Ibn Sahl (full name: Abū Saʿd al-ʿAlāʾ ibn Sahl Persian: ابوسعدالعلاءِبن سعل (ابن سهل); c. 940–1000) was a Persian mathematician and physicist of the Islamic Golden Age, associated with the Buyid court of Baghdad. Despite attempts by professionals in the field of onomastics, neither his country of origin nor his religious allegiance could be parsed. 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. 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 no geometric aberrations, known as anaclastic lenses. In the remaining parts of the treatise, Ibn Sahl dealt with parabolic mirrors, ellipsoidal mirrors, biconvex lenses, and techniques for drawing hyperbolic arcs. Ibn Sahl designed convex lenses that focus light rays that are parallel, which can cause an object to burn at a specific distance.
See also History of optics Abū Sahl al-Qūhī List of Persian scientists and scholars Snell's law
References
Sources Rashed, Roshdi (1990). "A Pioneer in Anaclastics: Ibn Sahl on Burning Mirrors and Lenses". Isis. 81 (3): 464–491. doi:10.1086/355456. JSTOR 233423. Rashed, R., Géométrie et dioptrique au Xe siècle: Ibn Sahl, al-Quhi et Ibn al-Haytham. Paris: Les Belles Lettres, 1993 Zghal, Mourad; et al. (2007). "The first steps for learning optics: Ibn Sahl's, Al-Haytham's and Young's works on refraction as typical examples" (PDF). In Nantel, Marc (ed.). Tenth International Topical Meeting on Education and Training in Optics and Photonics. Proceedings of the SPIE. Vol. 9665. p. 3. Bibcode:2007SPIE.9665E..09Z. doi:10.1117/12.2207465. S2CID 13875045. Retrieved 20 June 2011. Berggren, Len (2007). "Ibn Sahl: Abū Saʿd al-ʿAlāʾ ibn Sahl". In Thomas Hockey; et al. (eds.). The Biographical Encyclopedia of Astronomers. New York: Springer. p. 567. ISBN 978-0-387-31022-0. (PDF version) Selin, Helaine (1997). Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures. Springer Science & Business Media. pp. 432–433. ISBN 978-07-92-34066-9. Sarmiş, İbrahım (1999). İBN SEHL - An article published in Turkish Encyclopedia of Islam. Vol. 20. Istanbul: TDV İslâm Ansiklopedisi. p. 312. ISBN 978-97-53-89447-0.