It is a glass tube. He wants to narrow the light so he puts a couple of slits here.

这是根玻璃管子，他想要减少光的发散,所以在这里开了几个口子。

麻省理工公开课 - 固态化学导论课程节选

If we get the pressure in there just right, we will allow for gas electron collisions and then we get the glow that ultimately was sent through the slits.

如果我们把气压设置在一个适当程度，把气体电子碰撞也算在里面,我们得到的炽热,最终将通过裂缝传送。

麻省理工公开课 - 固态化学导论课程节选

and slits the thin-spun life.

它扯裂了我们羸弱的生命。

耶鲁公开课 - 弥尔顿课程节选

It's made of strong metal, it's got very thin slits to be able to see straight ahead, covered up; everything else is covered up, a good one will cover your neck as well.

头盔是坚固的金属制成,正面有一条很细的开口能让士兵看到前方,左右两边都包住,剩下所有地方都包住,好一点的头盔甚至能保护颈部

耶鲁公开课 - 古希腊历史简介课程节选