1. Introduction to Microscopes
"Two Stones on the Water“
Best Optical Micrograph

2. From ancient times, man has wanted to see things far smaller than could be perceived with the naked eye.

3. This led to the construction, in the 16th century, of a magnifier composed of a single convex lens, and this, in turn, led to the eventual development of the microscope.

4. Perhaps the most earliest pioneers in the history of the microscope are Thomas Digges of England and Hans and Zacharias Janssens of Holland.

5. Zacharias Janssens and his father Hans, a pair of Dutch spectacle makers built the first compound light microscope by mounting a lens at each end of a tube. Their microscopes had a magnification around 3X to 9X

6. But it was Anton van Leeuwenhoek who became the first man to make and use a real microscope. Leeuwenhoek ground and polished a small glass ball into a lens with a magnification of 270X, and used this lens to make the world's first practical microscope.

7. Because it had only one lens, Leeuwenhoek's microscope is now referred to as a single-lens microscope. Its convex glass lens was attached to a metal holder and was focused using screws.

8. Today, the term "microscope" is generally used to refer to this type of compound microscope.

9. In the compound microscope, the lens closer to the object to be viewed is refers to as the "objective", while the lens closer to the eye is called the "eyepiece“ or “ocular lens”.

10. Since its invention, the compound microscope has made tremendous contributions to the progress of science. Using a compound microscope that he had built himself, the 17th-century Englishman Robert Hooke discovered the fact that living things are composed of regularly shaped structures he called cells.

11. Robert Hooke (1635 – 1703) was the first to publish detailed drawings of objects observed through his compound light microscope

12. Hooke’s detailed drawings made his book very popular.

13. Hooke’s microscope.

14. Hooke’s drawing of thin sections of cork, from an oak tree
Hooke’s drawing of thin sections of cork, from an oak tree. Hooke observed these regularly-shaped structures in many different living things. He used the word “cell” to describe them, since they resembled the monastic cells (rooms) used by monks in a monastery.

15. Schleiden and Schwann were major contributors to the Cell Theory
Matthias Schleiden
1804 – 1881
Botanist
Theodore Schwann
1810 – 1882
Zoologist

16. Schleiden and Schwann 1830’s
Mathias Schleiden identified the first plant cells
He viewed a wide variety of plant specimens with a microscope and concluded that all plants are made up of cells.
Thomas Schwann made the same conclusion about animal cells.

17. Magnification The ability to increase the appearance of an object
The total magnification is the product of the magnification of the ocular lens (10X) and the objective lens being used (4 – 100x)
d’Youville’s compound microscopes have three objective lenses, producing the following magnifications:
40X (low power or scanning lens)
100X (medium power)
400X (high power)

18. Magnification

19. Resolution
The ability to distinguish between two closely spaced objects
Can be described as the sharpness or clarity of the image
For light microscopes, as magnification increases, the resolution decreases

20. Resolution
As magnification increases…
…resolution decreases.

21. Magnification vs. Resolution

22. Depth of Field The area of a specimen that is in focus at one time
At higher magnifications, the depth of field be comes shallower
Less of a specimen will be in focus at one time

23. Depth of field

24. Limitations for light microscopes
The smallest objects that can be viewed with a light microscope are about 200 nm, which is determined by the wavelength of visible light
Light waves pass over very small objects without being affected by them, like a wave of water passing over sand (small objects) compared to rocks (larger objects)
In order to view very small objects with good resolution, a different type of wave must be used – electron beams!

25. Further scientific advancements lead to the development of the first electron microscope in the 1930s. This enabled scientists to view the world from a completely different perspective.
The first practical electron microscope was built by Eli Franklin Burton and his students at the University of Toronto in 1938.
Types of Electron Microscopes
Transmission Electron Microscope
Scanning Electron Microscope
Scanning Tunneling Microscope

26. Transmission Electron Microscope

27. Electron microscopes
Specimens for transmission electron microscopes are encased in wax, then sliced in ultra-thin samples and placed on a metal grid
Specimens are therefore not alive
Beam of electrons are sent through the specimen and a sensor below captures an image which is displayed on a monitor

28. Transmission Electron Micrographs
Chloroplast located in spinach leaf Mitochondrion in an animal cell

29. Scanning Electron Micrographs
Human Head Louse
Fruit Fly Head

30. Most Bizarre Micrograph
Magnification: 100,000X
Title: The Debutantes' Ball
"At the debutante's ball, young nano-women gather in their finery at the edge of the stage to weep because the nano-boys won't dance with them.“ This is an image of a section of an anti-reflective coating (the nano-women) on a silicon base (the stage).

31. Spiders Make the Best Ever Post it Notes!
A scanning electron microscope (SEM) micrograph of the foot of the jumping spider E. arcuata. The very fine fringes at the base of it’s feet cause it to be very “sticky” against flat surfaces.