PicoQuant MultiHarp 150 - Page 21

PicoQuantGmbH MultiHarpSoftwareV.3.1.0.0
TheMultiHarphasaUSB3.0superspeedinterfacewhichisbackwardscompatiblewithUSB2.0.Inorderto
obtainthemaximumthroughputitmustbeconnectedthroughUSB3.0orhigher.ConsultyourPCmanualasto
whetherandwhereitprovideshighspeedUSB2.0orsuperspeedUSB3.xconnectors.Thelattercanusually
beidentifiedbytheirbluecolor.TheMultiHarpwillnotworkwithaUSB1.xconnection.However,allcurrentPCs
shouldreadilyprovideUSB3.0connectivity.RecentPCsmayprovideUSB3.1or3.2connectionswhichare
backwardcompatiblewithUSB3.0andshouldbefineforrunningtheMultiHarp.IfthePChasnoUSB3.xports
youcaninstallaUSB3.xadaptercardbutthismaynotprovidethesamethroughputasanon-boardcontroller.
AlwaysuseaqualityUSBcableratedforUSB3.0orhigherspeed.Thecablelengthmustnotexceed5meters
(~16ft).Forbestreliabilitywerecommendedtousetheprovidedcableof3meterslength.NotethattheUSB
specificationdoesnotallowcableextensionsotherthandedicatedactiveextensioncablesorhubs.TheMulti-
HarpshouldworkflawlesslythroughsuitableUSBhubs.Thisisalsoavalidwayofextendingthemaximumca-
blelength.Afterahub,anothercableofupto5metersisallowed.Note,however,thathubsmaylowerthedata
throughput.Forthesamereasonsitisrecommendednottoconnectotherdeviceswithhighbandwidthrequire-
mentstothesamehub.
Thestepsbelowdescribehowtoconnectthesignalsforyourexperiment.Theinputsforthephotondetector(s)
andthesyncsignalareSMAconnectorslocatedonthefrontpaneloftheMultiHarp.TheyarelabeledSYNC
andCH1...CHxwithlargestxdependentonthemodel.Thesyncinputistypicallyusedforsynchronizationwith
alaserandCH1..CHxaredetectorsignalinputs.Thesyncinputcanalsobeusedfordetectorsifalasersyncis
notrequired,e.g.,inantibunchingmeasurementsoringenerictimetaggingapplications.Allinputsaretermi-
natedwith50Ohmsinternally.Usequality50Ohmscoaxcableswithappropriateconnectors.Forinterfacingto
BNCconnectors,usestandardadapters.CarefullyscrewontheSMAconnectorsforsyncanddetector(s)until
theyarehand-tight.Donotusewrenches.YourMultiHarpshipswithadedicatedSMAconnectortoolthatallows
convenienthandlinginlimitedspacewithoutriskofover-tightening.NotethatPMTdetectorsoperatewithhigh
voltagesthatmaydischargethroughthesignalcable.Makesuresuchdetectorsareswitchedoffandfullydis-
chargedbeforeconnectingordisconnectingthem.
Incaseoftimeresolvedfluorescenceexperimentswithapulsedexcitationsource,thesyncsignalmustbecon-
nectedtothesyncinputandthedetectorsignal(s)mustbeconnectedtothedetectorinput(s).Ifcoincidence
correlationexperimentsbetweentwo(ormore)detectorsignalsaretobecarriedout,youneedtodecide
whetheryouwillbeusinghistogrammingorTTTRmodesT2/T3.InthecaseofhistogrammingandT3mode
connectonedetectortothesyncinputandoneormoretothedetectorinputs.HistogrammingandT3timingwill
alwaysbewithrespecttothesyncinput.InT2modeitispossibletodeterminetherelativetimingbetweenallin-
putsbutthisrequiresoff–linedataanalysis(seesection5.3).
Connecttheothersignalcableendstotheappropriatesignalsources(50Ω)inyourexperimentalsetup.Thein-
putsoftheMultiHarpacceptpositiveornegativepulseswithpeakvaluesofupto+1.2Vor-1.2V,respectively.
Thesoftwareallowsselectingthetriggeredge(rising=1orfalling=0)andthetriggerlevel.Allinputsshouldbe
operatedwithsimilarpulseamplitudestominimizecross-talk.Theoptimumamplituderangeis100to200mV.
Belowthisrangeyoumaypickupnoise,abovetheremaybecross-talk.MostPMTandMCPdetectorswillre-
quireapre–amplifiertoreachenoughsignallevel.TTL–SPAD–detectorsmustbeconnectedthroughanattenu-
atororanattenuatinginverter(PicoQuantSIA400).Never connect TTL signals directly, as this may cause
damage.WeakPMTdetectorsshouldbeconnectedthrougha20dBhighspeedpre–amplifier.MCP–PMTde-
tectorsshouldbeconnectedthroughanamplifierwithslightlyhighergain.Whendetectorswithsmallsignalsare
beingusedincombinationwithlaserdriversfromPicoQuant'sPDLSeries,thesyncpulsesfromthelaserdriver
shouldbeattenuatedby10to15dBtofallintotheoptimumrangeforsmallestcross-talk.Similarattenuationis
recommendedonthedetectorsignalswhendetectorswithNIMoutputareused.Suitableattenuatorandampli-
fierdevicesareavailablefromPicoQuant.
IMPORTANT:switchthehighvoltagesupplyofPMTsoffandallowtheirelectrodestodischargebeforeconnect-
ingthem.Theirhighvoltagechargemaydamagethepre–amplifier.Observetheallowedmaximumratingsfor
theinputsignallevels.Abovetheselevelshardwaredamagewilloccur.Ifyouarenotsurewhatsignalsyour
setupdelivers,useafastoscilloscopetocheckthesignallevelandshapebeforeconnectingthemtotheMulti-
Harp.Allsignalsshouldhavefastrisetimesofnomorethanafewns.Slowersignalsmaydegradetimingaccu-
racy.
DonotconnectanythingotherthandedicatedhardwaretotheSub-Dmulti-pinconnector(controlport).Itispro-
videdforhardwareexpansion(notablyexperimentcontrol)andmustnotbeusedotherwise.Seesection8.3.2
forpinassignments.Itisrecommendedtostartinstrumentsetupwithoutanythingconnectedtothecontrolport.
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