초록 ▼

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. T

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.

대표청구항 ▼

In a method of studying physical properties of a testpiece surface to obtain a direct point-to-point comparison between the testpiece surface and a reference surface having known properties, said method comprising the steps of: (a) transmitting electromagnetic radiation toward the testpiece surface

In a method of studying physical properties of a testpiece surface to obtain a direct point-to-point comparison between the testpiece surface and a reference surface having known properties, said method comprising the steps of: (a) transmitting electromagnetic radiation toward the testpiece surface to be studied; (b) polarizing said electromagnetic radiation prior to its reaching said testpiece surface to produce polarized radiation; (c) reflecting said polarized electromagnetic radiation from said testpiece surface so as to produce polarized reflected radiation; and (d) analyzing said polarized reflected radiation so as to extinguish said polarized reflected radiation; the improvement comprising the additional reflecting step, between steps (b) and (d), of additionally reflecting said polarized radiation at said reference surface having known surface properties, thereby providing further polarization; wherein said reflecting step (c) and said additional reflecting step comprises reflecting at the same angle of incidence; wherein said reflecting step (c) and said additional reflecting step are accomplished by respective reflecting surfaces, and wherein the radiation reflected at one of said respective reflecting surfaces has a polarization component which, being parallel to the plane of incidence at said one surface, is perpendicular to the plane of incidence at the other of said respective reflecting surfaces; wherein said additional reflecting step enables said direct point-to-point comparison between the reference surface and the testpiece surface to be made, while at the same time providing phase-shift compensation, by means of said further polarization; and wherein said analyzing step (d) comprises extinguishing radiation of the same state of polarization as exists before the first one of said reflecting step (c) and said additional reflecting step to be executed.