Flowcell - Thermo Scientific Surveyor RI Plus Hardware Manual

1
Introduction
Theory of Operation

Flowcell

8 Surveyor RI Plus Detector Hardware Manual
When there is a difference in the refractive indices of the sample and reference solvents in the
flowcell, the image on the photodiode moves horizontally as illustrated in
Figure 7. Movement of the image on the photodiode
Image
Diode A Diode B
a. No difference in the
refractive index
The electrical signals emitted respectively from the diodes A and B change in proportion to
the movement of the image. A signal corresponding to the difference in refractive index can be
obtained from the difference between the two signal outputs.
The flowcell consists of a reference compartment and a sample compartment. During normal
operation, the reference compartment is shut off from the solvent path. You can replace the
solvent in the reference compartment by using the purge control feature provided in the
ChromQuest data system.
Figure 8 shows a block diagram of the flowcell:
• When the Purge Control is On, solvent flows through both the sample and the reference
compartments of the flowcell.
• When the Purge Control is Off, the reference compartment of the flowcell is shut off
from the solvent path.
Image
Diode A Diode B
b. Some difference in the
refractive index
Figure 7.
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