Light can be a “material” too
Light: For a very, very long time, the Sun was the only relevant light source on this planet. Until about 300,000 years ago, when prehistoric humans discovered fire as a source of heat and light. But it wasn’t until 1879 that Edison’s incandescent lamp marked the beginning of electric lighting. Candles and petroleum lamps were still in daily use in Europe up until the 20th century. In research settings, light as a non-substantial material is used for a wide variety of purposes. German researchers, for instance, supply micro-algae with lots of light from which the plankton cells generate energy by means of photosynthesis. In return, the algae provide valuable ingredients for cosmetics, pharmaceuticals, and foods. Once all the valuable substances have been used up the residual biomass is processed into biogas. Light as a material has a wide range of applications. For instance, the nuisance of having to fill one’s mouth with an unpleasant paste to obtain dental impressions might end soon. A novel scanner developed in Jena at the Fraunhofer Institute for Applied Optics and Precision Engineering can measure the shape of a set of teeth with accuracy down to a few micrometers. To do so, the scanner projects extremely delicate light strips onto the tooth surface. The strips place themselves exactly over the enamel and measure the tooth contours. With these data, a machine can precisely mill dental prostheses. Other applications for efficiently using light as a material via novel solar cells are being investigated at the Fraunhofer Institute for Solar Energy Systems in Freiburg. In the case of organic solar cells, for instance, flexible semiconductor material replaces the stiff silicon plates of conventional modules. Soft cells like these can be sewn into jackets and pants to generate electricity on the go. The researchers have applied pigments to other photovoltaic components. Installed on windows, they supply electricity and at the same time provide sun protection.