PROBLEM TO BE SOLVED: To provide a method for evaluating correct transparency regardless of the reflectivity of a measuring region.SOLUTION: Respective lights are radiated to a first irradiation region and a second irradiation region including the first irradiation region, the outgoing lights returning from the first irradiation region and second irradiation region are received, and the irradiation light quantities to the first and second irradiation regions and the outgoing light quantities of the outgoing lights received from the first and second irradiation regions are determined. When the ratios O1/I1 and O2/I2 between the irradiation light quantities and the outgoing light quantities in each irradiation region is assumed to be &alpha1 and &alpha2, the transparency is evaluated by making &alpha2 to be reflectivity R and (1-&alpha1/&alpha2) to be transparency T or making &alpha1 to be reflectivity R and (1-&alpha2/&alpha1) to be transparency T.COPYRIGHT: (C)2010,JPO&INPIT【課題】測定領域の反射率にかかわらず、正しい透明性の評価を行える方法の提供。【解決手段】本発明は、第1の照射領域と第1の照射領域を含む第2の照射領域とにそれぞれ光を照射して第1及び第2の照射領域から戻って来る射出光をそれぞれ受光し、第1及び第2の照射領域へのそれぞれの照射光量と、第1及び第2の照射領域から受光したそれぞれの前記射出光の射出光量とを求め、各照射領域についての前記照射光量と前記射出光量との比O1/I1及びO2/I2をα1及びα2としたときに、α2を反射率R、(1-α1/α2)を透明性Tとするか、又はα1を反射率R、(1-α2/α1)を透明性Tとして透明性を評価する。【選択図】図1
