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31
v .
OPTIONAL ACCESSORIES
2.
Quartz
Wedge
To be inserted into the compensator slot of the Intermediate tube instead
of the 1/4,1. & tint plate. (Fig.25)
The quartz wedge is engraved with scale and used for the rough
measurement of retardation in the range of 1 A-6A.
Fig.25
1) Detecting extinction position
Detect the position where the part of the specimen to be measured
becomes darkest by rotating the stage under the crossed Nicols.
2) Detecting subtraction position
Rotate the stage 45° to bring it from the extinction position to the
diagonal position. Insert the quartz wedge into the optical path, and
confirm that the interference color of the part of the specimen to be
measured changes toward the lower order side.
If the color changes toward the higher order side, rotate the stage
another 90°.
3) Measurement
Slide the quartz wedge along the slot, and the interference color
changes.
Stop sliding the quartz wedge where the dark stripe covers the part of
the specimen to be measured. In this position, find the part with no
object under the same dark stripe, and compare the interference
color of that part with the Interference Color Chart to assume the
amount of retardation.
If the view field around the part to be measured is entirely filled with
the object, restrict the illumination to the part to be measured by
means of the field diaphragm, remove the specimen from the optical
path and then compare the interference color with the Chart.
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