flint glass

Definition: Type of optical glass characterised by high dispersion and high refractive index. * Family of glasses with Abbe number less than 50 with refractive index of 1.6 or less, and Abbe number less than 55 with refractive index above 1.6. * Relatively soft and not durable, therefore its use as the outer element in a system is avoided. * One of the major families of glass.
Leading questions
Optical glasses are mixtures of oxides of silicon, mainly, plus oxides of aluminium and rare earth metals plus lead. Larger quantities of lead increases refractive index and dispersion. Lead glass elements were popular with designers but not with users: the glass is very heavy.

Related Terms: crown glass

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