1. Introduction to the Microscope

2. The First Light Microscopes
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

3. How Light Microscopes Work
First, the objective lens gathers light from the specimen and magnifies the image
Most microscopes have several objective lenses that can be rotated into position to provide different levels of magnification (4X, 10X, 40X)
The ocular lens in the eyepiece magnifies and transmits the image to your eye
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.
EX.
40X (objective lens) x 10X (ocular lens) = 400X magnification

4. Images Produced by Light Microscopes
Amoeba
Streptococcus bacteria
Anthrax bacteria
Plant cells
Human cheek cells
Yeast cells

5. Beyond Light Microscopes
Light microscopes are limited by their resolution.
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
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

7. Types of Electron Microscopes
Transmission electron microscopes (TEMs) pass a beam of electrons through a thin specimen
Scanning electron microscopes (SEMs) scan a beam of electrons over the surface of a specimen
Specimens from electron microscopy must be preserved and dehydrated, so living cells cannot be viewed

8. Images Produced by Electron Microscopes
Cyanobacteria
(TEM)
Lactobacillus
(SEM)
Campylobacter
(SEM)
Deinococcus
(SEM)
Avian influenza
virus
House ant
Yeast
Human eyelash

9. Microscope Care Always carry with 2 hands
Only use lens paper for cleaning
Do not force knobs
Always store covered
Keep objects clear of desk and cords

10. Microscope Parts Eyepiece Body Tube Revolving Nosepiece Arm
Objective Lens
Stage
Stage Clips
Coarse Focus
Diaphragm
Fine Focus
Light
Base

11. Using the Microscope Place the Slide on the Microscope Use Stage Clips
Click Nosepiece to the lowest (shortest) setting
Look into the Eyepiece
Use the Coarse Focus

12. Using High Power Follow steps to focus using low power
Click the nosepiece to the longest objective
Do NOT use the Coarse Focusing Knob
Use the Fine Focus Knob to bring the slide
into focus