Photodiode Array Detector
Functionality

Unlike conventional (1 or 2-channel) UV Detectors, multi-channel detectors (PDAs) send the entire spectrum of the light source (a), in focused form (b), through the flow cell (c). Thus, absorption not only causes the intensity of a single wavelength to change, but that of all wavelength portions of the entire spectrum. After that, the white light is dispersed spectrally using a grating (d). The resulting spectrum is measured by adjoining photodiodes (e) almost synchronously.

Dionex detectors store this information analog to a UV channel via the signal 3D Field. Apart from the quality of the optics and the grating, the number and size of the photodiodes determine the Optical Resolution of the detector.

 Tip:

The optical resolution cannot be considered by itself, but must be seen in connection with the achieved signal-to-noise ratio!