Method and system for optical characterization of patterned samples

A system for use in measurements in patterned samples, the system comprising:

• (a) an illumination unit and a light detection unit which are configured to define an illumination channel for illuminating a region of a sample with an illuminating beam and a collection channel for detecting collected light by a detector, which generates data indicative of detected light;
• (b) a polarization unit comprising at least one polarization filter located in the collection channel and configured and operable to allow passage of light of a polarization state different from polarization of the illuminating light beam to the detector for generating a measured data piece corresponding to the light detected in a measurement, and
• (c) a control unit configured and operable to receive the data indicative of the detected light from same patterned region of a sample and generating and analyzing at least first and second corresponding measured data pieces, where the first and second measured data pieces correspond to detected light of different polarization states which are different from the polarization of the illuminating light beam, and generating output indicative of a condition of symmetry of the pattern in said region of the sample.