Patent ID: 7342661
Filing Date: 2008-03-11
Classification: G01J,G01N

Abstract:
1. An ellipsometer for evaluating a sample comprising: a light source for generating a probe beam which is directed to interact with the sample; a detector for measuring the intensity of the probe beam after interaction with the sample and generating output signals in response thereto; an optical element located in the path of the probe beam and being one of a polarizer or a retarder, said optical element being rotatable through 360 degrees about the propagation axis of the probe beam; and a processor for analyzing the output signals as a function of the rotational position of the optical element, said processor for extracting a first DC component from the output signals obtained during the first 180 degrees of rotation of the optical element and a second DC component from the output signals obtained during the second 180 degrees of rotation of the optical element, said processor using the first DC component to normalize the output signals obtained during the first 180 degrees of rotation of the optical element and using the second DC component to normalize the output signals obtained during the second 180 degrees of rotation of the optical element.