Apparatus and method for the detection of condensation on a measurement surface

Device for detecting condensation on a measurement surface comprises: a sensor element (101) that generates an output signal that is proportional to the condensation; an evaluation circuit to which the output signal is fed and which detects the onset of condensation formation; and compensation means forming part of the evaluation circuit which are used to determine a background signal from a sensor signal when there is no condensation on the windscreen, said background signal being used to compensate the sensor signal under operating conditions. Independent claims are also included for the following:- (a) an evaluation device; (b) and a method for detecting condensation of a measurement surface.