Patent ID: 6885454

Claim:
A measuring apparatus comprising: a measuring unit equipped with a transparent dielectric block and a thin film layer formed on one surface of said dielectric block; first beam incidence means for making a first light beam enter said dielectric block at various angles of incidence so that a condition for total internal reflection is satisfied at an interface between said dielectric block and said thin film layer; and first photodetection means for receiving a predetermined polarized light component of said first light beam totally reflected at said interface; wherein said measuring unit is measured a plurality of times and a change in the state of attenuated total reflection during the plurality of measurements is detected; and wherein said measuring apparatus further comprises: tilt measurement means for measuring a longitudinal tilt of said interface which changes said incidence angles during said plurality of measurements; and calculating means for obtaining a measured value in which errors due to said longitudinal tilt have been corrected according to said longitudinal tilt measured by said tilt measurement means.