A method for locating at least one optical marker in a diffusing medium, the marker having at least one optical property different from the diffusing medium, wherein: a) a pulsed radiation interacts with the medium and the at least one optical marker, producing an optical signal, and at least one acquisition of data of the optical signal is performed, each acquisition including one or more time components of interest, due to the at least one marker, and a spurious component, due to the medium other than the at least one marker, b) a multidimensional array X is formed from the optical signal data of the at least one of the acquisitions, c) the array X is processed by factorization into a product of only two non-negative multidimensional arrays A and S, and d) at least one of the time components is extracted from the arrays A and S.
