Mirror support cell

In astronomy, a mirror support cell - more commonly mirror cell - is a component of a reflecting telescope that supports the mirror in place to hold optical alignment, allow collimation adjustment, and protect it from falling out. The common usage of the word denotes the cell that holds the primary mirror (M1), however technically it could also be used to denote the support assembly (usually called a spider or strut) for the secondary mirror (M2) or other mirrors.