A diffractive optical element device for use in spectroscopy, where broadband light is emitted from a light source towards the optical element and from there is transmitted to at least one detector. The optical element has a plurality of diffractive dispersively focusing patterns, preferably partly integrated into each other, whose respective centers are two-dimensionally offset relative to each other in order to produce a plurality of spectra, where at least two are separate, but offset relative to each other and/or partly overlapping. In an alternative embodiment, the optical element consists of either one diffractive optical element that is related to a wavelength and produces a spectrum, or at least two diffractive optical elements which are related to respective wavelengths and which produce at least two mutually partly overlapping spectra to give a composite spectrum. The optical element is capable of producing at least one indication of upper and/or lower wavelength value in the spectrum.