Geometrical scaling law for laser-induced micro-projectile impact testing

•Geometrical scaling laws for the LIPIT with relative thick metallic film are obtained and validated for the first time.•Numerical model of LIPIT is built, and the influences of the dimensionless parameters on the dimensionless launch speed of micro-projectiles are analyzed.•Dimensionless formulas for predicting the launch speeds of micro-projectiles of LIPIT are proposed, rendering an effective method for analyzing and optimizing the LIPIT experiments.