A filter wheel and a spectrometer including the filter wheel are disclosed. The filter wheel has a first support structure on which a first plurality of filters are mounted and a second support structure on which at least one filter is provided. A radiation source generates a radiation beam, and a beam splitter splits the radiation beam into a first detection path and a second detection path. The first plurality of filters are selectively movable into the first detection path. The at least one filter on the second support structure is arranged to be disposed in the second detection path. The spectrometer includes a first radiation detector that detects radiation that passes through the selected filter in the first detection path, and a second radiation detector that detects radiation passing through the filter in the second detection path.