PicoQuant MultiHarp 150 - Acquisition

PicoQuantGmbH MultiHarpSoftwareV.3.1.0.0
Unitsarenanoseconds(ns),thepermittedrangeisfrom0to160ns.NotethatTdead=0doesnotreallymean
zerodeadtime,instead,theinputwillthenoperateatitsshortest(native)deadtimeofabout650ps.Whena
deadtime>0issetthenthetiminghardwarewillsuppresseventsfallingintothedeadtime.Thisisonlyasup-
pressionoffurtherprocessinganddoesnotpreventtheTDCtogointoanother(native)deadtime.
Typethevalueasanintegerintheeditboxandpress<Enter>orclickonApply.Thevaluecanbeenteredin
stepsofnanosecondsbutnotethattheactualstepisapproximatedonlytotheinstrument’sbaseresolution(5,
10or80psdependentonthemodel).Alternatively,usethespincontrolnexttotheeditboxtoincrement⁄decre-
mentthecurrentvalue.Inthiscasechangestakeeffectimmediatelywithoutpressing<Enter>.
Theprogrammabledeadtimeisonlyavailablewithsuitablefirmware(“gateware”),whichmustbeversion0.8or
higher.DevicesshippedafterSeptember2019willhaveitbydefault.OtherwisetheeditboxforTdeadwillre-
maingrayedout.Olderdevicescanbeupgraded,pleasecontactPicoQuant.
6.4.3. Acquisition
Resolution editboxandspincontrol
Usethissetofinputcontrolstospecifythetimeresolution.Unitsarepicoseconds(ps).Possiblechoicesarethe
device'sbaseresolutionandsuccessivemultiplesbytwo.Typethedesiredresolutionvalueasanintegerinthe
editboxandpress<Enter>orclickonApply.Alternatively,usethespincontrol(nexttoit)toincrement/decre-
mentthecurrentvalue.Inthiscase,changestakeeffectimmediatelywithoutpressing<Enter>.Incaseofen-
teringvaluesotherthanvalidresolutions,thenextsuitableresolutionstepischosenautomatically.
Therearealways2
16
=65536timebinsinonehistogram.Withthechosenresolution,therespectivetimerange
coveredis65536*Resolution.Thechoiceofrangemustbeacompromisebetweenresolutionandtimespan
covered.Thesmallestrangeoffersthebestresolutionandtheshortestspan(viceversaforthelargestrange).
Forhighsyncratesthehighestresolutionisusuallymostappropriate,sincethesmallestrangestillcoversthe
fullsyncperiod.Forlowersyncratesthehistogramrangemaybetoosmalltocoverthefullsyncperiod.The
decaycurveregionofinterestmaythereforelieoutsidetheacquisitionwindowof65536timebins.Apartfrom
switchingtoalowerresolutionitispossibletoshifttheacquisitionwindowrelativetothesyncframebymeans
oftheoffset.Notethatworkingwithverylongtimespans(lowsyncrates)athighcountratesalsorequireslong
acquisitiontimestominimizenoticeable“steps”intheacquiredhistograms.
Acquisition Time editboxandspincontrol
Setthedesiredmeasurementtimehere.Unitsareseconds(s).Thepermittedrangeis0.001to360,000sin
stepsof0.001s.Typethedesiredvalueintheeditboxandpress<Enter>orclickonApply.Alternatively,use
thespincontrol(nexttoit)toincrement/decrementthecurrentvalue.Inthiscase,changestakeeffectimmedi-
atelywithoutpressing<Enter>.Thedefaultincrement/decrementpermouseclickislogarithmic.
Offset editboxandspincontrol
Forhighsyncratesthehighestresolutionisusuallymostappropriate,sincethesmallestrangestillcoversthe
fullsyncperiod.Theoffsetshouldinthesecasesalwaysbesetto0.
Forlowersyncratesthehistogramrangemaybetoosmalltocoverthefullsyncperiod.Themeasurementre-
gionofinterestmaythereforelieoutsidetheacquisitionwindowof65536histogrambins.Apartfromswitching
toalowerresolutionitispossibletoshifttheacquisitionwindowrelativetothesyncframebymeansofsetting
theoffset>0.
Usethissetofinputcontrolstospecifythedesiredoffset.Unitsarenanoseconds(ns).Possibleoffsetsarein
therangefrom0to100,000,000ns.Typethevalueasanintegerintheeditboxandpress<Enter>orclickon
Apply.Theoffsetvaluecanbeenteredinstepsofnanosecondsbutwillinternallyberoundedtothenearest
multipleof the  device’sbaseresolution.Alternatively,use  the  spin  control  next  totheeditbox to incre-
ment⁄decrementthecurrentvalue.Inthiscasechangestakeeffectimmediatelywithoutpressing<Enter>.
Internallytheoffsetissubtractedfromeachstart–stopmeasurementbeforeitisusedtoaddressthehistogram
bintobeincremented.Therefore,increasingtheoffsetmeansshiftingthesignalonthescreentotheleft,to-
wardsearliertimes.
Notethattheoffsethasnoeffectontherelativetimingoflaserpulsesandphotonevents.Itmerelyshiftsthere-
gionofinterestwheredataistobecollected.Therelativetimingoflaserpulsesandphotoneventscanonlybe
controlledbymeansofcabledelaysandtheinputoffsetsdescribedinsections6.4.1and6.4.2.Thelattermay
benecessaryinordertoshiftyourfluorescencedecaywithinthesyncframesothatitisnottruncated.
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