Mirror 20545 225513308 2008-07-14T02:18:55Z 68.196.111.12 /* Instruments */ {{otheruses4|wave reflectors (mainly, specular reflection of visible light)}} [[Image:Mirror.jpg|frame|right|A mirror, reflecting a [[vase]].]] A '''mirror''' is an object with a surface that has good [[specular reflection]]; that is, it is smooth enough to form an [[image]]. The most familiar type of mirror is the [[plane mirror]], which has a flat surface. [[Curved mirror]]s are also used, to produce [[magnification|magnified]] or diminished images or focus light or simply distort the reflected image. Mirrors are most commonly used for [[personal grooming]] (in which case the old-fashioned term "looking-glass" can be used), decoration, and architecture. Mirrors are also used in scientific apparatus such as [[telescope]]s and [[laser]]s, [[camera]]s, and industrial machinery. Most mirrors are designed for [[visible light]]; however, mirrors designed for other types of waves or other [[wavelength]]s of [[electromagnetic radiation]] are also used, especially in optical [[#Instruments|instruments]]. ==History== The earliest manufactured mirrors were pieces of polished stone such as [[obsidian]], a naturally occurring [[volcanic glass]]. Examples of obsidian mirrors found in [[Anatolia]] (modern-day Turkey) have been dated to around 6000 BC. Polished stone mirrors from central and south America date from around 2000 BC onwards.<ref name="Enoch">[http://www.optvissci.com/pt/re/ovs/pdfhandler.00006324-200610000-00017.pdf History of Mirrors Dating Back 8000 Years], Jay M. Enoch, School of Optometry, University of California at Berkeley</ref> Mirrors of polished copper were crafted in [[Mesopotamia]] from 4000 BC,<ref name="Enoch"/> and in ancient Egypt from around 3000 BC.<ref>[http://www.tekniskamuseet.se/templates/Page.aspx?id=12447 The National Museum of Science and Technology, Stockholm]</ref> In China, bronze mirrors were manufactured from around 2000 BC.<ref>[http://www.chinavoc.com/arts/handicraft/bronze/patternchange.asp Chinavoc.com]</ref> [[Metal]]-coated [[glass]] mirrors are said to have been invented in [[Sidon]] (modern-day Lebanon) in the first century AD,<ref>[http://www.digitalegypt.ucl.ac.uk/metal/mirrors.html Mirrors in Egypt], Digital Egypt for Universities</ref> and glass mirrors backed with [[gold leaf]] are mentioned by the Roman author [[Pliny the Elder|Pliny]] in his [[Natural History (Pliny)|''Natural History'']], written in about 77 AD.<ref>[http://www.umich.edu/~kelseydb/Exhibits/WondrousGlass/RomanGlass-Wondrous.html Wondrous Glass: Images and Allegories], Kelsey Museum of Archaeology</ref> The Romans also developed a technique for creating crude mirrors by coating blown glass with molten lead.<ref>[http://www.c-s-p.org/Flyers/9781847181930-sample.pdf The Book of the Mirror], Cambridge Scholars Publishing, edited by Miranda Anderson</ref> [[Refraction|Refracting]] [[parabolic mirror]]s were first described by the [[Islamic physics|Arabian physicist]], [[Ibn Sahl]], in the 10th century, and was later described again by [[Ibn al-Haytham]] (Alhazen) in his famous ''[[Book of Optics]]'' (1021).<ref>Roshdi Rashed (1990), "A Pioneer in Anaclastics: Ibn Sahl on Burning Mirrors and Lenses", ''[[Isis (journal)|Isis]]'' '''81''' (3), p. 464-491 [464-468].</ref> Ibn al-Haytham discussed [[Curved mirror|concave and convex mirrors]] in both [[Cylinder (geometry)|cylindrical]] and [[Spherical geometry|spherical geometries]],<ref>R. S. Elliott (1966). ''Electromagnetics'', Chapter 1. [[McGraw-Hill]].</ref> described spherical and parabolic mirrors,<ref>Dr. Nader El-Bizri, "Ibn al-Haytham or Alhazen", in Josef W. Meri (2006), ''Medieval Islamic Civilization: An Encyclopaedia'', Vol. II, p. 343-345, [[Routledge]], New York, London.</ref> carried out a number of experiments with mirrors, and solved the problem of finding the point on a convex mirror at which a ray coming from one point is reflected to another point.