Fog can play a key role in cloaking military invasions and the actions of intruders. Physical security experts seek to overcome it but it can be difficult to field test security cameras, sensors, or other equipment in fog that is often too thick. Researchers at Sandia National Laboratories have developed a controlled fog chamber in a tunnel owned by the Air Force Research Laboratory. The researchers say the chamber will help develop and validate cameras’ and sensors’ abilities to penetrate fog, knowledge that could lead to improved surveillance at sites. The chamber also could be used to answer fundamental optics questions, which in time could lead to improved security camera lenses and medical imaging equipment, safer aircraft landings, and better vision for drivers in fog.
The Sandia researchers used cloud microphysics to generate fog for video analytics and environmental testing. In the atmosphere, fog forms from a seed particle, such as pollen or sea salt, surrounded by layers of water. Seed particles differ based on the fog’s location. By consulting journals or traveling to a region, the researchers can measure the droplet size distribution and chemical composition of different fogs worldwide and then alter the seed particles to customize the fog. The longer the fog’s seed particles hold onto the water layer, the longer they are visible for testing. The length of the test depends on the relative humidity in the chamber.