makerfaire.com:

Maker Faire Bay Area 2009
More Hidden Messages

Location: Meeting Pavilion 515

My Covert Public Message display from last year's Maker Faire is back and has a new kind of hidden message display: This year's project uses a series of LEDs to display two alternating messages, one in visible light and the other in invisible infrared light. The infrared LEDs are visible by looking at them through a digital camera (still, cell phone camera, video camera, etc). The LEDs display the messages via Persistence of Vision. The LEDs are mounted to the spokes of a bicycle wheel, spun by a fan motor (with speed control). The display is synchronized to center the messages and has Plexiglas covers to protect the viewer from moving parts.

Web site: http://jetson.googlepages.com/covertpublicmessages2

About the Maker(s)

Robert Hermes
Weekend craftsman, builder, designer and dreamer. Admires workmanship and creativity. Likes loud noises, spontaneous combustion, and anything with power. Works primarily with wood, electronics, and food. Plays well with others.
http://jetson.googlepages.com/home