crown glass

== English == === Etymology === So called from a crown-like shape given to it in the process of blowing. === Noun === crown glass (usually uncountable, plural crown glasses) An early type of window glass made by blowing glass into a hollow globe (crown) and then flattening it on a punty, reheating and spinning out into a flat disk by centrifugal force. (optics) A variety of glass used in lenses and other optical components due to its low refractive index and dispersion. Originally crown glass was made from alkali-lime silicates with approximately 10% potassium oxide, but similar properties may be attained with other recipes. ==== Translations ==== ==== See also ==== bullseye === Further reading === Crown glass (window) on Wikipedia.Wikipedia Crown glass (optics) on Wikipedia.Wikipedia