<ref name=Deek>Dr. Mahmoud Al Deek. "Ibn Al-Haitham: Master of Optics, Mathematics, Physics and Medicine, ''Al Shindagah'', November-December 2004.</ref> By the 11th century, clear glass mirrors were being produced in [[Al-Andalus|Moorish Spain]].<ref name=Ajram>{{cite book|author=Dr. Kasem Ajram|title=The Miracle of Islam Science|edition=2nd Edition|publisher=Knowledge House Publishers|year=1992|id=ISBN 0-911119-43-4}}</ref> Some time during the early [[Renaissance]], European manufacturers perfected a superior method of coating glass with a tin-mercury [[amalgam]]. The exact date and location of the discovery is unknown, but in the 16th century, [[Venice]], a city famed for its glass-making expertise, became a centre of mirror production using this new technique. Glass mirrors from this period were extremely expensive luxuries.<ref>[http://links.jstor.org/sici?sici=0039-3630%28199302%2938%3A1%3C3%3ATTMIMT%3E2.0.CO%3B2-8 The Tin-Mercury Mirror: Its Manufacturing Technique and Deterioration Processes], Per Hadsund, Studies in Conservation, Vol. 38, No. 1 (Feb., 1993)</ref> The [[Saint-Gobain]] factory, founded by royal initiative in France, was an important manufacturer, and [[Bohemia]]n and German glass, often rather cheaper, was also important. The invention of the [[silvering|silvered-glass]] mirror is credited to German chemist [[Justus von Liebig]] in 1835. His process involved the deposition of a thin layer of metallic silver onto glass through the chemical reduction of silver nitrate. This silvering process was adapted for mass manufacturing and led to the greater availability of affordable mirrors. Nowadays, mirrors are often produced by the [[vacuum deposition]] of [[aluminium]] (or sometimes silver) directly onto the glass substrate. ==Manufacturing== Most mirrors are made by applying a reflective coating to a suitable substrate. The most common such substrate is [[glass]], due to its ease of fabrication, its rigidity, and its ability to take a smooth finish. The reflective coating is typically applied to the ''back'' surface of the glass, so that it is protected from corrosion and accidental damage. (Glass is much more scratch-resistant than most substrates.) The substrate is shaped, polished and cleaned, and is then coated. Glass mirrors are most often coated with [[silver]] or [[aluminium]], implemented by a series of coatings: # tin # silver # chemical activator # copper # paint The tin is applied because the silver will not bond with the glass. The activator causes the tin/silver to harden. Copper is added for long-term durability.<ref name="How It's Made ep 305">Episode 305 of [[How It's Made]], filmed at [http://www.laverreriewalker.com/ La Verrerie Walker Ltée] in [[Ajou, Quebec|Ajou]], [[Quebec]], [[Canada]]</ref> The paint protects the coating on the back of the mirror from scratches and other accidental damage. In some applications, generally those that are cost-sensitive or that require great durability, mirrors are instead made from a single, bulk material such as polished metal. For technical applications such as [[laser]] mirrors, the reflective coating is typically applied by [[vacuum deposition]] on the ''front'' surface of the substrate. This eliminates double reflections and reduces absorption of light in the mirror. Cheaper technical mirrors use a silver, aluminium, or [[gold]] coating (the latter typically for [[infrared]] mirrors), and achieve reflectivities of 90–95% when new. A protective overcoat may be applied to prevent [[oxidation]] of the reflective layer. Applications requiring higher reflectivity or greater durability use [[dielectric mirror|dielectric coatings]], which can achieve reflectivities as high as 99.999% over a narrow range of wavelengths. ==Effects== :''See also [[Mirror image]] and [[Specular reflection]]'' [[Image:Waves reflecting from a curved mirror.PNG|frame|right|In this diagram plane waves reflect off a parabolic mirror to form waves converging onto a focal point.]] In a plane mirror, a [[parallel (geometry)|parallel]] beam of [[light]] changes