Varian Cary 5000 User Manual - Smallsamples
4
beamhitsthecenterofmirrorM3thenuseM3sothebeamhitsthecenterofthe
sample.Someofthemirrorsaremorecomplicatedtoadjust(althoughthesecan
oftenbeleftalone).Forhelpwithalignment,talktooneoftheGLAsandread
thealignmentinstructions,whichcanbefoundunderHelp.
Smallsamples
Mosttypicallabsamplesaresmallerinsizethanwhattheinstrumentwasdesignedto
measure.Forallthreetypesofmeasurements(T,C,andR),itisbesttounderfillthe
samplearea.
Spotsize-Therearetwowaysof
reducingthebeamspotsize:
1)Slitwidth:Thesimplestwayis
toreducebeamsizeisbytheslit
width.Clickonthe
Setup
the
options
tab.Underslitheight,
switchtoReduced.Ittakesabouta
minutefortheslittochange.
2)Smallspotkit:Therearealsoa
seriesoflensesthatcanbeputin
theopticalpathtofocusthebeam
intoasmallerspotonthesample.
Againtherearethreelenseswith
differentfocallengthsandmarked
T,C,andRforthethreepositionsof
theintegratingsphere.Also,the
largemirror(M3)isswitchedout
foraonewithadifferentcurvature;
thismirrorisalwayskeptintheT
position,regardlessofthetypeof
measurementbeingmade.
3)Aperturekitforreflection
measurements
Fornormalincidencereflectionmeasurements,theopencircleintherearofthe
integratingsphereisseveralinchesindiameter.Thereareaseriesofapertures,
whichhavethewhiteSpectralonmaterial(sameroughenedTeflonthatisinsidethe
integratingsphere),thatcanslideontotheslotonthebackoftheintegratingsphere.
Thespring-loadedmountthatholdsthesampleagainsttheintegratingspherefirst
needstobetakenoff.Slideontheappropriateapertureandtheneithertapeyour
sampleontothebackoftheaperture,orputbackonthespring-loadedsample
mount.
Ifthebeamspotoverfillstheaperture,youcancorrectforthis“straylight”by
performingaZero/baselineCorrection.Normally,the0%TBaselinescanisrunby
blockingthebeambeforeitenterstheintegratingsphere,whichaccountsfor
Figure4Photoofdiffusereflectanceaccessorywith
beampath.