Leica DM LSP Bedienungsanleitung Seite 11

Quartz wedge
The quartz wedge (46.6) is inserted into the com-
pensator slot (43.20). It allows phase shifts from
0 to about 4 λ (orders).
Circular polarization
Birefringent objects exhibit four extinction posi-
tions for one stage rotation. Particularly when
scanning a large area of the specimen, some of
the birefringent objects will always happen to be
at the extinction position. Circular polarization is
used for simultaneous observation of the inter-
ference colours of all objects:
Remove the specimen from the light path or find
an empty area of the specimen. Cross the polar-
izers exactly – they must also be exactly at the
N – S/E – W positions.
Insert quarter-wave compensator (46.5) in the
compensator slot (43.20). Push the quarter-wave
compensator (46.1) into the slot above the po-
larizer (43.10) and rotate until the empty field of
view appears at its darkest position (first cross
polarizers exactly!). The quarter wave compen-
sator that can be integrated in the condenser
disc (9.6) is not suitable for circular polarization.
1
2
3
Fig. 46 Compensators
1, 2 λ /4 and λ compensator in holder Ø 32 mm. Only for polarized light microscopes: 3 λ /4 and
λ compensator for condenser disk, 4, 5 λ /4 and λ compensators for compensator slot (43.20),
6 Quartz wedge, 7 Tilting compensator, 8 Brace-Koehler compensator
4
7
5
6
Compensators for quantitative measurements
Only in conjunction with polarized light micro-
scopes in transmitted light. Adjustable compen-
sators 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 =
8
d
Γ
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