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Glass Code
A glass code is a method of classifying glasses for optical use, such as the manufacture of lenses and prisms. There are many different types of glass with different compositions and optical properties, and a glass code is used to distinguish between them. There are several different glass classification schemes in use, most based on the catalogue systems used by glass manufacturers such as Pilkington and Schott Glass. These tend to be based on the material composition, for example ''BK7'' is the Schott Glass classification of a common borosilicate crown glass. Technical definition The international glass code is based on U.S. military standard MIL-G-174, and is a six-digit number specifying the glass according to its refractive index at the Fraunhofer d- (or D3-) line, 589.3 nm, and its Abbe number In optics and lens design, the Abbe number, also known as the Vd-number or constringence of a Transparency (optics), transparent material, is an approximate measure of the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glass
Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window panes, tableware, and optics. Some common objects made of glass are named after the material, e.g., a Tumbler (glass), "glass" for drinking, "glasses" for vision correction, and a "magnifying glass". Glass is most often formed by rapid cooling (quenching) of the Melting, molten form. Some glasses such as volcanic glass are naturally occurring, and obsidian has been used to make arrowheads and knives since the Stone Age. Archaeological evidence suggests glassmaking dates back to at least 3600 BC in Mesopotamia, Ancient Egypt, Egypt, or Syria. The earliest known glass objects were beads, perhaps created accidentally during metalworking or the production of faience, which is a form of pottery using lead glazes. Due to its ease of formability int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes the behaviour of visible light, visible, ultraviolet, and infrared light. Light is a type of electromagnetic radiation, and other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for by using the Classical electromagnetism, classical electromagnetic description of light, however complete electromagnetic descriptions of light are often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of Ray (optics), rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lens (optics)
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), usually arranged along a common axis. Lenses are made from materials such as glass or plastic and are ground, polished, or molded to the required shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called "lenses", such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. Lenses are used in various imaging devices such as telescopes, binoculars, and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia. History The word ''lens'' comes from , the Latin name of the lentil (a seed of a lentil pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prism (optics)
An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled—elements with two parallel surfaces are ''not'' prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides. Not all optical prisms are geometric prisms, and not all geometric prisms would count as an optical prism. Prisms can be made from any material that is transparent to the wavelengths for which they are designed. Typical materials include glass, acrylic and fluorite. A dispersive prism can be used to break white light up into its constituent spectral colors (the colors of the rainbow) to form a spectrum as described in the following section. Other types of prisms noted below can be used to reflect light, or to split light into components with different polarizations. Types Dispersive ''Dispersive prisms'' are used to break up light into its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pilkington
Pilkington is a glass-manufacturing company which is based in Lathom, Lancashire, England. It includes several legal entities in the UK, and is a subsidiary of Japanese company Nippon Sheet Glass (NSG). It was formerly an independent company listed on the London Stock Exchange and a constituent of the FTSE 100 Index. Established in 1826 as the ''St Helens Crown Glass Company'', the company gradually grew to become the largest employer in St Helens, where it was originally based. It was renamed ''Pilkington Brothers'' in 1845 following the ending of the partnership with the Greenall family. The business continued to expand, becoming ''Pilkington Brothers Limited'' after its incorporation in 1894. In 1903, it became the sole British manufacturer of plate glass as well as the dominant producer of sheet glass. After the First World War, Pilkington was one of only two large glass manufacturers remaining in Britain, the other being Chance Brothers; the firm gradually expanded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schott Glass
Schott AG is a German multinational glass company specializing in the manufacture of glass and glass-ceramics. Headquartered in Mainz, Rhineland-Palatinate, Germany, it is owned by the Carl Zeiss foundation, Carl Zeiss Foundation. The company's founder and namesake, Otto Schott, is credited with the invention of borosilicate glass. History Founding In 1884, Otto Schott, Ernst Abbe, Carl Zeiss and his son Roderich Zeiss founded the ''Glastechnische Laboratorium Schott & Genossen'' (Glass Technical Laboratory Schott & Associates) in Jena, Thuringia, Germany which initially produced optical glasses for microscopes and telescopes. In 1891, the Carl Zeiss Foundation, founded two years earlier by Ernst Abbe, became a partner in the glass laboratory. Jena glass, an early borosilicate glass, was one of its early manufactured products. Otto Schott's invention of borosilicate glass, resistant to chemicals, heat and temperature change, paved the way for new technical glasses for ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borosilicate Glass
Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (≈3 × 10−6 K−1 at 20 °C), making them more resistant to thermal shock than any other common glass. Such glass is subjected to less thermal stress and can withstand temperature differentials without fracturing of about . It is commonly used for the construction of reagent bottles and flasks, as well as lighting, electronics, and cookware. For many other applications, soda-lime glass is more common. Borosilicate glass is sold under various trade names, including Borosil, Duran, Pyrex, Glassco, Supertek, Suprax, Simax, Bellco, Marinex (Brazil), BSA 60, BSC 51 (by NIPRO), Heatex, Endural, Schott, Refmex, Kimax, Gemstone Well, United Scientific, and MG (India). Single-ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Glass (optics)
Crown glass is a type of optical glass used in lenses and other optical components. It has relatively low refractive index (≈1.52) and low dispersion (with Abbe numbers between 50 and 85). Crown glass is produced from alkali-lime silicates containing approximately 10% potassium oxide and is one of the earliest low dispersion glasses. History The term originated from crown-glass windows, a method of window production that began in France during the Middle Ages. A molten blob of glass was attached to a pole and spun rapidly, flattening it out into a large disk from which windows were cut. The center, called the "crown" or "bullseye", was too thick for windows, but was often used to make lenses or deck prisms.''A Dictionary of the English Language - Volume 1, Part 1'' by Samuel Johnson, Robert Gordon Latham, Henry John Todd -- longmans, Green & Co. 1866 Page 314 Types The borosilicate glass Schott BK7 ( glass code 517642) is an extremely common crown glass, used in precisi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refractive Index
In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refraction, refracted, when entering a material. This is described by Snell's law of refraction, , where and are the angle of incidence (optics), angle of incidence and angle of refraction, respectively, of a ray crossing the interface between two media with refractive indices and . The refractive indices also determine the amount of light that is reflectivity, reflected when reaching the interface, as well as the critical angle for total internal reflection, their intensity (Fresnel equations) and Brewster's angle. The refractive index, n, can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is , and similarly the wavelength in that me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fraunhofer Line
The Fraunhofer lines are a set of spectral absorption lines. They are dark absorption lines, seen in the optical spectrum of the Sun, and are formed when atoms in the solar atmosphere absorb light being emitted by the solar photosphere. The lines are named after German physicist Joseph von Fraunhofer, who observed them in 1814. Discovery In 1802, English chemist William Hyde WollastonMelvyn C. UsselmanWilliam Hyde WollastonEncyclopædia Britannica, retrieved 31 March 2013 was the first person to note the appearance of a number of dark features in the solar spectrum. In 1814, Joseph von Fraunhofer independently rediscovered the lines and began to systematically study and measure their wavelengths. He mapped over 570 lines, designating the most prominent with the letters A through K and weaker lines with other letters. Modern observations of sunlight can detect many thousands of lines. About 45 years later, Gustav Kirchhoff and Robert Bunsen noticed that several Fraunhofer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abbe Number
In optics and lens design, the Abbe number, also known as the Vd-number or constringence of a Transparency (optics), transparent material, is an approximate measure of the material's dispersion (optics), dispersion (change of refractive index versus wavelength), with high values of ''Vd'' indicating low dispersion. It is named after Ernst Abbe (1840–1905), the German physicist who defined it. The term Vd-number should not be confused with the Normalized frequency (fiber optics), normalized frequency in fibers. The Abbe number, V_\mathsf d\ , of a material is defined as : V_\mathsf d \equiv \frac, where n_\mathsf C, n_\mathsf d, and n_\mathsf F are the refractive indices of the material at the wavelengths of the Fraunhofer lines, Fraunhofer's C, d, and F spectral lines (656.3 nanometre, nm, 587.56 nm, and 486.1 nm respectively). This formulation only applies to the visible spectrum, human vision. Outside this range requires the use of different spectral lines. Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barium Oxide
Barium oxide, also known as baria, is a white hygroscopic non-flammable chemical compound, compound with the formula BaO. It has a Cubic crystal system, cubic structure and is used in cathode-ray tubes, crown glass, and Catalysis, catalysts. It is harmful to human skin and if swallowed in large quantity causes irritation. Excessive quantities of barium oxide may lead to death. It is prepared by heating barium carbonate with coke (fuel), coke, carbon black or tar or by thermal decomposition of barium nitrate. Uses Barium oxide is used as a coating for hot cathodes, for example, those in cathode-ray tubes. It replaced lead(II) oxide in the production of certain kinds of glass such as optical crown glass (optics), crown glass. While lead oxide raised the refractive index, it also raised the optical dispersion, dispersive power, which barium oxide does not alter. Barium oxide also has use as an ethoxylation catalyst in the reaction of ethylene oxide and Alcohol (chemistry), alcohols ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
