Ryf Axio Lab.A1 Operating Manual page 88

Carl Zeiss
Fig. 4-10 Axio Lab.A1 for transmitted light
conoscopy
CAUTION
The movements of rotary knobs A and BL and the respective setting wheels are coupled with
one another. Only one control element should therefore be operated at a time and the
movement of the other should not be inhibited or blocked. Mechanical damage may otherwise
occur.
If rotary knob BL is set to the on position, if it is not already at the on position rotary knob A is
automatically carried.
If, on the other hand, rotary knob A is set to the off position, if it is not already at the off
position rotary knob BL is automatically carried.
Place a selected crystal in the center of the crossline reticle.
Swivel in objective N-Achroplan 50x/0.8 Pol or EC Plan-Neofluar 40x/0.9 Pol and focus with the
focusing drive.
If necessary, close the luminous-field aperture to avoid superimposition of the axial figure by axial
figures of neighboring crystals. The smallest crystal range that can be faded out is 170 μm.
Switch on Bertrand lens BL (Fig. 4-10/1) (Position on). The axial figure will appear in the field of view.
Bring the axial figure into focus with setting wheel (Fig. 4-10/5).
(4) Evaluation
Crystalline anisotropic specimens can be separated into optical uni- and biaxial, in each case with
"optically positive" or "negative" character.
Uniaxial crystals display a black cross when the optical axis is parallel to the direction of view.
Depending on the size of the birefringence and specimen thickness, concentrically arranged
colored interference rings (so-called isochromes) may appear (see also Fig. 4-11 second row).
This cross remains closed when the stage is rotated. Depending on the section it may lie within or outside
the displayed objective pupil.
With optically biaxial crystals, the cross resolves into two dark hyperbola branches (the so-called
isogyres) depending on stage rotation, which are surrounded by colored interference patterns
depending on the amount of birefringence and specimen thickness (suggestive of the figure "8").
88
OPERATION
Lighting and contrasting method in transmitted light
430037-7144-001
Set the microscope as in the transmitted light
brightfield according to KÖHLER (see Section
4.1.1).
Place the specimen on the stage and focus on
it.
Swivel the analyzer into the beam path (on
position) with rotary knob A (Fig. 4-10/2). The
direction of oscillation can be changed using
the setting wheel (Fig. 4-10/4) of the analyzer.
Axio Lab.A1
04/2013