ELLIPSOMETER WITH TWO LASERS

摘要

Ellipsometer having light source means which provide a first light beam (g1) having a first angular frequency ( omega 1) and a second light beam (g2) having a second angular frequency ( omega 2), a neutral beam splitter (N) having a front face for receiving a measuring beam (g'm2), which during operation is produced by scanning a sample (S;OD1;OD2) with the second light beam (g2), and a rear face for receiving the first light beam (g1), wherein, during operation, an interference beam is formed at the rear face, wherein the light source means comprise two separate laser sources (L1, L2) and the ellipsometer is provided with a control circuit (C) having at least one input for receiving information with regard to the first and second angular frequencies ( omega 2, omega 1) or the difference between the two and at least one output, coupled to at least one of the two laser sources, for controlling the difference between the first and second angular frequencies ( omega 2, omega 1).