1. The Microscope

2. Microscope History
Microscopes are instruments which produce a magnified image to help us to examine small objects and their fine details which our eye cannot see.
Microscopes range from simple devices such as a magnifying glass up to high end compound or electron microscopes .

3. Early Microscopes
Simple Microscope
Compound Microscope

4. Microscopes used today
Compound Microscope

5. There are similarities in all microscopes:
Magnify a small object
Separate fine details in order to achieve a high resolution

6. 6

7. Types of Microscopes Simple Dissecting Compound
Scanning Electron Microscope (SEM)
Transmission Electron Microscope (TEM).

8. Using a Microscope to Explore the Cell
Resolution or Resolving power
The ability to distinguish between two objects that are close together
High resolution
Low resolution 8

9. 1. Simple Microscope
Similar to a magnifying glass and has only one lens
A lens enlarges an image and bends the light toward your eye.

10. 2. Compound light microscope
Light source: Lamp
Resolution: limited to about 0.2 µm (micrometers)
Magnification: 2000X
2 D image produced
Image seen: In eyepiece
Specimen Preparation: Stain cells on a slide
Type of specimens can be used: Both 10

12. Total Magnification To get the total magnification: Eyepiece Lens X
Objective Lens =
Total Magnification

13. Low Power = 4 x
Medium Power = 10 x
High Power = 40 x

14. 3. Electron Microscope Used to see objects that are smaller than 2µm
There are 2 types of electron microscopes:
A. Transmission Electron
B. Scanning Electron

15. A. Transmission Electron Microscope (TEM)
How it works:
Light Source: Electrons pass through
Resolution: µm
Magnification: 500,000x
Type of image: 2 D
Where image is seen: On a screen/ monitor
Specimen preparation: Very complex
Types that can be used: Dead

16. 16

17. B. Scanning Electron Microscope (SEM)
How it works:
it passes a narrow beam of electrons over the surface of a specimen.
The specimens must be coated with a very thin film of metal, usually gold.  As electrons bounce off the specimen a television screen picks up the image.
It produces a 3-D image.

19. Light Source: Electrons pass over surface of specimen
How it works:
Light Source: Electrons pass over surface of specimen
Resolution: µm
Magnification: 300,000x
Type of image: 3 D
Where image is seen: On a screen/ monitor
Specimen preparation: Sprayed with gold
Types that can be used: Dead or alive

21. Mitochondria in human liver cell21

22. TEM
SEM
Magnification: 500,000x
Resolution: µm
Magnification: 300,000x
Resolution: µm
*** SEM have lower resolutions than TEM, but they have the advantage of providing 3-D images
Some specially designed SEM’s allow you to observe living specimens

23. 1. Compound Light Microscope (pg.20)
Consists of 2 lens
Light Source: light (passes through specimen)
Resolution: 200nm or 0.2µm
Magnification: 2000x
Image produced: 2D
Where image is seen: Eyepiece
Specimen Prep: Slicing/staining
Type of Specimen: Dead or alive

24. 2. Transmission Electron Microscope (TEM)
Light Source: electrons (passed through specimen)
Resolution: 0.2nm or µm
Magnification: 500,000x
Image produced: 2D
Where image is seen: Projected on screen/monitor = picture! (internal study)
Specimen Prep: very complex – cross sections
Type of Specimen: Dead

25. 3. Scanning Electron Microscope (SEM)
Light Source: electrons (passed through specimen)
Resolution: 5 nm or µm
Magnification: 300,000x
Image produced: 3D
Where image is seen: Projected on tv screen (study surface of specimen)
Specimen Prep: Sprayed with gold coating
Type of Specimen: Dead or alive