Researchers at the City of Paris Industrial Physics and Chemistry Higher Educational Institution (ESPCI) have shown that opaque substances can actually be viewed through, and can be made to perform like optical lenses, using laser light and a bit of mathematics. The technology may allow viewing of cells and other biological components through tissue that would otherwise shield them.
In order to demonstrate their approach to characterize opaque substances, the researchers first passed light through a layer of zinc oxide, which is a common component of white paints. By studying the way the light beam changed as it encountered the material, they were able to produce a numerical model called a transmission matrix, which included over 65,000 numbers describing the way that the zinc oxide layer affected light. They could then use the matrix to tailor a beam of light specifically to pass through the layer and focus on the other side. Alternatively, they could measure light emerging from the opaque material, and use the matrix to assemble of an image of an object behind it.
In effect, the experiment shows that an opaque material could serve as a high quality optical element comparable to a conventional lens, once a sufficiently detailed transmission matrix is constructed.
Abstract in Physical Review Letters: Measuring the Transmission Matrix in Optics: An Approach to the Study and Control of Light Propagation in Disordered Media
Viewpoint in APS Physics: The information age in optics: Measuring the transmission matrix
More: Physicsists find a way to see through paint, paper, and other opaque materials …