like chaos. As the beams intersect with the cylinders, they are either reflected or refracted. The incidence angle equals the reflected angle for a mirrored surface. A refracted beam continues at an angle given by Snell's law. If the internal angle of incidence exceeds a critical angle (the inverse sine of the ratio of indices of refraction), the beam will reflect rather than refract.