a bit of history of the microscope · the microscope got it’s ... bulb located at the base of the...
TRANSCRIPT
A Bit of
History of
the
Microscope
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Clipart from Microsoft Office Online
The microscope got it’s
name because it
allows us to view minute
things.
Micro means very small.
Scope (suffix) means
viewing or observing.
.
Microscopes use a light
source. The light source is a light-
bulb located at the base of the
microscope. The light source lights
up the specimen by passing light
through a thin, almost transparent
part of the specimen.
History of the microscope
Spectacles were known in Italy in
1200
The early simple “microscopes” which were really
only magnifying glasses had one power, usually
about 6X - 10X . One thing that was very common
and interesting to look at was fleas and other tiny
insects. These early magnifiers were hence called
“flea glasses”.
Around 1590, two Dutch spectacle makers, Zaccharias
Janssen and his father Hans started experimenting with
these lenses. They put several lenses in a tube and
discovered objects were greatly enlarge. This was the
first compound microscope.
Anthony Leeuwenhoek of Holland (early 1700’s) became
very interested in lenses while working with magnifying glasses
in a dry goods store. He used to count the threads in cloth.
He taught himself new methods for grinding and polishing
tiny lenses which gave him greater magnifications.
has since been called the "Father of Microscopy"
Robert
Hooke’s
Microscope
Hooke wanted to know what something living looked like when it was strongly magnified. Since he knew that he would need to cut a really thin layer to view through his microscope, he chose to view a piece of easily-sliced cork tree…
Hooke’s microscope
http://en.wikipedia.org/wi ki/Image:Hooke_Micr oscope-03000276-FIG-4.jpg
Cork oak (Quercus suber) with
sections of cork removed
Eric G. Carle—Shostal/EB Inc.
This is a photograph of a cork tree (from which we cut cork).
Cork
http://en.wikipedia.org/wiki/Image:Cork_Trees_Ubrique.jpg
When Hookeviewed
the thin layer of
cork through
his micro-scope,this is
what he saw:
http://upload.wikimedia.org/wikipedia/commons/1/17/Cork_Micrographia_Hooke.png
The small structures that “make up” cork reminded Hooke of the prison cells of his century…This is why we say living things are made of cells.
What Hooke
saw
through his
scope…
Modern Prison Cells
http://upload.wikimedia.org/wikipedia/commons/1/17/Cork_Micrographia_Hooke.png http://en.wikipedia.org/wiki/Image:Oxford_Castle.JPG
http://en.wikipedia.org/wiki/Image:Prison_cell.jpg
…so he named the small structures
“cells.”Cork Cells
(Cells from
a Cork Tree)
Modern Prison Cells
http://upload.wikimedia.org/wikipedia/commons/1/17/Cork_Micrographia_Hooke.png http://en.wikipedia.org/wiki/Image:Oxford_Castle.JPG
http://en.wikipedia.org/wiki/Image:Prison_cell.jpg
1931- An electron microscope depends
on electrons rather than
light to view an object.
Electron microscopes make it possible
to view objects slightly larger than
an atom.
Microscopes are compound, meaning
they have two or more lenses used
to magnify objects.
These lenses bend
the light.
Schleiden and Schwann
•
http://upload.wikimedia.org/wikipedia/commons/a/ab/Matthias_Jacob_Schleiden.jpg
Proposed cell theory:
1. All living things are composed of cells2. Cells are the basic unit of structure and
function in living things3. All cells are produced by other cells
Our Microscope
Photo by D. Tresten, 2002
•Zeiss Compound Microscope•Invented > 200 yrs ago
•Invented by Karl Zeiss
•It’s the one used in science labs all over the world. It’s called a Zeiss microscope.
Which type of lens is in a microscope?
• Convex Lens(Pooches out in the middle!)
• Concave Lens(Caves in in the middle!)
A convex lensis used in themicroscope.
In Which Objects would Convex
Lenses be Used?Click to see
7 images
In Which Objects might Concave
Lenses be Used?Click to see
7 images
Eye piece
Body tube
Base
Coarse
adjustment
knob
Arm
Fine
adjustment
knob
Revolving
nosepiece
Diaphragm
Light source
Stage opening
Stage clips
Stage
Magnify 10 X
Objective
lens
Total Magnification -What is it?
To find the total magnification at which a microscope is set, just multiply the power of the eyepiece (10x) times the power of the objective that is in place.
Click to practice finding total magnification…
Magnification: Multiply
If…
Eye piece 10 X
Objective Lens 4 x
Total magnification is 40 X
Practice calculating Total Magnification:
If the eye piece is 10 x and the objective lens is 40 x the
magnification is...
If the eye piece is 10 x and the objective lens is 20 x the
magnification is...
If the eye piece is 10 x and the objective lens is 10 x the
magnification is...
400x
200x
100x
In effect, it can magnify objects up to 1 million times. Nevertheless,
all electron microscopes suffer from a serious drawback.
Since no living specimen can survive under their high vacuum,
they cannot show the ever-changing movements that characterize a
living cell.
Magnification: X 1,000
Mosquito head
Magnification: X 200
Black Widow Spider Claw
Moth wing
Cucumber Skin
Staple through paper
Toilet paper
Hypodermic Needle
Foot of a House Fly
Deer Tick
Microscope Rules
1. Always use two hands
to carry a microscope!
One hand goes under the base
and one on the arm.
2. Do not touch the lenses.
If they are dirty, ask your
teacher for
special lens paper or ask the teacher
to clean the lenses for you.
3.Be cautious when handling
glass slides.
Notify teacher if a slide
breaks.
Students should not
handle broken glass.
4. Always keep the scope
away from the _______ of
the_________.
Care of the Microscope
Page 3 of 3
edge
table
Microscopes are not toys!!
They are expensive tools!!
How to Use the Microscope
1. STAGE down! (away from objectives)
2. Plug in the microscope.
3. Twist 4x (Low-Power) OBJECTIVE until it
clicks into place! (using nosepiece NOT objectives)
4. Stage CLIPS out!
5. SLIDE on
6. Stage CLIPS back in (carefully placed on top
of slide)
7. Switch on LAMP
Before using the Scope,
Wake It Up:
Use of the Microscope
Page 1
Always put our microscopes
“to bed” after labs:
Use of the Microscope
Page 4
1. Lamp off
2. Unplug
3. Stage down (Away from objectives)
4. All slides are removed
5. Clips IN
6. Clean stage
7. Dust cover ON
8. Put all slides and other materials in proper places