Decoration to Demonstration: A New Point Source for 3D Ray Tracing

Possibly the greatest irony of physics education is the difficulty of demonstrating optics in a visible way. The two most common solutions to this conundrum are to either use "all-inclusive"optical apparatuses, like a large- format camera, or to rely on classic ray-tracing diagrams. While the former looks elegant while demonstrating the inverted nature of its images at the front of a classroom, its inner workings and method of inverting remain mysterious. The mechanics of the latter are more evident but are limited to two dimensions and the willingness of students to accept the drawing as fact. More advanced solutions include computer modeling of 3D optics or benchtop ray-tracing demonstrations, but between these the demonstrator effectively trades a third dimension for verisimilitude. A more encompassing solution would be a means to trace rays in three dimensions through a variety of optical devices. Previously, the rub has been identifying a viable point source of rays for classroom demonstrations. In this paper, we present such a source and several sequences of demonstrations utilizing it. © 2021 American Association of Physics Teachers.