Waters 2996, Operator'S Manual

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32 Principles of the 2996 PDA Detector Optics
4
Figure 4-2 Benzene Spectrum at 1.2 nm Resolution
4.3 Measuring Light at the Photodiode
The 2996 Photodiode Array Detector measures the amount of light striking the photodiode
array to determine the absorbance of the sample in the flow cell.
The array consists of 512 photodiodes arranged in a row. Each photodiode acts as a
capacitor by holding a fixed amount of charge.
Light striking a photodiode discharges the diode (Figure 4-3). The magnitude of the
discharge depends on the amount of light striking the photodiode.
nm
A
b
sor
bance