Evolution of Microscopes: From Antiquity to Modern Innovations

1. Notes – Microscope History, Parts, & Usage

2. History of the Microscope • Circa 1000AD – The first vision aid was invented (inventor unknown) called a reading stone. It was a glass sphere that magnified when laid on top of reading materials. • Circa 1284 - Italian, Salvino D'Armate is credited with inventing the first wearable eye glasses. • 1590 – Two Dutch eye glass makers, Zaccharias Janssen and son Hans Janssen experimented with multiple lenses placed in a tube. The Janssens observed that viewed objects in front of the tube appeared greatly enlarged, creating both the forerunner of the compound microscope and the telescope.

3. Zacharias Jansen (1580 – 1638) • A Dutch spectacle-maker associated with the invention of the first optical telescope while trying to find a way to make magnification even greater, to help people with seriously poor eyesight. • Jansen is sometimes also credited for inventing the first truly compound microscope.

4. History of the Microscope • 1665 – English physicist, Robert Hooke looked at a sliver of cork through a microscope lens and noticed some "pores" or "cells" in it. • 1674 – Anton van Leeuwenhoek built a simple microscope with only one lens to examine blood, yeast, insects and many other tiny objects. Leeuwenhoek was the first person to describe bacteria, and he invented new methods for grinding and polishing microscope lenses that allowed for curvatures providing magnifications of up to 270 diameters, the best available lenses at that time. • 18th century – Technical innovations improved microscopes, leading to microscopy becoming popular among scientists. Lenses combining two types of glass reduced the "chromatic effect" the disturbing halos resulting from differences in refraction of light.

5. Robert Hooke(1635 – 1703) • An English natural philosopher and architect. • When Hooke viewed a thin cutting of cork he discovered empty spaces contained by walls, and termed them pores, or cells. The term cells stuck and Hooke gained credit for discovering the building blocks of all life.

6. Antonie van Leeuwenhoek(1632-1723) • Dutch microscopist who was the first to observe bacteria and protozoa.

7. History of the Microscope • 1830 – Joseph Jackson Lister reduces spherical aberration or the "chromatic effect" by showing that several weak lenses used together at certain distances gave good magnification without blurring the image. This was the prototype for the compound microscope. • 1872 – Ernst Abbe, then research director of the Zeiss Optical Works, wrote a mathematical formula called the "Abbe Sine Condition". His formula provided calculations that allowed for the maximum resolution in microscopes possible. • 1903 – Richard Zsigmondy developed the ultramicroscope that could study objects below the wavelength of light. He won the Nobel Prize in Chemistry in 1925.

8. History of the Microscope • 1932 – Frits Zernike invented the phase-contrast microscope that allowed for the study of colorless and transparent biological materials for which he won the Nobel Prize in Physics in 1953. • 1931 – Ernst Ruska co-invented the electron microscope for which he won the Nobel Prize in Physics in 1986. Electron microscopes make it possible to view objects as small as the diameter of an atom. • 1981 – Gerd Binnig and Heinrich Rohrer invented the scanning tunneling microscope that gives three-dimensional images of objects down to the atomic level. Binnig and Rohrer won the Nobel Prize in Physics in 1986. The powerful scanning tunneling microscope is the strongest microscope to date.

9. Parts of a Microscope • Body Tube • Revolving Nose Piece • Low Power Objective Lens • Medium Power Objective Lens • High Power Objective Lens • Stage Clips • Diaphragm • Light Source • Eye Piece • Arm • Stage • Course Adjustment • Fine Adjustment • Base

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

11. Nose Piece • The Nose Piece holds the objective lenses and can be turned to increase the magnification

12. Objective Lenses (High, Medium, & Low) • The Objective Lenses increase magnification (usually from 10x to 40x)

13. Stage Clips • These 2 clips hold the slide/specimen in place on the stage.

14. Diaphragm • The Diaphragm controls the amount of light on the slide/specimen Turn to let more light in or to make dimmer.

15. 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

16. Eye Piece • Magnifies the specimen image

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

18. Stage • Supports the slide/specimen

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

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

21. Base • Supports the microscope

22. 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

23. 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

24. Carry a Microscope Correctly

25. 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.

26. 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).

27. Proper Set Up 1) Always carry the microscope with two hands…one on the arm and the other on the base. 2) Remove the cover and neatly fold. Place in a safe spot on your desk. 3) Clean the eyepiece with lens paper. Never use paper towel or tissue. 4) Turn on the light source. 5) Check to make sure the lowest power objective is in place. Make sure the revolving nosepiece “clicks” into place. 6) Lower the stage to its lowest position using the coarse adjustment. 7) Check to see that the diaphragm is set on the highest setting (5) or open all the way. It is best to start with all the light possible and reduce if needed.

28. Viewing Your Specimen 1) Prepare your slide and fasten it to the stage using the stage clips. Never pull up hard on the clips…they are spring loaded and will break easily. 2) Make sure the specimen (what you want to look at) is directly over the hole in the stage where the light comes through. 3) Look through the eyepiece and raise the stage using the coarse (big) adjustment until your specimen comes into focus. If it isn’t perfectly clear, then raise or lower the stage ever so slightly until it is. (If you are wearing eyeglasses…you may want to remove them.) 4) Once the object is in focus, move the slide appropriately to view the exact part of the specimen you want. Make sure the arrow (pointer) is surrounded by what you want to see in the next highest power. 5) Without touching coarse or fine adjustment, switch the revolving nosepiece so the medium-power objective “clicks” into place.

29. Viewing Your Specimen 6) Follow steps 3 and 4 again for focusing in medium power. 7) Finally, without touching coarse or fine adjustment, turn the nosepiece so the high-power objective “clicks” into place. NEVER touch the coarse adjustment anymore!!!!! Don’t touch anything and look through your eyepiece. (These microscopes are “par-focal” which means if it is focused in medium power, then it should be focused in the highest power.) 8) If the specimen appears to be “fuzzy” or out of focus, then ever so slightly turn the fine adjustment away from you first…if that doesn’t work…then turn it slightly towards your body. NEVER make a full turn or spin the fine adjustment…this ruins the calibration and is completely unnecessary! **It is important to keep in mind that the specimens you are looking at are three dimensional and the fine focus actually helps you to focus “through” the layers of what you are looking at. You will be frustrated at first but your skills will improve with time. Practice patience! 9) Draw what is required by the teacher or lab. Make sure you label all the necessary parts and include the name of what you are drawing and the total magnification power.

30. Proper Clean Up 1) Make sure the lowest power objective is clicked into place. 2) Lower the stage to the lowest setting using the coarse adjustment. 3) Remove the slide from the stage. (If you haven’t done steps 1 and 2…you could damage the microscope or slide!) 4) Turn off the light source and put the cover back on. 5) Clean up the slides as the teacher directs…listen for specific directions regarding cleaning up the specimens…it is not the same for each lab.

36. Time to Sing  Parts of the Microscope SONG