crown glass


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crown glass

a compound of lime, potash, alumina, and silica; commonly used in lenses; has a low dispersion (52.2) relative to index of refraction (1.523).
References in periodicals archive ?
It is softer than crown glass (see above), with a higher index of refraction and higher dispersion.
Hall therefore decided to make a convex lens out of crown glass and a concave lens out of flint glass, designed in such a way that the two would fit together to form a single biconvex lens.
It's best to see the aurora borealis away from any light pollution, such as at the fab Golden Crown Glass Igloos near Levi in Lapland, where the heated glass roofs are kept ice free for optimum star gazing.
new museum including crown glass (architectural + transport); (Hereinafter referred to as lot 2);3.
CVF is v ratio which describes t he variation in surface power of an optical medium when compared with a standard reference index (1.498 for plastic and 1.523 for Crown glass. Table 1 summarises the typical CVF figures for various indices of plastic and glass material.
The FS22 has a 16(W) x 24(L) mm crown glass finger scanning window and includes a Live Finger Detection (LFD) function for spoof prevention.
The firm, which began in 1826 as St Helens Crown Glass, employs nearly 1,300 people in the Merseyside town.