Leica DM2000 - Differential Interference Contrast

53
9. Contrast Methods
Attention!
Always use the polarizer with the labeled side
facing upward, as otherwise the integrated
heat protection filter is ineffective and the
special polarizer will become useless
(discolouring!).
• Bring the polarizer and analyzer into cross po-
sition until they reach maximum darkness.
• Remove the object or find an empty area of
the specimen.
• Push the analyzer into the stand as far as
the 2nd clickstop or switch on the module.
• Remove compensators from the light path.
• Rotate the polarizer until you observe the
maximum extinction position in the eye-
piece (fig 63).
• Fix the cross position thus determined with
the clamping screw.
• If necessary:
Insert the λ or λ/4 compensator into the filter
holder integrated in the condenser holder and
rotate to the left, roughly as far as the stop.
CLP/PH condenser:
Insert the λ or λ/4 compensator in the slot on
the side of the condenser.
Condensers UCLP and UCA/P:
Rotate the condenser disk into position λ or
λ/4.
Alternative:
4x20 mm compensators can be pushed into
the compensator slot.
9.1.6 Differential Interference Contrast
• Insert a specimen, rotate a suitable objective
into place and bring the image into focus.
•Turn the disk in the UCA/P condenser to the
brightfield position.
• If present: switch the fluorescence illuminator
into an empty position or filter system A.
• Pull the objective prism slide out of the tube
slit.
• Set the Köhler illumination exactly (→⊇p. 31).
• Remove the specimen or find an empty area of
the specimen.
• Bring the polarizer and analyzer into cross po-
sition until they reach maximum darkness, as
described at 9.1.5 Polarization.
!
Fig. 63
Crossing the polarizers when observing through a focusing
telescope or Bertrand lens, high-aperture Pol objective
a exactly crossed, b not exactly crossed
Pos. a cannot be set if there is strain in the condenser or
objective, Pos. b is adequate for polarization contrast.
ab