its direction as a whole, while still remaining parallel; the images formed by a plane mirror are [[virtual image]]s, of the same size as the original object (see [[mirror image]]). There are also [[concave mirror]]s, where a parallel beam of light becomes a [[Convergence|convergent]] beam, whose rays intersect in the [[Focus (optics)|focus]] of the mirror. Lastly, there are [[convex mirror]]s, where a parallel beam becomes divergent, with the [[ray (optics)|rays]] appearing to diverge from a common intersection "behind" the mirror. Spherical concave and convex mirrors do not focus parallel rays to a single point due to [[spherical aberration]]. However, the ideal of focusing to a point is a commonly-used approximation. [[Parabolic reflector]]s resolve this, allowing incoming parallel rays (for example, light from a distant star) to be focused to a small spot; almost an ideal point. Parabolic reflectors are not suitable for imaging nearby objects because the light rays are not parallel. A beam of light reflects off a mirror at an angle of reflection that is equal to its angle of incidence (if the size of a mirror is much larger than the wavelength of light). That is, if the beam of light is shining on a mirror's surface at a 30° angle from vertical, then it reflects from the point of incidence at a 30° angle from vertical in the opposite direction. This law mathematically follows from the interference of a [[plane wave]] on a flat boundary (of much larger size than the wavelength). ==Applications== [[Image:mirror.globe.arp.500pix.jpg|thumb|right|200px|Reflections in a spherical convex mirror. The photographer is seen at top right]] ===Safety and easier viewing=== [[Rear-view mirror]]s are widely used in and on [[vehicle]]s (such as [[automobile]]s, or [[bicycles]]), to allow drivers to see other vehicles coming up behind them. Some [[motorcycle helmet]]s have a built-in so-called MROS (Multiple Reflective Optic System): a set of reflective surfaces inside the helmet that together function as a rear-view mirror.[http://www.reevu.nl] There exist rear view [[sunglasses]], of which the left end of the left glass and the right end of the right glass work as mirrors. Convex mirrors are used to provide a wider [[field of view]] than a flat [[mirror]]. They are sometimes placed at [[road junction]]s, and corners of places such as [[parking lot]]s to allow people to see around corners to avoid crashing into other vehicles or [[shopping cart]]s. They are also sometimes used as part of security systems, so that a single [[video camera]] can show more than one [[angle]] at a time. [[Mouth mirror]]s or "dental mirrors" are used by [[dentist]]s to allow indirect vision and lighting within the mouth. Their reflective surfaces may be either flat or curved. Mouth mirrors are also commonly used by [[engineer]]s to allow vision in tight spaces and around corners in equipment. ===Two-way mirrors {{Anchor|One-way mirror}}=== {{main|Two-way mirror}} A ''two-way mirror'', also sometimes referred to as a ''one-way mirror'' or ''one-way glass'', reflects some percentage of the light and lets some other percentage pass. It is a sheet of glass coated with a layer of metal only a few dozen atoms thick, allowing some of the light through the surface (from both sides). It is used between a dark room and a brightly lit room. People on the brightly lit side see their own reflection — it looks like a normal mirror. People on the dark side see through it — it looks like a [[transparency (optics)|transparent]] window. It may be used to observe criminal suspects or customers. The same type of mirror, when used in an [[optical instrument]], is called a ''half-silvered mirror'' or [[beam splitter]]. Its purpose is to split a beam of light so that half passes straight through, while the other half is reflected — this is useful for [[interferometry]]. The reality television program [[Big Brother (TV series)|Big Brother]] makes extensive use of two-way mirrors throughout its set to allow