Patent ID: 10274307

Abstract:
A film thickness measurement device includes a light source, an imaging component, and a controller. The controller estimates unknown variables I1(j), I20(j), k(j), and t(i) based on the Formula (1), where i represents an observation point number of an interference image captured by the imaging component, j represents a number for a type of wavelength of monochromatic light, λ(j) represents wavelength of the monochromatic light, n represents a refractive index of a semi-transparent film, g(i,j) represents a brightness value observed at an observation point, I1(j) represents an intensity of reflected light from a front face of the semi-transparent film, I20(j) represents an intensity of reflected light from a rear face of the semi-transparent film when there is no absorption of light in the semi-transparent film, k(j) represents an absorption coefficient of the semi-transparent film, and t(i) represents a film thickness of the semi-transparent film.