12
A15.0908 Series
3-9
Adjust the Field Diaphragm
By limiting the diameter of light entering the
condenser, the field diaphragm can prevent other light
and strengthen the image contrast. When the image is
just on the edge of the field of view, the objective can
perform best and obtain the clearest image.
◎
For Reflected Illumination
(1) Turn the field diaphragm turntable
①
to the
lowest, to minimize the field diaphragm (See Fig. 25).
(2) The image of field diaphragm can be observed in
the view field through eyepiece.
(3) Plug the two M4 hexa spanners into the left and
right field diaphragm centering bolthole
②,
until the
image is adjusted to the center.
(4) Open the field diaphragm gradually, if the image
of field diaphragm is inscribed with the field of view,
then the field diaphragm is centered correctly (See Fig.
26).
(5) In actual use, enlarge the field diaphragm a little,
to make its image circumscribed to the field of view.
◎
For Transmitted Illumination
Rotate the field diaphragm adjustment ring
③
in
clockwise, to enlarge the field diaphragm; otherwise,
to decrease it in counterclockwise. (See Fig. 23)
3-10
Adjust the Aperture Diaphragm
The aperture diaphragm decides the numerical
aperture of the illumination system. If the N.A. of
illumination system matches with the N.A. of the
objective, it can obtain better resolution and contrast,
and increase the depth of field.
As the contrast of microscopic samples is usually low,
it is advised to adjust the diameter of aperture
diaphragm to be 70%-80% of the N.A. of objective (it
is allowed to take down the eyepiece and observe
through the eyepiece tube). In actual use, adjust it on
the basis of good contrast and comfortable
observation.
Fig.26
Fig.25
Summary of Contents for A15 0908 Series
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