|a. This shows how opaque white objects scatter incident light. When laser light is used, a completely unpredictable interference pattern, known as speckle, is formed. |
b. By exactly matching the wavefront of the incident light to scattering in the opaque object, the object acts as a lens that focuses light sharply.
c. Measured transmission for an unshaped wavefront. The little light that is transmitted forms a speckle pattern.
d. Measured transmission with a wavefront that inverts diffusion. Light is focused to a point that is a factor of 1000 more intense than for the unshaped wavefront.
(Credit: Ivo Vellekoop and Allard Mosk)