Fiber Optics Essays (4499 words) - Optical Fiber, Fiber Optics

Fiber Optics Fiber optics produced by special methods from silica glass and quartz which replaced copper wire is very useful in telecommunications, long distance telephone lines and in examining internal parts of the body (endoscopy). Equipment for photography is available with all current fiber-optic endoscopes. Through a process known as total internal reflection, light rays beamed into the fiber can propagate within the core for great distances with remarkably little attenuation or reduction in intensity. In general, the methods of fiber production fall into three categories; (a) the extrusion method for synthetic fibers; (b) hot drawing of fibers from molten bulk material through an orifice; and (c) drawing of uncoated, coated and multiple fibers from assemblies of rods and tubes fed through a hollow cylindrical furnace. Three forms of fiber optics components have been proposed for the improvement of the image quality, field angle and photographic speed of various types of optical systems. These fiber optics elements, in the form of a field flattener, a conical condenser and distortion corrector, can be used separately or combined into a single unit called a "Focon". BOAZ? ?NVERSTES MAKNA M?HENDSL DEPARTMANI MALZEME DERS D?NEM PROJES YAZ OKULU 2000 ?ZET G?n?m?zde bakr tellerin yerini alan silikon camndan ve kristalinden ?retilen fiber optikler, telekom?nikasyonda, uzun mesafeli telefon hatlarnda ve insan v?cudunun i? ksmlarn inceleyen endoskopilerde kullanlmaktadr. Fotoraf ekipmanlarnda da b?t?n fiber-optik endoskoplara kullanlmaktadr. Tam i? yansma olarak bilinen ilem yoluyla, fiberin i?inde toplanan k nlar, uzun mesafeler boyunca iddetinde kk bir azalma ve bozulmayla yol alabilmektedir. Genellikle, fiber ?retimleri kategoridedir; Sentetik fiber ?retiminde dna ?karma methodu; Erimi d?kme maddelerden azlarna doru oluan fiberlerin scak ?izimleriyle, kaplanm,kaplanmam veya kark fiberlerin ?izimleriyle. ?eit olan fiber optik par?alar; g?r?nt? kalitesini, ?eitli optik sistemlerdeki alan a?s ve fotografik hzlar gelitirmek i?in dn?lm?t?r. Bu fiber optik elemanlar; alan d?zletirici, konik younlatrc ve sapma d?zenleyici ekillerindedir ve ayr veya "Focon" ad verilen ?nite i?in birlemi olarak kullanlabilirler. LIST OF FIGURES Figure 2.1 Photograph of the earliest bundle of uncoated aligned fibers Page 7 Figure 3.1 Core of a step index fiber Page 8 Figure 3.2 Schematic diagram of a typical fiber drawing Page 9 Figure 3.3 Preform manufacturing apparatus used in Silica-Quartz Page 11 Figure 3.4 Comparison of static,dynamic and spitial filtering imagery Page 12 Figure 4.1 Field flattener system of photography Page 13 Figure 4.2 Showing the image transmission through a conical fiber bundle Page 14 Figure 4.3 Fiber optics distortion correctors Page 14 Figure 4.4 Limiting resolution of Focon system Page 15 Figure 5.1 Single lens reflex camera Page 16 TABLE OF CONTENTS 1. INTRODUCTION 2. HISTORY OF FIBER OPTICS 3. WHAT IS FIBER OPTICS? 3.1 WHAT IS SILICA? 3.2 WHAT IS QUARTZ? 3.3 WHAT IS ENDOSCOPIC PHOTOGRAPHY? 4. ENDOSCOPIC PHOTOGRAPHY ELEMENTS 4.1 FIELD FLATTENER 4.2 CONICAL CONDENSER 4.3 DISTORTION CORRECTOR 4.4 FOCON RESOLUTION 5. ENDOSCOPIC PHOTOGRAPHY TECHNIQUES 5.1 COLOUR PHOTOGRAPHY WITH FIBRE-OPTIC ENDOSCOPES 5.2 CINE- ENDOSCOPY 5.3 CLOSED CIRCUIT COLOUR TELEVISION ENDOSCOPY 5.4 GASTRO-CAMERA EXAMINATION 6. CONCLUSION 7. REFERENCES 8. APPENDIX 1. INTRODUCTION The technology of fiber drawing for nonoptical applications is old and fairly standard. Very-small-diameter glass and quartz fibers were made as early as by Faraday. In the early stages of the production of glass fibers on an industrial scale, the main application of the fibers was envisaged in the textile industry. More recently, they have been used for insulation against sound, heat and electricity. Presently, very fine fibers are being made of materials such as glass, quartz, nylon, polystyrene, polymethylcrylate. Of these, glasses, quartz and plastics are preferred for optical use because of their higher visible light transmission, longer thermal working range, better surface characteristics and mechanical strength. Furthermore, it has been shown that glass fibers can have greater tensile strength than can be expected from the bulk material. 2. HISTORY OF FIBER OPTICS The conduction of light along transparent cylinders by multiple total internal reflections is a fairly old and well known phenomenon. It is entirely possible that grecian and other ancient glassblowers observed and used this phenomenon in fabricating their decorative glassware. In fact, the basic techniques used by the old Venetian glassblowers for making ?millifiore' form an important aspect of present-day fiber optics technology. However, the earliest recorded scientific demonstration of this phenomenon was given by John Tyndall in 1870. In demostration Thyndall used an illuminated vessel of water and showed that, when a stream of water was allowed to flow through a hole in the side of the vessel, light was conducted along the curved path of the stream. In 1951 when A.C.S. van Heel in Holland and H.H. Hopkins and N.S. Kapany studied on the transmission of images along an aligned bundle