HANDHELD SUNBEAM

Popular Science, Feb 2008 by Mone, Gregory

YOU BUILT WHAT?!

A hacked-together flashlight that can shine for miles

RALF OTTOW was standing in front of his bathroom mirror one morning when he noticed that his forehead was sunburned. He hadn't been out tanning - his homemade flashlight had fried his skin.

The 45-year-old Dutch optics engineer has been building his own lights since he was eight but his recent 38-million-candlepower creation, the Maxablaster, is more like a miniature star. To start, Ottow stripped out the innards of a powerful commercial flashlight and switched in a mercury arc bulb, which generates light by creating an ultra-hot plasma between two closely spaced electrodes inside the gas-filled central chamber of the lamp. That results in a brighter, more focused beam but also kicks more untraviolet light (hence the sunburn, a product of early testing). So he added a specially coated reflector and designed, ground, and coated a new glass window that would trap UV rays while still pumping out light.

Powered by a pack of 54 batteries, the Maxablaster can put a bright spot of light on a cloud four miles high and illuminate a house from just as far. But Ottow doesn't use it to spook his neighbors. "It's not a torch you'd walk your dog with," he says. "It would probably cook your dog."-GREGORY MONE