Then there's a secondary mirror and it bounces off of that.

然后有一个副镜，它从副镜上反射出去。

The other, 'less important' mirror is called a 'secondary' mirror. So there are 3 mirrors.

另一个“不太重要” 的镜子被称为“次要” 镜子。 所以有3个镜子。

For example, the Hubble space telescope has four struts that support its small secondary mirror, and their imprint causes the 4-pointed stars in hubble photos.

例如，哈勃太空望远镜有四根柱子支撑它的副镜，这些柱子在哈勃拍的照片上会留下四角星的印记。

Ten days after launch, if all goes well, Webb will move its small secondary mirror to face its giant primary mirror, which will still be folded up.

发射十天后， 如果一切顺利， 韦伯将把它的小副镜移到面对它的巨大主镜， 主镜仍然是折叠的。