Process for determining the surface state of highways in particular, and device for carrying out this process
First Claim
1. A method as ascertaining the surface condition, particularly of traffic routes, with a view to dryness, wetness or icing, in which the surface is irradiated by a radiation source with an infrared component, and the reflected radiation is simultaneously measured in different wavelength ranges characterising water and ice, information on the surface condition being obtained in dependence on the measured signals, wherein the reflected radiation is simultaneously measured selectively in at least four wavelength ranges lying in the area between 800 and 1250 nm, a first and a second wavelength range being so selected that they are influenced to only a small degree by an absorption of the water molecules, independently of the state of aggregation, and a third and fourth wavelength are selected so that they are characteristic for water and ice, and in that an influence of the background, caused by the depth of penetration, on the 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.
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Accused Products
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.
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Citations
9 Claims
- 1. A method as ascertaining the surface condition, particularly of traffic routes, with a view to dryness, wetness or icing, in which the surface is irradiated by a radiation source with an infrared component, and the reflected radiation is simultaneously measured in different wavelength ranges characterising water and ice, information on the surface condition being obtained in dependence on the measured signals, wherein the reflected radiation is simultaneously measured selectively in at least four wavelength ranges lying in the area between 800 and 1250 nm, a first and a second wavelength range being so selected that they are influenced to only a small degree by an absorption of the water molecules, independently of the state of aggregation, and a third and fourth wavelength are selected so that they are characteristic for water and ice, and in that an influence of the background, caused by the depth of penetration, on the 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.
- 5. A device of ascertaining the surface condition, particularly of traffic routes, as regards dryness, wetness or icing, with a radiation source with an infrared component for irradiating the surface, an optical condenser system in the beam path in front of the surface to be tested, an optical arrangement collecting the reflected component of the electromagnetic radiation, and a wavelength-selective receiver arrangement, which receives the reflected radiation in accordance with a plurality of wavelength ranges, and an evaluation unit for evaluating the wavelength-selective signals, wherein the receiver arrangement is provided for reception of radiation in four wavelength ranges in a field between 800 and 1250 nm, a first and second wavelength range being so selected that they are influenced to only a small degree by absorption of the water molecules, independently of the state of aggregation, and a third and fourth wavelength range are so selected that they are characteristic for water and ice, and in that the evaluation device is provided in order to compensate for an influence of the background of the signals measured in the third and fourth wavelength ranges by means of the information from the signals measured in the first and second wavelength ranges.
Specification