The invention relates to the characterization of samples which are located in their many hundreds up to tens or hundreds of thousands on a sample support plate in a regular pattern, a so-called array, by ionization with matrix-assisted laser desorption and mass spectrometric measurement, for example. The invention proposes that the position of the sample pattern, and thus the position of each sample in the measuring instrument, for example a mass spectrometer, should be determined by measuring at least two finely structured internal position recognition patterns, such as fine crosses. The position recognition patterns are preferably applied as the samples are generated, with the same apparatus which also generates the sample pattern. A mass spectrometer in which laser spots with diameters of only four to five micrometers can be generated, which can preferably be positioned with an accuracy of one micrometer or better, is particularly suitable for the characterization.