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EyeTech Laboratory
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The EyeTech uses a
unique time-size mapping technology called Laser Obscuration Time to directly
measure particles size.
A He-Ne laser beam
passes through a rotating wedge prism and is focused down to a small spot. The
result is a circular movement of a focused laser beam. The laser beam scans the
individual particles in the measurement zone. As the particles within the sample
volume are individually bisected by the laser spot, interaction signals are
generated. These signals are then detected by a photodiode.
Since the beam
rotates at a constant speed, the duration of interaction (obscuration) provides
a direct measurement of the individual particlesize. The interaction signals are
collected by a dedicated data acquisition card and analyzed in 600 discrete size
intervals.
Sophisticated pulse
analysis algorithms are employed to reject out-of-focus and off-center
interactions.
The strength of the
Laser Obscuration Time principle is that it relates solely and directly to
particle size, rather than to secondary properties from which size may be
inferred. This eliminates inconsistencies due to sample refractive index,
viscosity variations, Brownian Motion and thermal convection.
Routine calibration
is not required, and to a large degree, results are not dependent on the optical
properties of the particulates or the medium. Problems of coincidence and
orifice clogging are avoided by using interaction pulse analysis to provide an
optically defined measurement zone, rather than a mechanically defined
orifice.
Simultaneously
offering high resolution and wide dynamic range, the Laser Obscuration Time
analysis generates the most accurate one-dimensional sizing of
particles.
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EyeTech Laboratory |
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