lec 1 Part of Microscop.pdf Microscopy The science of investigating small objects and structures using a microscope

Microscopy
The science of investigating small objects and
structures using a microscope

1. Lecture 1:
Medical Laboratory Instrumentation
Parts of Microscope
1
Dr. HalahKamal
1stClass
College of Medical Sciences Technology/
University of Al-Mashreq

2. –Introduction
•Itisanimportantdevicethatproducesamagnifiedimageof
objectstoosmalltobeseenwiththenakedeye.The
microscopeiswidelyusedinmedicineandbiology
•Biologistsusemicroscopestostudycells,cellparts,and
organismsthataretoosmalltobeseenwiththenakedeye.
•Microscopesbothenlargetheimageofanobjectandshow
itsdetailstoosmallenlarge.
Microscopy-Thescienceofinvestigatingsmallobjectsand
structuresusingamicroscope.
Microscope:Micron=small(Greek),scope=aim

3. TheHistoryoftheMicroscopeandEarlyCellStudies
•Janssen&ZachariasJansen(1590)
Constructedthefirstsimplelightmicroscope,whileexperimenting
withseverallensesinatube,discoveredthat:nearbyobjectsappeared
greatlyenlarged.
•RobertHooke(1665)
Usedacrudemicroscopetoobservea:thinsliceofcork.Hewasthe
firsttousetheword“cell”todescribethesmallestunitsoflife.
•Anton van Leeuwenhoek )1674(
Hewasthefirsttoseeanddescribemicroorganismsundera
microscope.Heobservedadropofpondwaterteemingwithlife.He
referredtothesesmallmicroorganismsas“tinyanimalcules”.

4. There are two types of microscopes:
1. Light Microscopes:
Lightpasses through one or more lenses to produce an enlarged
image of a specimen.
2. Electron Microscopes:
Forms an image of a specimen using a beam of electrons rather
than light.

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Principle:
•Thelightmicroscopeoperatesontheprinciplethatlight
energywillpassthroughandaroundathinobject,such
asstudymicromoleculessuchasbloodcells,bacteria,
fungi,andprotozoa,etc.withaidoflensesforminga
magnifiedimpressiononthevisualsensorylayerofthe
eye.
•Themaincomponentsofthecompoundlightmicroscope
includealightsourcethatisfocusedonthespecimenbya
condenserlens.

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ImportantPropertiesofLightMicroscopes
1.Magnification:Powerofmicroscopeenlargeofan
object(Degreeofenlargement).
•PowerofMagnificationrangingfrom4Xto100X.
2.Resolution:Powerofthemicroscopetoshowdetail
clearlyasseparateanddistinct.
Types of microscope Resolving power
Compound Microscope 200 nanometers
Scanning Electron Microscope10 nanometers
Transmission Electron Microscope0.2 nanometers

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3.Contrast:Itisdefinedasthedifferenceinlight
intensitybetweentheimageandtheadjacent
backgroundrelativetotheoverallbackgroundintensity
(differencesinintensityand/orcolorcreateimage
contrast).Ingeneral,aminimumcontrastvalueof0.02
(2%)isneededbythehumaneyetodistinguishthe
differencesbetweentheimageanditsbackground.

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CompoundLightMicroscopePartsandFunctions
A-Framework
❖Head:Itisanintegralpartofthemicroscopeasitholdsthe
ocularlensandconnectsittotheobjectivelenses.
1.Ocular(eyepiece)-Whereyoulooktoseetheimageofyour
specimen.
-Powerofit10X(magnifies10times).
-Containslensesthatcontributetototalmagnification.
2.Bodytube-Connectstheeyepiecetotheobjectivelenses.
3.RevolvingNosepiece-Thisisthepartthatholdstwoor
moreobjectivelensesandcanberotatedtoeasilychange
power.
4.Objectivelenses-Containlensesthatcontributetototal
magnification.

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❖Arm:It is the part of a microscope that connects between the
head andthebase. It helps to carry the microscope easily.
❖Base: It is the bottom part of the microscope, usually made up
of durable material as it supports the microscope to standand
provides stabilityand have the optical parts of microscope.
❖Mechanical Stage:
•Stage-The flat platform where you place your slidesover
stage opening.
•Stage Clips-hold the slide in place.
•Stage Opening (Aperture)-allows light to pass
through/around specimen.

