[讨论]Internal Transmittance 怎么来的?

抱歉不知道中文怎么译

找玻璃的时候总是看到它

虽然它是吸收系数的另一种表示方式. 可是我想问它是测出来的还是算出来的?

如果是测出来的,怎么测?

如果是据 R+T+A=1 算出来的,那它一般用在什么场合?有什么明显意义?

Internal transmittance, ti, is defined as the transmission through a filter glass after the initial reflection losses are accounted for by dividing external transmission, T, by the reflection factor Pd. ti = T / PdExample:The external transmittance for a nominal 1.0 mm thick filter glass is given as T1.0 = 59.8 % at 330 nm. The reflection factor is given as Pd = 0.911. Find the external transmittance T2.2 for a filter that is 2.2 mm thick. Solution:t1.0 = T1.0 / Pd = 0.598 / 0.911 = 0.656t2.2 = [t1.0]2.2/1.0 = [0.656]2.2 = 0.396T2.2 = t2.2 * Pd = (0.396)(0.911) = 0.361

So, for a 2.2 mm thick filter, the external transmittance at 330 nm would be 36.1%

thanks

计算公式？？？？