Patent ID: 7834991

Claim:
An apparatus for determining surface properties, comprising: at least a first radiation device which emits radiation onto a surface to be analyzed; at least a first radiation detector device which receives at least part of the radiation emitted by the at least one radiation device and then scattered by the surface and outputs at least a first measurement signal which is characteristic of the scattered radiation; at least one second radiation detector device which receives at least part of the radiation emitted by the at least one radiation device and then scattered by the surface and outputs at least a second measurement signal which is characteristic of the scattered radiation; an absorption device for absorbing the radiation reflected by the surface; and a processor device that takes into account the position of the apparatus with respect to the surface from a relation between the first measurement signal and the second measurement signal, wherein the first radiation detector device is offset by a first predefined angle β1 with respect to the direction of the radiation reflected by the surface, the second radiation detector device is offset by a further predefined angle β2 with respect to the direction of the radiation reflected by the surface, the angles β1 and β2 are essentially equal and opposite to one another with respect to the direction of the radiation reflected by the surface, and both the radiation device and the first radiation detector device and the second radiation detector device are all arranged in the same plane of an observed beam path, and wherein the absorption device is arranged at the reflection angle of the reflected radiation with respect to the surface.