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Dioptre
A dioptre (British spelling) or diopter (American spelling) is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dioptre = 1 m−1. It is normally used to express the optical power of a lens or curved mirror, which is a physical quantity equal to the reciprocal of the focal length, expressed in metres. For example, a 3-dioptre lens brings parallel rays of light to focus at metre. A flat window has an optical power of zero dioptres, as it does not cause light to converge or diverge. Dioptres are also sometimes used for other reciprocals of distance, particularly radii of curvature and the vergence of optical beams. The main benefit of using optical power rather than focal length is that the thin lens formula has the object distance, image distance, and focal length all as reciprocals. Additionally, when relatively thin lenses are placed close together their powers approximately add. Thus, a thin 2.0-dioptre lens placed close to a t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focal Length
The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light. A system with a shorter focal length bends the rays more sharply, bringing them to a focus in a shorter distance or diverging them more quickly. For the special case of a thin lens in air, a positive focal length is the distance over which initially collimated (parallel) rays are brought to a focus, or alternatively a negative focal length indicates how far in front of the lens a point source must be located to form a collimated beam. For more general optical systems, the focal length has no intuitive meaning; it is simply the inverse of the system's optical power. In most photography and all telescopy, where the subject is essentially infinitely far away, longer focal length (lower opti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Power Of A Lens
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes the behaviour of visible light, visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for by using the Classical electromagnetism, classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of Ray (optics), rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thin Lens Formula
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), usually arranged along a common axis. Lenses are made from materials such as glass or plastic, and are ground and polished or molded to a desired shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called lenses, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. Lenses are used in various imaging devices like telescopes, binoculars and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia. History The word ''lens'' comes from '' lēns'', the Latin name of the lentil (a seed of a lentil plant), bec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Additive
Additive may refer to: Mathematics * Additive function, a function in number theory * Additive map, a function that preserves the addition operation * Additive set-functionn see Sigma additivity * Additive category, a preadditive category with finite biproducts * Additive inverse, an arithmetic concept Science * Additive color, as opposed to subtractive color * Additive model, a statistical regression model * Additive synthesis, an audio synthesis technique * Additive genetic effects * Additive quantity, a physical quantity that is additive for subsystems; see Intensive and extensive properties Engineering * Feed additive * Gasoline additive, a substance used to improve the performance of a fuel, lower emissions or clean the engine * Oil additive, a substance used to improve the performance of a lubricant * Weakly additive, the quality of preferences in some logistics problems * Polymer additive * Pit additive, a material aiming to reduce fecal sludge build-up and control ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smith-Kettlewell Institute
The Smith-Kettlewell Eye Research Institute is a nonprofit research institute in San Francisco, California, with a focus on vision science and rehabilitation engineering. It was founded in 1959 by Arthur Jampolsky and Alan B. Scott, when some members of Stanford University's Ophthalmology Department elected to stay in San Francisco rather than move to Palo Alto. Scientific contributions The Institute did early experiments in sensory substitution, especially the substitution of tactile information for visual information to help blind people navigate and other methods to obtain accessible technology. This research is often performed by scientists who are blind, such as Josh Miele. The institute's use of botulinum toxin in humans as a therapy to treat strabismus. This initial therapeutic use led to later cosmetic use in Botox. Other impactful work involved Anthony Norcia's study of vision in infants and Erich Sutter's invention of the multifocal electroretinogram and of the mu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johannes Kepler
Johannes Kepler (; ; 27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his laws of planetary motion, and his books ''Astronomia nova'', ''Harmonice Mundi'', and ''Epitome Astronomiae Copernicanae''. These works also provided one of the foundations for Newton's theory of universal gravitation. Kepler was a mathematics teacher at a seminary school in Graz, where he became an associate of Prince Hans Ulrich von Eggenberg. Later he became an assistant to the astronomer Tycho Brahe in Prague, and eventually the imperial mathematician to Emperor Rudolf II and his two successors Matthias and Ferdinand II. He also taught mathematics in Linz, and was an adviser to General Wallenstein. Additionally, he did fundamental work in the field of optics, invented an improved version of the refracting (or Keplerian) telescope, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioptrice