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❖Optical parts:
1.Aperture-Theholeinthestagethroughwhichthebase
(transmitted)lightreachesthestage.
2.Coarseadjustment-Largeroundknobonthesideofthe
microscopeusedforfocusingthespecimen.
3.FineAdjustment-Smallroundknobonthesideofthe
microscopeisusedtofine-tunethefocusofyourspecimen.
4.Mirror/Lightsource-usedtoreflectlighttothespecimen.
ILLUMINATION-Lamp, sunlight, battery operated, lamp,
60W bulb, Quartz, halogen light.
FILTERS-Blue, Green, Heat absorbing filters,
Barrier filters..
5.PowerSwitch:Itisanelectricalswitchpresentatthe
bottomofthemicroscope(base)inordertoswitchoffthe
lightsource.

13. 1-Coarseadjustment:Itisaknobpresenton
thearmofamicroscope.
Themainfunctionofthisknobistomovethe
specimenupordowntoadjusttheslide
containingspecimeninordertobringitto
focusandshowthebestimagepossible.
Thecoarseadjustmentshouldbecarefully
movedandadjustedtoattaindesiredresults.
2-Fineadjustment:Thisknobisasubpartof
theCoarseadjustmentknob.
Itisusedtobringthespecimenintosharp
focus.
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B-Mechanicaladjustments(Focusingsystem)

14. 3-Slideadjustment
GlassSlide:Itisathinandflatpieceofglassusedinthe
microscope.
Atypicalglassslideisofdimensions75*26mmandabout
1mmthick.
Thespecimeniskeptontheglassslideandputunderthe
objectiveinordertostudyit.
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15. 4-Condenseradjustment:Itisusedtocollectandfocusthe
lightfromtheilluminatorontothespecimen.Itislocated
underthestageofteninconjunctionwithaniris
diaphragm.
5.IrisDiaphragm:Controlstheamountoflightthat
reachesyoureyethroughtheaperture.
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C-Magnificationsystem(Lenses):
1-Eyepiece(Ocularlens):Itisamagnifyinglensattachedto
themicroscopewhichhelpsinmagnifyingthesampleobject.
Itiscalledaneyepieceasweneedtoplaceoureyenearitin
ordertoseethemagnifyingimageofthesample.Theeyepiece
maybemonocularorbinocular.Eyelensesmagnification
10X.
2.Objectivelens:MountedonNosepiece.Itforms
magnifiedrealimage.Therearefourobjectivelensesina
standardmicroscopeasfollows:
1-ScanningObjective(4X):Istheshortestobjectiveis
usefulforgettinganoverviewoftheslide(especiallyhandy
withsomeoftheslidesthatcontainwholeorganslikea
sectionofthespinalcord,lung,digestivetract,ovary…).

17. 2-LowPowerObjective(10X):Isthenextshortestobjectiveis
probablythemostusefullensforviewingslides.
3-HighPowerObjective(40X):Itisobjective(sometimes
calledthe"high-dry"objective)isusefulforobservingfine
detailsuchasthestriationsinskeletalmuscle,the
arrangementofHaversiansystemsincompactbone,typesof
nervecellsintheretina,etc.
4-OilImmersionObjective(100X):Highestmagnification.
Itisusedforobservingthedetailofindividualcellssuchas
whitebloodcells,thecellsinvolvedinspermatogenesis.Oil
preventsrefractionoflightoutwardsandallowsittopass
straightintoobjective
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•Theimageproducedbytheobjectivelensisthenmagnified
againbytheeyepiecelens,whichactsasasimplemagnifying
glass.Themagnifiedimagecanbeseenbylookingintothe
eyepiecelens.
•Magnificationformula-calculatetotalmagnification
Total Magnification= Ocular power Mag. * Objective power
Mag.
Ocular Objective
10x red 4 = 40x
10x yellow 10 = 100x
10x blue 40 = 400x
10x oil 100=1000X

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