Microscopes
A guide to use, general
Maintenance, and repair tailored
to the Olympus CX-21
microscope
Topics
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Principles of Operation
Diagrams
Applications
History
Safety
Operation
Preventive Maintenance
Common Failure Modes
Basic Troubleshooting
Principles of Operation
 Compound optical
microscopes use a light
source and a series of
lenses and to produce a
magnified image of a
specimen
 The light gathering/
focusing capacity of a
lens is primarily
determined by its
surface curvature
http://www.education.com/study-help/article/physicshelp-compound-microscope/
Principles of Operation
 Eyepiece
 Focus light onto eyes
 10x magnification
 Objective
 Collect light from the sample and magnify image
 Labeled with magnification (i.e. 4x/10x) and
numerical aperture (i.e. 0.10/0.25)
 Mechanical Stage
 Moves the specimen in the x and y directions on
the stage
Principles of Operation
 Condenser
 Collects light from light sources and
focuses it on the specimen
 Aperture Iris Diaphragm
 Controls the amount of light that reaches
the specimen
 Coarse and Fine Adjustment Knobs
 Move stage up and down to bring
specimen into focus
Principles of Operation
Inputs
Outputs
AC Voltage
Light Source
Specimen on stage
Magnified image of specimen
Diagrams
Applications
 To view objects that are not
visible to the naked eye
 For cell counting
 Used to view cells and
diagnose disease:
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Malaria
Roundworms
Tuberculosis
Dysentery
Cryptosporidium
Giardia
Ring-form trophozoites of P. falciparum in a thick blood smear
http://dpd.cdc.gov/dpdx/HTML/Malaria.htm
History
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2nd Century BC: Ptolemy describes a stick
that appears to bend in water
1st Century: Romans experiment with glass
and observe objects appear larger when
viewed through glass
12th Century: Salvino D’Armante makes first
eye glasses
1590: Dutch spectacle makers mount two
lenses in a tube to create first compound
microscope
1609: Galileo Galilee develops compound
microscope with concave and convex lens
1665: Robert Hooke’s book Micrographia
documents observations through the
microscope
1674: van Leeuwenhoek achieves greater
magnification allowing observation of bacteria
http://www.history-of-the-microscope.org/microscope-history-timeline-design-development-inventions.php
Safety
 Biological contamination: Gloves
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Wear PPE
Treat all blood and bodily fluids as if they are contaminated
 Before using, read the owner's manual
 Grounded electrical connection
 Location & Storage
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Do not use under vibration
Do not store in high humidity
Do not store in dusty areas
Keep clean
Avoid intense temperatures
Operation
 Place specimen on stage in bow-shaped
lever
 Choose objective
 Always start with lowest magnification
 Adjust aperture iris diaphragm to
correspond to objective
 Turn on light source
 Bring image into focus with adjustment
knobs
 Adjust stage and light intensity as needed
Operation
Working Distance
Objective
Working
Magnification Distance
4X
18.5
10X
10.6
40X
0.6
100X
0.13
Operation
Using the 100x immersion objective
1.
2.
Before engaging immersion
objective (100x), place a drop of oil
onto the specimen.
Engage the immersion objective
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3.
4.
Make sure oil is free of bubbles
Use ONLY the fine adjustment knob
to bring the specimen into focus
After use, remove oil from objective
front lens by wiping with lens paper
moistened with lens cleaner
Preventive Maintenance
 Daily Preventive Maintenance
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Clean
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Objective (after using immersion oil)
Body of microscope
 Yearly Preventive Maintenance
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Microscope frame
Check observation tube:
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Optical axis
Left/right axis
Revolving axis
Parfocality
Resolution
 As needed
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Grease replacement parts
Preventive Maintenance
Inspection sheet can help
serve as a troubleshooting
checklist
Common Modes of Failure
 Electrical/Power Failure
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Light does not turn on when power switch is turned on
 Light bulb burned out
 Objective not placed in alignment
 Dirty components
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Eyepiece
Objectives
Filters
 Fungus growth due to high humidity
 General User Error
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Not in focus
Brightness not adjusted properly
Objective not rotated fully into secured position
Troubleshooting
 Electrical Unit
 If lamp does not turn on when power
switch is turned on, there is a problem
with the electrical unit, unless…
Troubleshooting
 Electrical Unit
 If light bulb is not the issue, check that
microscope is plugged in and outlet has
power (use another device you know to
be working to validate this)
 Verify the cord shows no obvious
damage
 Verify that the fuse is intact
Troubleshooting
 If the previous steps do not reveal
the cause of failure
 The problem is most likely the circuit
board itself
 Replacing individual components is not
feasible, entire board needs replaced
 If an identical microscope exists that is not
usable for another reason, harvesting its
circuit board is an option. See the manual
for instructions on removing the circuit
board
Troubleshooting
 Coarse/Fine adjustment knobs do not
turn smoothly
 Knobs need to be greased
Troubleshooting
 Stage falls down spontaneously or an
in-focus image quickly moves out of
focus
 Cause: tension on coarse adjustment
knob is too loose, needs to be adjusted
Troubleshooting: Stage Movement
 If the stage does not move smoothly
in the x or y directions, the tension of
the x/y wires must be adjusted