An ATR spectrometer configured to analyse the chemical composition of a sample, wherein the ATR spectrometer comprises: an ATR crystal having an entry surface being immediately arranged on an entry end of the ATR crystal and an exit surface being immediately arranged on an exit end of the ATR crystal which is arranged opposite to the entry end; at least one infrared light source being arranged on the entry surface; a line array of infrared light detectors being arranged on the exit surface; and at least one additional infrared light detector, separate from the line array, being arranged on the exit surface, wherein the at least one infrared light source is adapted to emit infrared light that enters the ATR crystal via the entry surface and is guided to the infrared light detectors in the line array and to the at least one additional infrared light detector under total internal reflection and under interaction with the sample being arranged immediately adjacent to the ATR crystal; wherein the ATR spectrometer additionally comprises a wavelength dispersive element being arranged in the path of the infrared light from the exit surface to the line array so that the line array is adapted to measure a spectrum of the infrared light, and a wavelength filter being arranged in the path of the infrared light from the exit surface to the at least one additional infrared light detector; wherein the infrared light detectors in the line array and the at least one additional infrared light detector are each adapted to output an electrical signal being indicative of the amount of the infrared light impinging on the respective infrared light detector; wherein at least one infrared light detector in a group of infrared light detectors consisting of the infrared light detectors in the line array and the at least one additional infrared light detector, is chosen to be a chosen infrared light detector for a signal correction, and the ATR spectrometer is adapted to use the electrical signal of the at least one chosen infrared light detector to correct the electrical signals of all the other infrared light detectors in the group of infrared light detectors, wherein the spectral resolution for at least one of the at least one additional infrared light detectors is higher than for all of the infrared light detectors in the line array. an ATR crystal having an entry surface being immediately arranged on an entry end of the ATR crystal and an exit surface being immediately arranged on an exit end of the ATR crystal which is arranged opposite to the entry end; at least one infrared light source being arranged on the entry surface; a line array of infrared light detectors being arranged on the exit surface; and at least one additional infrared light detector, separate from the line array, being arranged on the exit surface, wherein the at least one infrared light source is adapted to emit infrared light that enters the ATR crystal via the entry surface and is guided to the infrared light detectors in the line array and to the at least one additional infrared light detector under total internal reflection and under interaction with the sample being arranged immediately adjacent to the ATR crystal; wherein the ATR spectrometer additionally comprises a wavelength dispersive element being arranged in the path of the infrared light from the exit surface to the line array so that the line array is adapted to measure a spectrum of the infrared light, and a wavelength filter being arranged in the path of the infrared light from the exit surface to the at least one additional infrared light detector; wherein the infrared light detectors in the line array and the at least one additional infrared light detector are each adapted to output an electrical signal being indicative of the amount of the infrared light impinging on the respective infrared light detector; wherein at least one infrared light detector in a group of infrared light detectors consisting of the infrared light detectors in the line array and the at least one additional infrared light detector, is chosen to be a chosen infrared light detector for a signal correction, and the ATR spectrometer is adapted to use the electrical signal of the at least one chosen infrared light detector to correct the electrical signals of all the other infrared light detectors in the group of infrared light detectors, wherein the spectral resolution for at least one of the at least one additional infrared light detectors is higher than for all of the infrared light detectors in the line array.