FILM THICKNESS MEASURING METHOD FOR SURFACE LAYER OF ELECTROPHOTOGRAHIC SENSITIVE BODY

摘要

PROBLEM TO BE SOLVED: To provide a film thickness measuring method for the surface layer of an electrophotographic sensitive body that can precisely measure the thickness of the surface layer of an electrophotographic sensitive body having a dispersed filler as a specific layer which was hardly measured without being affected by the light diffusion by the filler and easily measure a surface layer which is relatively thin and has curvature and is suitable to even a surface layer with a small light absorption quantity. SOLUTION: The film thickness of the surface layer having the filler dispersed is measured by making thermal excitation light modulated intermittently in specific cycles determined by a film thermal property value incident on the surface of the surface layer having the dispersed filler and detecting the phase delay behind the modulation frequency of a generated sound wave.