User guide to TIM, a ray-tracing program for forbidden ray optics

TIM is a ray-tracing program that can model very general light-ray-direction changes, so general, in fact, that they can lead to physically impossible light-ray fields [1]. We wrote TIM as a tool for our research on windows that perform precisely those light-ray-direction changes. They can do this by compromising other aspects of the light field, but this compromise can be unnoticeably small. We call such components METATOYs [1, 2]. The name TIM started off as an acronym for The Interactive METATOY, but is now beginning to morph into the name of the head with the luscious lips that appears when TIM starts up (Fig. 1). We built a number of other special features into TIM. These include the abilities to