DISPOSITIVOS ÓPTICOS Introdução e revisão

Apresentação em tema: "DISPOSITIVOS ÓPTICOS Introdução e revisão"— Transcrição da apresentação:

1 DISPOSITIVOS ÓPTICOS Introdução e revisão
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2 Dispositivos ópticos Conceitos e princípios
Dispositivo que cria, manipula ou mede radiação eletromagnética. Existe alguma classificação? Categoria? Tipos? Wikipedia? Dispositivos e/ou instrumentos? Lente, óculos, zoom Dispositivo óptico para mouse óptico? Dispositivo óptico Real? Virtual? Dispositivo: 1. Regra, preceito. 2. Mecanismo ou conjunto de meios dispostos pára certo fim. Instrumento: 1. Objeto, em geral mais simples que o aparelho, que serve de agente mecânico na execução de qualquer trabalho. Dispositivo ótico virtual Um dispositivo ótico virtual é uma descrição de dispositivo que suporta armazenamento ótico virtual, assim como uma descrição de dispositivo ótico real suporta armazenamento ótico real. De 1 a 35 descrições de dispositivo ótico virtual podem estar ativas ao mesmo tempo no servidor. Você cria um dispositivo ótico virtual selecionando os parâmetros RSRCNAME(*VRT) ou TYPE(632B) no comando CRTDEVOPT (Criar Descrição de Dispositivo (Ótico)). Lado óptico Lado fotônico Dispoptic 2008

3 Wikipedia http://en.wikipedia.org/wiki/Category:Optical_devices
Category:Optical devices A [+] Astronomical observatories I [+] Interferometers L [+] Lasers [+] Lenses M [+] Microscopes [+] Mirrors O [+] Optical filters [+] Optoelectronics P [+] Photography equipment P cont. [+] Planetaria [+] Prisms R [+] Refractometers T [+] Telescopes Dispoptic 2008

4 Pages in category “Optical devices” Optical Instruments
Panoramagram Passive infrared sensor Periscope Phased array optics Photodetector Photometer Photomultiplier Photoresistor Phototube Polarimetry Polarizer Polychromator Polyrama Panoptique Prism (optics) Prism coupler Pseudoscope Q Quantum well infrared photodetector R Remote camera Retroreflector Ring laser gyroscope S Scioptric ball Sight (device) Silver halide Solid immersion lens Spatial filter Spatial light modulator Spectralon Spectrophotometer Spotting scope Star diagonal Sun photometer T Optical table Tachistoscope Teleidoscope Telescope Theodolite Tiny Ionospheric Photometer Turbinlite U Ultrafast monochromator User:Slicky/Microscopy in science V Video camera Videoscope Visby lenses W Wave plate Z Zograscope Zone plate A AN/PVS-14 AN/PVS-22 ARROW waveguide Acousto-optic modulator Optical amplifier Arrayed waveguide grating Astrograph Optical attenuator Autocollimator B Beam dump Beam homogenizer Bicycle reflector Binoculars Binoviewer Borescope C Camera Camera lucida Camera obscura Catadioptric system Catoptric cistula Optical cavity Colorimeter Comparison Microscope Culpascope D Diaphragm (optics) Dielectric wireless receiver Diffraction grating Dipleidoscope Dome magnifier Dynameter E Echelle grating EcoSCOPE Electro-Optix Electro-optic modulator Endoscopy Eye relief Eyepiece F Faraday rotator Fiberscope Finderscope Focus finder G Golf mirror Graphoscope Ground glass Gyro gunsight Gyrotron H Haploscope Hidden camera Hinman Collator Hollow cathode lamp HoloVID Holographic grating Hydroscope I Image-stabilized binoculars Indirect ophthalmoscope Optical interleaver J Jeffree cell K Kaleidica Kaleidoplex Kaleidoscope L Laser Laser beam profiler Laser microphone Lens (optics) Light table Liquid mirror Loupe Lovibond comparator M Magneto-optical trap Maser Megalethoscope Mirror mount Optical modulator Monochromator Monocular N Night vision device Nuller O Opera glasses Optical axis gratings Optical circulator Optical flat Optical hybrid Optical isolator Optical microcavity Optical power meter Optical tape Optode Dispoptic 2008

