Because it came from optics, you know, rays of sunlight and so on And in fact, even when we first started pulling synthetic fiber, the first synthetic fiber cellulose was referred to as ray on, because it looked like a ray that was being pulled.

因为它源自光学，比如太阳光线等等,实际上，及时当我们首先开始抽出,人造纤维，第一根人造纤维的纤维素,叫做光线，因为那条在被抽出的纤维素,看起来像是一道光线。

麻省理工公开课 - 固态化学导论课程节选

This is the equivalent to ray optics, isn't it?

这与X射线是等价的，是不是？

麻省理工公开课 - 固态化学导论课程节选

This is ray optics.

它就是X光。

麻省理工公开课 - 固态化学导论课程节选