cameramen in special black hallways to use movable cameras to videotape contestants without their coming in contact with the workers. Contrary to popular belief, passive one-way mirrors that operate directionally between equally lit rooms do not exist. The laws of physics do not allow for real, passive one-way mirrors or windows (ones that do not need external energy); if such a device were possible, one could break the [[second law of thermodynamics]] and make energy flow from a cold object to a hot one, by placing such a mirror between them. One-way windows can be made to work with polarized light, however, without violating the second law.<ref>{{cite web|url=http://www.usna.edu/Users/physics/mungan/Scholarship/FaradayIsolators.pdf |title=Faraday Isolators and Kirchhoff’s Law: A Puzzle |accessdate=2006-07-18 |last=Mungan |first=C.E. |year=1999 |format=pdf}}</ref><ref>Rayleigh, ''On the magnetic rotation of light and the second law of thermodynamics'', Nature (London), Vol. '''64''', p. 577 (Oct. 10, 1901).</ref> [[Faraday isolator|Optical isolator]]s are one-way devices that are commonly used with lasers. ===Signalling=== With the [[sun]] as light source, a mirror can be used to signal by variations in the orientation of the mirror. The signal can be used over long distances, possibly up to 60 [[kilometre]]s on a clear day. This technique was used by [[Indigenous peoples of the Americas|Native American]] tribes and numerous [[military|militaries]] to transmit information between distant outposts. Mirrors can also be used for rescue, especially to attract the attention of search and rescue helicopters. Specialised signalling mirrors are available and are often included in military survival kits. ===Technology=== ====Televisions and projectors==== Microscopic mirrors are a core element of many of the largest [[HDTV|high-definition]] [[televisions]] and video [[projectors]]. A common technology of this type is [[Texas Instruments]]' [[DLP]]. A DLP chip is a postage stamp-sized microchip whose surface is comprised of an array of millions of microscopic mirrors. The picture is created as the individual mirrors move to either reflect light toward the projection surface ([[pixel]] on), or toward a light absorbing surface (pixel off). Other projection technologies involving mirrors include [[LCoS]]. Like a DLP chip, LCoS is a microchip of similar size, but rather than millions of individual mirrors, there is a single mirror that is actively shielded by a [[liquid crystal]] [[matrix]] with up to millions of [[pixels]]. The picture is formed as light is either reflected toward the projection surface (pixel on), or absorbed by the activated [[LCD]] pixels (pixel off). LCoS-based televisions and projectors often use 3 chips, one for each primary color. Large mirrors are used in rear projection televisions. Light (for example from a DLP as mentioned above) is "folded" by one or more mirrors so that the television set is compact.<!-- Image with unknown copyright status removed: [[Image:rear_screen_how_it_works_1.jpg]] --> ====Instruments==== [[Telescope]]s and other precision instruments use ''front silvered'' or [[first surface mirrors]], where the reflecting surface is placed on the front (or first) surface of the glass (this eliminates reflection from glass surface ordinary back mirrors have). Some of them use silver, but most are aluminum, which is more reflective at short wavelengths than silver. All of these coatings are easily damaged and require special handling. They reflect 90% to 95% of the incident light when new. The coatings are typically applied by [[vacuum deposition]]. A protective overcoat is usually applied before the mirror is removed from the vacuum, because the coating otherwise begins to corrode as soon as it is exposed to oxygen and humidity in the air. ''Front silvered'' mirrors have to be resurfaced occasionally to keep their quality. The reflectivity of the mirror coating can be measured using a [[reflectometer]] and for a particular