5 Lente composta como dispositivo ergonômico
Sem dispositivo óptico Dor de cabeça, coluna,... Com dispositivo óptico Dispositivo óptico Lente de 3 segmentos Ergonomia Acepções ■ substantivo feminino Rubrica: engenharia industrial. 1    estudo científico das relações entre homem e máquina, visando a uma segurança e eficiência ideais no modo como um e outra interagem 1.1    otimização das condições de trabalho humano, por meio de métodos da tecnologia e do desenho industrial Etimologia erg(o)- + -nomia Sinônimos biotecnia, biotécnica Dispoptic 2008

6 As próximas 7 transparências representam parte significativa de aplicações de dispositivos ópticos na Indiana School for the Blind and Visually Impaired Dispoptic 2008

7 Types of Optical Devices
Indiana School for the Blind and Visually Impaired Types of Optical Devices Distance Devices Dispoptic 2008 intra.isbrockets.org/teams/dept_outreach/ _Update/index_files/typesofdistancedevices.ppt

8 Binoculars Dispoptic 2008

9 Monocular Dispoptic 2008

10 Full-Field Bioptic Systems
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11 Bioptic Systems Dispoptic 2008

12 Sunfilters Dispoptic 2008

13 Night Vision Scopes Dispoptic 2008

14 Explanation of optical devices - Succeed in Physical Science. Also refer to optics, physics, lenses, lasers, telescope, microscope, spectrometer, WBT, education, distance learning, Ron Kurtus, School for Champions. Copyright © Restrictions Optical Devices by Ron Kurtus (revised 6 October 1999) Have you ever wondered how a camera works? Or why you need a flashlight to see in the dark? Or how a magnifying glass can make things look bigger? Or why a rainbow looks so colorful? There are many devices that use the visible electromagnetic waves we call light. Some of these devices create light, some detect light, and others manipulate the beams of light for some use. See lesson on Electromagnetic Waves See lesson on Visible Light See Simulated Optics Experiments on Curved Mirrors and Single Lenses. This lesson will answer those questions. There is a mini-quiz near the end of the lesson. Dispoptic 2008

15 Conceitos de Armazenamento Ótico Virtual
Conceitos de Armazenamento Ótico Virtual Armazenamento ótico virtual consiste em objetos que, quando utilizados juntos, imitam mídia CD ou DVD em unidades de disco. Os CDs ou DVDs imitados parecem mídia real para o servidor. Os objetos que o armazenamento ótico virtual utiliza são os seguintes: Imagem virtual Uma imagem virtual é um objeto que contém os dados que normalmente estão em um CD ou DVD real. A imagem virtual é um arquivo de fluxo que reside no sistema de arquivos integrado. Você deve inicializar uma imagem virtual para que possa gravar nela. No caso de um backup e recuperação, também é possível estender imagens virtuais. Dispositivo ótico virtual Um dispositivo ótico virtual é uma descrição de dispositivo que suporta armazenamento ótico virtual, assim como uma descrição de dispositivo ótico real suporta armazenamento ótico real. De 1 a 35 descrições de dispositivo ótico virtual podem estar ativas ao mesmo tempo no servidor. Você cria um dispositivo ótico virtual selecionando os parâmetros RSRCNAME(*VRT) ou TYPE(632B) no comando CRTDEVOPT (Criar Descrição de Dispositivo (Ótico)). Dispoptic 2008

16 Pinças ópticas e aplicações
As pinças ópticas são consideradas como uma ferramenta para micromanipulação sem contacto de partículas microscópicas (10nm a 10um) que podem ser armadilhadas no foco de um laser de baixa potência e podem ser manipulados tridimensionalmente movimentando a amostra ou a armadilha. Onde? Ciências biológicas e coloidais. Como? Trasladores (movimentadores) Dispoptic 2008

