Optical glass is a special way.made clear glass, which is used as a part for optical devices. It differs from the usual purity and increased transparency, uniformity and colorlessness. Also in it the dispersion and refractive power are strictly normalized. Compliance with such requirements increases the complexity and cost of production.
You can find many examples of home use lenses, for example, a magnifying glass - an ordinary magnifying glass - will help create a small projector from an ordinary smartphone, but optical glasses appeared not so long ago.
Lenses have been known since antiquity, but the first seriousan attempt to create glass, similar to what is used in modern devices, can be attributed to the XVII century. So, the German chemist Kunkel in one of his works mentioned the phosphoric and boric acids included in the glass component. He also spoke about the borosilicate crown, which is close to some modern materials in composition. This can be called the first successful experience in the production of glass with certain optical properties and a sufficient degree of physical and chemical homogeneity.
Manufacturing of optical glasses in industrialThe scale began at the beginning of the XIX century. Swiss Gian, together with Fraunhofer, implemented a relatively stable method of producing such glass at one of the factories in Bavaria. The key to success was the reception of melt mixing using circular movements of a vertically immersed clay rod in glass. As a result, it was possible to obtain optical glass of satisfactory quality, with a diameter of up to 250 mm.
In receiving color optical glassesadditives of substances containing copper, selenium, gold, silver and other metals are used. Cooking comes from the charge. It is loaded into refractory pots, which, in turn, are placed in a glass melting furnace. The composition of the charge can include up to 40% of glass waste, an important point is the consistency of the composition of cullet and boiling glass. The glass melt during cooking is continuously mixed using a spatula made of ceramic or platinum. Thus, a homogeneous state is achieved.
Periodically, the melt is taken on the sample,which quality is controlled. An important stage of cooking is clarification: in the glass melt from the clarifying substances initially added to the mixture, the release of a significant amount of gases begins. Large bubbles are formed, which quickly rise, capturing smaller bubbles, which inevitably form during the cooking process.
В завершение горшки извлекаются из печи, после then slowly cool down. Cooling, delayed by special techniques, can last up to eight days. It must be uniform, otherwise there may be mechanical stresses in the mass that cause cracks.
Optical glass is a material for production.lenses. They, in turn, are divided by type into collecting and dispersing. The biconvex and flat-convex lenses, as well as the concave-convex, bearing the name "positive meniscus" belong to the collectors.
Optical glass has several characteristics:
Colored optical glass is used for the production of absorption filters. Depending on the material, there are three main types of optical glasses:
Inorganic glass contains oxides and fluorides. Quartz optical glass also refers to inorganic (chemical formula SiO2).Quartz has a slight refraction and high light transmittance, it is characterized by heat resistance. A wide range of transparency allows it to be used in modern telecommunications (fiber optic cables, etc.), and silicate glass is indispensable in the manufacture of optical lenses, for example, a magnifying glass is made of quartz.
Clear silicate glass can be eitheroptical and technical. Optical is made by smelting rock crystal, the only way to get a completely homogeneous structure. In opaque glasses, small gas bubbles inside the material are responsible for the color.
In addition to silica-based silica glassso-called silicon glass is also produced, which, despite a similar base, has other optical properties. Silicon cells are able to refract X-rays and transmit infrared radiation.
Так называемое оргстекло производится на основе synthetic polymer material. This transparent and hard material belongs to thermoplastics and is often used as a replacement for silica glass. Plexiglas is resistant to many environmental factors, such as high humidity and low temperatures, but it is much softer and, therefore, more sensitive to mechanical stress. In view of its softness, organic optical glass is simply in processing - even the simplest tool for cutting metal can "take" it.
This material is great for laser processing, it is easy to put a pattern or engraving on it. As a lens, it perfectly reflects infrared rays, but transmits ultraviolet and X-rays.
Optical glasses are widely used forproduction of lenses, which, in turn, are used in many optical systems. A single collecting lens is used as a magnifying glass. In technology, lenses are an important or main part of such systems as binoculars, optical sights, microscopes, theodolites, telescopes, as well as cameras and video equipment.
Не менее важны оптические стекла для нужд ophthalmology, because without them it is difficult or impossible to correct visual deficiencies (myopia, astigmatism, hyperopia, accommodation disturbance and other diseases). Eyeglass lenses with diopters can be made from both quartz glass and high-quality plastic.
Optical glasses are important and most expensive.component of any telescope. Many amateurs themselves collect refractors, this requires a little, but most importantly - a convex glass lens.
At the beginning of the last century for the manufacture of oneA powerful astronomical lens, or rather its polishing, took several years. For example, in 1982, millionaire Charles Yerkes was asked by the head of the University of Chicago, William Harper, to finance the observatory. Yerks invested about three hundred thousand dollars in it, and forty thousand went to buy a lens for the most powerful telescope at the time on the planet. The Observatory was named after financier Yerks, and so far this refractor with a lens diameter of 102 cm is considered the largest in the world.
Telescopes with a large diameter are reflectors, in which a mirror is a light-collecting element.
There is another type of lens used asin astronomy and in ophthalmology - glass with convex-concave surfaces, which is called meniscus. It can be of two types: scattering and collecting. In the scattering meniscus, the extreme part is thicker than the central part, and in the collecting part the central part is thinner.
