MiniOFS is designed by Dr. Sten L�¶fving is used to make direct measurements of visual range. The sensor is sensitive for particles in a zone about 25 cm ahead of the location of the sensor who limit the visibility in the air. These particles are normally the microscopic water particles constituting fog, but they may also be snowflakes, raindrops or air pollutants. But the most indications of low visibility are because of fog or snow. The MiniOFS is probably the cheapest visibility sensor on the market. It is well known that fog causes many accidents in road traffic and elsewhere. You can read about how MiniOFS can reduce serial collisions in fog.