The invention relates to a spectrometer (1) comprising a dispersive element of a light beam formed of a set of spectral components, the dispersive element generating spatial dispersion of the spectral components in the form of a dispersion spectrum (6) spatially spread, at least one photon detector (5, 52) comprising at least one detection element (51) being provided at one point of said dispersion. According to the invention, a matrix optical electromechanical device (3) is provided between the dispersive element and the detector in the dispersion spectrum, said electromechanical device being formed of a matrix of optical elements, each of the optical elements being able to send back a portion of the dispersion spectrum according to at least two directions in relation to a control signal, in order to enable the selection of at least one sub-assembly of the spectrum for said detection element. A method and an application of the spectrometer are claimed.