?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F557%2F&rft.title=Determining+Index+Data+from+Refracted%2FDiffracted+Rays&rft.creator=Bourland%2C+J.&rft.subject=Materials&rft.description=An+optical+fiber+is+a+cylindrical+waveguide+of+visible+(or+near+visible)+light+composed+of+silica+doped+with+germanium+oxide+(Ge02).+The+guiding+is+accomplished+by+varying+the+level+of+Ge02+in+the+fiber+to+create+an+index+of+refraction+in+the+fiber+that+varies+with+the+radius+of+the+fiber.+The+fiber+is+manufactured+by+creating+a+large+cane+with+a+radius+on+the+order+of+centimeters+that+goes+through+a+sequence+of+heatings+and+extrusions+until+it+reaches+the+finished+size%2C+which+has+a+radius+on+the+order+of+microns.%0D%0A%0D%0ATo+assess+the+quality+of+optical+fibers+during+their+manufacture%2C+it+is+common+to+measure+the+index+of+refraction+of+a+cane+during+an+intermediate+step+of+the+process.+The+index+of+refraction+varies+with+the+radius+of+the+cane%2C+and+is+written+n(r).+The+desired+profile+varies+depending+on+the+future+use+of+the+optical+fiber%2C+but+a+standard+profile+is+a+simple+parabola.%0D%0A%0D%0AThe+actual+profile+in+an+optical+fiber+does+not+match+the+desired+profile+due+to+the+way+in+which+optical+fibers+are+manufactured.+A+glass+blank+is+spun+on+a+lathe+while+a+flame+that+is+fed+an+appropriate+level+of+silica+and+Ge02+moves+rapidly+back+and+forth+along+the+cane.+Soot+from+the+flame+is+deposited+on+the+spinning+blank.+Naturally+the+deposition+will+create+spiral+patterns+of+doping+on+the+cane.+This+creates+oscillations+in+the+level+of+Ge02%2C+and+therefore+in+the+desired+refractive+index.+Because+soot+is+being+deposited+at+a+constant+volumetric+rate%2C+the+wavelength+of+the+oscillation+decreases+as+the+radius+of+the+cane+increases.+The+flame+travels+up+and+back+along+the+cane+in+each+layer%2C+so+the+layer+structure+has+two+local+maxima+in+each+full+oscillation.%0D%0A%0D%0ABecause+the+oscillatory+behavior+of+n(r)+is+unimportant+in+the+final+product%2C+Corning+asked+to+determine+a+way+to+remove+the+noise+in+the+measurements+of+n(r)+caused+by+the+oscillations%2C+and+determine+the+background+profile.&rft.date=1995&rft.type=Study+Group+Report&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F557%2F1%2FDetermining-index-data-from-refracted-diffracted-rays.pdf&rft.identifier=++Bourland%2C+J.++(1995)+Determining+Index+Data+from+Refracted%2FDiffracted+Rays.++%5BStudy+Group+Report%5D+++++