Optical phase measurement method and system

A measurement system for use in measuring parameters of a patterned sample, the system comprising:

• a broadband light source;
• an optical system configured as an interferometric system;
• a detection unit;
• and
• a control unit;
• wherein the interferometric system is configured to provide spectral phase retrieval, comprises a beam splitter, and defines illumination and detection channels having a sample arm and a reference arm comprising a reference reflector, and is configured for inducing an optical path difference between the sample and reference arms while maintaining a fixed distance between at least a portion of the reference reflector and the beam splitter;
• the detection unit comprises a two dimensional sensor configured and operable for detecting a combined light beam formed by a light beam reflected from said reflector and a light beam reflected from a sample as a result of an illumination of the sample with a line of light, and generating measured data that comprises spectrograph data that is indicative of spectral interference pattern formed by at least two spectral interference signatures;
• and
• said control unit is configured and operable for receiving the measured data and applying a model-based processing to the spectral interference pattern for determining one or more parameters of the pattern in the sample.