DISPLACEMENT MEASURING INSTRUMENT

摘要

PROBLEM TO BE SOLVED: To measure the surface of a substance which is formed on a glass substrate and transmits light without being affected by the reflection state of a metal pattern formed on the glass substrate. SOLUTION: The measurement light emitted by the light source 1 of a projection part 10 is converted by aλ/2 plate 3 into S-polarized light, which irradiates the substance W2 transmitting the light of a body W to be measured at an incidence angleϕ1 (70 deg.). Its reflected light is made incident on the photodetecting element 7 of a photodetection part 11 at a reflection angleϕ2 and a quantity of displacement is detected. The reflection intensity of the measurement light on the surface of the substance W2 transmitting the light can be increased and the displacement quantity of the surface can accurately be measured without being affected by the reflection state of the reverse surface of the substance transmitting the light.