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e. Remove one eyepiece from the microscope eyepiece tube and insert the
centering telescope.
f. Turn the light of microscope on and observe from
the telescope.
g. Turn the top of the telescope (
Fig.25
) until the dark
ring image is in focus. If the dark ring is hard to find,
put a normal white print paper on the stage and
under the objective then you will see the dark ring
as shown in
Fig.24
(a)
.
h. If the bright ring is still obscure as in
Fig.24
(b)
,
raise or lower the condenser by adjusting the
condenser focusing knob (or the microscope
focusing knob if necessary) till the bright ring is in
focus and the dark ring is visible.
i. If the two ring images are not coincided as shown in
Fig.24 (c)
, adjust the two centering screws on the
condenser ring plate till the two rings are coincided
with each other as shown in
Fig.24 (d)
.
j. Remove the centering telescope and replace it with the
eyepiece.
3) Performing the phase contrast observation
After you center the ring plate, you can perform the phase
contrast observation the same way as a normal bright field
microscope.
Note:
when change to another phase contrast objective
and corresponding condenser ring plate, the focusing and
centering of bright ring and dark ring should be repeated
following the procedures from
2)-b to 2)-h
.
Tips:
Make the illumination as bright as possible.
The thinner the specimen, the better the image.
(a)
(b)
(d)
(c)
Fig.24
Fig.25
