Echelle spectometer with improved use of the detector by means of two spectrometer arrangements

A spectrometer assembly comprising:

• a light source emitting radiation, the radiation having a wavelength spectrum in a first and second wavelength range;
• a housing with an entrance slit;
• an Echelle grating for spectrally dispersing said radiation entering through said entrance slit in a main dispersion direction into a plurality of orders;
• a dispersion element for separating said orders by means of spectrally dispersing said radiation in a lateral dispersion direction, said lateral dispersion direction forming an angle with said main dispersion direction of said Echelle grating and thereby generating a two dimensional spectrum with said plurality of orders being separated from each other;
• an imaging optical system for imaging said two dimensional spectrum onto an imaging plane;
• a detector array with a two-dimensional arrangement of a plurality of detector elements in said imaging plane
• wherein said Echelle grating, dispersion element and imaging optical system form a first spectrometer for generating said radiation spectrum in said first wavelength range of said light source on said detector and
• a further spectrometer having a further dispersion element and a further imaging optical system for the generation of a radiation spectrum in said second wavelength range which is different from said first wavelength range on said detector;
• wherein said spectra of said first and second wavelength ranges spatially at least partially superimpose on said detector, and said lateral dispersion is designed such that dark spaces are present between said orders of said two dimensional spectrum of said first spectrometer on said detector adapted to at least partially receive said spectrum of said second spectrometer imaged thereon.