Projection; Correct Positioning; Sharp Focusing - Nikon V-14 Instructions Manual

For this purpose, the use of a half-reflecting mirror is necessary on the projection
lens. Such an illumination is suited for inspecting smooth shiny surfaces, engraved
graduation, pattern, etc.
Slip on the half-reflecting mirror to the projection lens 10 X or 20 X. When using
the projection lens 50X or 100x, bring the built-in half-reflecting mirror to an angle
of 45 degrees by turning the small outside knob counterclockwise as far as it will go,
For the other types of illuminations, turn the knob in the reverse direction to bring
the mirror away out of the light path.
Important points for the correct surface illumination are as follows:
1. Face the half-reflecting mirror correctly toward the surface illuminator, other-
wise the brightness on the projected image will not be obtained eq ual at the
top and the bottom.
2. Throw the light exactly toward the center of the window glass, or the image
will show a brightness difference at the right and the left.
3. Supply the light to a full extent to avoid darkness or brightness difference at
the center and at the periphery of the screen.
Depending upon whether the oblique or vertical illumination is used, the position
and inclination of the surface illuminator and the convergence of the light should be
differently adjusted. Even in the same type of illumination, the most suitable lighting
conditions are not the same according to the magnification chosen. Therefore, it is
necessary, every time the type of illumination or magnification is changed, to adjust
the conditions so that the best illuminating effect, that is, the most and uniform
brightness is attained throughout the entire area of the screen.
(1)
Correct positioning
In projecting the image, the procedures are
to be taken in the following order:
Fig. 18
(Fig. 18)
The surface or section of specimen to be
projected should be placed at a right angle
to the optical axis of the projection lens.
In case the specimen has a flat top surface
parallel to its flat bottom, it only needs to
place the specimen on the stage without
any flxture, because the surface of the
stage is exactly at a right angle
to the optical axis of the lens.
However, for specimens of cylin-
drical form, such as pin, shaft,
screw, etc., it is necessary to
employ a fixture, such as V-block
and center support (Fig. 19),
which holds them in position.
(2)
Sharp focusing
Focusing is performed by rais-
2. Projection
Fig. 19
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