Via Gizmag, two Fraunhofer Institutes have teamed up to develop a clever and simple way of treating window glass to make it sensitive to motion and, thus, perfect for security purposes. The combination hardware-software system is able to discriminate between expected motion, i.e., a passing car, and suspicious movement that would warrant an alarm. The base of the system is a special coating applied to the glass:
“The glass is coated with a fluorescent material,” explains IAP group manager Dr. Burkhard Elling. “The coating contains nanoparticles that convert light into fluorescent radiation.”
The “light” in this case would actually be the invisible light of a UV lamp(s). Although other light sources could trigger the same reaction, UV presents a less obvious and intrusive approach. At least one sensor tuned to fluorescent light would also positioned on an edge of the glass. In the normal state, the UV is constant shines on the glass and the sensor continuously reads a steady level of fluorescent radiation. However, if something passes between the lamp and the window glass, the sensor detects a drop in the fluorescent level and triggers an alert. So what happens if light from another source shines on the window (e.g., someone turns on a lamp or light from a passing car illuminates the glass) or a small animal passes near? This is where the software comes in. First, the sensitivity of the system could be tuned to ignore small objects such as a bird or pet animal. Second, the software can distinguish between UV-generated radiation and that which comes from other sources. If several sensors are installed, things can get even more interesting. The software can then start drawing conclusions about the incidental light, or the size, speed and direction of something approaching the window. Fraunhofer researchers are still working to optimize the coating, but they already know that it could be applied either by a spray (during manufacturing or as an aftermarket add-on) or by rolling on a film. Fraunhofer’s Applied Polymer Research IAP (Potsdam-Golm, Germany) and Computer Architecture and Software Technology FIRST (Berlin) institutes are behind these innovations.