MicroscopyMicroscopy
Light and Electron MicroscopyLight and Electron Microscopy
The First Light MicroscopesThe First Light Microscopes
Around 1590 Zaccharias and Hans Janssenexperimented with lenses in a tube, leadingto the forerunner of the microscope and thetelescopeAround 1590 Zaccharias and Hans Janssenexperimented with lenses in a tube, leadingto the forerunner of the microscope and thetelescope
In the late 1600’s, Anton van Leeuwenhoekwas the first to see bacteria, yeast, and manyother microbes using a microscopeIn the late 1600’s, Anton van Leeuwenhoekwas the first to see bacteria, yeast, and manyother microbes using a microscope
How Light Microscopes WorkHow Light Microscopes Work
First, the objective lens gathers light from thespecimen and magnifies the imageFirst, the objective lens gathers light from thespecimen and magnifies the image
Most microscopes have several objective lenses thatcan be rotated into position to provide differentlevels of magnification (4X, 10X, 40X)Most microscopes have several objective lenses thatcan be rotated into position to provide differentlevels of magnification (4X, 10X, 40X)
The ocular lens in the eyepiece magnifies andtransmits the image to your eyeThe ocular lens in the eyepiece magnifies andtransmits the image to your eye
The magnification of the ocular lens is 10XThe magnification of the ocular lens is 10X
To find the total magnification of the microscopeyou are using, multiply the magnification of theobjective lens by the magnification of the ocularlens.To find the total magnification of the microscopeyou are using, multiply the magnification of theobjective lens by the magnification of the ocularlens.
For example: 40X (objective lense) x 10X (ocularlense) = 400X magnificationFor example: 40X (objective lense) x 10X (ocularlense) = 400X magnification
The Parts of a Light MicroscopeThe Parts of a Light Microscope
Light source: Could be a mirror, butmost likely it is a bulb built into thebaseLight source: Could be a mirror, butmost likely it is a bulb built into thebase
Diaphragm: Adjusts the amount oflight striking an objectDiaphragm: Adjusts the amount oflight striking an object
Objective lens: Gathers light andmagnifies imageObjective lens: Gathers light andmagnifies image
Ocular lens (eyepiece): Magnifiesobjects and focuses light to your eyeOcular lens (eyepiece): Magnifiesobjects and focuses light to your eye
Stage: Holds slideStage: Holds slide
Can be moved using the coarse or fineadjustment knobs to bring the objectinto focusCan be moved using the coarse or fineadjustment knobs to bring the objectinto focus
Stage clips: Hold slide in placeStage clips: Hold slide in place
Base and arm: Structural support forthe microscopeBase and arm: Structural support forthe microscope
Can you name the parts?Start on the left side and work from the top down. Then go to the rightside and work from the top down.Can you name the parts?Start on the left side and work from the top down. Then go to the rightside and work from the top down.
Nice Job !
Objective Lenses
Stage
Diaphragm
Light Source
Base
Fine adjustment
Course adjustment
Stage clip
Arm
Ocular lens (eyepiece)
Images Produced by LightMicroscopesImages Produced by LightMicroscopes
Amoeba
Streptococcus bacteria
Anthrax bacteria
Human cheek cells
Plant cells
Yeast cells
Beyond Light MicroscopesBeyond Light Microscopes
Light microscopes are limited bytheir resolution.Light microscopes are limited bytheir resolution.
Light microscopes cannot produceclear images of objects smallerthan 0.2 micrometersLight microscopes cannot produceclear images of objects smallerthan 0.2 micrometers
The electron microscope wasinvented in the 1930’s by MaxKnott and Ernst RuskaThe electron microscope wasinvented in the 1930’s by MaxKnott and Ernst Ruska
Electron microscopes use beamsof electrons, rather than light, toproduce imagesElectron microscopes use beamsof electrons, rather than light, toproduce images
Electron microscopes can viewobjects as small as the diameter ofan atomElectron microscopes can viewobjects as small as the diameter ofan atom
Types of Electron MicroscopesTypes of Electron Microscopes
Transmission electron microscopes (TEMs) passa beam of electron through a thin specimenTransmission electron microscopes (TEMs) passa beam of electron through a thin specimen
Scanning electron microscopes (SEMs) scan abeam of electrons over the surface of aspecimenScanning electron microscopes (SEMs) scan abeam of electrons over the surface of aspecimen
Specimens from electron microscopy must bepreserved and dehydrated, so living cells cannotbe viewedSpecimens from electron microscopy must bepreserved and dehydrated, so living cells cannotbe viewed
Images Produced by ElectronMicroscopesImages Produced by ElectronMicroscopes
Cyanobacteria
(TEM)
Lactobacillus
(SEM)
Campylobacter
(SEM)
Deinococcus
(SEM)
House ant
Avian influenza
virus
Human eyelash
Yeast
Using Microscopes to Visualize theThree Shapes of BacteriaUsing Microscopes to Visualize theThree Shapes of Bacteria
Cocci (round)Cocci (round)
Bacilli (rod)Bacilli (rod)
Spirilla (spiral)Spirilla (spiral)
Light microscope:Light microscope:
Three shapes of bacteria
taken with an SEM
Bacilli
Cocci
Spirilla
ReferencesReferences
http://education.denniskunkel.com/catalog/product_info.php?products_id=1123http://education.denniskunkel.com/catalog/product_info.php?products_id=1123
http://inventors.about.com/library/inventors/blroberthooke.htmhttp://inventors.about.com/library/inventors/blroberthooke.htm