Optical glass

Rams' Horn Necklace
MFA# 1998.190

Description

A fine grade of glass used in microsopes, telescopes, binoculars, cameras, and other items requiring visual acuity. Primary patents for making optical glass were made in 1798 by P.L. Guinand, a Swiss inventor. Commercial processes for making consistent quality glass were developed in the mid 19th century when the Chance brothers in England introduced the melt-stirring process. Concurrent work in Germany by the Zeiss Company, Ernst Abbe, and Otto Schott established Jena Glass Works as a major supplier of optical glass. Optical glass is clear, flawless, and has a very controlled refractive index. Flint glass produces a higher refractive index and dispersive power while soda-lime glass, or crown glass, produces a lower refractive index and lower dispersive power. Optical glasses are cooled slowly and sometimes annealed for months to minimize distortions.

Synonyms and Related Terms

crystal; lens; eyeglass; magnifying glass; flint glass

Resources and Citations

• Encyclopedia Britannica, http://www.britannica.com Comment: "industrial glass" [Accessed May 5, 2004].

• Edward Reich, Carlton J. Siegler, Consumer Goods: How to Know and Use Them, American Book Company, New York City, 1937

• Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997

• The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998