The invention discloses a method and device for measuring the complex
refractive index of a coarse thin film on a glass surface. The method is characterized in that a
prism, a matching fluid and a
glass slide are assembled into a composite
prism, one side of the
glass slide is plated with a coarse thin film to be measured, and the thin film to be measured is positioned at the bottom of the composite
prism; the refractive indexes of the prism, the matching fluid and the
glass slide are the same; a
laser beam comes into the bottom surface of the composite prism from one side of the composite prism,
light beam reflected by the interface of the coarse thin film and the composite prism comes out from the other side surface of the composite prism, and the
light intensity of reflected light is measured; the composite prism is rotated step by step or the incident angle of the composite prism is changed step by step to obtain a curve which shows that the reflective
light intensity changes along with the incident angle, the curve is compared with the
light intensity of the incident
light beam to obtain an experimental curve which shows that the
reflectivity of the thin film to be measured changes with change of the incident angle, the intensity total
reflectivity is calculated, and the complex
refractive index of the thin film to be measured is calculated according to the intensity total
reflectivity. The method is high in
measurement precision, is not limited by the
refractive index of the composite prism, and can be used for measuring the complex refractive index of the coarse thin film.