1. Dr. Samah Kotb Nasr Eldeen
The Microscope
Dr. Samah Kotb Nasr Eldeen

2. Microscopy

3. The History Many people experimented with making microscopes
Was the microscope originally made by accident? (Most people were creating telescopes)
The first microscope was 6 feet long!!!
The Greeks & Romans used “lenses” to magnify objects over 1000 years ago.

4. Anthony van Leeuwenhoek
The History
Hans and Zacharias Janssen of Holland in the 1590’s created the “first” compound microscope
Anthony van Leeuwenhoek and Robert Hooke made improvements by working on the lenses
Robert Hooke
Anthony van Leeuwenhoek
Hooke Microscope

5. The History
Zacharias Jansen
The “First” Microscope

6. How a Microscope Works Convex Lenses are
curved glass used to make microscopes
(and glasses etc.)
Convex Lenses bend
light and focus it in
one spot.

7. How a Microscope Works Ocular Lens (Magnifies Image) Objective Lens
(Gathers Light,
Magnifies
And Focuses Image
Inside Body Tube)
Body Tube
(Image Focuses)
Bending Light: The objective (bottom) convex lens magnifies and focuses (bends) the image inside the body tube and the ocular convex (top) lens of a microscope magnifies it (again).

8. The Parts of a Microscope

9. Ocular Lens
Body Tube
Nose Piece
Arm
Objective
Lenses
Stage
Stage
Clips
Coarse Adjustment
Diaphragm
Fine Adjustment
Light Source
Base

10. Parts of light microscope

11. Body Tube
The body tube holds the objective lenses and the ocular lens at the proper distance
Diagram

12. Nose Piece
The Nose Piece holds the objective lenses and can be turned to increase the magnification.
Diagram

13. Objective Lenses
The Objective Lenses increase magnification (usually from 10x to 40x)
Diagram

14. Stage Clips
These 2 clips hold the slide/specimen in place on the stage.
Diagram

15. Diaphragm
The Diaphragm controls the amount of light on the slide/specimen

16. Light Source
Projects light upwards through the diaphragm, the specimen and the lenses
Some have lights, others have mirrors where you must move the mirror to reflect light

17. Ocular Lens/Eyepiece
Magnifies the specimen image

18. Arm
Used to support the microscope when carried. Holds the body tube, nose piece and objective lenses

19. Stage
Supports the slide/specimen

20. Coarse Adjustment Knob
Moves the stage up and down (quickly) for focusing your image

21. Fine Adjustment Knob
This knob moves the stage SLIGHTLY to sharpen the image

22. Base
Supports the microscope

23. Magnification

24. Magnification
To determine your magnification…you just multiply the ocular lens by the objective lens
Ocular 10x Objective 40x:10 x 40 = 400
So the object is 400 times “larger”
Objective Lens have
their magnification
written on them.
Ocular lenses usually magnifies by 10x

25. Caring for a Microscope
Clean only with a soft cloth/tissue.
Make sure it’s on a flat surface.
Don’t bang it.
Carry it with 2 HANDS…one on the arm and the other on the base.

26. Carry a Microscope Correctly

27. Types of microscopes

28. 1) Bright Field (absorption). 2) Dark Field (scattering).
3) Phase-contrast (phase change).
4)Polarization (scattering by birefringent specimen).
5) Differential interference contrast (DIC) (gradients of optical thickness).
6) Fluorescent (frequency change as a result of absorption/emission by fluorophores).
Microscopes utilises one or several of the described light properties:
*) Absorption - bright microscopy
*) Scattering - collect only scattered light - Dark-field
*) Change of phase - phase contrast
*) Split in two components when scattered by birefringent specimen - polarization
*) Gradients of optical thickness - DIC optics
*) Change of frequency as a result of absorption/emission by fluorophores - Fluorescent 28

29. Examples of microscopes

30. 1) Light Microscope
Is one of many tools and techniques that allow us to study the cells that are between 1 and 100 µm.
1 micrometer (µm) = 10-3mm =10-6m
1 nanometer (nm) = 10-3 µm = 10-9m

31. Compound Light Microscope

32. 2) Electron microscope:
is used to revealed many
organisms and sub cellular structure that were impossible to resolve with the light microscope.

33. 3) Dark-Field Microscope33

34. 4) Phase Contrast Microscopy
Suitable for unstained specimens
Human glial cells 34

35. 5) Polarized microscopy example
Focal conic texture under polarized microscopy of the hexagonal columnar liquid crystalline phase formed by the self-complementary CGCGAATTCGCG DNA oligomer. 35

36. 6) Fluorescent Microscopic Images
Human cortical neurons
Human brain glioma cells 36

37. 7) Fluorescent Microscopic images
Fluorescence/DIC combination, cat brain tissue infected with Cryptococcus 37

38. 8) Brain bow 38

39. Why do we use the oil immersion:
The most important lens for microbiology is the oil immersion lens because:
It’s the highest magnification
It decreases the refraction of light between the glass of lens and the slide
It obtains a clear , finely detailed image.

40. Carry a Microscope Correctly

41. Using a Microscope Start on the lowest magnification
Don’t use the coarse adjustment knob on high magnification…you’ll break the slide!!!
Place slide on stage and lock clips
Adjust light source (if it’s a mirror…don’t stand in front of it!)
Use fine adjustment to focus