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Opticians Of The Medieval Islamic World
An optician, or ''dispensing optician'', is a technical practitioner who designs, fits and dispenses lenses for the correction of a person's vision. Opticians determine the specifications of various ophthalmic appliances that will give the necessary correction to a person's eyesight. Some registered or licensed opticians also design and fit special appliances to correct cosmetic, traumatic or anatomical defects. These devices are called shells or artificial eyes. Other registered or licensed opticians manufacture lenses to their own specifications and design and manufacture spectacle frames and other devices. Corrective ophthalmic appliances may be contact lenses, spectacles lenses, low vision aids or ophthalmic prosthetics to those who are partially sighted. The appliances are mounted either on the eye as contact lenses or mounted in a frame or holder in front of the eye as spectacles or as a monocle. Opticians may work in any variety of settings such as joint practice, hospi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Navy 021029-N-3228G-001 Adjusting A Customer's Eyeglasses
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five major unincorporated territories, nine United States Minor Outlying Islands, Minor Outlying Islands, and 326 Indian reservations. The United States is also in Compact of Free Association, free association with three Oceania, Pacific Island Sovereign state, sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Palau, Republic of Palau. It is the world's List of countries and dependencies by area, third-largest country by both land and total area. It shares land borders Canada–United States border, with Canada to its north and Mexico–United States border, with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnifying Glass
A magnifying glass is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle. A magnifying glass can be used to focus light, such as to concentrate the sun's radiation to create a hot spot at the focus for fire starting. A sheet magnifier consists of many very narrow concentric ring-shaped lenses, such that the combination acts as a single lens but is much thinner. This arrangement is known as a Fresnel lens. The magnifying glass is an icon of detective fiction, particularly that of Sherlock Holmes. History "The evidence indicates that the use of lenses was widespread throughout the Middle East and the Mediterranean basin over several millennia". The earliest explicit written evidence of a magnifying device is a joke in Aristophanes's ''The Clouds'' from 424 BC, where magnifying lenses to ignite tinder were sold in a pharmacy, and Pliny the Elder's "lens", a glass globe filled with water, used to cauteri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyeglass Prescription
An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient. If an eye examination indicates that corrective lenses are appropriate, the prescriber generally provides the patient with an eyewear prescription at the conclusion of the exam. The parameters specified on spectacle prescriptions vary, but typically include the patient's name, power of the lenses, any prism to be included, the pupillary distance, expiration date, and the prescriber's signature. The prescription is typically determined during a refraction, using a phoropter and asking the patient which of two lenses is better, or by automated refractor, or through the technique of retinoscopy. A dispensing optician will take a prescription written by an optometrist and order and/or assemble the frames and lenses to then be dispensed to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lensometer
A lensmeter or lensometer (sometimes even known as focimeter or vertometer), is an ophthalmic instrument. It is mainly used by optometrists and opticians to measure the back or front vertex power of a spectacle lens and verify the correct prescription in a pair of eyeglasses, to properly orient and mark uncut lenses, and to confirm the correct mounting of lenses in spectacle frames. Lensmeters can also verify the power of contact lenses, if a special lens support is used. The parameters appraised by a lensmeter are the values specified by an ophthalmologist or optometrist on the patient's prescription: sphere, cylinder, axis, add, and in some cases, prism. The lensmeter is also used to check the accuracy of progressive lenses, and is often capable of marking the lens center and various other measurements critical to proper performance of the lens. It may also be used prior to an eye examination to obtain the last prescription the patient was given, in order to expedite the subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pince-nez
Pince-nez ( or , plural form same as singular; ) is a style of glasses, popular in the late 19th and early 20th centuries, that are supported without earpieces, by pinching the bridge of the nose. The name comes from French ''pincer'', "to pinch", and ''nez'', "nose". Although pince-nez were used in Europe since the late 14th century, modern ones appeared in the 1840s and reached their peak popularity around 1880 to 1900. Because they did not always stay on the nose when placed, and because of the stigma sometimes attached to the constant wearing of eyeglasses, pince-nez were often connected to the wearer's clothing or ear via a suspension chain, cord, or ribbon so that they could be easily removed and not lost. Varieties Rivet spectacles The earliest form of eyewear for which any archaeological record exists comes from the middle of the 15th century. It is a primitive pince-nez whose frames were made from pieces of either metacarpal bone from the forelimb of a bull or f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lorgnette
