Patent ID: 8531678

Claim:
A measurement system for measuring in a patterned structure having a periodic pattern, the system comprising: an illumination assembly comprising a light source directing incident substantially unpolarized light of substantially broad wavelengths band onto the structure in a plane of incidence, a collection-detection assembly comprising a detector for detecting light returned from the structure and generating measured data representative thereof, and a controlled polarizer located in an optical path of the light returned from the structure and propagating towards the detector, thereby providing detected light having certain selected polarization state relative to the plane of incidence, so that the detector provides an output corresponding to the detected light of said certain selected polarization state, said measured data being indicative of said output of the detector; a control unit configured and operable to be responsive to the generated measured data for analyzing the measured data corresponding to said selected polarization state of the detected light, and deriving one or more parameters of the patterned structure from said output of the detector.