Origins & Early Life

Ibn Sahl (full name: Abū Saʿd al-ʿAlāʾ ibn Sahl Persian: ابوسعدالعلاءِبن سعل (ابن سهل); c. 940–1000) was a mathematician and physicist of the Islamic Golden Age, associated with the Buyid court of Baghdad. He is known to have written an optical treatise around 984. The text of this treatise was reconstructed by Roshdi Rashed from two manuscripts (edited 1993).: Damascus, al-Ẓāhirīya MS 4871, 3 fols., and Tehran, Millī MS 867, 51 fols.

Pivotal Works & Achievements

The Tehran manuscript is much longer, but it is badly damaged, and the Damascus manuscript contains a section missing entirely from the Tehran manuscript. The Damascus manuscript has the title Fī al-'āla al-muḥriqa "On the burning instruments", the Tehran manuscript has a title added in a later hand Kitāb al-harrāqāt "The book of burners". Ibn Sahl is the first Muslim scholar known to have studied Ptolemy's Optics, and as such an important precursor to the Book of Optics by Ibn Al-Haytham (Alhazen), written some thirty years later. Ibn Sahl dealt with the optical properties of curved mirrors and lenses and has been described as the discoverer of the law of refraction (Snell's law). Ibn Sahl uses this law to derive lens shapes that focus light with...

Enduring Legacy & Impact

The historical impact and works continue to influence the modern world.

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