Lumenoise is the latest project developed by Niklas Roy during his stay in La Gaîté Lyrique in Paris. Niklas worked on a light pen which turns any CRT-TV into an audiovisual synthesizer. It paints abstract geometric patterns and sounds directly onto the screen. It is a playful and performative device, as anything that you do will cause an instantaneous reflection in the gadget’s sonic and visual output. See more;
Unlike modern flat TV’s, old school CRT’s draw the image line by line onto their phosphorescent screen. A photo transistor, placed on a tube TV’s surface, can recognize when the part of the image is drawn underneath it. If this photo transistor is connected with a micro controller which generates the video signal, the controller can localize the exact position of the photo transistor on the screen. That’s the whole trick. This image (click here to see it) shows an animation which illustrates the process how the electron beam inside a CRT draws an image.
You can read more about the process and download everything to make one of these light pens here. The following video + screenshots show how it works: