| 摘要 |
An optical system is presented for use in a measurement system (100) for use in measurements of thin films of a workpiece (W), the system comprising an optical assembly (14), comprising illuminator assembly, a detector assembly, and a light directing assembly (FA-OF) for directing illuminating light to a plurality of measurement sites in the workpiece (W) arranged in an array of substantially concentric ring-like regions, such that an area defined by the measurement sites within one of the substantially concentric ring-like regions is substantially equal to that of the other substantially concentric ring-like region. |
