Crown glass

noun

Definitions

Noun
  1. 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. uncountable, usually
  2. 2
    optical glass of low dispersion and low refractive index wordnet
  3. 3
    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. uncountable, usually

    "The convex half of an achromatic lens is composed of crown glass."

  4. 4
    a glass blown into a globe which is later flattened and spun to form a disk wordnet

Etymology

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

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