17 Optical Tweezers and Applications
Optical Tweezers and Applications Optical tweezers are an instrument for contactless micromanipulation of microscopic particles. Objects ranging in size from about 10nm to 10um can be trapped close to the focus of a low(ish) power laser beam and manipulated in three dimensions by moving either the sample or the trap position. There is a wide variety of applications—particularly in biology and colloid science—from 'simple' translators to trap arrays and high precision force measurements. How do tweezers work? Light possesses both energy and momentum. An interaction between radiation and matter can result in an exchange of momentum. Consider a dielectric sphere placed in a laser beam (figure 1a). The sphere acts like a miniature lens; the refraction or reflection of light at a dielectric interface alters the direction, and hence the momentum of the light. Due to the spatial intensity profile of the laser beam more light is refracted towards left than the right. The light therefore gains overall momentum towards the left which, by Newton's third law, means that the sphere gains momentum in the opposite direction (towards the right, or more precisely, towards the highest laser intensity). Closer examination reveals that the force is related to the gradient of laser intensity, and it is therefore often referred to as gradient force. As a consequence, the sphere is drawn into the region of highest light intensity. While this mechanism confines the sphere in the directions perpendicular to the beam propagation, another process is used to trap in the direction parallel to the beam. When placed in the path of a laser beam, the sphere will feel 'radiation pressure' caused by the stream of photons scattering off its surface, giving the sphere momentum in the direction of the beam (this effect can be seen on a much larger scale in the field of astronomy—a comet's tail as seen from earth is caused by radiation pressure from the sun). If the laser beam is focused very tightly (figure 1b) there is also a gradient force against the propagation direction of the beam which can balance the radiation pressure from the beam. In this manner, a three-dimensional single beam trap can be created to trap microscopic particles. Dispoptic 2008

18 Pinças ópticas Figure 1a) Lateral Trapping Figure 1b) Axial Trapping
                                     Figure 1a) Lateral Trapping Figure 1b) Axial Trapping Gradient force pulls particles towards the highest laser intensity in transverse direction (a) and for a strongly focussed beam also in longitudinal direction (b). Click on figures (1a) and (1b) for larger versions Desde que a intensidade do feixe de laser não é completamente plana, i.e. constante na sua seção transversal, existem forças que empurram as partículas na direção de maior intensidade seja na transversal ou na longitudinal.. Dispoptic 2008

19 Pinças Ópticas Dispoptic 2008

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21 The Defense Advanced Research Projects Agency (DARPA) has awarded an $8 million, four-year,basic-research program grant to the California Institute of Technology to initiate research in photonics technologies. The technical focus of the effort will be on optofluidics, an exciting new research area based on the use of microfluidic devices to control optical processes, and which is expected to result in a new generation of small-scale, highly adaptable, and innovative optical devices. To conduct the research, Caltech is establishing a new center called the Center for Optofluidic Integration. The center will spearhead efforts directed toward a new class of adaptive optical devices for numerous applications in sensing, switching, and communications. Dispoptic 2008

22 Importância No atual momento das comunicações e sensoriamento, os dispositivos ópticos tem uma relevância enorme no desenvolvimento de novas técnicas através de novos materiais (meta-materiais, nanoestruturas, etc) Óptica e Fotônica Tese doutorado: Kevin H. Smith (BYU) All-optical networks remain a goal of the research community which promise \increased bandwidth, faster service provisioning, easier management, reduced costs, and greater reliability [4]." Fiber-optic sensors are also making progress in many di®erent applications including sensing of \rota- tion, acceleration, electric- and magnetic-¯eld measurement, temperature, pressure, acoustics, vibration, linear and angular position, strain, humidity, viscosity, chemical measurements, and a host of other sensor applications [5]." Dispoptic 2008

23 Uma revisão geral Dispoptic 2008

24 Sinais de fogo, fumaça, códigos visuais
Fibras Ópticas Um pouco de história: Sinais de fogo, fumaça, códigos visuais 1790 Claude Chappe, Paris-Lille (230 Km), Semáforo = telegrafo óptico 1870 John Tyndall – jato de água Alexander Graham Bell, Charles Sumner Tainter Fotofone Dispoptic 2008

25 Semáforo 5 minutos para transmitir a uma distância de 190 km
Dispoptic 2008 5 minutos para transmitir a uma distância de 190 km

26 Mapa da França com semáforo
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27 John Tyndall 1870 Dispoptic 2008

28 O homem que guiou a luz. Daniel Colladon (38) professor na Universidade de Genebra demonstrou como guiar a luz em 1841. Dispoptic 2008