metal it will be different for different wavelengths of light. This is exploited in some [[optical]] work to make [[cold mirror]]s and [[hot mirror]]s. A cold mirror is made by using a transparent substrate and choosing a coating material that is more reflective to visible light and more transmissive to [[infrared]] light. A hot mirror is the opposite, the coating preferentially reflects infrared. Mirror surfaces are sometimes given thin film overcoatings both to retard degradation of the surface and to increase their reflectivity in parts of the spectrum where they will be used. For instance, aluminum mirrors are commonly coated with silicon dioxide or magnesium fluoride. The reflectivity as a function of wavelength depends on both the thickness of the coating and on how it is applied. For scientific [[optics|optical]] work, [[dielectric mirror]]s are often used. These are glass (or sometimes other material) substrates on which one or more layers of dielectric material are deposited, to form an optical coating. By careful choice of the type and thickness of the dielectric layers, the range of wavelengths and amount of light reflected from the mirror can be specified. The best mirrors of this type can reflect &gt;99.999% of the light (in a narrow range of wavelengths) which is incident on the mirror. Such mirrors are often used in [[lasers]]. In astronomy, [[adaptive optics]] is a technique to measure variable image distortions and adapt a [[deformable mirror]] accordingly on a timescale of milliseconds, to compensate for the distortions. Although the most of mirrors are designed to reflect visible light, surfaces reflecting other forms of electromagnetic radiation are also called "mirrors". The mirrors for other ranges of [[electromagnetic waves]] are used in optics and [[astronomy]]. Mirrors for radio waves are important elements of [[radio telescope]]s. A [[Mangin mirror]] is a combination lens and concave mirror and is widely used in optical instruments and even sometimes in cameras.[http://www.jmloptical.com/level2/ProductInfo/m_spherical_info.aspx] [http://www.aavso.org/publications/ejaavso/ej14.pdf][http://www.bobatkins.com/photography/tutorials/mirror.html] =====Face-to-face mirrors===== Some devices use two or more mirrors facing one another to generate multiple reflections: * [[Fabry-Pérot interferometer]] * [[Laser]] (which contains an [[optical cavity]]) * some types of [[catoptric cistula]] * momentum-enhanced [[solar sail]][http://blag.xkcd.com/2008/02/15/the-laser-elevator/] The reflected images between these mirrors give the appearance of an [[infinite regress]]. ====Military applications==== It has been said that [[Archimedes]] used a large array of mirrors to burn [[Ancient Rome|Roman]] ships during an attack on Syracuse. This has never been proven or disproved; however, many have put it to the test. Recently, on a popular [[Discovery Channel]] show, [[MythBusters]], a team from [[MIT]] tried to recreate the famous "Archimedes Death Ray". They were [http://web.mit.edu/2.009/www//experiments/deathray/10_Mythbusters.html successful] at starting a fire on a ship at 75 feet away; however, previous attempts to light the boat on fire using only the bronze mirrors available in Archimedes' time were unsuccessful, and the time taken to ignite the craft would have made its use impractical, resulting in the MythBusters team deeming the myth "busted". (However, see [[solar power tower]] for a practical use of this technique.) ====Seasonal lighting==== <!-- If this technique becomes popular, don't let this section grow into a vast list of examples. --> Due to its location in a steep-sided valley, the Italian town of [[Viganella]] gets no direct sunlight for seven weeks each winter. In 2006 a €100,000 computer-controlled mirror, 8×5&nbsp;m, was installed to reflect sunlight into the town's piazza. In early 2007 the similarly situated village of [[Bondo, Switzerland]], was considering applying this solution as well.