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An achromatic doublet, which combines crown glass and flint glass. A concave lens of flint glass is commonly combined with a convex lens of crown glass to produce an achromatic doublet lens because of their compensating optical properties , which reduces chromatic aberration (colour defects).
This means the lens's F-number value is fixed to the overall designed focal ratio of the optical system (the diameter of the primary mirror divided into the focal length). The inability to stop down the lens results in the catadioptric lens having a short depth of field.
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 n d at the Fraunhofer d- (or D 3-) line, 589.3 nm, and its Abbe number V d also taken at that line.
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 .
Glazing, which derives from the Middle English for 'glass', is a part of a wall or window, made of glass. [1] [2] Glazing also describes the work done by a professional "glazier". Glazing is also less commonly used to describe the insertion of ophthalmic lenses into an eyeglass frame. [3]
This is a very basic surface characterization and is easy to achieve. It describes a scratch whose brightness is less than that of a scratch at visibility grade 80 and a dig with a diameter of up to 0.5 mm (50 hundredths = 50/100=0.5). 60-40 is considered "commercial" quality, while for demanding laser applications 20-10 or even 10-5 are used. [6]
A building in Canterbury, England, which displays its long history in different building styles and glazing of every century from the 16th to the 20th included. Architectural glass is glass that is used as a building material. It is most typically used as transparent glazing material in the building envelope, including windows in the external ...
Glare4 has three plies, so its glass fiber layers are each 0.375 mm (0.0148 in; 14.8 mils) thick. Glare5 has four plies, with individual glass fiber layers of 0.5 mm (0.020 in; 20 mils) thickness. [citation needed] Glare sheets have typical overall thicknesses between 0.85 and 1.95 mm (0.033 and 0.077 in; 33 and 77 mils). [23]
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