29 Detalhes históricos • Reflexão Total Interna(TIR) é atribuída a John Tyndall (1854 experimento em Londres). • Livro City of Light (Jeff Hecht, 1999) relata a historia do TIR. • Primeira demonstração em Genebra em 1841 por Daniel Colladon (Comptes Rendus, vol. 15, pp , Oct. 24, 1842). • A luz fica confinada ao longo do caimento da água. Dispoptic 2008

30 primeira transmissão de voz, através de luz não guiada
Graham Bell fotofone primeira transmissão de voz, através de luz não guiada Dispoptic 2008

31 Dispoptic 2008

32 Dispoptic 2008

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34 E o telefone? 1870 Elisha Gray e Alexander Graham Bell
Bem antes do fotofone! Fixo =========== via fio de cobre, ponto a ponto Sem fio ========= ondas de radio, celulares Via satélite ====== satélites geoestacionários VoIP =========== Voice Over Internet Protocol Biography Alexander Bell was born in Edinburgh on 3 March He was the middle of three children, all boys. Both brothers died of tuberculosis. His father was Professor Alexander Melville Bell and his mother was Eliza Grace Symonds Bell. At age 11, he adopted the middle name 'Graham' out of admiration for Alexander Graham, a family friend. Many called Bell "the father of the deaf". This reference may be regarded as ironic, due to his belief in the practice of eugenics[citation needed], as well as his strong audist stance. With both his mother and wife deaf, he hoped to eliminate hereditary deafness. His family was associated with the teaching of elocution: his grandfather, Alexander Bell, in London, his uncle in Dublin, and his father, Alexander Melville Bell, in Edinburgh, were all elocutionists. His father published a variety of works on the subject, several of which are still well known, especially his treatise on Visible Speech, which appeared in Edinburgh, in In this treatise, he explains his methods of how to instruct deaf mutes to articulate words and read other people's lip movements to decipher meaning. Bell was educated at the Royal High School, Edinburgh, Scotland, from which he graduated at the age of 13. At the age of 16, he secured a position as a pupil-teacher of elocution and music, in Weston House Academy, at Elgin, Moray, Scotland. The following year, he attended the University of Edinburgh, but graduated from the University College of London. It is while he was in Scotland that he is thought to have first turned his attention to the science of acoustics, with a view to ameliorate the deafness of his mother. From 1867 to 1868, he served as an instructor at Somerset College, Bath, Somerset, England. In 1870, at the age of 23, he and his parents emigrated to Canada, where they settled at Brantford, Ontario. That same year, he became a Canadian citizen. In Canada, Alexander Bell continued an interest, begun in Scotland, in the study of the human voice and ear (his father was an authority on speech disorders), but also, explored a method of communication with electricity. He designed a piano which, by means of electricity, could transmit its music at a distance. In 1871, he accompanied his father to Montreal, Quebec, Canada, where his father was offered a position to teach his System of Visible Speech. Subsequently, his father was invited to introduce the Visible Speech System into a large school for mutes at Boston, Massachusetts, United States, but he declined the post, in favor of his son. Thus, teaching his father's system, Alexander Bell became professor of Vocal Physiology and Elocution at the Boston University School of Oratory. Bell speaking into prototype model of the telephone At Boston University, he continued his research in the same field and endeavored to find a way to transmit musical notes and articulate speech. In early 1875 Bell visited the famous scientist Joseph Henry who was then director of the Smithsonian Institution and asked Henry's advice on an electrical multi-reed apparatus which Bell hoped would transmit the human voice by telegraph. Henry replied that Bell had "the germ of a great invention". When Bell said that he did not have the necessary knowledge, Henry replied "Get it!" That greatly encouraged Bell to keep trying. What happened next is described below in the section on the telephone. On July 11, 1877, a few days after the Bell Telephone Company began, Bell married Mabel Hubbard, daughter of Boston lawyer Gardiner Hubbard who helped finance Bell's work and organise the new telephone company. Mabel was one of Bell's pupils and deaf. They had four children: Elsie May Bell ( ), Marian Hubbard Bell (Daisy) ( ), and two sons who died in infancy. In 1880, Bell received the Volta Prize which he used to fund the Volta Laboratory in Washington, D.C. In 1882, Bell became a naturalised citizen of the United States. In 1883, Bell and Gardiner Hubbard established the publication Science. In 1886, Bell starts buying land on Cape Breton Island in Nova Scotia, Canada which he leaves in the care of a friend, the writer David Narbaitz. In 1888, Bell was one of the founding members of the National Geographic Society and became its second president ( ). He was the recipient of many honors. The French Government conferred on him the decoration of the Légion d'honneur (Legion of Honor), the Académie française bestowed on him the Volta Prize of 50,000 francs, the Royal Society of Arts in London awarded him the Albert Medal in 1902, and the University of Würzburg, Bavaria, granted him a Ph.D. He was awarded the AIEE's Edison Medal in 1914 for "For meritorious achievement in the invention of the telephone." In 1891 Bell began experiments to develop motor-powered heavier-than-air aircraft. In 1898 Bell began experiments with tetrahedral kites. In 1898 Bell became the President of the National Geographic Society and regent of the Smithsonian Institution ( ). In 1907 Bell founded the Aerial Experiment Association. In 1908 Bell began development of the hydrodrome (hydrofoil). Bell died of Pernicious anemia[1] on 2 August 1922, age 75, at his private estate, Beinn Bhreagh, located on Nova Scotia's Cape Breton Island near the village of Baddeck. He was buried atop Beinn Bhreagh mountain overlooking Bras d'Or Lake. He was survived by his wife and two of their four children. Father- Alexander Melville Bell Mother- Eliza Grace Symonds (Bell) Grandfather- Alexander Bell The telephone Main article: Invention of the telephone In 1874, telegraph message traffic was rapidly expanding and had become "the nervous system" of commerce in the words of Western Union president William Orton. Orton had contracted with inventors Thomas Edison and Elisha Gray to find a way to send multiple telegraph messages on each telegraph line to avoid the great cost of constructing new lines. When Bell mentioned to Gardiner Hubbard and Thomas Sanders, parents of two of Bell's students, that he (Bell) was working on a method of sending multiple tones on a telegraph wire using a multi-reed device, Hubbard and Sanders began to financially support Bell's experiments. Patent matters would be handled by Hubbard's patent attorney Anthony Pollok.