ABSTRACT
Mirrors come in all shapes and sizes, but from an engineering point of view, just what is a mirror? There are large mirrors such as the highly structured lightweight Hubble Space Telescope’s primary mirror, the segmented 10-m mirror of the Keck telescope, and the active thin shell primary mirror of the 8-m Gemini telescope. There are small scanner mirrors, flip mirrors in cameras, and cooled mirrors in high energy systems. Is the mirror the reflecting surface or the structure that contains the reflecting surface? A good definition is that the mirror consists of the reflecting surface and whatever it takes to support that surface. A mirror is then an optomechanical system in itself.
