Abstract: The invention relates to a procedure for determining an identification of a sample of material, or its properties. Electromagnetic radiation from a radiation source (1) is reflected or transmitted through the sample. The radiation from the sample is collected and analyzed over several channels (7, 7', 7"), which modulate the radiation with a spectral transmission function which is unique for each channel. The modulated radiation is transmitted to one or several detectors (9, 9', 9") which produce output signals which are further electronically processed. The spectral range of each of the individual channels is common to all of the channels. Within the common range the channels are provided with different spectral transmission functions (7, 7',7") which are optimally chosen for a given application.