[2] Bell was able to hire an assistant Thomas A. Watson who was an experienced electrical designer and mechanic. Bell and Watson experimented with acoustic telegraphy in 1874 and On June 2, 1875, Watson accidentally plucked one of the reeds and Bell at the receiving end of the wire heard the overtones of the reed, overtones that would be necessary for transmitting speech. This led to the "gallows" sound-powered telephone which on July 1 was able to transmit indistinct voice-like sounds, but not clear speech. Meanwhile, Elisha Gray was also experimenting with acoustic telegraphy and thought of a way to transmit speech using a water transmitter. On Monday February 14, 1876, Elisha Gray filed a caveat with the U.S. patent office for a telephone design that used a water transmitter. 2 hours earlier, Monday February 14, 1876, Bell's lawyer filed an application with the patent office for the telephone. There is a debate about who arrived first. [3] On February 14, 1876, Bell was in Boston. Hubbard, the lawyer who was paying for the costs of Bell's patents, told his patent lawyer Anthony Pollok to file Bell's application in the U.S. Patent Office. This was done without Bell's knowledge. This patent 174,465 was issued to Bell on March 7, 1876 by the U.S. Patent Office which covered "the method of, and apparatus for, transmitting vocal or other sounds telegraphically … by causing electrical undulations, similar in form to the vibrations of the air accompanying the said vocal or other sound." Three days after his patent issued, Bell experimented with a water transmitter, using an acid-water mixture. Vibration of the diaphragm caused a needle to vibrate in the water which varied the electrical resistance in the circuit. When Bell spoke the famous sentence "Mr Watson—Come here—I want to see you" into the liquid transmitter, Watson, listening at the receiving end, heard the words clearly. The story about the spilled battery acid is a story that Watson told many years later and may have happened on a different day. Bell and his partners Hubbard and Sanders offered to sell the patent outright to Western Union for $100,000. The president of Western Union balked, countering that the telephone was nothing but a toy. Two years later, he told colleagues that if he could get the patent for $25 million he’d consider it a bargain. By then the Bell company no longer wanted to sell the patent.[4] In 1879 the Bell company acquired Edison's patents for the carbon microphone from Western Union. This made the telephone practical for long distances, unlike Bell's voice-powered transmitter that required users to shout into it to heard at the receiving telephone, even at short distances. The Bell company lawyers successfully fought off several lawsuits. On 13 January 1887 the Government of the United States moved to annul the patent issued to Alexander Graham Bell on the grounds of fraud and misrepresentation. The prosecuting attorney was the Hon. George M. Stearns under the direction of the Solicitor General George A. Jenks [5] The Bell company won that case. The Bell Telephone Company was created in 1877, and by 1886 over 150,000 people in the U.S. owned telephones. Bell and his investors became millionaires. Bell company engineers made numerous other improvements to the telephone which developed into one of the most successful products. Competitors Meanwhile, the Italian Antonio Meucci, who had already created the first model of telephone in Italy in 1834, tested electric transmission of the human voice in Cuba in 1849, and demonstrated his electric telephone in NY, USA in He had paid for a "caveat" for the telephone in In summer 1872 Meucci asked Edward B. Grant (Vice President of American District Telegraph Co. of New York) the permission to test his telephone apparatus on the company's telegraph lines. He gave Grant a description of his prototype and copy of his caveat. Up to 1874 Meucci had only the money to renew his caveat while looking for funding for a true patent. After waiting two years without receiving an answer, Meucci went to Grant and asked him to be given back his documents, but Grant answered he had lost them. The same year the caveat expired because Meucci lacked the money to renew it.[6]. After Bell received his patent in 1876, Meucci took Bell to court in order to establish his priority, but he lost the case because, due to a series of circumstances, he could not prove much material evidence of his inventions apart from reconstructing them during the trial and calling witnesses. Some historians and researchers claim there was a miscarriage of justice also due to ethnic and social discrimination. On the initiative of the Italian American deputate Vito Fossella, with the Resolution 269 the U.S. House of Representatives recognised the work previously done by Antonio Meucci: the Resolution recognised that Meucci gave his prototypes to Western Union, which afterwards claimed they had lost them; at the same time, Meucci could not find money to renew his "caveat"; It was claimed that Bell worked in the same department where Meucci's prototypes were allegedly stored and later on patented the telephone as his own invention, however this is unfounded given that Bell never worked at Western Union [7] [8] Bell Telephone Company also won in the trial "The U.S. Government Versus Antonio Meucci" by a decision on July 19th 1887 by judge William J. Wallace (Circuit Court, S. D. New York.) "The experiments and invention of one Antonio Meucci, relating to the transmission of speech by an electrical apparatus [...] do not contain any such elements of an electric speaking telephone as would give the same priority over or interfere with the said Bell patent." [9]. Dispoptic 2008

