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Topic: Lens


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In the News (Sat 20 Jul 19)

  
 Lens (optics) - Wikipedia, the free encyclopedia
where n is the refractive index of the lens material, n' is the refractive index of the medium which the lens is in and d is the distance along the lens axis between the two surfaces (known as the thickness of the lens).
In the latter, an object at the focal length distance from the lens is imaged at infinity.
Chromatic aberration is caused by the dispersion of the lens material, the variation of its refractive index n with the wavelength of light.
en.wikipedia.org /wiki/Lens_(optics)   (1970 words)

  
 Fisheye lens - Wikipedia, the free encyclopedia
Fisheye lenses achieve extremely wide angles of view by foregoing a rectilinear image, opting instead for a special mapping (for example: equisolid angle), which gives images a characteristic convex appearance.
In photography, a fisheye lens is a wide-angle lens that projects deliberately distorted images.
A panorama by rotating lens or stitching images (cylindrical perspective) is not a fisheye photo.
en.wikipedia.org /wiki/Fisheye_lens   (434 words)

  
 Zoom lens - Wikipedia, the free encyclopedia
Early forms of zoom lenses were used in optical telescopes to provide continuous variation of the magnification of the image, and this was first reported in the proceedings of the Royal Society in 1834.
This compensation may be done by mechanical means (moving the complete lens assembly as the magnification of the lens changes), or optically (arranging the position focal plane to vary as little as possible as the lens is zoomed).
For example, a zoom lens with focal lengths ranging from 100 mm to 400 mm may be described as a "4x" zoom.
en.wikipedia.org /wiki/Zoom_lens   (1080 words)

  
 Intraocular lens - Wikipedia, the free encyclopedia
Insertion of an intraocular lens is the most commonly performed eye surgical procedure; cataracts are the most common eye disease.
An intraocular lens (or IOL) is an implanted lens in the eye, usually replacing the existing crystalline lens because it has been clouded over by a cataract.
Intraocular lenses have been used since 1999 for correcting larger errors in myopic (near-sighted), hyperopic (far-sighted), and astigmatic eyes.
en.wikipedia.org /wiki/Intraocular_lens   (1213 words)

  
 Lens flare - Wikipedia, the free encyclopedia
Lens flare patterns typically spread widely across the scene and change location with the camera's movement relative to light sources, tracking with the light position and fading as the camera points away from the bright light until it causes no flare at all.
Lens flare is the light scattered in lens systems through generally unwanted image formation mechanisms, such as internal reflection and scattering from lens inhomogeneities.
The spatial distribution of the lens flare typically manifests as several starbursts, rings, or circles in a row across the image or view.
en.wikipedia.org /wiki/Lens_flare   (477 words)

  
 Lens (optics) - Wikipedia, the free encyclopedia
The beam after passing through the lens appears to be emanating from a particular point on the axis in front of the lens; the distance from this point to the lens is also known as the focal length, although it is negative with respect to the focal length of a converging lens.
where n is the refractive index of the lens material, n' is the refractive index of the medium which the lens is in and d is the distance along the lens axis between the two surfaces (known as the thickness of the lens).
If the lens is biconvex or plano-convex, a collimated or parallel beam of light travelling parallel to the lens axis and passing through the lens will be converged (or focused) to a spot on the axis, at a certain distance behind the lens (known as the focal length).
en.wikipedia.org /wiki/Lens_(optics)   (2334 words)

  
 its7
Accuracy of determination of lens optical centre displacement is defined by the angular aperture of lens, by the source sizes and by the type of observation system.
Local deformations of the ITS,such as mutual offset and torsion of the end-cones, possible ellipticity, saggings and torsions of the detector ladders will bring about the offset of the detectors from the basic position inside the ITS, and will decrease the accuracy of the position determination.
Fig.8: Results of measurements of sagging of one of the space frames 1.1m structures that provided about 52 mcm sagging under the uniformely distributed load of Si-detectors.
feofilov.home.cern.ch /feofilov/its7.htm   (2334 words)

  
 Photographic lens - Wikipedia, the free encyclopedia
The lens may usually be focused by adjusting the distance from the lens assembly to the image-forming surface, or by moving elements within the lens assembly.
The maximum usable aperture of a lens is usually specified, as the focal ratio or f-number, which is equal to the focal length divided by the actual aperture diameter in the same units.
The two main optical parameters of a photographic lens are the focal length and the maximum aperture.
en.wikipedia.org /wiki/Photographic_lens   (1292 words)

  
 Lens (optics) - Wikipedia, the free encyclopedia
The beam after passing through the lens appears to be emanating from a particular point on the axis in front of the lens; the distance from this point to the lens is also known as the focal length, although it is negative with respect to the focal length of a converging lens.
If the lens is biconvex or plano-convex, a collimated or parallel beam of light travelling parallel to the lens axis and passing through the lens will be converged (or focused) to a spot on the axis, at a certain distance behind the lens (known as the focal length).
In the latter, an object at the focal length distance from the lens is imaged at infinity.
en.wikipedia.org /wiki/Lens_(optics)   (2541 words)

