Optical phase measurement system and method

A system for use in measurements on patterned structures, the system comprising an optical measurement device comprising:

• an illumination unit configured and operable for focusing light onto an illuminating spot on a structure at least partially covering at least two different regions of the structure to thereby cause light reflections from said at least two different regions;
• and
• a light detection unit collecting light including the light reflections of said at least part of the at least two different regions, the collected light therefore comprising an interference pattern formed by interference of at least two complex electric fields reflected from said at least two different regions, and being therefore indicative of a phase response of the structure, carrying information about properties of the structure.