10. Trouble Shooting
Problem | Cause/Remedy |
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Bright Field
The specimen can not be brought into focus.
Use the correct immersion medium.
Lay the specimen with the cover glass to- wards the top.
Make sure that the cover glass thickness is correct and that is conform to the indication on the objective.
Check the condenser centering.
Dark Field
No definite DF contrast is possible.
Be sure that a DF objective is being used.
The objective aperture setting is too high (maximum 0.75). If necessary, reduce the ob- jective aperture using the iris diaphragm on the objective.
Check the condenser centering.
The image is unevenly or not uniformly illumi- nated.
The magnification is too weak. Use a higher magnification.
Undesirable stray light | Clean the specimen and neighboring lenses |
| (→ p. 65). |
Phase contrast
No phase contrast is possible.
The specimen is too thick.
The refraction index of embedding material and object is identical.
The cover glass is not placed evenly. Therefore, check the centering of the light rings (→ p. 39).
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