35 Pq o fotofone não evoluiu?
Que tipos de dificuldades para enviar a luz? O que houve com os fios de cobre? Atualmente ~10% das redes utilizam fibra óptica Dispoptic 2008

36 FIBRAS ÓPTICAS 1920 Independentemente - John Logie Baird (UK) e Clarence W. Hansell (USA) – patentes sobre o uso de arranjos de encanamentos ou tarugos transparentes para transmissão de imagens ou fac-símiles. 1954 Independentemente - Abraham Van Heel (Dinamarca) e Harold H. Hopkins (UK) – uso de maço de fibras revestidas e não revestidas no transporte de imagens. Dispoptic 2008

37 Imunidade à interferência eletromagnética
Fibras Vantagens baixa atenuação largura de banda Imunidade à interferência eletromagnética baixo peso (rvidro~2,5 g/cm3, rcobre ~8,9 g/cm3) sigilo isolação elétrica Dispoptic 2008

38 acoplamento e emenda da fibra derivações limitadas
Fibras Desvantagens acoplamento e emenda da fibra derivações limitadas padrão dos sistemas ópticos fragilidade da fibra Dispoptic 2008

39 Bloco dielétrico – sanduíche
Guias de onda de luz Duas categorias: Bloco dielétrico – sanduíche Confinamento da propagação planar em n1 n1 n2 n3 Dispoptic 2008

40 Fibras ópticas: Guias de onda de luz
De vidro ou plástico, de simetria cilíndrica Com secção transversal anular n2 n1 n1 > n2 GRIN Dispoptic 2008

