James Brown's Rapidly-Spinning 3D Display Is Driven by a "Somewhat Dizzy" Raspberry Pi
With 3D-printed collimators and a motor, 2D LED matrices are transformed into a glasses-free 3D display — just keep your fingers clear.
Maker James Brown's latest project is an attempt to 3D-print lenticular lenses and collimators with which to produce a rapidly-spinning three-dimensional display from two-dimensional LED panels — with surprising success.
"This is the current approach for reducing the horizontal field of view of the screens — a big heavy box o' slats," Brown writes of the initial prototype. "I'd like to make a lenticular array, but that's a whole side quest. The black filament is surprisingly shiny. My first attempt turned out to be a light pipe, and didn't restrict the view. In this version, the slats have a zigzag profile."
The idea is simple enough: the 3D-printed slats sit over the top of a 2D LED array, which is fed an image as it spins around a circle — combining horizontal view restrictions with a persistence of vision (POV) effect which allows the viewer to perceive depth despite the use of a 2D LED matrix.
Finding the 3D-printed collimators "a pain," Brown's second prototype used a 3D-printed mold to cast lenticular lenses from silicone. "I got a lens out of it in the end," Brown writes. "It does make it more directional, but there’s more light off axis than I need."
The third prototype, though, returned to the slat collimator design — and with an increase in speed, the depth effect is easily visible. In short videos shared to Mastodon, Brown shows the camera rotating around the rapidly-spinning display — and peering to look round the sides of a 3D dinosaur head and a wireframe cube.
"The depth is smeared more than I want because the collimators are too shallow (because I don't like prints that take more than 16 hours to complete)," Brown explains. "I want to make them tighter, and spin the whole thing faster to compensate. The nice thing about these LED panels is that they're very high framerate (and cheap!). I'm updating these at 1.5kHz — with three of them in a ring, that's 4.5kHz. Just driven in software from a (somewhat dizzy) Raspberry Pi."
More information on the project, work on which is ongoing, is available in Brown's Mastodon thread.