<ref>[http://news.bbc.co.uk/2/hi/europe/6189371.stm BBC NEWS | Europe | Italy village gets 'sun mirror'<!-- Bot generated title -->]</ref><ref>[http://www.cbsnews.com/stories/2007/02/12/ap/world/mainD8N8AED80.shtml Swiss Officials Want to Spread Sunshine, Swiss Officials May Build Giant Mirror to Give Light to Sunless Village - CBS News<!-- Bot generated title -->]</ref> ===Leisure=== ====Decoration==== Mirrors, typically large and unframed, are frequently used in [[interior decoration]] to create an illusion of space, and amplify the apparent size of a room. Mirrors are used also in some schools of [[feng shui]], an ancient [[Culture of China|Chinese]] practice of placement and arrangement of space to achieve harmony with the environment. The softness of old mirrors is sometimes replicated by contemporary artisans for use in interior design. These reproduction antiqued mirrors are works of art and can bring color and texture to an otherwise hard, cold reflective surface. It is an artistic process that has been attempted by many and perfected by few. A decorative reflecting [[sphere]] of thin metal-coated glass, working as a reducing wide-angle mirror, is sold as a [[Christmas ornament]] called a ''bauble''. ====Entertainment==== The [[house of mirrors|hall of mirrors]], commonly found in [[amusement park]]s, is an attraction in which a number of distorted mirrors are used to produce unusual reflections of the visitor. Mirror mazes, also found in amusement parks, contain large numbers of mirrors and sheets of glass. The idea is to navigate the disorientating array without bumping into the walls. Mirrors are often used in [[Magic (illusion)|magic]] to create an [[illusion]]. One effect is called [[Pepper's ghost]]. Illuminated rotating [[disco ball]]s covered with small mirrors are used to cast moving spots of light around a dance floor. Mirrors are employed in [[kaleidoscope]]s, personal entertainment devices invented in [[Scotland]] by sir [[David Brewster]]. ====Art==== [[Filippo Brunelleschi]] discovered linear perspective with the help of the mirror, [[Leonardo da Vinci]] called the mirror the "master of painters". He recommended. "When you wish to see whether your whole picture accords with what you have portrayed from nature take a mirror and reflect the actual object in it. Compare what is reflected with your painting and carefully consider whether both likenesses of the subject correspond, particularly in regard to the mirror. The mirror is the central device in some of the greatest of European paintings: [[Jan Van Eyck]]'s [[Arnolfini Portrait]], [[Diego Velazquez]]'s [[Las Meninas]] and [[Edouard Manet]]’s [[A Bar at the Folies-Bergère]]. Without a mirror, the great [[self portrait]]s by [[Dürer]], [[Rembrandt]], [[Van Gogh]] and [[Frida Kahlo]] could not have been painted. [[M. C. Escher]] used special shapes of mirrors in order to have a much more complete view of the surroundings than by direct observation ([[Hand with Reflecting Sphere]]). [[István Orosz]]’s [[anamorphosis|anamorphic]] works are images distorted such way that they only become clearly visible when reflected in a suitably-shaped and positioned mirror. Some other contemporary artists use mirrors as the material of art, like in mirror-sculptures and paintings on mirror surfaces. Some artists build special mirror installations as the neon mirror cubes by [[Jeppe Hein]]. Painters depicting someone in front of a mirror often also show the person's reflection. This is a kind of abstraction—in most cases the angle of view is such that the person's reflection should not be visible. Similarly, in movies and still photography an actor or actress is often shown ostensibly looking at him or herself in the mirror, and yet the reflection faces the camera. In reality, the actor or actress sees only the camera and its operator in this case, not their own reflection. ====Literature==== Mirrors play a powerful role in cultural literature, from the self-loving [[Narcissus]] of Greek Mythology to the Biblical reference