Troubleshooting in Microscope

“I can focus my slide under 10×, but not under 40×.”

A common reason for this is that the slide is upside down. Double check which side the smear is on (may not be the same side as the label!) and try focusing again. Another cause could be dried immersion oil on the 40× objective that is obstructing your view. When switching from oil immersion (100×) to 40×, there is a good chance that the tip of the 40× objective could be dragged through some immersion oil. If it is not immediately cleaned off, it will dry, producing a thick haze. To fx: Use lens paper and lens cleaner to clean the end of the 40× objective. This may need to be repeated several times depending on how thick the dried oil is. After cleaning, use a dry piece of lens paper to polish the objective. To avoid the problem: Clean up oil immediately after use. Clean the end of the 100× objective and any heavy oil present on the slide before moving back down to 40× objective.

“In hematology, when I focus under 40×, my red blood cells appear shiny.”

This is most likely due to water artifact during the staining and drying process. To make visualization of the cells easier, add a small drop of immersion oil to your slide. Gently spread the drop of oil over the area you will be examining. Wipe of excess oil using the side of your finger. Be very gentle when doing this, and use a clean finger each time you wipe. Wiping too hard or rough will cause your smear to rub off. This technique will leave a very thin layer of oil on your smear. The film is thin enough that you can use the 40× objective without running the risk of the lens becoming contaminated with oil. Try focusing under 40× again, and the shininess should have been resolved.

“There’s no light coming from the illuminator.”

The first assumption is always that the bulb is burnt out, but it is a good idea to check a couple of other possibilities as well. If the iris diaphragm is closed and the brightness of the illuminator is at its lowest, the light may be so small that it appears as if there is no light present. Check to make sure the cord is fully plugged into the back of the microscope. This plug can become dislodged slightly during transport and microscope set up. If your microscope is the type that uses fuses, it may be the fuse—not the bulb—that needs replacing. When the microscope is not in use, be sure to turn it off. This will help prolong the life of the bulb.

Clean up

When the use of the microscope is complete, following proper clean up procedures will improve the quality of images that are viewed and extend the life of the microscope and its components:

1. Remove the slide from the stage and dispose of it properly.
2. Clean any oil residue or sample material that may have contaminated the stage surface.
3. Lower the stage and move the smallest objective into place.
4. Clean the objective lens and oculars after every use. The order in which they are cleaned is important. Cleaning the 100× objective first and then moving onto other parts will result in immersion oil being spread onto all other components. Using lens tissue and lens cleaner, begin with cleaning the oculars, then the 4× objective, the 10× objective, 40× objective, and finish with the 100× objective lens.