Waters 2998 - Measuring Light at the Photodiode Array

1-6 2998 PDA Detector Optics Principles
Benzene spectrum at different resolutions
Measuring light at the photodiode array
The 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 a row of 512 photodiodes. Each photodiode acts as a
capacitor initially holding a fixed amount of charge.
Light striking a photodiode discharges the diode. The magnitude of the
discharge depends on the amount of light striking the photodiode.
Absorbance
nm
230.00 250.00 270.00
1.2 nm
3.6 nm