Abstract: This invention provides an apparatus and method for characterization of thin film structures. More particularly, the present invention provides methods and devices for fast and accurate identification of optical constants, thickness, interface roughness and stresses of a sensing film structures by spectropolarimetric imaging technique. This invention also provides the method for active in-line manufacturing diagnostics and process control. The invention is broadly applicable with most important applications being manufacturing diagnostics, process control, quality control and characterization of solar cells, flat panel displays and semiconductor structures.