Magazine article Science News

Newton's Dusty Mirror: Old Experiment Inspires Ultrafast Imaging

Magazine article Science News

Newton's Dusty Mirror: Old Experiment Inspires Ultrafast Imaging

Article excerpt

Occasionally, science museums can stimulate new science. Inspired by an exhibit on an optical experiment performed by Isaac Newton, physicists have taken the first X-ray snapshot of a microscopic explosion.

Physicists Henry Chapman and Sasa Bajt took their daughter to the Chabot Space and Science Center in Oakland, Calif., in 2005. There, they saw a replica of an experiment in which Newton had sent abeam of light through a hole in a screen. The beam reflected off a mirror and back onto the screen--where Newton was surprised to see concentric rings of light.

Scientists later determined that the rings were due to microscopic specks of dust. Light bounced off each dust grain twice, on its way to the reflective surface and on the way back. Interference between those two sources of scattered light, as crests and troughs of their waves either reinforced or canceled each other, created the rings.

Chapman and Bajt, both of Lawrence Livermore (Calif.) National Laboratory, realized that they could set up a similar experiment at FLASH, a laser facility in Hamburg, Germany. FLASH is the first free-electron laser to operate in the extreme ultraviolet, or soft-X-ray, part of the spectrum. Free-electron lasers use bursts of electrons to create pulses of laser light lasting only femtoseeonds, or millionths of a billionth of a second. These devices could in a few years create high-energy, or hard, X rays that have wavelengths small enough to resolve single atoms. …

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