Johannes Kepler (; ; 27 December 1571 – 15 November 1630) was a German astronomer, German mathematician, mathematician, astrologer, Natural philosophy, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his Kepler's laws of planetary motion, laws of planetary motion, and his books ''Astronomia nova'', ''Harmonice Mundi'', and ''Epitome Astronomiae Copernicanae''. These works also provided one of the foundations for Isaac Newton, Newton's theory of Newton's law of universal gravitation, universal gravitation. Kepler was a mathematics teacher at a seminary school in Graz, where he became an associate of Hans Ulrich von Eggenberg, Prince Hans Ulrich von Eggenberg. Later he became an assistant to the astronomer Tycho Brahe in Prague, and eventually the imperial mathematician to Rudolf II, Holy Roman Emperor, Emperor Rudolf II and his two successors Matthias, Holy Roman Emperor, Matthias and Ferdinand II, Holy Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferdinand Monoyer
Ferdinand Monoyer (9 May 1836 – 11 July 1912) was a French ophthalmologist, known for introducing the dioptre in 1872. He invented the Monoyer chart, used to test visual acuity. He inserted his name in the random letters of the chart. It appears when one reads vertically from bottom to top on each side. Biography Monoyer was of Alsatian heritage by his mother and his father was a French military doctor. He was an associate professor of medical physics at the Faculty of Medicine, University of Strasbourg in 1871. Later, he was the director of the Ophthalmic Clinic of the Faculty of Medicine, Nancy-Université from 1872 to 1877. He was also professor of medical physics at the Faculty of Medicine, University of Lyon The University of Lyon (french: Université de Lyon), located in Lyon and Saint-Étienne, France, is a center for higher education and research comprising 11 members and 24 associated institutions. The three main universities in this center are: C ..., fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophthalmologist
Ophthalmology ( ) is a surgery, surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a medical degree, a doctor specialising in ophthalmology must pursue additional postgraduate residency (medicine), residency training specific to that field. This may include a one-year integrated internship that involves more general medical training in other fields such as internal medicine or general surgery. Following residency, additional specialty training (or fellowship) may be sought in a particular aspect of eye pathology. Ophthalmologists prescribe medications to treat eye diseases, implement laser therapy, and perform surgery when needed. Ophthalmologists provide both primary and specialty eye care - medical and surgical. Most ophthalmologists participate in academic research on eye diseases at some point in their training an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vision Care
Ophthalmology ( ) is a surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a medical degree, a doctor specialising in ophthalmology must pursue additional postgraduate residency training specific to that field. This may include a one-year integrated internship that involves more general medical training in other fields such as internal medicine or general surgery. Following residency, additional specialty training (or fellowship) may be sought in a particular aspect of eye pathology. Ophthalmologists prescribe medications to treat eye diseases, implement laser therapy, and perform surgery when needed. Ophthalmologists provide both primary and specialty eye care - medical and surgical. Most ophthalmologists participate in academic research on eye diseases at some point in their training and many include research as part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deutsches Institut Für Normung
' (DIN; in English, the German Institute for Standardisation Registered Association) is the German national organization for standardization and is the German ISO member body. DIN is a German Registered Association ('' e.V.'') headquartered in Berlin. There are currently around thirty thousand DIN Standards, covering nearly every field of technology. History Founded in 1917 as the ' (NADI, "Standardisation Committee of German Industry"), the NADI was renamed ' (DNA, "German Standardisation Committee") in 1926 to reflect that the organization now dealt with standardization issues in many fields; viz., not just for industrial products. In 1975 it was renamed again to ', or 'DIN' and is recognised by the German government as the official national-standards body, representing German interests at the international and European levels. The acronym, 'DIN' is often incorrectly expanded as ' ("German Industry Standard"). This is largely due to the historic origin of the DIN as "NADI" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Metre
Reciprocal length or inverse length is a quantity or measurement used in several branches of science and mathematics. As the reciprocal of length, common units used for this measurement include the reciprocal metre or inverse metre (symbol: m−1), the reciprocal centimetre or inverse centimetre (symbol: cm−1). Quantities measured in reciprocal length include: *absorption coefficient or attenuation coefficient, in materials science * curvature of a line, in mathematics *gain, in laser physics *magnitude of vectors in reciprocal space, in crystallography *more generally any spatial frequency e.g. in cycles per unit length *optical power of a lens, in optics *rotational constant of a rigid rotor, in quantum mechanics *wavenumber, or magnitude of a wavevector, in spectroscopy *density of a linear feature in hydrology and other fields; see kilometre per square kilometre In optics, the dioptre is a unit equivalent to reciprocal metre. Measure of energy In some branches ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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