Leica DMR Bedienungsanleitung Seite 82

Ellip tical Sénarmont comp ensator
(λ/4 compensator in subparallel position)
Measurement is executed in monochromatic
light (546 nm), and a 360° rotatable analyser
(30.1) is necessary. Normally this compensator is
used to measure phase differences of up to the
first order, although higher phase differences
can be measured,
compensator does not produce the entire phase
difference but only the amount that is in excess
of a whole wavelength or a multiple thereof.
Whole wavelengths must be determined with a
tilting compensator, quartz wedge, or estimation
of the interference colour. Accuracy is higher
than with the tilting compensator alone.
Tilting comp ensator B (Berek comp ensator)
measuring up to 5 orders
Compensator (57.8)
measurements in monochromatic or white light
of up to 5 orders phase difference. The phase
difference can be read directly from the sum of
the two angles of compensation produced when
the compensator plate is tilted in both direc-
tions, from a supplied calibration chart.
82
(57.6) )
too. However,
with MgF plate
2
Tilting comp ensator K, measuring up to 30 orders
(57.7)
For the measurement of phase differences in
white or monochromatic light up to the
maximum phase difference mentioned above.
The compensator plate is made of calcite;
evaluation is based on simple calculation by
the means of enclosed tables and the stated
calibration constant. A programmed computer
can be used for evaluation of measurements
taken with tilting compensators. The necessary
formulae and parameters are given in:
Kornder, F. and W. J. Patzelt: The use of
minicomputers to evaluate polarization-optic
compensator measurements. – Leitz Scientific
and Technical Information IX/1, 30 – 32, 1986.
Conoscopy of crystals
or
Only with the Leica DM RXP polarized light
microscope:
interference patterns (Fig. 59a/b) in the exit pupil
of the objective (i.e. inside the objective). These
are also called conoscopic images. The shape
of these interference patterns and the way they
change when compensators are used supply
information on the number of the crystal axes
(uniaxial or biaxial crystals), the orientation of
these axes and the plus or minus sign of the
birefringence (positive or negative birefringent
crystal).
Birefringent crystals cause