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SAMPLE TYPES AND SAMPLE PRESENTATION
Sample presentation
The instrument is calibrated for samples which are flat and fill the aperture of the
nosecone. The nosecone defines the distance from the sensor to the sample, defines the
orientation of the sample, and blocks external light. Samples should be presented to the
instrument so that they contact the entire circumference of the nosecone.
Homogenous samples
The instrument will center weight average the light it collects from the sample. This
means that the center of the sample, relative to the aperture of the nosecone will count the
most. If the sample is the same appearance over the entire aperture at all angles we call
the sample homogenous. If possible, try to find a flat homogenous area of the sample to
measure. If this is not possible use the largest (relative to the aperture) , flattest
homogenous area you can. Measure several times. You should have several
measurements which agree. Use the measurements which agree and discard the others.
If the sample is thin, flat and homogenous then the sample should be placed on a flat
surface and the instrument placed on the sample. In this configuration the two metal feet
at the back of the unit will provide a three point mount with the nosecone. The landing
pad provided with the instrument is intended to provide a flat surface with consistent
backing color for measuring thin flat samples.
If the sample is thick, but homogenous, and you have another material of the same
thickness you may use the other material to support the back feet of the unit. If not, you
should hold the unit against the sample or clamp the sample against the nosecone
between your thumb and fingers. In this case it is important that you keep the nosecone
flat against the unit during the measurement.
If the sample is curved you should attempt to get as much of the sample in contact with
the circumference of the nosecone as possible. In this case you should perform multiple
measurements at different presentations and keep the measurements which agree.
When the sample is not flat enough to form a good light block with the nosecone, results
may be improved by reducing external light with a dark cloth.