  
 Lens (anatomy) - Wikipedia, the free encyclopedia
During the fetal stage, the development of the lens is aided by the hyaloid artery.
The lens or crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to focus on the retina.
In adults, the lens depends entirely upon the aqueous and vitreous humors for nourishment.
en.wikipedia.org /wiki/Lens_(vision)   (380 words)

  
 LENS (FRANCE) - LoveToKnow Article on LENS (FRANCE)
N.N.E. of Arras by rail on the Deule and on the Lens canal.
lens, lentil, on account of the similarity of the form of a lens to that of a lentil seed), in optics, an instrument which refracts the luminous rays proceeding from an object in such a manner as to produce an image of the object.
The most important type of lens is the spherical lens, which is a piece of transparent material bounded by two spherical surfaces, the boundary at the edge being usually cylindrical or conical.
www.1911encyclopedia.org /L/LE/LENS_FRANCE_.htm   (380 words)

  
 PANASONIC Belgium - Standard Lens
A lens with the focal distance that is closest to the field of vision of the human eye, which is approximately 50 mm.
www.panasonic.be /servlet/PB/menu/1042708_l2   (23 words)

  
 Prime - Wikipedia, the free encyclopedia
Prime (lending market sector), within which lending product providors are focused on selling products (mortgage, loan or credit card) to the individual who is high-value and/or has a good credit history - as opposed to the subprime market sector.
Prime ideal, subset of a ring in mathematics
Prime element in the integral domain of mathematics
en.wikipedia.org /wiki/Prime   (199 words)

  
 Prime lens - Wikipedia, the free encyclopedia
In film and photography, a prime lens is a photographic lens whose focal length is fixed, as opposed to a zoom lens, which has a variable focal length.
Prime lenses are not as versatile as their zoom counterparts, but are often of superior optical quality and lower cost.
In 35mm photography a "normal" prime commonly refers to a prime lens with 50mm focal length because it renders an image most like what is seen by the human eye in real life.
en.wikipedia.org /wiki/Prime_lens   (256 words)

  
 ninemsn Encarta - Lens (optics)
The distance from the centre of the lens to the principal focus is known as the focal length of the lens.
Rays of light striking the lens parallel to the principal axis are refracted by the “prisms” in such a way that they all pass through a single point, the principal focus of the lens.
After polishing, the lens is “edged” by grinding the edge until the physical centre and the optical centre of the lens coincide.
au.encarta.msn.com /encyclopedia_761553453/Lens_(optics).html   (844 words)

  
 Photographic lens - Wikipedia, the free encyclopedia
The lens may usually be focused by adjusting the distance from the lens assembly to the image-forming surface, or by moving elements within the lens assembly.
The maximum usable aperture of a lens is usually specified, as the focal ratio or f-number, the focal length divided by the actual aperture in the same units.
An extreme wideangle lens of large aperture must be of very complex construction to correct for optical aberrations, which are worse at the edge of the field and when the edge of a large lens is used for image-forming.
en.wikipedia.org /wiki/Camera_lens   (1272 words)

  
 Contact lens - Wikipedia, the free encyclopedia
Intraocular contact lenses, also known as an implantable contact lenses, are special small corrective lenses surgically implanted in the eye's posterior chamber behind the iris and in front of the lens to correct higher amounts of myopia and hyperopia.
Contact lenses usually serve the same corrective purpose as conventional glasses, but are lightweight and virtually invisible—many commercial lenses are tinted a faint blue for visibility.
Before touching the contact lens or one's eyes, it is important to thoroughly wash and rinse hands with a soap that does not contain moisturizers or allergens such as fragrances.
en.wikipedia.org /wiki/Contact_lens   (3880 words)

  
 Lens, Belgium - Wikipedia, the free encyclopedia
Lens is a municipality located in the Belgian province of Hainaut.
On January 1, 2005 Lens had a total population of 3,908.
en.wikipedia.org /wiki/Lens,_Belgium   (64 words)

  
 Focal length - Wikipedia, the free encyclopedia
For a diverging lens (e.g., a concave lens), the focal length is negative, and is the distance from the lens to the point at which a collimated beam appears to be emerging from after passing through the lens.
For a converging lens (e.g., a convex lens), the focal length is positive, and is the distance from the lens at which a beam of collimated light will be focused to a single spot.
The focal length of a lens is the distance along the optical axis from the lens to the focus (or focal point).
en.wikipedia.org /wiki/Focal_length   (414 words)

