Leica DM R Serie Mode D'emploi page 81

Insert quarter-wave compensator (57.5) in the
tube slot.
Push the quarter-wave compensator (57.1) into
the slot underneath the condenser (27.6) and
rotate until the empty field of view appears at its
darkest position (first cross polarizers exactly!).
Compensators for quantitative measurements
Only in conjunction with polarized light micro-
scopes in transmitted light. Adjustable com-
pensators are used for exact measurements of
phase differences. For a known specimen thick-
ness d and the measured phase difference
gamma (Γ) the birefringence ∆n' can be worked
out using the following formula:
Γ= d x ∆n' [nm] or ∆n = –
Fig. 57a/b Compensators
1, 2 λ/4 and compensator for pos. 27.6. Only for polarized light microscopes: 3 λ/4 and λ compensator for 8-position disc (54.16),
4, 5 λ/4 and compensator for tube slot (54.13), 6 Rotatable λ/4 compensator (Sénarmont compensator), 7 Quartz wedge,
8 Tilting compensator, 9 Brace-Koehler compensator
1
2
3
d
Γ
4
5
6
7
To perform the measurement, the compensator
is introduced into the tube slot and adjusted
until the object to be measured is in its maximum
extinction position. For this purpose the object
has to be moved into a certain diagonal position.
With HC P tube optics the measurement areas
can be isolated with an iris diaphragm (58-I with
54.11) Further details are given in the
instructions for the use of the compensators.
The following compensators are available:
Ellip tical Brace-Koehler comp ensator (57.9)
Rotary compensator with compensator plate of
about λ/10 difference. Measurement is carried
out in white or in monochromatic light.
Measurement range up to approx. 50 nm.
8
9
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