Spectral or optical resolution is one of the most important characteristics of a spectrometer. It is related to the bandpass and determines the minimum difference in wavelength that can be separated by the optical elements of the spectrometer. A lower value for optical resolution will correspond to a higher resolution.
Factors that Affect the Optical Resolution
There are three main elements that define the optical resolution of a spectrometer:
- The entrance slit sets the minimum spectral image size for a given wavelength that is formed on the detector and will cover a small number of pixels. For two spectral lines to be separated, it is necessary to disperse them over at least three pixels.
- The diffraction grating determines the operational range of wavelengths of the spectrometer (how far the wavelengths are dispersed at the detector).
- The detector determines the maximum number and size of pixels in which the spectrum can be digitized.
When considering all the components that comprise the spectrometer (slit , diffraction grating and detector), is also important to take into account the core size of the optical fiber. When using optical fiber with a large core, optical resolution can be improved by selecting a slit with a smaller size width. This reduces the amount of light that enters the spectrometer.
How do we Measure Optical Resolution
How to Change the Resolution of your Spectrometer?