Each mirror, protected by blue plastic, is polished to an accuracy within one millionth of an inch, 3,000 times thinner than a human hair.

• 每个镜片都用蓝色塑胶保护,它被磨得很光滑精确度控制在百万分之一英寸以内,比一个人的头发还要薄3,000倍。