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A ray trace through a prism with apex angle α. Regions 0, 1, and 2 have indices of refraction, , and , and primed angles ′ indicate the ray's angle after refraction.. Ray angle deviation and dispersion through a prism can be determined by tracing a sample ray through the element and using Snell's law at each interface.
The first-order design of an achromat involves choosing the overall power of the doublet and the two glasses to use. The choice of glass gives the mean refractive index, often written as n d {\displaystyle n_{d}} (for the refractive index at the Fraunhofer "d" spectral line wavelength ), and the Abbe number V {\displaystyle V} (for the ...
Cut glass wine glass made of lead glass. Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. [1] Lead glass contains typically 18–40% (by mass) lead(II) oxide (PbO), while modern lead crystal, historically also known as flint glass due to the original silica source, contains a minimum of 24% PbO. [2]
Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00. Traditionally, flint glasses were lead glasses containing around 4–60% lead(II) oxide; however, the manufacture and disposal of these glasses were sources of pollution.
The glasses from this period contain high levels of barium oxide and lead, distinguishing them from the soda–lime–silica glasses of Western Asia and Mesopotamia. [27] At the end of the Han Dynasty (AD 220), the lead-barium glass tradition declined, with glass production only resuming during the 4th and 5th centuries AD. [ 28 ]
The Prismatic World Tour was the third concert tour by American singer Katy Perry, in support of her fourth studio album, Prism (2013). The tour began on May 7, 2014, at Belfast, Northern Ireland's Odyssey Arena and ended on October 18, 2015, at Alajuela, Costa Rica's Parque Viva after six legs. [2]
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