Crown glass

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crown glass

[′krau̇n ‚glas]

(materials)

A soda-lime glass, typically having 72% SiO₂, 13% CaO, and 15% Na₂O, which is hard and will take a simple polish; highly transparent for visible light.

Crown glass

1. An early form of window glass, cut from blown disks.

2. The glass made by blowing a mass of molten material, which is then flattened into a disk and spun into a cular sheet.

crown glass

A handmade glass of soda-lime composition, used for windows; manufactured in the early 19th century by a now-obsolete process in which a hollow sphere of glass was blown while still very soft, then spun to form a large, nearly flat circular disk. During the spinning process, ripple lines were formed in a pattern of concentric circles, with their center at the center of the spun disk; this central area was used in a bull’s eye window. Also see glass.

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References in periodicals archive ?

Some small loss from CR39 and Crown glass does not cause too many problems.

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Richter's design called for BK-7 optical glass, but since this is difficult to obtain in Argentina I opted for ophthalmic crown glass instead.

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For most designs, prisms made of Bak4 (barium light crown glass) are preferred over the industry-standard Bk7 (borosilicate crown).

Skygazing with binoculars: binoculars as an astronomical instrument? Why not! Some timely advice before you buy

Seeing the Northern Lights is high on most people's wish–lists and this dream came true for me in the coolest of locations – the Golden Crown Glass Igloos in Levi, Lapland (inghams.co.uk).

PACKED WITH LOVE; Looking for inspiration for a Valentine's Day break? Here are some romantic destinations to fall in love with, from heavenly hotels to heart-melting igloos

Since the prism and lens are both made of very similar crown glass, experienced amateurs could even grind and polish the crown's curved surface directly onto the prism, avoiding the need to make a separate lens.

A short Newtonian with a spherical mirror

But it's best to see them away from any light pollution, such as at the fabulous Golden Crown glass igloos near Levi, or mountain restaurants like Tsokka above Pyha, where we were taken to.

LIGHT FANTASTIC; Step into the magical world of Lapland, where you can catch the spellbinding aurora borealis, enjoy the call of the wild and dive into thrilling adventures

Thus crown glass reflects 4.2 percent, flint 5.6 percent, and Pyrex 3.6 percent.