41 Propriedades: Duas categorias: FIBRAS ÓPTICAS
Propagação confinada ao núcleo, n1, por reflexão total interna, mesmo assim qdo a fibra é envergada ou enrolada Duas categorias: Índice de refração degrau (n1 é constante) Índice de refração gradiente (GRIN) Dispoptic 2008

42 um caso do núcleo com índice de refração parabólico?
GRIN GRIN – GRadient INdex O índice de refração é função do raio = diferença de índice relativo a = raio do núcleo a = tipo de perfil do GRIN = 1 perfil triangular = 2 perfil parabólico = ∞ perfil degrau core-cladding index difference Δ = n1 􀀀 n2 n1 ; (1.2.1) and the so-called V parameter defined as V = k0a(n21 􀀀 n22 ) 1=2 ; (1.2.2) where k0 = 2π=λ , a is the core radius, and λ is the wavelength of light. The V parameter determines the number of modes supported by the fiber. Fiber modes are discussed in Section 2.2, where it is shown that a step-index fiber supports a single mode if V < 2:405. Optical fibers designed to satisfy this condition are called single-mode fibers. The main difference between the single-mode and multimode fibers is the core size. The core radius a is typically 25–30 μm for multimode fibers. However, single-mode fibers with Δ 0:003 require a to be < 5 μm. The numerical value of the outer radius b is less critical as long as it is large enough to confine the fiber modes entirely. Trabalho: qual é a equação de propagação dos raios dentro da fibra para um caso do núcleo com índice de refração parabólico? Dispoptic 2008

43 Teoria de propagação n1 Ar n2 no n1 > n2 Meio externo da fibra: Ar
Fibra com índice de refração degrau Aplicação da Lei de Snell em cada interface A medida que q0 diminui qi Até atingir o ângulo qc qo = qa qdo qi = qc Todos os raios que incidem com ângulo menor que qase propaga na guia de onda por reflexão interna total. Abertura numérica NA de uma guia de onda, uma espécie de medida ou característica que mostra o quanto que a guia de onda consegue receber luz Dispoptic 2008

44 Teoria de propagação n1 Ar Ar n2 no n1 > n2
onde pela Lei de Snell sinqc=n2/n1 Dispoptic 2008

45 Diferença de índice de refração entre núcleo e revestimento
Parâmetros numa fibra Diferença de índice de refração entre núcleo e revestimento Parâmetro V que determina o número de modos suportados por uma fibra. Caso específico V<2.405 → monomodo a é o raio do núcleo Dispoptic 2008

46 Alguns exemplos 1.- Uma fibra óptica com um núcleo de vidro flint denso, n1 = 1,66, e um recobrimento de vidro crown, n2 = 1,52. Qual é o maior ângulo de abertura (metade do ângulo do cone de luz que entra na fibra) para que a luz que seja transmitida ao longo da fibra? Dispoptic 2008

47 Notar que aumentando q1 diminui q3
.....cont n1 n2 q3 ≥ qc onde qc é o ângulo crítico para que o feixe de luz seja totalmente refletido para dentro do núcleo. Notar que aumentando q1 diminui q3 A solução será Colocando q3 = qc para determinar q1 utilizando a lei de Snell Dispoptic 2008

48 Substituindo na primeira eq:
....cont n1 n2 Em A: Em B: Substituindo na primeira eq: Dispoptic 2008 Sendo n1 = 1,66 e n2 = 1,56 O valor calculado de q1 é 42o

49 Outro exemplo 2.- Qual é o raio de menor curvatura que podemos dobrar numa fibra óptica com núcleo de 0,05mm sem perder luz? O índice de refração do núcleo é 1,66 e da cobertura é de 1,52 Adotamos a suposição de que um feixe de luz ABCDE incide de forma colimada na fibra. Observamos que o feixe E incide com o menor ângulo na interface núcleo/cobertura. Dispoptic 2008

50 Cont. Adotamos a suposição de que um feixe de luz ABCDE incide de forma colimada na fibra. Observamos que o feixe E incide com o menor ângulo na interface núcleo/cobertura. Basta colocar esse ângulo como se fosse o ângulo crítico, evitando perdas. Pela definição Pela figura Dispoptic 2008

51 Várias configurações de fabricação
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52 Próxima Aula Descrição mais apropriada sobre a propagação da luz em guias de onda, tratamento ondulatório, através das eqs de Maxwell. Dispoptic 2008