to [[Through a Glass Darkly]]. The evil queen in the European fairy-tale [[Snow White]] asked, "Mirror, mirror, on the wall... who's the fairest of them all?" Some of the best-loved uses of mirrors in literature include Lewis Carroll's [[Alice's Adventures in Wonderland]] and the Mirror of Erised in the [[Harry Potter]] series. Horror movies about mirrors include [[Candyman (film)]]. ==Mirrors and superstition== It is a common [[superstition]] that someone who breaks a mirror will receive seven years of bad luck. One of the many reasons for this belief is that the mirror is believed to reflect part of the [[soul]], therefore, breaking the mirror will break part of the soul. However, the soul is said to regenerate every seven years, thus coming back unbroken. To counter this one of many rituals has to be performed, the easiest of which is to stop the mirror from reflecting the broken soul by grinding it to dust.{{Fact|date=January 2008}} The belief might also simply originate from the high cost of mirrors in times gone past. According to legend, a [[vampire]] has no reflection in mirrors because it is an [[undead]] creature and has already lost its soul. Another superstition claims it is bad luck to have two mirrors facing each other.{{Fact|date=January 2008}} A childhood game that freaks kids out is chanting [[Bloody Mary (folklore)]] in a mirror. ==Mirrors and animals== [[Image:Whipsnade elephant summer 2006.jpg|thumb|150px|right|The Asian elephant can recognise its own reflection in a mirror]] Experiments have shown that only large-brained social animals are able to recognise that a mirror shows a reflection of themselves.<ref>{{cite web |url=http://www.newscientist.com/article/dn10402-elephants-see-themselves-in-the-mirror.html |title=Elephants see themselves in the mirror |accessdate=2007-05-24 |last= |first= |authorlink= |coauthors= |date=30 October 2006 |year= |month= |format= |work=Peter Aldhous |publisher=[[New Scientist]] |pages= |language= |archiveurl= |archivedate= |quote= }}</ref> Animals that have shown they are able to use a [[mirror test|mirror to study themselves]]: * [[Asian elephant]]s * [[Bonobo]]s * [[Common chimpanzee]]s * [[Dolphin]]s * [[Orangutan]]s * [[Pig]]s * [[Llama]]s ==Unusual types of mirror== Other types of reflecting device are also called "mirrors". For example metallic reflectors are used to reflect infrared light (such as in [[space heater]]s), or [[microwave]]s. [[Image:WW1AcousticMirrorKilnsea(PaulGlazzard)Jan2007.jpg|right|thumb|4.5 metre high acoustic mirror near [[Kilnsea]] Grange, East Yorkshire, UK]] An [[acoustic mirror]] is a passive device used to reflect and perhaps to focus [[sound wave]]s. Acoustic mirrors were used for selective detection of sound waves, especially during [[World War 2]]. They were used for detection of enemy aircraft prior to the development of [[radar]]. Acoustic mirrors are used for remote probing of the atmosphere; they can be used to form a narrow [[diffraction-limited system|diffraction-limited]] beam.<ref name="U1">{{cite journal | url=http://www.springerlink.com/content/w613354427150024 | author=M. A. Kallistratova | coauthors= | title=Physical grounds for acoustic remote sensing of the atmospheric boundary layer | journal=Lecture Notes in Earth Sciences | volume=69 | pages=3–34 | year=1997 }}</ref> They can also be used for underwater "imaging". ''Active mirrors'' are mirrors that amplify the light they reflect. They are used to make [[disk laser]]s.<ref name="Ueda">{{cite journal| url=http://bookstore.spie.org/index.cfm?fuseaction=DetailPaper&ProductId=143686&coden=PSISDG | author=K. Ueda| coauthors=N. Uehara| title=Laser-diode-pumped solid state lasers for gravitational wave antenna| journal=[[Proceedings of SPIE]]| volume=1837| pages=336–345| year=1993| doi=10.1117/12.143686}}</ref> The amplification is typically over a narrow range of wavelengths, and requires an external source of power. An [[atomic mirror]] is a device which reflects [[matter waves]]. Usually, atomic mirrors work at [[grazing incidence]]. Such a mirror can be used for [[atomic interferometry]] and [[atomic holography]]. It has been proposed that they can be used for non-destructive imaging systems with nanometer resolution.