Nikon LABOPHOT-POL Gebruiksaanwijzing - Pagina 17
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ACCESSORIES
1. Senarmont Compensator
To be inserted into the compensator slot of the
intermediate
tube "P" in place of the 1/4 \ &
tint plate to measure the retardation with the
accuracy of the \ unit. (F ig 23)
Fig. 23
1) Detecting of extinction
position
Rotate the stage with the specimen under
the crossed Nicols to find out the direction
where the specimen part for measurement
appears darkest.
2)
Detecting of subtraction position
Rotate the stage 45° to bring it to the dia-
gonal position from the extinction position
and confirm that the interference color of
the specimen part for measurement changes
toward
the lower order side by inserting
the 1/4 \
&
tint plate into the optical path.
If the color changes toward higher order
side, rotate
the
stage further
by 90°.
2.
Quartz Wedge
The quartz wedge is used instead of the 1/4 \
& tint plate that is in the compensator slot of
the intermediate tube
"P"
(Fig 24)
With this wedge the retardation
in the range of
1\ ~ 6\ can roughly be measured.
Fig. 24
1) Detecting of extinction
position
Detect the position
where the specimen
part for measurement becomes darkest by
rotating the stage under the crossed Nicols.
2) Detecting of subtraction position
Rotate the stage 45° to bring it tQ the dia-
gonal positio·n from the extinction
position
and confirm that the interference color of
the specimen part for measurement changes
toward
the lower order side by inserting
the quartz wedge into the optical path.
If the color
changes toward
the higher
order side, rotate the stage fu rther by 90°.
When the fi Iter GI F is used: \ = 546nm
3) Measurement
Inserting
the filter
GIF
into
the filter
receptacle, replace the 1/4 \
&
tint plate
by the compensator.
Rotate the analyzer so as the specimen part
for measurement becomes as dark as possi-
ble.
Let the angle of the above analyzer rota-
tion be 8° then the retardation R (nm) will
be obtained as follows:
_8\
R
=
180
where \
wave
length
of
the
light
used
for
the
measurement
17
3) Measurement
By sliding the quartz wedge along the slot,
the interference color changes consequent-
ly.
The wedge sliding is to be stopped when
the specimen part for measurement comes
under the dark stripe, then compare the
interference color of the view field beyond
the specimen but under the same dark
stripe with the Interference Color Chart to
assume the amount of retardation.
If the view field is entirely filled with the
specimen around the part to be measured,
restrict the illumination
of the view field
except around the part for measurement
by means of the field diaphragm; remove
the specimen away the optical
path and
then compare the interference color with
the chart.