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How to Use Examination Plates
The polarizing intermediate tube has a slot for examination plates. It is used not only for the
standard P-CL 1/4
λ
& tint plate but also for the optional P-CS Senarmont compensator, the PCW
quartz wedge, or so on to perform the retardation measurement.
To use an objective of 10x or higher magnification in standard observation, place the top
lens of the P swing-out condenser into the optical path. To perform the retardation
measurement or to perform evaluation by interference color, the illumination light must be
as parallel to the optical axis as possible. So, the condenser aperture diaphragm must be
stopped down or the top lens of the swing-out condenser must be swung out (the aperture
diaphragm is fully opened), even if an objective of 10x or higher is used.
P-CL 1/4
λ
& tint plate
The P-CL 1/4
λ
& tint plate has an empty hole in the
center. By pushing it into the slot, the sensitive color plate
(530 nm) is placed into the optical path. Pulling it out
places the 1/4
λ
plate into the optical path.
This plate is used for recognition of very weak
birefringence and the determination of X' and Z' of the
specimen.
P-CS Senarmont compensator
Remove the P-CL 1/4
λ
& tint plate from the slot of the polarizing intermediated tube and insert the
P-CS Senarmont compensator into the slot.
You can measure retardation of light up to 1
λ
with the following steps.
1 Determination of extinction position
Rotate the stage with the specimen under the crossed Nicols to find the direction where the
part of the specimen to be measured appears darkest.
2 Determination of subtraction position
Rotate the stage 45 degree from the extinction position to place a diagonal position. Insert the
P-CL 1/4
λ
& tint plate into the optical path and confirm that the interference color of the
section of the specimen to be measured changes toward the lower order side. If the
interference color changes toward the higher order side, rotate the stage another 90 degree.
3 Measurement
Place the GIF filter on the field lens and remove the P-CL 1/4
λ
& tint plate and locate the P-
CS Senarmont compensator.
Rotate the analyzer so that the section of the specimen to be measured becomes darkest.
When the rotation angle of the analyzer at that time is taken to be theta (
θ
) degrees, then
retardation (R) (nm) is determined with the following formula:
R =
θ
180
λ
(
λ
: wavelength to be used)
The value of
λ
when using the GIF filter is 546 nm.
0
BINO
PH
OTO
PHOTO
BINO &
P-CL 1/4
λ
& tint plate
