Transcript Microscopy

Microscopy
Light and Electron Microscopy
The History
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Many people experimented with making microscopes
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Was the microscope originally made by accident? (Most
people were creating telescopes)
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The first microscope was 6 feet long!!!
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The Greeks & Romans used “lenses” to magnify
objects over 1000 years ago.
The First Light Microscopes
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Around 1590 Zaccharias and Hans Janssen
experimented with lenses in a tube, leading
to the forerunner of the microscope and the
telescope
In the late 1600’s, Anton van Leeuwenhoek
was the first to see bacteria, yeast, and many
other microbes using a microscope
The History
Zacharias Jansen
1588-1631
The “First” Microscope
The History
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Hans and Zacharias Janssen of Holland in the
1590’s created the “first” compound
microscope
Anthony van Leeuwenhoek and Robert
Hooke made improvements by working on
the lenses
Anthony van Leeuwenhoek
1632-1723
Hooke Microscope
Robert Hooke
1635-1703
How a Microscope Works
Ocular Lens
(Magnifies Image)
Body Tube
(Image Focuses)
Objective Lens
(Gathers Light,
Magnifies
And Focuses Image
Inside Body Tube)
•Bending Light: The objective (bottom) convex lens
magnifies and focuses (bends) the image inside the body tube
and the ocular convex (top) lens of a microscope magnifies it
(again).
How to Use A Light Microscope
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First, the objective lens gathers light
from the specimen and magnifies the
image
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The ocular lens in the eyepiece
magnifies and transmits the image to
your eye
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Most microscopes have several objective lenses
that can be rotated into position to provide
different levels of magnification (4X, 10X, 40X)
The magnification of the ocular lens is 10X
To find the total magnification of the
microscope you are using, multiply
the magnification of the objective
lens by the magnification of the
ocular lens.
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For example: 40X (objective lense) x 10X
(ocular lense) = 400X magnification
The Parts of a Light Microscope
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Light source: Could be a mirror, but
most likely it is a bulb built into the
base
Diaphragm: Adjusts the amount of
light striking an object
Objective lens: Gathers light and
magnifies image
Ocular lens (eyepiece): Magnifies
objects and focuses light to your eye
Stage: Holds slide
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Can be moved using the coarse or fine
adjustment knobs to bring the object
into focus
Stage clips: Hold slide in place
Base and arm: Structural support for
the microscope
Can you name the parts?
Start on the left side and work from the top down. Then go to the right
side and work from the top down.
Ocular lens (eyepiece)
Arm
Objective Lenses
Stage clip
Stage
Course adjustment
Diaphragm
Fine adjustment
Light Source
Base
Nice Job !
Images Produced by Light
Microscopes
Amoeba
Streptococcus bacteria
Anthrax bacteria
Human cheek cells
Plant cells
Yeast cells
Resolution pp.18-19
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Resolution : the ability to distinguish between
two objects that are very close together
Beyond Light Microscopes
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Light microscopes are limited by
their resolution.
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Light microscopes cannot produce
clear images of objects smaller than
0.2 micrometers
The electron microscope was
invented in the 1930’s by
Max Knott and Ernst Ruska
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Electron microscopes use beams of
electrons, rather than light, to
produce images
Electron microscopes can view
objects as small as the diameter of an
atom
Types of Electron Microscopes
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Specimens from electron microscopy must
be preserved and dehydrated, so living cells
cannot be viewed
 Transmission
electron microscopes (TEMs)
pass a beam of electron through a thin
specimen
 Scanning electron microscopes (SEMs) scan a
beam of electrons over the surface of a
specimen
Images Produced by Electron
Microscopes
Cyanobacteria
(TEM)
House ant
Lactobacillus
(SEM)
Avian influenza
virus
Campylobacter
(SEM)
Human eyelash
Deinococcus
(SEM)
Yeast
Using Microscopes to Visualize the
Three Shapes of Bacteria
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Cocci (round)
Bacilli (rod)
Spirilla (spiral)
Three shapes of bacteria
taken with an SEM
Light microscope:
Cocci
Bacilli
Spirilla
Magnification
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To determine your magnification…you just
multiply the ocular lens by the objective lens
Ocular 10x Objective 40x:10 x 40 = 400
So the object is 400 times “larger”
Objective Lens have
their magnification
written on them.
Ocular lenses usually magnifies by 10x
Caring for a Microscope
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Clean only with a soft cloth/tissue
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Make sure it’s on a flat surface
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Don’t bang it
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Carry it with 2 HANDS…one on the arm and
the other on the base
Carry a Microscope Correctly
Using a Microscope
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Start on the lowest magnification
Don’t use the coarse adjustment knob on high
magnification…you’ll break the slide!!!
Place slide on stage and lock clips
Adjust light source (if it’s a mirror…don’t stand
in front of it!)
Use fine adjustment to focus
Calculations
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Field of View : whole circular area that you see when you
look through the microscope
Total Magnification : ocular (10x) times the objective lens
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Low power :
10x * 4x
Medium power : 10x * 10x
High power : 10x * 40x
= 40x
= 100x
= 400x
Field Diameter : distance across the field of view
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Low power [40x]
= 4.5 mm = 4 500 μm
Medium power [100x] = 1.8 mm = 1 800 μm
High power [400x]
= 0.45 mm = 450 μm
Finding Field Diameter
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If you find field diameter on a low power
magnification, you can use this to calculate the
field diameter at higher magnifications
high power field diameter low power magnification
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low power field diameter high power magnification
Calculating Estimated
Actual Size of a Specimen
Field Diameter
ActualSize 
# of specimensfittingacrossfield diameter
Field diameter
•Determine by evaluating which objective lens was used to view
specimen
•Ensure units are μm
# of specimens fitting across field diameter
•Estimate how many specimens fit across the field diameter width
wise
Calculating Estimated
Actual Size of a Specimen
Field diameter
•Viewed under medium power
•Field of View is 1 800 μm
# of specimens fitting across field diameter
• estimate 3 times across
1 800 m
Actual Size 
 600 m
3
Calculating Magnification
of a Drawing
width of drawing
Magnification of drawing 
actualsize of specimen
Width of drawing
•Use a ruler to measure your drawing width-wise
•Convert you units to μm
Actual size of specimen
•See previous slides
Biological Drawings
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What you need:
Blank paper
 Sharp pencil
 Ruler
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Use firm clear lines
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No shading/colour
Large drawing
Underline titles
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Labels
 Top right corner:
Neatly printed
name & date
 To the right
 Bottom right corner:
 Even column
total magnification
 Parallel lines/do not cross
 Ruler used
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References
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http://education.denniskunkel.com/catalog/product_info.php?pr
oducts_id=1123
http://micro.magnet.fsu.edu/
http://inventors.about.com/library/inventors/blroberthooke.htm
http://www.cerebromente.org.br/n17/history/neurons1_i.htm
Google Images
http://science.howstuffworks.com/light-microscope1.htm