 Its use in military applications was limited, since glass reflectors of any kind were thought to be too fragile and susceptible to enemy gunfire.Mangin mirrors are used in illumination and image forming optics such as search lights, headlamps, aircraft gunsights and head-mounted displays.Many Catadioptric telescopes use negative lenses with a reflective coating on the back surface that are referred to as "Mangin mirrors", although they are not single-element objectives like the original Mangin, and some, like the Hamiltonian telescope, predate the Mangin's invention by over 60 years.