The most important feature of a spectrometer is the resolution of the spectrum (or light). The spectral resolution of a system determines the peak spectrum, the maximum number that the spectrometer can resolve. For example, if a spectrometer with a wavelength range of 200nm has a spectral resolution equal to 1NM, the system will be able to solve a maximum of 200 independent wavelengths (peaks) across the spectrum.
In the dispersive array spectrometer, there are those that determine spectral resolution of 3 major factors: slit, diffraction grating, and detector. The slit determines the minimum image size that the optical holder can form in the detector plane. The diffraction grating determines the total wavelength range of the spectrometer. The detector determines the discrete point in which the spectrum can be digitized to the maximum number and size.