[en] A microscopic calculation of composits particle optical potential has been done using a realistic nucleon-helion interaction and folding it with the density distribution of the targets. The second order effects were simulated by introducing a scaling factor which was searched on to reproduce the experimental scattering results. Composite particle optical potential was also derived from the nucleon-nucleus optical potential. The second order term was explicitly treated as a parameter. Elastic scattering of 20 MeV ³H on targets ranging from ⁴⁰Ca to ²⁰⁸Pb to ²⁰⁸Pb have also been analysed using phenomenological optical model. Agreement of these results with the above calculations verified the consistency of the microscopic theory. But the equivalent sharp radius calculated with n-helion interaction was observed to be smaller than phenomenological value. This was attributed to the absence of saturation effects in the density-independent interaction used. Saturation has been introduced by a density dependent term of the form (1-c zetasup(2/3)), where zeta is the compound density of the target helion system. (author)