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The deck prism laid flush into the deck, the glass prism refracted and dispersed natural light into the space below from a small deck opening without weakening the planks or becoming a fire hazard. In normal usage, the prism hangs below the overhead and disperses the light sideways; the top is flat and installed flush with the deck, becoming ...
Rockwell vault light, with one large piece of glass [16] Sidewalk prisms developed from deck prisms, which were used to let light through the decks of ships. The earliest pavement light (Rockwell, 1834) [16] used a single large round glass lens set in an iron frame. The large lens was directly exposed to traffic, and if the lens broke, a large ...
It was frequently used around the turn of the 20th century to provide natural light to underground spaces and areas far from windows. [14] Prism glass can be found on sidewalks, where it is known as vault lighting, [15] in windows, partitions, and canopies, where it is known as prism tiles, and as deck prisms, which were used to light spaces ...
Optical glass refers to a quality of glass suitable for the manufacture of optical systems such as optical lenses, prisms or mirrors.Unlike window glass or crystal, whose formula is adapted to the desired aesthetic effect, optical glass contains additives designed to modify certain optical or mechanical properties of the glass: refractive index, dispersion, transmittance, thermal expansion and ...
The riddle goes: “There is a green glass door, and some things can go through it and some things cannot.” The person posing the riddle then offers a series of pairs of items, only one item ...
In the technical terminology of gemology, dispersion is the difference in the refractive index of a material at the B and G (686.7 nm and 430.8 nm) or C and F (656.3 nm and 486.1 nm) Fraunhofer wavelengths, and is meant to express the degree to which a prism cut from the gemstone demonstrates "fire". Fire is a colloquial term used by ...
The B in BK7 indicates that it is a borosilicate glass composition. BAK-4 barium crown glass (glass code 569560) has a higher index of refraction than BK7, and is used for prisms in high-end binoculars. In that application, it gives better image quality and a round exit pupil. An achromatic doublet, which combines crown glass and flint glass.
Deck prisms carried light through the upper decks of ships and spread it in the decks below. Similarly, on land, prisms in sidewalk lights were used to light basements and vaults. Prism tiles were used vertically, usually as a transom light above a window or door. [6] They were also built into fixed and movable canopies, sloped glazing, and ...