Waters 2410 Operator's Manual page 24

θ
Reference Side
of Flow Cell
θ
Figure 1-5 How Refraction Changes φ
Effect of Refraction on φ
As the beam of light moves along the light path to the photodiode, it encounters and is
refracted by the air in the optics bench assembly, the fused quartz walls of the flow cell,
the solvent in the reference side of the flow cell, and the solution in the sample side of the
flow cell.
Of these refractors, only the solution in the sample side of the flow cell changes over the
course of a run. As a result, the reference external angle of deflection ( φ ) does not change
until a change in the RI of the sample causes the light beam to be refracted from its zero
position.
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Y
n
φ
n
Y
n + ∆n
Sample Side
of Flow Cell
φ
= ∆x
n
Theory of Operation
1
23