The mirror has an f/2.7 hyperboloidal shape. It is made from a two foot (61 | cm | in | sing on | abbr on) thick fused quartz disk that is
Kaynak: Nicholas U. Mayall Telescope

A translation of the passage describing the device:The rays of light, falling on the inner surface of the hyperboloidal mirror, converge in
Kaynak: The Garin Death Ray

These are the equilateral-hyperboloidal coordinates described by Alexander Macfarlane and Carmondy (1997 p 38). Next, form three
Kaynak: Split-quaternion