简介：Weproposeimprovedmultilevelfilters(IMLFs)involvingtheabsolutevalueoperationintothealgorithmicframeworkoftraditionalmultilevelfilters(MLFs)toimprovetherobustnessofinfraredsmalltargetenhancementtechniquesunderacomplexinfraredclutteredbackground.Comparedwiththewidelyusedsmalltargetenhancementmethodswhichonlydealwithbrighttargets,theproposedtechniquecanen-hancetheinfraredsmalltarget,whetheritisbrightordark.Experimentalresultsverifythattheproposedtechniqueisefficientandpractical.

简介：Weproposeanovelsmall-anglemeasuringopticalmethodbasedontheastigmaticeffectoftwoorthogonallyplacedcylindricallenses.Accordingtotheone-to-onecorrespondencebetweenthelaserspotshapeandtheangle,theangleisdetermined.Wetheoreticallyanalyzethemeasuringrangeanddemonstratethatalongerdistancebetweentherotatingaxisandtheopticalaxisleadstoasmallermeasuringrange,butbettersensitivity.Also,anassociatedexperimentalsystemisestablishedandameasuringrangeof0.94mrad(cubicfitr=0.9993)aswellasagoodlinearrangeof0.37mrad(linearfitr=0.9994)witharesolutionof8μradisachieved.

简介：ThisLetterpresentsamethodofanopticalsensorformeasuringwavelengthshifts.Thesystemconsistsofadiffractiongratingandatotalinternalreflectionheterodyneinterferometer.Asaheterodynelightbeamstrikesagrating,thefirst-orderdiffractionbeamisgenerated.Thelightpenetratesintoatotalinternalreflectionprismatananglelargerthanthecriticalangle.Awavelengthvariationwillaffectthediffractiveangleofthefirst-orderbeam,thusinducingaphasedifferencevariationofthelightbeamemergingfromthetotalinternalreflectionsinsidethetrapezoidprism.Boththeexperimentalandtheoreticalresultsrevealthat,forthefirst-orderdiffractivebeam,thesensitivityandresolutionlevelsaresuperiorto5°/nmand0.006nm,respectively,intherangeofwavelengthfrom632to634nm,andaresuperiorto3.1°/nmand0.0095nmintherangefrom632to637nm.Forthetheoreticalsimulationofthefourth-orderdiffractivebeam,theyaresuperiorto6.4deg∕nmand0.0047nmintherangefrom632to637nm.

简介：Inthiswork,wereportabroadbandterahertzwavemodulatorbasedonatop-gategraphenefieldeffecttransistorwithpolyimideasthegatedielectriconaPETsubstrate.ThetransmissionoftheterahertzwaveismodulatedbycontrollingtheFermilevelofgrapheneviathepolyimideasthetop-gatedielectricmaterialinsteadofthetraditionaldielectricmaterials.Itisfoundthattheterahertzmodulatorcanachieveamodulationdepthof~20.9%withasmalloperatinggatevoltageof3.5Vandalowinsertionlossof2.1dB.