1. Microscopes
Can you see me?

2. Definition
An instrument that has one or more lenses that produce an enlarged image of an object.

3. Old School
There are two basic types of microscopes.
Simple
Compound

4. Simple Microscopes This type of microscope only has ONE lens.
These were the first scopes use by biologist

5. Compound Microscopes
A Dutch Scientist, Janssen, put two magnifying glasses together in 1590
Then in the 1600’s, Van Leeuwenhoek, made a better version and a new type was born.

6. The Compound Light Microscope

7. The Compound Light Uses light to pass through the two or more lenses.
The lenses magnify and bend the light to your eye.

8. The Compound Light Total magnification is expressed as total power.
You multiply the powers together to get the total magnification of the microscope.
Total power=eyepiece x objective
Ex. Eyepiece 20x & objective 40x, total power = 800x
Objects are measured in micrometers (one millionth of a meter or one thousandth of a mm)

9. Preparing a Wet-Mount Slide
Obtain a thin slice of a specimen
Place the specimen in the center of the slide
Drop water or stain on the specimen
Lower a coverslip at a 45° angle over the specimen. Avoid air bubbles!
Blot any excess water or stain at the edge of the coverslip

10. PROS & CONS of Light Scopes
Pros: inexpensive, use light, commonly used in classrooms, specimen does not have to be “preserved” (killed)
Cons: limited magnification, poorer resolution (resolution = clarity)

11. L King through a LIGHT Microscope
When you examine an object on low power and then switch to high power, the field of view is reduced because the magnification is greater
SO YOU SEE LESS AREA BECAUSE THE OBJECT APPEARS TO INCREASE IN SIZE!

12. Stereomicroscope
These are light microscopes that have lenses for each eye. They are use for thick objects like insects.

13. Other Microscopes Dissection-used to look at specimens
Less detail than compound microscopes

14. Why use these scopes?
The stereoscope and dissecting scopes are used to examine larger internal structures of live organisms.

15. Other Microscopes ELECTRON MICROSCOPES
-uses beams of electrons to help view the image
Two types:
1) Scanning electron-projects a 3-D magnified image
2) Transmission electron-gives extreme magnification, up to 500,000X

16. Pro’s & Con’s of Electron Microscopes
Pro’s - can see a lot more detail - higher magnification & better resolution (clarity)
Con’s - VERY expensive, specimen must be preserved (Dead)