And then he just takes that narrow column of light and he admits it to a prism. And what the prism does is takes a tiny, tiny difference in wavelength and refracts it through a different angle.

他只取了那个窄光柱,然后把它对准一个棱镜，棱镜所做的就是,测量出波长的细微差别,然后从不同的角度测定它的折射度。

麻省理工公开课 - 固态化学导论课程节选

And if the prism is of sufficient dimension that angle can be magnified.

如果这个棱镜有多个面,可以把角度也放大。

麻省理工公开课 - 固态化学导论课程节选