Cheap Projector Uses Prisms to Create Color Images from B&W
Source: Andrew Liszewski

Before LEDs and lasers came along, video projectors would shine white light through a rotating color wheel to produce full-color images. But researchers at Dartmouth College and Disney Research Zürich have come up with a more unusual projection approach using prisms and very precise computer-generated black and white images.

What’s most remarkable about this unique setup isn’t that all the components cost less than $30; it’s that there are no visible colors involved until the final projection appears. That’s remarkable unless you’re the type who always points out that white light is technically all colors combined. You’d be right, and kind of an annoying know-it-all, but that’s the key to how this projection system works.



A full-color source image is passed through a custom algorithm developed by the researchers which generates two unique black and white images that are used as masks on either side of a prism. The first mask, full of tiny slits, sits in front of the prism and produces thousands of tiny “pixel” rainbows as light passes through both of them. The second black and white mask sits behind the prism and serves to block the colors of the raindow not required to reconstruct the full-color image being projected.

The results, at least in their current form, are nowhere near as sharp, vibrant, or crisp as what you’d get from a more conventional digital projector. But there’s some exciting potential here when it comes to both miniaturizing and making projectors simpler and more affordable. One day the flash on the back of your smartphone might double as a surprisingly decent projector if this research pans out.