How does the Mastersizer do it?
There are two distinct procedures involved in measuring a sample on the
Mastersizer.
.
Firstly there is the capturing of the scattering pattern from the sample - this
is known as the “measurement”. This is the purpose of the optical unit.
The detector within the optical unit is made up of many individual
detectors. Each detector will collect the light scattering from a particular
range of angles. A typical light scattering pattern is shown below.
Each bar in the histogram represents the light scattering from one of the
detector elements.
The detector takes a “snap-shot” of the scattering pattern. Obviously this
snap-shot will only capture the scattering pattern from the particles that
where passing through the analyser beam at that particular time. Taking
only one snap-shot may not give you a representative reading of the
scattering pattern. To overcome this the Mastersizer takes many snap-shots
(known as sweeps) and averages the result. Typically over 2000 sweeps are
made for each measurement, with each sweep taking 2mS.
.
Secondly, once the measurement is complete the raw data contained in the
measurement can be analysed by the Malvern software using one of the
theories above.
The measurement data is analysed by first selecting a “presentation”. A
presentation is a predicted scattering pattern from theoretical particles. The
software has many presentations on disc that represent particles of different
materials suspended in different dispersants. You will choose the
presentation that matches the sample and dispersant you are measuring.
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Obscuration = 10.3 % Data Background
ILL 1857
CHAPTER 3
Getting Started
Page 3.2
MAN 0101
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