youdao

A usually adjustable opening in an optical instrument, such as a camera or a telescope, that limits the amount of light passing through a lens or onto a mirror.

光学仪器上的一个可调开口，如照相机或望远镜，它控制穿过镜头的或到镜面的光的数量。

youdao

In this paper, we introduce a mirror smoothness surveying instrument which is designed from the principle of mirror Moire topography.

本文介绍一种以作者提出的掠射式镜面莫尔轮廓法的原理为依据而设计的镜面平整度测试仪。

youdao

Miri will be fixed inside a cage-like structure called the Integrated Science Instrument Module and positioned just behind the big mirror.

BBC: Science & Environment