简介:Wehavedesignedanddemonstratedasimple,widefield-of-view(FOV=60°)foveatedimagingsystemutilizingadeformablemirror.Thedeformablemirrorisusedtodynamicallycorrecttheoff-axisaberrationsthatlimittheusefulFOVofthesystem.ThesystemmimicstheoperationofhumaneyethroughcreatinganimagewithvariablespatialresolutionandcanbemadesignificantlysmallerandmorecompactthanaconventionalwideFOVsystem.Experimentsshowthatthissystemcanbeusedinmanyareaswheresize,weight,anddatatransmissionbandwidtharecritical.
简介:ThisLetterproposesabrand-newfilamentdiametermeasurementmethodbasedonwhatiscalled'dualdiffraction,'inthatagratingisaddedbehindthefilamenttomakefulluseofitssubdivisionandamplificationcharacteristics.Highermeasurementaccuracyisachievedbythismethodcomparedwiththetraditionaldiffractionmethod.Toverifyitsaccuracy,threestandardfilamentswithnominalvaluesof100.2,120.1,and140.8μmaremeasuredbythedualdiffractionmethodandtraditionaldiffractionmethodunderthesameexperimentalconditions.Therelativemeasurementerrorsofthenewmethodarelessthan0.75%,anditsaveragerelativeerrorisreducedby56%comparedwiththetraditionaldiffractionmethod.
简介:Quantumkeydistribution(QKD)isamajorresearchtopicbecauseitprovidesunconditionalsecurity.Unfortunately,manyimperfectionsremaininQKD’sexperimentalrealization.TheFaraday–Michelson(FM)QKDsystemisproposedtoeliminatetheseimperfectionsusingpolarization.However,thelongarm’sphasemodulator(PM)hasanunexpectedinsertionloss,meaningthatthestatesentisnolongerperfect.Inthisletter,weproposeanalternativeFM-QKDsystemstructure,andanalyzethesecurityandkeygenerationrateincomparisonwiththeoriginalsystemviadifferentanalysismethods.WefindanobviouskeyrateimprovementwhenthePMinsertionlossisnotextremelysmall.