A spectrometer comprising: an infrared source for projecting an infrared beam; a gas sample cell (G, 102) positioned in the path of the infrared beam; a scanning mirror (14, 32, 46, 60, 64, 68, 106) bearing a diffraction grating comprising a plurality of parallel lines and positioned in the path of the infrared beam after passage thereof through the gas sample cell; a resonant scanner drive system adapted to oscillate the scanning mirror about an axis parallel to the diffraction grating lines; a first focusing element (16, 62, 66, 108) positioned to focus at least one band of interest of the infrared beam as diffracted by the diffraction grating; a first detector (18, D, 110) positioned to receive the at least one focused band of interest; a first detector readout circuit operatively coupled to the first detector to receive a signal from the first detector, a splitter (44, 47) positioned in the path of the diffracted infrared beam from the scanning mirror; a second focusing element positioned in a respective path of the discrete bands of interest; a second detector positioned to receive a focused discrete band of interest; and a second detector readout circuit operatively coupled to the second detector to receive a signal from the second detector; characterized in that the resonant scanner drive system comprises: a taut band having a first end and a second end, the taut band providing a rotational axis for the diffraction grating, wherein the diffraction grating is fastened at a first side of the taut band; a holding frame supporting the first end and the second end of the taut band; a permanent magnet fastened to a second side of the taut band and mounted with the magnetic pole axis normal to the plane of the grating; an electro-magnet at the second side of the taut band, wherein the scanning mirror (14, 32, 46, 60, 64, 68, 106) is driven by the magnetic interaction between the permanent magnet and the electro-magnet, the electro-magnet having a "C"-shaped core with a winding wound around the center section of the "C" and having two pole-pieces, wherein a line between the two pole-pieces is perpendicular to the axis of the taut band; anda first and a second spacer, wherein the first spacer is provided between the diffraction grating and the taut band, wherein the second spacer is provided between the permanent magnet and the taut band. an infrared source for projecting an infrared beam; a gas sample cell (G, 102) positioned in the path of the infrared beam; a scanning mirror (14, 32, 46, 60, 64, 68, 106) bearing a diffraction grating comprising a plurality of parallel lines and positioned in the path of the infrared beam after passage thereof through the gas sample cell; a resonant scanner drive system adapted to oscillate the scanning mirror about an axis parallel to the diffraction grating lines; a first focusing element (16, 62, 66, 108) positioned to focus at least one band of interest of the infrared beam as diffracted by the diffraction grating; a first detector (18, D, 110) positioned to receive the at least one focused band of interest; a first detector readout circuit operatively coupled to the first detector to receive a signal from the first detector, a splitter (44, 47) positioned in the path of the diffracted infrared beam from the scanning mirror; a second focusing element positioned in a respective path of the discrete bands of interest; a second detector positioned to receive a focused discrete band of interest; and a second detector readout circuit operatively coupled to the second detector to receive a signal from the second detector; a taut band having a first end and a second end, the taut band providing a rotational axis for the diffraction grating, wherein the diffraction grating is fastened at a first side of the taut band; a holding frame supporting the first end and the second end of the taut band; a permanent magnet fastened to a second side of the taut band and mounted with the magnetic pole axis normal to the plane of the grating; an electro-magnet at the second side of the taut band, wherein the scanning mirror (14, 32, 46, 60, 64, 68, 106) is driven by the magnetic interaction between the permanent magnet and the electro-magnet, the electro-magnet having a "C"-shaped core with a winding wound around the center section of the "C" and having two pole-pieces, wherein a line between the two pole-pieces is perpendicular to the axis of the taut band; anda first and a second spacer, wherein the first spacer is provided between the diffraction grating and the taut band, wherein the second spacer is provided between the permanent magnet and the taut band.