a bit of history of the microscope · the microscope got it’s ... bulb located at the base of the...

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