<ref name="nanoscope">{{cite journal | url=http://stacks.iop.org/0953-4075/39/1605 | author= D.Kouznetsov | coauthors=H. Oberst, K. Shimizu, A. Neumann, Y. Kuznetsova, J.-F. Bisson, K. Ueda, S. R. J. Brueck | title=Ridged atomic mirrors and atomic nanoscope | journal=[[Journal of Physics B]] | volume=39 | pages=1605–1623 | year=2006 | doi=10.1088/0953-4075/39/7/005 }}</ref> [[Cold mirror]]s are dielectric mirrors that reflect the entire visible light spectrum while efficiently transmitting infrared wavelengths. Conversely, [[hot mirror]]s reflect infrared light while allowing visible light to pass. These can be used to separate useful light from unneeded infrared to reduce heating of components in an optical device. They can also be used as dichroic [[beamsplitters]]. [[Corner reflector]]s use three flat mirrors to reflect light back towards its source. They are used for emergency location, and even [[laser ranging]] to the [[Moon]]. X-ray mirrors produce specular reflection of [[X-ray]]s. All known types work only at angles near grazing incidence, and only a small fraction of the rays are reflected.<ref name="pro00">{{cite journal | title= X-ray parabolic collimator with depth-graded multilayer mirror | author= V.V.Protopopov | coauthors= V.A.Shishkov, and V.A.Kalnov | pages=4380–4386 | journal=[[Review of Scientific Instruments]] | year= 2000 | volume=71 | issue=12 | doi= 10.1063/1.1327305 }}</ref> ==See also== {{wiktionary|Mirror}} * [[Anamorphosis]] * [[Aranmula kannadi]] * [[Bronze mirror]] * [[Cold mirror]] and [[Hot mirror]] * [[Deformable mirror]] * [[Dielectric mirror]] * [[Digital micromirror device]] * [[Home decor]] * [[Mirror armour]] (an oriental partial plate armour from polished metal mirrors) * [[Mirror writing]] * [[Perfect mirror]] * [[Periscope]] * [[Rear-view mirror]] * [[Reflectivity]] * [[Silvering]] * [[TLV mirror]] — An ancient type of Chinese mirror from the [[Han Dynasty]]. * [[Venus effect]] ==Notes== {{reflist}} ==Bibliography== * ''Mirror, Mirror: A History of the Human Love Affair with Reflection'', Mark Pendergrast. Basic Books (2003). ISBN 0-465-05471-4 . * ''On reflection'', [[Jonathan Miller]], National Gallery Publications Limited (1998). ISBN 0-300-07713-0 . *''The Mirror: A History'', Sabine Melchior-Bonnet, Routledge, 2001, ISBN 0415924480 ==External links== * [http://books.google.com/books?hl=en&id=P-c1g6QIPHIC&dq=mirror+history&printsec=frontcover&source=web&ots=LfmtU-zNjJ&sig=ZqkBUsx18w_zoq_lH5-7Pl1zTIk#PPP1,M1 The Mirror: A History by Sabine Melchior-Bonnet at Google Books] * [http://yvesdore.com/mirror.html The Narcissus Syndrome Revisited by Yves Doré] * [http://www.glasswebsite.com/video/mirror.asp How Mirrors Are Made (video)], Glass Association of North America] * [http://www.williamsantiquemirrors.co.uk/Reproduction-Mirrors.htm How Antique Mirrors can be reproduced] * [http://www.bathroom-mirror.info/ Information on Bathroom Mirrors] [[Category:Reflective building components]] [[Category:Mirrors| ]] [[Category:Optics]] [[Category:Glass applications]] [[ast:Espeyu]] [[gn:Itagecha]] [[az:Güzgü]] [[bg:Огледало]] [[ca:Mirall]] [[cs:Zrcadlo]] [[da:Spejl]] [[de:Spiegel]] [[el:Κάτοπτρο]] [[es:Espejo]] [[eo:Spegulo]] [[fa:آینه]] [[fr:Miroir]] [[ko:거울]] [[hi:दर्पण]] [[id:Cermin]] [[it:Specchio]] [[he:מראה]] [[la:Speculum]] [[lv:Spogulis]] [[lt:Veidrodis]] [[ml:കണ്ണാടി]] [[ms:Cermin]] [[nl:Spiegel (optica)]] [[nds-nl:Spegel]] [[ja:鏡]] [[no:Speil]] [[nn:Spegel]] [[nrm:Mireus]] [[ps:هينداره]] [[pl:Lustro]] [[pt:Espelho]] [[ro:Oglindă]] [[qu:Rirpu]] [[ru:Зеркало]] [[scn:Specchiu]] [[simple:Mirror]] [[sk:Zrkadlo]] [[sl:Zrcalo]] [[sr:Ogledalo]] [[fi:Peili]] [[sv:Spegel]] [[ta:தளவாடி]] [[th:กระจกเงา]] [[chr:ᏓᏎᏘ]] [[tr:Ayna (optik)]] [[uk:Дзеркало]] [[yi:שפיגל]] [[bat-smg:Zelkorios]] [[zh:鏡子]]