User guide to TIM, a ray-tracing program for forbidden ray optics
  This user guide outlines the use of TIM, an interactive ray-tracing program with a number of special powers. TIM can be customised and embedded into internet pages, making it suitable not only for research but also for its dissemination. 
Dean Lambert, Alasdair C. Hamilton, George Constable, Harsh Snehanshu,   Sharvil Talati, Johannes Courtial
physics.ed-ph cs.GR