"Intro Lab" 0-B for Advanced Biology

1. Lab 0-B
Microscope Training

2. A Brief History
of the
Microscope

3. History
● The Greeks & Romans used “lenses” to magnify
objects over 1000 years ago.
● About 500 years ago, people began
experimenting with making microscopes
● Since many people were creating telescopes at
that time, was the microscope created by
accident?
● The first microscope was 6 feet long!

4. History
Hans and Zacharias Janssen of Holland in the
1590’s created the “first” compound microscope
Zacharias Jansen
1588-1631
The “First” Microscope

5. History
Anthony van Leeuwenhoek and Robert Hooke
made improvements by working on the lenses
Anthony van
Leeuwenhoek
1632-1723
Robert Hooke
1635-1703
Hooke Microscope

6. History
1655 – Robert Hooke used a
compound microscope to observe
pores in cork. He called them
“cells”
1673 – Anthony van Leeuwenhoek
saw single-celled organisms in
pond water

7. Types of
Microscopes

8. Compound Light Microscope
● first type of microscope
● most widely used
● light passes through 2 lenses
● can magnify up to 2000x

9. Specialized Versions
● Dissection microscope-- image appears three dimensional. It is
used for dissection to get a better look at the larger specimen. You
cannot see individual cells because it has a low magnification.
● Dark‐field microscope – useful in examining external details, such
as outlines, edges, grain boundaries and surface defects. Contains
a special feature that scatters light and causes it to reflect off the
specimen at an angle. A light object is seen on a dark background.
● Phase‐contrast microscope – has a special features that causes
light to pass through an object at different speeds. Live organisms
and internal cell parts such as mitochondria can be seen clearly
● Fluorescent microscope – uses ultraviolet light which excites the
electrons of the object and causes them to give off light in various
shades of color. Often used with a lab procedure called the
fluorescent‐antibody technique to help identify unknown bacteria.

10. Compound Light Images

11. Electron Microscope
● uses beams of electrons rather than light
● used to observe VERY small objects
● viruses, DNA, parts of cells
● Scanning models can
magnify up to 100,000x
● Transmission models can
magnify up to 250,000x

12. Compound vs. Electron

13. How does a
Compound Microscope
work?

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

15. How a Microscope Works
Ocular Lens
magnifies image
Objective Lens
gathers light, magnifies
and focuses image
inside body tube
Body Tube
image focuses and
is directed upward
to ocular lens
Microscopes work by bending light & magnifying the image:
The objective convex lens magnifies and focuses (bends)
the image inside the body tube and the ocular convex
lens of a microscope magnifies it (again).

16. The Parts
of a
Microscope

18. Body Tube
Forms a short tunnel which connects the
two different types of lenses and holds them
the proper distances apart
1

19. Nose Piece
Holds the objective lenses above the stage. Can
be rotated to select another objective (move up
or down to a different magnification power)
2

20. Objective Lenses
Increase magnification, usually two or three
lenses with various powers
3 (4x Objective)
4 (10x Objective)
5 (40x Objective)

21. Stage Clips
Hold the slide in place on the stage.
6
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22. Diaphragm & Condenser Unit
Often mounted together, they control the
amount and focus of the light
7
Condenser Height
Adjustment Knob Diaphragm
Control Lever

23. Diaphragm
Controls the amount of light that reaches
the slide (or the condenser)
Iris
Disc
Move the slide level
forward to dim the light
and back to increase
the amount of light

24. Condenser
Collects and focuses the light before it
reaches the stage

25. Light Source
Light enters near the base of the microscope
and travels upward through the diaphragm,
condenser, slide, and lenses to our eyes
8

26. Types of Lighting
Mirror
(non-electric)
Tungsten or LED
(powered)

27. Ocular Lens / Eyepiece
The part of the microscope we look through,
it magnifies the specimen image
9
Common powers: 5x, 10x,
12.5x, 15x, and 20x

28. Arm
Holds the body tube, nose piece and objective
lenses. Used to support the microscope when
carried.
10

29. Stage
Flat surface which supports the slide. A mechanical
stage allows for easy, smooth adjustments
11
X-Y Axis Slide
Control Knob

30. Coarse Adjustment Knob
Used first in the focusing sequence. Moves the
stage up & down quickly for basic focusing of the
image.
Use carefully when on the
highest power objective lens!
12

31. Fine Adjustment Knob
Used for fine-tuning. Moves the stage slowly
by small amounts to help sharpen the image.
13

32. Base
Supports the microscope, adds a stable
platform to keep the microscope steady.
14

33. Body Tube
Nosepiece
Objective 4x
Objective 10x
Objective 40x
Stage Clips
Condenser &
Diaphragm
Light Source
Ocular Lens /
Eyepiece
Arm
Stage
Coarse
Adjustment
Fine
Adjustment
Base

34. Magnification
and
Imaging

35. Imaging
● Magnification: increase of an object’s size
● Resolution: power to show details clearly
● Both are needed to see a clear image

36. Magnification
● To determine your magnification you just multiply
the ocular lens by the objective lens
● If the ocular lens is 10x and the objective lens is
40x, what magnification power do you have?
Ocular lens
(eyepiece)
Objective lens

37. Magnification
● 10 x 40 = 400
Magnification power is written with an “x”
● 400x
This means the object appears 400 times larger

38. Caring for the
Microscopes

39. Caring for a Microscope
● Wipe off the body and stage with a soft cloth
● Clean the lenses with special lens papers
● Always set it down on a flat, level surface
● Don’t bang on it or force any parts to move
● Make sure the cord is not a trip hazard

40. Carrying a Microscope Correctly
One hand
under the
base
One hand
gripping
the arm

41. Using
a
Microscope

42. Using a Microscope
Do not touch the coarse adjustment knob
when using the highest power objective!

43. Using a Microscope
1) Raise the objectives using the coarse adjustment knob so that the stage and the
objective are far from each other
2) Start with the nose piece turned to the lowest power objective
3) Place the slide on the stage, locking it in place with stage clips.
4) Move the stage to place the object directly under the objective.
5) Look at the slide through the eyepiece. Try to get a focused image of your object
by using the coarse adjustment knob.
6) If the object is not visible, slowly move the stage to view other areas of the slide
and use the coarse adjustment again.
7) Once your object is located and focused with the coarse adjustment knob, switch
to the fine adjustment knob to bring the image into sharp focus.
8) After getting a focused image, if you want to pursue a higher power image first
carefully adjust the stage to place the object directly into the center of view.
9) Then, turn the objective lens carefully to a lens with a high power start with #5
unless on the highest setting (then only use the fine adjustment!)

44. Using a Microscope
Images from the microscope are laterally inverted:
upside down AND backwards