The present invention provides an apparatus for inspection of a surface, including irradiating optics which are adapted to irradiate the surface with an irradiating beam having an adjustable polarization. The apparatus further includes at least one detector, each detector being associated with a respective analyzer having an orientation and adapted to generate signals in response to light received via the analyzer from an irradiated area on the surface, one of the at least one detector being adapted to receive scattered light from the irradiated area. The apparatus also includes a controller which is adapted to direct the irradiating optics to irradiate the irradiated area and which, in response to calibration signals generated thereby at the at least one detector, is adapted to set the adjustable polarization and the orientation of the respective analyzer of each detector.