A lorgnette () is a pair of spectacles with a handle, used to hold them in place, rather than fitting over the ears or nose. The word ''lorgnette'' is derived from the French ''lorgner'', to take a sidelong look at, and Middle French, from ''lorgne'', squinting. Their precise origin is debated: some sources describe English scientist George Adams the elder as their inventor, while others cite his son George Adams the younger. The lorgnette was usually used as a piece of jewelry, rather than to enhance vision. Fashionable ladies usually preferred them to spectacles. These were very popular at masquerade parties and used often at the opera. They were worn popularly in the 19th century. The lorgnette was employed as a prop and affectation by early 20th century trial lawyer Earl Rogers, and one is featured on the front cover dust jacket of his biography, ''Final Verdict'', by his daughter Adela Rogers St. Johns. Etymology This word comes from French ''lorgnette'', from ''lorgne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Isaac Hawkins
John Isaac Hawkins (1772–1855) was an inventor who practised civil engineering. He was known as the co-inventor of the ever-pointed pencil, an early mechanical pencil, and of the upright piano. Early life Hawkins was born 14 March 1772 at Taunton, Somerset, England,R. L. Tafel, ''Documents Concerning Swedenborg'', p. 1217 the son of Joan Wilmington and her husband Isaac Hawkins, a watchmaker. The father, Isaac Hawkins, would become a Wesleyan minister, but was expelled by John Wesley; and after moving the family to Moorfields in London he was a minister in the Swedenborgian movement, which John Isaac would also follow. John Isaac emigrated to the United States about 1790, attending the College of New Jersey, where he studied medicine and later, chemical filtration. Hawkins married in New Jersey, and was living at Bordentown and Philadelphia. In his own account, he was influenced by work of Georg Moritz Lowitz to try charcoal for filtration purposes, and ran an exhibition on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bifocals
Bifocals are eyeglasses with two distinct optical powers. Bifocals are commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism. History Benjamin Franklin is generally credited with the invention of bifocals. He decided to saw his lenses in half so he could read the lips of speakers of French at court, the only way he could understand them. Historians have produced some evidence to suggest that others may have come before him in the invention; however, a correspondence between George Whatley and John Fenno, editor of the ''Gazette of the United States'', suggested that Franklin had indeed invented bifocals, and perhaps 50 years earlier than had been originally thought. Despite this, the College of Optometrists concluded: :Unless further evidence emerges all we can say for certain is that Franklin was one of the first people to wear split bifocals and this act of wearing them caused his name to be associated with the ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benjamin Franklin
Benjamin Franklin ( April 17, 1790) was an American polymath who was active as a writer, scientist, inventor, statesman, diplomat, printer, publisher, and political philosopher. Encyclopædia Britannica, Wood, 2021 Among the leading intellectuals of his time, Franklin was one of the Founding Fathers of the United States, a drafter and signer of the United States Declaration of Independence, and the first United States Postmaster General. As a scientist, he was a major figure in the American Enlightenment and the history of physics for his studies of electricity, and for charting and naming the current still known as the Gulf Stream. As an inventor, he is known for the lightning rod, bifocals, and the Franklin stove, among others. He founded many civic organizations, including the Library Company, Philadelphia's first fire department, and the University of Pennsylvania. Isaacson, 2004, p. Franklin earned the title of "The First American" for his early and indefa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Ayscough
James Ayscough (born 1720, died 1759) was an English optician and designer and maker of scientific instruments. He was apprenticed to an optician named James Mann from 1743 to 1747. James Ayscough became known for his microscopes. His shop was in London between 1740 and 1759. Around the year 1752, James Ayscough introduced spectacles with double-hinged side pieces. Although he made clear lenses, he recommended lenses tinted blue or green to treat some vision problems. These spectacles with tinted lenses are believed to be the precursors to sunglasses Sunglasses or sun glasses (informally called shades or sunnies; more names below) are a form of protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damaging or discomforting the eyes. They can s .... In February 1755 he began to contribute to the ''Gentleman's Magazine'' a daily register of the weather, month by month. It included barometric reading of pressure, and two tempe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation from α-quartz to β-quartz takes place abruptly at . Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz, several of which are classified as gemstones. Since antiquity, varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings, especially in Eurasia. Quartz is the mineral defining the val ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
