CatoptricsCatoptrics (from κατοπτρικός katoptrikós, "specular", from κάτοπτρον katoptron "mirror") deals with the phenomena of reflected light and optical systems using mirrors. A catoptric system is also called a catopter (catoptre). Catoptrics is the title of two texts from ancient Greece: The Pseudo-Euclidean Catoptrics. This book is attributed to Euclid, although the contents are a mixture of work dating from Euclid's time together with work which dates to the Roman period.
Optical telescopeAn optical telescope is a telescope that gathers and focuses light mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct visual inspection, to make a photograph, or to collect data through electronic s. There are three primary types of optical telescope: Refracting telescopes, which use lenses and less commonly also prisms (dioptrics) Reflecting telescopes, which use mirrors (catoptrics) Catadioptric telescopes, which combine lenses and mirrors An optical telescope's ability to resolve small details is directly related to the diameter (or aperture) of its objective (the primary lens or mirror that collects and focuses the light), and its light-gathering power is related to the area of the objective.
Christiaan HuygensChristiaan Huygens, Lord of Zeelhem, (ˈhaɪɡənz , USˈhɔɪɡənz , ˈkrɪstijaːn ˈɦœyɣə(n)s; also spelled Huyghens; Hugenius; 14 April 1629 – 8 July 1695) was a Dutch mathematician, physicist, engineer, astronomer, and inventor who is regarded as a key figure in the Scientific Revolution. In physics, Huygens made seminal contributions to optics and mechanics, while as an astronomer he studied the rings of Saturn and discovered its largest moon, Titan.