On Burning Mirrors: focus of the parabolic mirror (Diocles)
Sobre los espejos ustorios: foco del espejo parabólico (Diocles)
- Date
- c. 200 BCE · confidence medium
- Place
- Alexandria, Egypt
- Credited to
- Diocles
- Field
- Communication
⚠️ Disputed: the sources disagree.
What was discovered
Diocles shows geometrically that a paraboloidal mirror concentrates parallel rays at a single point and studies other concave mirrors. It is the earliest surviving analysis of focusing by reflection.
The text survives only in Arabic translation and through Eutocius; Diocles' place of activity is conjectural (traditionally placed in the Alexandrian milieu). The date rests on his being later than Apollonius and earlier than Hypsicles.
What it led to
- design of point-focus mirrors and reflectors
- mathematical study of conics and their focal properties
- the mirror optics of Anthemius, Ibn Sahl and Ibn al-Haytham