| abstract |
There are proposed a method and a device for ascertaining the surface condition, particularly of traffic routes, as regards dryness, wetness or icing, in which the surface is irradiated by a radiation source with an infrared component, and the reflected radiation is measured simultaneously in different wavelength ranges characterizing water and ice. In this case at least four wavelength ranges are selected, permitting sufficient depth or penetration of the radiation into the surface. A first and a second wavelength range are so selected that they are influenced to a very small degree by absorption of the water molecules, and a third and fourth wavelength ranges are so selected that they are characteristic for water and ice. The influence of the background on signals measured in the third and fourth wavelength ranges is compensated for by means of the information in the signals measured in the first and second wavelength ranges. In dependence on the measured signals, therefore, a prediction can be made regarding the surface condition. |