In addition to being the secret sauce for Google Glass, here's another interesting implementation of optical prisms that's decidedly low-tech. The NeoLucida is a Kickstarter project created by two professors from the School of Art Institute of Chicago and Carnegie Mellon University. It's a modern take on the camera lucida, an 1800's technology composed of a prism on an adjustable stand, used to assist artists in drawing. Its principle is simple: a subject sits in front of the artist and camera lucida, and an optical image of the subject is reflected onto a drawing surface for the artist to trace over. The NeoLucida's innovation lies in its use of modern materials for its adjustable stand (a gooseneck arm), and low cost. Antique camera lucidas cost around $300 on eBay; the NeoLucida started at $30. Watch the video below to get a sense of how it works.
The NeoLucida's Kickstarter is completed (and was wildly successful), but its makers plan for a wide commercial release in early 2014. Expect an influx of inked portrait tote bags to hit Etsy around then.