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9. Measurement of solid sample
(2)-1 Desirable sample conditions
Most desirable sample size is 20 to 30mm long
by 8mm bread approximately. Cut a sample so
and clean and polish the cut surface.
(2)-2 Choosing test piece
Since each film sample is thin and small in
the lighting surface, it is difficult to measure
it owing to a small amount of incident light.
To compensate quantity of incident light, a
glass piece called test piece shall be put on
a sample for measurement.
It is the prerequisite to use a test piece is
that its Refractive Index is higher than that of
the sample.
There four kinds of test pieces of the
following are prepared for measurement of
film samples.
Test piece A (nD=1.516)
Test piece C (nD=1.620)
Test piece D (nD=1.740)
Test piece E (nD=1.92)
The
Test piece
D
(nD=1.740)
is
recommended for the NAR-2T.
(2) Measuring film samples
Fig. 9-4
(2)-3 Mounting sample on main prism
As shown in Fig. 9-4, a film sample must be
put on proper contact liquid dript on the
main prism, and put a proper test piece on
the sample after dripping another contact
liquid on the sample.
ە
Cautions on mounting sample
Wipe down respective contact surfaces of
the main prism, sample and test piece.
Before dripping contact liquid.
Carefully drip a small amount of contact
liquid (one drop of about 1mm in diameter)
on the center part of the main prism
surface and the sample respectively. If
contact liquid is dropt too much or there is
air bubble in it, it leads the measurement
into error in most cases.
Pay heed to the orientation of the sample
so that the polished clean sides face the
lighting and the main prism.
ࠐ
ࠐ
ࠐ
Film sample
Test piece
Main prism
Contact liquid
Note:
Choose a contact liquid,
refer to (1)-2 on page 26.
