Tip:Optical Resolution (Spectral Resolution)
The difference between two detectable wavelengths [in nm] that can only just be separated is referred to as the optical resolution of a photodiode array detector. It is determined by two factors:
Quality of grating required for spectral dispersion (optical bandwidth)
The values for the optical resolution of conventional detectors are approximately 2 - 6 nm (Dionex UVD 340U Detector: 1.9 nm (UV range); Dionex PDA/PDA-100/PDA-3000 Detector: 1.0 nm).
Tip:
The optical resolution is only one criterion for the quality of a detector. For a meaningful comparison of different detectors, combine the optical resolution and signal-to-noise ratio. In this connection, it is also important that the ratio between the individual factors is balanced. This correlation becomes clear when you look at benzene in the 230 - 265 nm range. A fine structure ("benzene finger") is recognizable only if the number of photodiodes, the imaging optics, and the Signal-to-Noise Ratio are in a sensible performance relation to each other.