WPI PIMT201, Instruction Manual

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18 World Precision Instruments
TIP : If desired, the filter may alternatively be placed in the condenser annulus slider
( Fig. 58 ) and slid into position for use ( Fig. 59 ).
Fig. 58—Filter in condenser annulus slider
Fig. 59—Condenser annulus slider in position
Phase Contrast Alignment
There are two phase contrast objectives included with the PIMT201 microscope,
the 10X and the 20X. On a simplified level, phase contrast imaging occurs by the
interference of light that is created by special masks in the light path. There are two
masks, each located in a different part of the light path, which must be positioned
correctly relative to each another to create the phase contrast effect.
The annular ring (condenser annulus) is located in the phase aperture frame, and
it has a light masking pattern that looks similar to Fig. 60 . The phase ring is the
conjugate of the condenser annulus, and its pattern is a ring that is the same size as
the white area in the condenser annulus pattern. The phase ring pattern is located in
the objective and cannot be adjusted by the user.
Condenser Annulus Phase Ring
Fig. 60—Annual Ring
The condenser annulus is adjustable by the user, and it is located in the phase
aperture frame. The user adjusts the position of the condenser annulus to establish
the proper relationship between the two masks to optimize the phase contrast effect.