Home > Lens (optics)
:This is about the optical device. For other uses, see the list at lens.A lens is a device for either concentrating or diverging light, usually formed from a piece of shaped glass. Analogous devices used with other types of electromagnetic radiation are also called lenses: for instance, a microwave lens can be made from paraffin wax.
In its usual form, a lens consists of a slab of glass or other optically transparent material (such as perspex) with two shaped surfaces of a particular curvature. It is the refractive index of the lens material and the curvature of the two surfaces that give a particular lens its particular properties. A lens works by refracting (bending) the light that passes through it, in a similar manner to a prism.
1 History
The earliest records of lenses date to Ancient Greece, with Aristophanes' play The Clouds ( 424 BC) mentioning a burning-glassA burning-glass is a large convex lens, which can focus the sun's rays on a small area and so ignite materials. Used in 18th century chemical studies for burning materials in closed glass vessels where the products of combustion could be trapped for analy (a convex lens used to focus the sunThe Sun (also called Sol is the star in our solar system. Planet Earth orbits the Sun. Other bodies that orbit the Sun include other planets, asteroids, meteoroids, comets and dust. Not all objects passing through the solar system have been orbitally capt's rays to produce fire). The writings of Pliny the ElderGaius Plinius Secundus ( 23 79) better known as Pliny the Elder was an ancient author and scientist of some importance who wrote Naturalis Historia''. He was the son of a Roman eques by the daughter of the senator Gaius Caecilius of Novum Comum. He was bo ( 23Alternate uses, see Number 23 Centuries: 1st century BC 1st century 2nd century Decades: 20s BC 10s BC 0s BC 0s 10s 20s 30s 40s 50s 60s 70s Years: 18 19 20 21 22 23 24 25 26 27 28 Events Greek geographer Strabo publishes Geography a work covering the worl- 79Centuries: 1st century BC 1st century 2nd century Decades: 0s BC 0s 10s 20s 30s 40s 50s 60s 70s 80s 90s 100s Years: 74 75 76 77 78 79 80 81 82 83 84 Events June 23 Titus succeeds his father Vespasian as Roman emperor. August 24, beginning of eruption of M) also show that burning-glasses were known to the Roman Empire60 and 400 with major cities. During this time only Dacia and Mesopotamia were added to the Empire but were lost before 300. The Roman Empire is the term conventionally used to describe the Roman state in the centuries following its reorganization under t, and mentions what is possibly the first use of a corrective lensA corrective lens is a prosthetic lens worn on or before the eye, used to treat myopia, hypermetropia, presbyopia and astigmatism. The most common types of corrective lens are spectacle lenses and contact lenses. Myopia (short sightedness) requires biconc: NeroThis article deals with the Roman emperor Nero. For other meanings, see Nero (disambiguation . Nero Claudius Caesar Augustus Germanicus ( December 15, 37 AD June 9, 68 AD), born Lucius Domitius Ahenobarbus was the fifth and last Roman Emperor of the Julio was known to watch the gladiatorial games through a concave-shaped emerald (presumably to correct for myopia). Seneca the Younger ( 3 BC-- 65) described the magnifying effect of a glass globe filled with water. The Arabian mathematician Alhazen (Abu Ali al-Hasan Ibn Al-Haitham), ( 965- 1038) wrote the first major optical treatise which described how the lens in the human eye formed an image on the retina. Widespread use of lenses did not occur until the invention of spectacles, probably in Italy in the 1280s.
