APPARATUS FOR STUDYING SURFACE PROPERTIES OF A TESTPIECE BY MEANS OF ELECTROMAGNETIC RADIATION

摘要

In a method and apparatus for studying surface properties of a testpiece, such as refractive index or thickness of a layer or film on said surface, electromagnetic radiation is directed on to the test surface or a reference surface which has known properties, and reflected on to the other surface. The angle of incidence in respect of the incident radiation, in relation to the respective surfaces, are the same, and the surfaces are so arranged that when the radiation is reflected from one surface on to the other, the parallel polarization component of the first reflection is the perpendicular component of the second reflection. Radiation in the same state of polarization as before the first reflection is extinguished by an analyzer, providing for point-to-point comparison between the two surfaces.