Chapter 3 Individual Operations
3.17 Episcopic Microscopy
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Centering the field diaphragm
(1)
Perform steps in “2.4 Episcopic Microscopy (with the Epi Illuminator Option)” and focus on
the specimen using the 10X objective under the episcopic illumination.
(2)
Lower the field diaphragm open/close lever to stop down the field diaphragm.
(3)
Turn the field diaphragm centering screws (on both sides) so that the field diaphragm
image is positioned in the center of the view field.
(4)
Adjust the field diaphragm image with the field diaphragm open/close lever and centering
screws so that it inscribes the view field.
(5)
To observe the specimen, raise the field diaphragm open/close lever so that the field
diaphragm image circumscribes the view field.
3.17.3
Aperture Diaphragm in the Epi Illuminator
Since the aperture diaphragm is for adjusting the
numerical aperture of the illumination system, this
diaphragm is related to the resolution, contrast, and
depth of focus of the optical image.
The aperture diaphragm open/close lever will change
the opening of the aperture diaphragm. Remove one of
the eyepieces, and then adjust the aperture diaphragm
opening while observing the objective's exit pupil in the
eyepiece tube. Generally, the aperture diaphragm
should be adjusted to about 70 to 80% of the
numerical aperture of the objective.
The diaphragm image may not appear in the case of
samples with low reflectivity. In this case, change to a
sample with a near-polished surface.
70~80
100
Field diaphragm image
Eye piece viewfield
Aperture diaphragm
open/close lever
Eye piece viewfield
Aperture diaphragm image