BBC Focus Magazine

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http://news.nationalgeographic.com/news ... -physical/

Scientists have figured out how "see" through opaque barriers by unscrambling what little light passes through.

The reason you can't see through thin materials such as dry paint, eggshells, paper, or skin is because any light that manages to pass through them is scattered in complicated and seemingly random ways.

(Related: "See-Through Goldfish Bred; Cuts Out Need for Dissection.")

However, it's actually possible to project light through such opaque materials and reveal objects hidden behind them, according to a new paper by scientists at the City of Paris's Industrial Physics and Chemistry Higher Educational Institution (ESPCI).

The trick is knowing exactly how materials alter light that enters them.

In experiments, the researchers shone a green laser beam at a roughly 80-micrometer-thick layer—that's 80 thousandths of a millimeter—of zinc oxide, a common ingredient in white paints. On the unseen side of the zinc layer were a series of tiny dots.