A way has been found to transmit simple images through opaque objects using ordinary light. Researchers have used the method to project an image through glass covered in thick paint. Some things we consider opaque, actually allow a small amount of light through, but it is scattered so much as it bounces around inside the opaque material's lattice of atoms that it was considered beyond practical use for transmitting an image. By reverse engineering the scattering process, physicists transmitted a simple image through a painted slide & reconstructed it on the far side. They worked out the slide's transmission matrix (how light bounces around inside it) by hitting it with a laser beam more than 1000 times, changing the shape of the beam each time & recording the different light patterns that made it through to a digital camera beyond. They then used the information to decode an image sent through the slide. "Once the matrix is known, reconstructing the image is very quick," said Sylvian Gigan of the Ecole Superieure de Physique et de Chimie Industrielles in Paris.
