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10. Measurements with the Microscope
10.1 Linear Measurements
The following are required for linear measure-
ments:
- Graticule with scale division* in eyepiece or a
digital linear measuring eyepiece*.
- Stage micrometer for calibration.
(→ fig. 50)
Micrometer Value
The micrometer value of the objective-eyepiece
combination used must be known before the
measurement, i.e. the distance in the specimen
that corresponds to the length of a division on
the graticule used.
Calibration:
• Align the stage micrometer and the graticule
parallel to each other by rotating the eyepiece
and adjust the zero marks of both scales to
exactly the same height
• Read how many scale divisions of the stage
micrometer correpond to how many on the
microscope scale (graticule)
• Divide the two values; the result is the
micrometer value for the total magnification
that has just been used
Example:
If 1.220 mm of the stage micrometer corresponds to 100
divisions of the measurement scale, the micrometer
value is 1.220:100 = 0.0122 mm = 12.2 μm. For extremely
low objective magnifications it may be that only part of
the measurement scale can be used for calibration.
Notes:
If using a magnification changer:
Remember to take the additional magnification
value* into consideration! We strongly recom-
mend you calibrate each objective separately
instead of extrapolating the micrometer values
of the other objectives from the calibration of
one objective.
Measurement errors may occur if the eyepiece
is not pushed into the tube as far as the stop.
Particularly large object structures can also be
measured on the stage with the verniers (0.1 mm);
the distance to be measured could be calculated
from a combined x and y measurement.
10. Measurements with the Microscope
Fig. 50
Scale division of the graticule in the eyepiece (left)
and image of the stage micrometer (right)