Method and system for measuring one or more parameters of a patterned structure, using light source producing an input beam of at least partially coherent light in spatial and temporal domains, a detection system comprising a position sensitive detector for receiving light and generating measured data indicative thereof, an optical system configured for focusing the input light beam onto a diffraction limited spot on a sample's surface, collecting an output light returned from the illuminated spot, and imaging the collected output light onto a light sensitive surface of the position sensitive detector, where an image being indicative of coherent summation of output light portions propagating from the structure in different directions.