Method and apparatus for measuring thickness variation of a thin sheet material, and probe reflector used in the apparatus

摘要

Optical displacement gauges 20 are respectively arranged on both sides of a thin sheet material w, and displacement of surface position of the thin sheet material w is measured by irradiating measurement light L1 to the surface of the thin sheet material w. Thickness variation of the thin sheet material w is obtained from the measurement results of displacement of the surface position of the thin sheet material w.