Beckman Coulter Navios, Instructions For Use Manual

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773232AH
3-2
Operation Principles
Laser Beam Shaping
The flow cell ( Figure 3.1 ) contains a rectangular channel. A pressurized stream of sheath fluid enters
the channel at the lower end and flows upward. The sensing area of the flow cell is at the center of
the channel.
While the sheath stream is flowing through the channel, a stream of sample is injected into the
middle of the sheath stream. As shown in
Figure 3.1 , the sheath stream surrounds, but does not mix
with, the sample stream. The pressure of the sheath stream focuses the sample stream so that the
cells flow through the laser beam single file. If the cells were to move through the laser beam in
different ways during sample flow, sample analysis could be distorted.
Figure 3.1
Flow Cell
Laser Beam Shaping
Before the laser beams reach the sample stream, cross-cylindrical lenses focus the beams (see
Figure 3.2 ). Focusing keeps the beam perpendicular to the sample stream flow while making the
beam small enough to illuminate only one cell at a time.
The first lens controls the width of the beam; the second, the height. The resulting elliptical beam
is focused on the sensing area of the flow cell.
1.
Waste out
2.
Debubble port
3.
Sheath stream enters here
4.
Sample stream enters here
b
c
d
e