Optica

work by Ptolemy

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 1, 2026

Quick Summary

Ptolemy, an Egyptian astronomer, mathematician, and geographer of Greek descent, made significant contributions to the field of optics. In his work, he conducted one of the earliest quantitative studies on the refraction of light as it passes between different transparent substances. He meticulously recorded pairs of angles of incidence and transmission for various media combinations. Ptolemy also established that an object and its mirror image form equal angles with a mirror, a principle he demonstrated through measurement rather than pure philosophical reasoning. His writings represent a culmination of Greco-Roman scientific achievements.123

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

6 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

Ptolemy
Mathematician
…study of visual perception in Optica (“Optics”), a work that only survives in a mutilated medieval Latin translation of an Arabic translation. The extent to which Ptolemy subjected visual perception to empirical analysis is remarkable when contrasted with other Greek writers on optics. For example, Hero of Alexandria (mid-1st century…
Read More
…study of visual perception in Optica (“Optics”), a work that only survives in a mutilated medieval Latin translation of an Arabic translation. The extent to which Ptolemy subjected visual perception to empirical analysis is remarkable when contrasted with other Greek writers on optics. For example, Hero of Alexandria (mid-1st century…
Read More