1. Microscopes A guide to use, general Maintenance, and repair tailored
to the Olympus CX-21
microscope

2. Topics Principles of Operation Diagrams Applications History Safety
Preventive Maintenance
Common Failure Modes
Basic Troubleshooting

3. 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

4. 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

5. 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

6. Principles of Operation
Inputs
Outputs
AC Voltage
Light Source
Specimen on stage
Magnified image of specimen

7. Diagrams

8. Ring-form trophozoites of P. falciparum in a thick blood smear
Applications
To view objects that are not visible to the naked eye
For cell counting
Used to view cells and diagnose disease:
Malaria
Roundworms
Tuberculosis
Dysentery
Cryptosporidium
Giardia
Ring-form trophozoites of P. falciparum in a thick blood smear

9. History
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

10. Safety Biological contamination: Gloves
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
Do not use under vibration
Do not store in high humidity
Do not store in dusty areas
Keep clean
Avoid intense temperatures

11. 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

12. Objective Magnification
Operation
Working Distance
Objective Magnification
Working Distance 4X
18.5
10X
10.6
40X
0.6
100X
0.13

13. Operation Using the 100x immersion objective
Before engaging immersion objective (100x), place a drop of oil onto the specimen.
Engage the immersion objective
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

14. Preventive Maintenance
Daily Preventive Maintenance
Clean
Objective (after using immersion oil)
Body of microscope
Yearly Preventive Maintenance
Microscope frame
Check observation tube:
Optical axis
Left/right axis
Revolving axis
Parfocality
Resolution
As needed
Grease replacement parts

15. Preventive Maintenance
Inspection sheet can help serve as a troubleshooting checklist

16. Common Modes of Failure
Electrical/Power Failure
Light does not turn on when power switch is turned on
Light bulb burned out
Objective not placed in alignment
Dirty components
Eyepiece
Objectives
Filters
Fungus growth due to high humidity
General User Error
Not in focus
Brightness not adjusted properly
Objective not rotated fully into secured position

17. Troubleshooting Electrical Unit
If lamp does not turn on when power switch is turned on, there is a problem with the electrical unit, unless…

18. 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

19. 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

20. Troubleshooting Coarse/Fine adjustment knobs do not turn smoothly
Knobs need to be greased

21. 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

22. 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