[en] The correlation measurements between light particles emitted during heavy ion collisions allow to estimate the time-space extension of the emitting sources. This report about the preliminaries of two correlation experiments is split into two parts. The first one describes a test experiment, performed to study the feasibility of a correlation experiment at very low relative momenta with the help of a magnetic spectrometer. The results will allow to determine the still unknown relative effects from the final state interaction and the combination of both Coulomb interaction and quantum statistics. A correlation study without experimental selection of the impact parameter gives unclear answers about the sizes and the temporal characteristics of the emitting systems. The second part analyses the sources of the alpha particles detected in the reaction chamber of the multidetector ORION used as a violence of the reaction filter. The results show that it is possible to consider as a good filter a fast information called 'prompt peak' (correlated to the neutron multiplicity detected with ORION). Under such conditions a study of two particle correlations from equilibrated systems with a reasonable statistics becomes thinkable. The results obtained allow to characterize the emitting sources (speed, intensity, temperature) as a function of the violence of the reaction for the system ²⁰⁸ Pb + ⁹³ Nb at 29 MeV/u. (author)