3 Product and Functional Description | 3.4 Microscopy and Contrast Methods
ZEISS
3.4.6.3 Measuring Path Differences
Measuring compensators are required for the accurate measurement of path differences,. These
compensators reset, i.e. compensate the path difference produced by the sample to zero (first or-
der black). While the addition position as well as the subtraction position are of interest for the
methods described above, only the subtraction position is relevant for measurements. Path differ-
ences in the sample can assume very small values (1/50 λ or 10 nm) and very large values (greater
than 10 λ or approx. 5500 nm and more) and thus determine the compensator appropriate for
the measurement.
The suitable compensator is determined as follows:
§
If more or less strong interference colors appear on the sample, the path difference ranges
approximately between 1/2 λ and 5 λ.
The suitable compensator is:
B 0-5 λ tilting compensator
§
If the sample-side color changes from light gray/white to a strong interference color, when a
lambda compensator (473704-0000-000) is inserted in the compensator slot, the path differ-
ence is (1/4 - 1/2) λ.
NOTICE
A prerequisite for the occurrence of the color change effect may be the
evaluation in two sample positions rotated at an angle of 90° from one another. For
this purpose, rotate the centered stage (by 2 click stops).
The suitable compensator is:
B 0-5 λ tilting compensator
or the DE SENARMONT compensation method up to 1 λ using the 546/4 nm SENARMONT
compensator.
NOTICE
The DE SENARMONT compensation method requires the use of the rotat-
able analyzer.
§
After insertion of the lambda compensator and rotation of the sample by 90°, the interfer-
ence color remains white; in this case, however, it is a "higher-order white" and thus the path
difference is > 5 λ.
The suitable compensator is:
K 0-30 λ tilting compensator
§
A dark gray appearing as the interference color indicates a very small path difference (λ/10 or
54.6 nm).
3.4.6.4 Circular Polarization Contrast
Unlike standard polarization contrast, circular polarization contrast does not show any dark (ex-
tinction) positions that depend on the angle of rotation (azimuth) of the sample relative to polar-
izer or analyzer. This means that, while you are rotating the stage, the image will always look the
same, as there are no bright and dark positions. With optical anisotropy all transparent samples
show the interference colors that are characteristic to them.
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Instruction Manual ZEISS Axioscope 5, Axioscope 5/7 MAT | en-US | Rev. 13 | 430035-7344-001
