Eye-safe laser radar for the detection of fog banks

The concept of a lidar is the optical synonym of the well known radar. It describes an optical remote sensing technique for the detection of the atmospheric parameters like the optical density, etc. The name lidar originates, analogous to radar, from the first application of this technology, the determination of the distance to large solid bodies (laser range finder). The evolution of the lidar technique reaches from the measurement of the distance to diffuse targets, for example clouds (cloud ceilometer), to the determination of the range resolved turbidity of the atmosphere (visibility sensor). The modern lidar systems have been reduced so far, that they can be built into a van or even a car. The problem of the eye-safety of the laser radiation has been solved by using low power laser diodes, but with a high repetition rate. The first results with a modified laser range finder, manufactured by Jenoptik GmbH, will be reported. This device, at the size of binoculars, promises to be a first approach for a handheld visibility sensor, measuring local turbidities, like fog banks.