The control of the structural properties of polysilicon obtained by excimer laser crystallization has become of great importance to further develop the polysilicon thin-film transistors technology. In this work we have investigated a new approach to achieve a control of the lateral growth mechanism through opportune spatial modulation of the light intensity. Two different techniques, based on patterned reflective metal layers, have been used: 1) direct deposition of Cr or Al/Cr metal layers on top of the amorphous silicon film; 2) irradiation through a patterned mask in contact with the sample.