Lenses, optical

A typical lens is made of transparent material and has one or two spherical surfaces. In this book, most cases refer to typical lenses. 

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The physics of X-ray refraction are analogous to the well known refraction of light by optical lenses and prisms, governed by Snell s law. The special feature is the deflection at very small angles of few minutes of arc, as the refractive index of X-rays in matter is nearly one. Due to the density differences at inner surfaces most of the incident X-rays are deflected [1]. As the scattered intensity of refraction is proportional to the specific surface of a sample, a reference standard gives a quantitative measure for analytical determinations. 

A modem use of uranine is in the manufacture of fluorescent laminates, eg, sheets, glass, and plastic films, that are transparent to electromagnetic waves and visible light rays (45). Such material might be used in windows, viewing partitions, and optical lenses. 

Corundum. Comndum [1302-75-5] (see Aluminum compounds) is a naturally occurring massive crystalline mineral composed of aluminum oxide. It is an impure form of the gems mby and sapphke. Prior to 1900 comndum was an important abrasive for the production of grinding wheels. Today it is mainly employed as a loose abrasive for grinding and polishing optical lenses. Almost all the world s supply of comndum now comes from Africa, primarily from Zimbabwe. 

Various polymers, such as polythiourethanes, polythioethers, and polythioacrylates, are used to produce resins which are transparent, colorless and have a high refractive index and good mechanical properties, useful for the production of optical lenses. Higher refractive indices are promoted by sulfur compounds and especially by esters of mercaptocarboxyhc acids and polyols such as pentaerythritol (41) (see Polymers containing sulfur). 

Diethylene glycol bis (chloroformate) [106-75-2] is the starting material for diethylene glycol bis(allyl carbonate) [142-22-3] CR-39, or Nouryset 200, monomer, used in the manufacture of break-resistant optical lenses, which is obtained by the reaction with aHyl alcohol [107-18-6] (59). Alternatively, it can be obtained from aHyl chloroformate [2937-50-0] and diethylene glycol (60) (see Allylmonomers and polymers). 

K2CO3 (from KOH and CO2), used chiefly in high-quality decorative glassware, in optical lenses, colour TV lubes and fluorescent lamps il is also used in china ware, textile dyes and pigments. 

Silicon Monoxide. SiO, mw 44.09, hard and abrasive, black to brn-black amorph or cubic crysts, mp > 1702°, bp 1880°, d 2.13-.20. Sol in coned aq alk and dil HF+HN03. Prepn is by subliming finely divided silicon at 1250° under high vacuum for 4 hrs. It is used as a coating for precision optical lenses... 

Transmission electron microscopy (TEM) resembles optical microscopy, except that electromagnetic instead of optical lenses are used to focus an electron beam on the sample. Two modes are available in TEM, a bright-freld mode where the intensity of the transmitted beam provides a two-dimensional image of the density or thickness of the sample, and a dark-field mode where the electron diffraction pattern is recorded. A combination of topographic and crystallographic information, including particle size distributions, can be obtained in this way [32],... 

If an inverse Fourier transform is calculated using the amplitudes and phases extracted from the FT for all the reflections, a lattice averaged map with pi symmetry is obtained (Fig. 5a). This map is not yet proportional to the projected potential. The various distortions introduced by the electron-optical lenses, crystal tilt etc. must first be corrected for. 

Although quartz crystals are suitable for the production of optical lenses, most lenses are manufactured from synthetically produced quartz due to the scarcity of good-grade large quartz crystals. 

NH4HF2 is used to solubilize silica and silicates in siliceous rocks of oil wells, thus to regenerate oil flow as a neutralizer for alkalies in textile plants and commercial laundries for removing stains from fabrics for treating, polishing and rapid frosting of glass plates, window panes, picture frames, ampoules and optical lenses to produce pure salts of metal fluorides in treat-... 

High refractive index optical lenses were prepared by Your et al. (1) consisting of trifluoroethyl methacrylate, butyl acrylate, phenyl ethyl acrylate, and ethylene glycol dimethacrylate. 

Medina et al. (2) prepared a high refractive index monomer component, (I), for use in optical lenses by the photoinduced [2 + 2] dimerization of dimethyl-maleiimide, (I), as illustrated in Eq. (1). 

Crosslinked poly(urea-urethane)s consisting of tris(4-isocyanatophenyl)-methane, trimethylolethane, and 4,4 -methylenebis(3-chloro-2,6-diethyl-aniline) were prepared by Rukavina et al. (2) and used in optical lenses. Polycaprolactone diol derivatives were also prepared by Rukavina et aL (3) and used in optical lenses. 

Free radically polymerizable sulfur-containing compounds, (II), were used by Ohta et al. (5) to prepared polymers, (III), useful in optical lenses as illustrated in Eq. (1). 

Optical lenses were prepared by Bojkova et al. (3) by reacting 1,1,1 -tris(hydroxy-methyl)propane with 4,4 -methylenebis(cyclohexyl isocyanate) and then postreacting with 2-mercaptoethyl sulfide. 

Other applications are in the manufacture of optical lenses,61 holograms62 and multilayer organic light-emitting devices.63... 

The norbornene derivative is polymerized by a ring opening metathesis polymerization, followed by a hydrogenation reaction. The polymers can be used for optical disks, optical lenses, and optical films or sheets. 

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