  
 The Columbia Encyclopedia, Sixth Edition: lens @ HighBeam Research
The lens of the eye is known as a crystalline lens.
Examples are the double convex lens (both surfaces curved outward as in the simple magnifying glass), the plano-convex (one flat and one convex surface), and the concavo-convex (one surface concave, the other convex).
LENS [lens] device for forming an image of an object by the refraction of light.
www.highbeam.com /library/doc0.asp?DOCID=1E1:lens&refid=ip_encyclopedia_hf   (750 words)

  
 Cieli Medicei - Eyepiece lens
Biconcave eyepiece lens mounted in a cardboard ring with the edge covered with red marbled paper.
The diameter of the lens is about 35 mm, the focal length -67 mm (the negative focal length means that the lens is diverging).
The lens is contained in a section of cardboard tube covered with red marbled paper.
www.imss.fi.it /news/cielimedicei/03/estrumento10.html   (750 words)

  
 RC Lens - Wikipedia, the free encyclopedia
In recent years, Lens have been competitive in the top level of French football, winning the league in the 1997-98 season, finishing second in 2001-02 and winning the Coupe de la Ligue in 2000.
Lens originally played in green (as the club's seat was located "Place Verte", literally Green Square) and black (for the coal dug in the area) stripes.
Three Lens players won the gold medal in the 1984 Los Angeles Olympic Games, strikers François Brisson and Daniel Xuereb who scored a goal apiece in France's triumph over Brazil 2-0 in the final at the Pasadena Rose Bowl in front of a 103,000 crowd, and defender Didier Sénac.
en.wikipedia.org /wiki/RC_Lens   (601 words)

  
 Photography - Wikipedia, the free encyclopedia
For example, using a long lens and a large aperture, such as might be used with a large format camera, a subject's eyes might be in sharp focus while the tip of his nose is noticeably blurred.
The first photograph is considered to be an image produced in 1826 by the French inventor Nicéphore Niépce on a polished pewter plate covered with a petroleum derivative called bitumen of Judea.
Photographers control the camera to expose the light recording material (usually film or a charge-coupled device) to light.
en.wikipedia.org /wiki/Photography   (3879 words)

  
 Lens flare - Wikipedia, the free encyclopedia
Lens flare is the light scattered in lens systems through generally unwanted image formation mechanisms, such as internal reflection and scattering from material inhomogeneities in the lens.
Lens flare patterns typically spread widely across the scene and change location with the camera's movement relative to light sources, tracking with the light position and fading as the camera points away from the bright light until it causes no flare at all.
Lens flare is extremely difficult to control when a bright light source like the sun is just outside the frame.
en.wikipedia.org /wiki/Lens_flare   (485 words)

  
 Gravitational lens - Wikipedia, the free encyclopedia
A gravitational lens is formed when the light from a very distant, bright source (such as a quasar) is "bent" around a massive object (such as a massive galaxy) between the source object and the observer.
This gravitational lens was discovered accidentally by Dennis Walsh, Bob Carswell, and Ray Weymann using the Kitt Peak National Observatory 2.1 meter telescope.
The process is known as gravitational lensing, and is one of the predictions of Albert Einstein's general relativity theory.
en.wikipedia.org /wiki/Gravitational_lens   (1562 words)

  
 Lens, Pas-de-Calais - Wikipedia, the free encyclopedia
Lens, along with Douai, forms the metropolitan area (in French: aire urbaine) of Douai-Lens, whose population at the 1999 census was 552,682.
Lens is commune in northern France, in the Pas-de-Calais département.
Lens will also be from 2009 the location of the Louvre-Lens.
en.wikipedia.org /wiki/Lens,_France   (1562 words)

  
 Electrostatic lens - Wikipedia, the free encyclopedia
An electrostatic lens is a lens that transports electrons emitted from a sample to an electron analyser.
There are several types of electrostatic lenses: cylinder lenses, aperture lenses, and quadrupole lenses.
Systems of electrostatic lenses can be designed in the same way as optical lenses, so electrostatic lenses easily magnify or converge the electron trajectories.
en.wikipedia.org /wiki/Electrostatic_lens   (1562 words)

  
 LaserMyEye :: Encyclopedia :: Gas permeable (GP) contact lens
For this reason, GP lens wearers need to consider carefully their visual needs, preferences and expectations from laser eye surgery as they have a higher probability than average of trading off vision quality for reduction of dependence on corrective lenses.
Additionally, GP lens wearers need to be cautious about the amount of time their lenses should be removed before their surgery.
A contact lens made of a material that allows oxygen to pass through.
www.lasermyeye.org /encyclopedia/gplens.html   (303 words)

  
 Concave lens - Wikipedia, the free encyclopedia
A concave lens is a lens with inward-curving (concave) surfaces: the ends are wide, the middle is thin.
Nicholas of Cusa is believed to have been the first to discover the benefits of concave lens for the treatment of myopia in 1451.
Concave lenses can be used in telescopes, microscopes, and eyeglasses.
en.wikipedia.org /wiki/Concave_lens   (96 words)

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