Meiji Techno ML 8500 Series, Instruction Manual

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DARKFIELD ILLUMINATION SET UP
The reflective Darkfield Illuminator is designed as shown here:
As the above illustrates, the light does not pass the objective
directly and illuminate the specimen with the light bundle inclined
against the light axis, and observation is made possible only
through scattered or refracted light.
When you observe flat surface of glass or mirror, you will see nothing in the dark. But, when you
observe a specimen which includes refractive substance to scatter light, the clear image of the
substance can be seen.
[1] Slide the Illumination
Selector to the position
where Darkfield stopper
comes across the Light
Axis centrally.
[2] Open up both irises for
Field(a) and Aperture(b).
[3] Focus down on the specimen just in the same way as for the Brightfield observation. (The image is
observed in a different way from that of the Brightfield observation. That is, we can see an image
formed from light scattered by features in the object, the detail thus appearing bright against a dark
background.)
[4] Brightness of illumination can be adjusted by Intensity Control knob, just in the same way as for the
Brightfield observation.
POLARIZING FACILITY
POLARIZER
Slide the Illumination Selector to the position where
Polarizer comes across the Light Axis centrally.
4 5
[7] After you have focused on the specimen, proceed as follows:-
Move the sliders on which the two binocular eyepiece tubes are mounted in
and out until the distance between them is exactly the same as the
distance between the pupils of the observers eyes. (This is the
“interpupillary distance”.)
[8] When this is done, note the dimension which is displayed in the window of the slider. Always
remember to set to this distance when using the microscope. It will be different for different observers,
so they will have to check the best setting for themselves.
[9] To get best focus with both eyes the eyetube heights should be adjusted to take into account the
interpupillary distance mentioned [5] and [6] above. First, set the tube Length Adjustment Ring
to the
reading which corresponds to the dimension shown in the binocular slider window. Do this for the left
hand eyepiece only. Now focus to get the sharpest possible image in the left hand eyepiece, using the
microscope fine adjustment. Then turn the right hand Tube Length Adjustment Ring until the image is
equally sharp in the viewer’s right eye.
As these Rings function also for dioptric
correction the dimension set may not, in
this case, exactly correspond to the
window’s indication.
[10] Now turn the field iris adjustment
lever(a) until the field iris is seen in the
field of view.
[11] Your light source may require centering adjustment if the field of view seems unevenly illuminated.
Centering controls are located on the side of the light source housing which is built in at the back of the
vertical illuminator.
[12] CENTERING ADJUSTMENT
To move the bulb vertically, loosen Clamp
Screw
and turn the Backing Plate
clockwise or counterclockwise slightly.
To move the bulb horizontally, turn the
Lamp Centering Control
.
[13] Close down the filed iris (using the
lever(a) on the vertical illuminator) until the image of the filed iris is in focus on the specimen. Then
open it back out until the image of the iris disappears from the field of view.
[14] Now adjust the aperture iris (using lever(b) on the vertical illuminator), closing it down slowly while
observing the field of view. A point will be reached where there is a sudden distinct drop in brightness
of the field of view. When this occurs, open up the iris slightly, just until this brightness condition
reverses, but no more.
[15] This procedure should be followed each time objectives are changed.
Field of view
Fused
Window
Length Adjustment Ring
Clamp screw
Backing plate
Lamp centering control
(a) (b)
Polarizer
Empty hole for Brightfield
Darkfield stopper
Illumination Selector
Polarizer
Empty hole for Brightfield
Darkfield stopper