Leica DM4000 B Bedienungsanleitung Seite 63

Simple overview observations
• Place the transmitted light specimen on the
polarizer.
• Turn the condenser head inward.
• Focus through the condenser using a low-
power magnifying lens, such as a 5x.
Although this method does not provide good im-
aging performance; it does make it possible to
view rows of specimen very quickly.
λ/4- and λ plate, quartz wedge
Depending on their design, λ/4 and λ plates are
installed on the underside of the condenser or,
for polarizing microscope, in the 8x condenser
disk (the vibration direction γ runs:
are inserted in the tube slot. An automatic,
spring-mounted dust cover flap closes the tube
slot.
For the IC/P analyzer, the λ plate can be activat-
ed by turning it so that the mark "I" is facing up-
wards.
When the plate is activated, the path difference
is increased or reduced according to Fig. 68.
The corresponding color changes can be used
to determine the vibration direction γ according
to the larger refractive index (i.e. refractive
index n ). (The quartz wedge (69.7) allows
γ
various color shifts
microscope.)
9. Contrast methods for Leica DM4000 B/DM4500 P/DM5000 B
) or they
on the polarizing
Circular polarization
When the specimen stage is rotated, birefrin-
gent specimens show 4 extinction positions.
When a larger number of birefringent speci-
mens are present, a few birefringent specimens
always show up randomly in the extinction posi-
tion. Circular polarization is used for simulta-
neous interference color observation of all
specimens:
• Remove the specimen from the beam path or
locate the blank position of the specimen.
• Cross the polarizers precisely. The polarizers
must be positioned exactly in the N – S/E – W
direction. This means that the analyzer must
either be set exactly at 90° or 0° of polariza-
tion.
Fig. 68 Interference color with dependence on the path
difference or on the thickness and color changes in the addi-
tion and subtraction areas of the λ and λ/4 plates.
200
– λ
400
600
800
+ λ
1000
1200
1400
1600
schwarz
lavendelgrau
graublau
gelblichweiß
lebhaftgelb
rotorange
λ
tiefrot – –
4
indigo
λ
himmelblau
+ –
4
grünlichblau
hellgrün
reingelb
orangerot
dunkelviolettrot
indigo
grünlichblau
meergrün
grünlichgelb
fleischfarben
kaminrot
mattpurpur
63