crown glass

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English[edit]

Etymology[edit]

So called from a crown-like shape given to it in the process of blowing.

Noun[edit]

crown glass (usually uncountable, plural crown glasses)

  1. 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.
  2. (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.
    The convex half of an achromatic lens is composed of crown glass.

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