An ellipsometer includes a stage, a light source, a polarizer, a detector, and a processor. The stage is configured to support a substrate including a pattern. The light source is configured to emit illumination toward the substrate. The polarizer is configured to polarize the illumination. The detector is configured to generate, in association with a plurality of azimuthal angles, data corresponding to polarized illumination reflected from the substrate. The processor is configured to: control rotation of the stage in association with sequential inspection of the pattern at the plurality of azimuthal angles, and determine asymmetry of the pattern based on the data. Each azimuthal angle of the plurality of azimuthal angles corresponds to a different rotational state of the stage.