A new experiment conducted by researchers at the City of Paris Industrial Physics and Chemistry Higher Educational Institution (ESPCI) has shown that it’s possible to focus light through opaque materials and detect objects hidden behind them, provided you know enough about the material.

They produced a numerical model called a transmission matrix, which includes over 65,000 numbers describing the way that a material scatters light in a layer of material. 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.