简介:Anovellenssystemwithcorrectionofsecondaryspectrumwithoutusinganomalousglassesispresented.Thelenssystemcomprisesfourseparatedlenscomponents,withthreeofthembeingsubapertures.Twoexamplesofapochromatictelescopearepresented,bothwiththeuseoftypicalnormalglasses,namelycrownK9andflintF5glasses,andlow-costslightlyanomalousdispersionglasses.Secondaryspectrumandotherchromaticaberrationsofthetwodesignexamplesarecorrected.
简介:Asimplifiedringcavityforachievingaunidirectionalroomtemperaturemulti-wavelengtherbium-dopedfiberringlaserwithoutopticalisolatorisdemonstrated.ThefiberringcavityisbuiltinsuchawaythattheopticalfieldspropagatingintwodirectionssufferdifferentlossescausedbyonesampledfiberBragggrating.Furthermore,simultaneousmulti-wavelengthlasingwith0.8-nmintervalsisdemonstratedwithsinusoidalphasemodulationjustbeforethesampledfiberBragggratingtopreventsingle-wavelengthlasingandunstablewavelengthoscillation.
简介:Theeffectsofvacuum-inducedcoherence(VIC)onthepropertiesoftheabsorptionandgainoftheprobefieldinanequispacedthree-levelladderatomicsystemareinvestigated.Itisfoundthatlasingwithoutinversion(LWI)isremarkablyenhancedduetotheeffectofVICinthecaseofthesmallincoherentpumprate.
简介:Alightpurplishredsapphireisheattreatedinanairtightcrucible.Thesamplechangeslittleincolorafterreceivingheattreatmentat1100°C,butturnstolightblueandblueafterbeingtreatedat1200°Cand1300°C,respectively.Beforeheating,theUV-VISabsorptionspectraofthesamplearedominatedbythe551nmbroadabsorptionbandcontributedbythed-electrontransition~4A_2→~4T_2ofCr~(3+).Afterheating,theUV-VISabsorptionspectraaredominatedbythe563nmbroadabsorptionbandcontributedbytheintervalencechargetransferofFe~(2+)-Ti~(4+).ThexrayphotoelectronspectroscopytestrevealsthattheFe~(2+)andTi~(4+)ioncontentsincreasewithincreasingtemperature.ThesapphirechangingfromlightpurplishredtoblueintheheatingprocessisowingtothefactthattheFe~(2+)andTi~(4+)contentsgrowandtheintervalencechargetransferofFe~(2+)-Ti~(4+)selectivelyabsorbsUV-VISlight.
简介:Inordertodeterminetheappropriatetreatmentinterval,267patientswhounderwent3sessionsoftreatmentwithQ-switchedalexandritelaserweredividedinto4groupsaccordingtotreatmentinterval,andtheirclinicalresponseswerecompared.Amongthem,187wereaskedabouttheprocessofpigmentfading.Moreover,lightandtransmissionelectronmicroscopywereperformed.Itwasnotedthattheclinicalresponseofthe5-6monthintervalgroupwassignificantlybetterthanthatofthe3-4monthgroup,butshowednosignificantdifferencefromthatofthe7-8or≥9monthgroup.80.21%ofinvestigatedpatientsstatedthatmarkedpigmentfadingcouldnolongerbeobserved7monthsafterirradiation.4monthsafterirradiation,thedegeneratedmelanosomesandcelldebriswerestillscatteredamongcollagenfibers,scavengedgraduallybymacrophage.Inconclusion,anappropriatetreatmentintervalis5-6months.