TM 5-3610-257-14
a.
The densitometer employs a technique whereby density of an unknown sample is converted to a time
period. This time period is precisely proportional to the density of the sample. Measurement of the time period results in a
digital readout which is calibrated in terms of density. The entire measurement cycle occurs within 1/50 of a second.
b.
A regulated power supply provides low voltage power for the filament lamp located within the reflection
probe housing.
c.
Within the probe housing, light from the prefocused lamp is directed by a lens and mirror and caused to
strike the unknown sample. The light strikes the sample at a 90 degree angle relative to the surface. Diffused light from
the surface of the sample is collected by a group of fiber optic bundles. The bundles are spaced evenly between 0 degree
and 360 degrees at a 45 degree angle relative to the surface. Light collected by the fiber optic bundles is directed back to
the densitometer. The light passes through a filter system and is directed on the photosensitive cathode of the
photomultiplier tube. Power from the internal power supply is periodically applied to the photomultiplier tube dynode
network. Each cycle of power results in the measurement of the unknown sample density.
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