The hackaday / make / street tech world has covered a lot of neat “persistence of vision” things lately. Basically, these involve a microcontroller that controls LEDs to light in a particular pattern such that as the device is waved around (or, in some variatinos, the shoe or bike wheel to which it’s attached moves) a perceptible image – usually text – is created. [Update: some more really cool bike-wheel PoV displays are here.]
New Scientist reports that researchers in Japan have taken this a big step further:
The display utilises an ionisation effect which occurs when a beam of laser light is focused to a point in air. The laser beam itself is invisible to the human eye but, if the intensity of the laser pulse exceeds a threshold, the air breaks down into glowing plasma that emits visible light.
The required intensity can only be achieved by very short, powerful laser pulses – each plasma dot, or “flashpoint”, lasts for only about a nanosecond. But the resulting image appears to last longer due to persistence of vision. As with film and television, the impression of a continuous image is maintained by refreshing the flashpoints.
The neat-o factor here is considerable, and there are certainly some cool human-friendly applications of something like this to be discovered. On the other hand, the article starts: “The night sky could soon be lit up with gigantic three-dimensional adverts…“. Oh, great.
(via smartmobs)
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