Bille and his team work with an optical instrument called an active mirror—a device used in astronomical telescopes to spot newly emerging stars and far distant galaxies.
Surely, please watch me in the hand mirror. I'll reach under the gum with a measuring instrument.
完全可以，请看手镜里我是怎样做的，我要用计量用具捅到牙龈底下。
3
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.