Jeulin 571 042 Mode D'emploi page 10

Observation
Binocular polarizing microscope
Ref :
571 042
ENGLISH
- The height at which the stage rise can be limited using the locking lever
situated at the base of the coarse-focusing knob on the left of the stand. To
adjust the limit:
- screw in the X 40 objective (or X 100 if one has been added).
- lower the lever to unlock it by pushing it back;
- gently raise the stage while looking at it sideways until the slide almost
touches the lens (about 2 mm away);
- raise the lever and lock it. The stage will not rise above the limit thus set.
Repeat these operations to change the setting.
- Under the stage there is a light condenser that is moved using the knob on
the right, an adjustable iris diaphragm and a filter holder designed to hold a
(blue) filter for observing very transparent preparations.
- Adjust the lighting by seeking the best position of the condenser, then shut
down the diaphragm to increase contrast and depth of field, but not too much
so as to alter the resolution.
- Using the rotating stage: this is graduated to 2/10ths over 360° and is fitted
with slide holders to hold histological or mineralogical slide preparations in
place. A locking screw enables the stage to be locked in a chosen position.
- Centring the rotating stage: in order to align the rotational centre of the stage
with the optical axis of the lens, the state must be centred. If centring is not
optimal it can be corrected using the two adjustment screws (on either side
on the edge of the stage). Use a small screwdriver or suitable key.
- fcus on the slide without polarizing the light, and mark out an easily
identifiable point in the field of vision.
- position the slide so that this point lies in the centre of the eyepiece.
- rotate the stage; if the chosen point turns in a circle in the fild of vision,
the two screws must be adjusted to centre it correctly.
- gradually reduce the size of the circle in which the point moves until the
latter remains fixed (see figure, below).
- the stage is now ready for observation of the slide with the objective in
place.
4 Polarisation
Reference works:
"Détermination des minéraux des roches au microscope polarisant", Marcel
Roubault, Lamarre Poinat, publishers.
"Guide de pétrologie descriptive", Ronan Hébert, Nathan Université,
publishers.
4.1 Polarizer and analyser
The polarizer is placed above the light condenser; it is removable. I should be
rotated 360° to lie at an angle of 90° to the analyser (see above: setting up.
paragraph 6).
The analyser is incorporated in the head of the microscope. When the tab (A)
is pushed in the analyser is not in place (light is not analysed); when the tab is
pulled fully out, the analyser is in place (light is analysed).
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