物质对光辐射有选择性吸收,这种吸收遵从Lambert-Beer定律或简称Beer定律,即穿透吸光物质溶液后的光强与原入射光强比(透光率)的负对数——吸光度,正比例于溶液的浓度和液层厚度。据此,发展形成了分光光度分析法。但是,真正入射试液的光强和透过试液后的光强却很难在实验中测定,因为试液必须由某种容器盛放,比如盛放在通常说的比色皿中,而光辐射与皿壁存在着 Substance selectively absorbs light radiation, this absorption follows the Lambert-Beer law or Beer’s law, which is the negative logarithm of the ratio of light intensity (light transmittance) after penetrating the light-absorbing substance solution - absorbance , Proportional to the solution concentration and layer thickness. Accordingly, the development of the formation of spectrophotometry. However, the light intensity of the real incident test solution and the light intensity after passing through the test solution are very difficult to experimentally determine, because the test solution must be contained in some kind of container, such as the commonly used cuvette, Light radiation and dish wall exist