We report on a new experimental technique for controlling lamellar (nonfaceted) eutectic microstructures and testing their stability in thin-sample directional solidification (TDS) of a model transparent alloy (CBr4–C2Cl6). We observe the solidification front in real time by optical microscopy. We use micromanipulation with a holographic laser spot array for perturbing the solidification front on a scale ranging from one to ten times the average lamellar spacing value (typically 10–100µm). These perturbations arise from local heating due to the absorption of the laser light by the liquid slightly ahead of the front. We show that the laser spot perturbation technique can be efficiently used as a tool for mapping out the large range of accessible lamellar spacings and for creation of desired patterns such as smooth spacing gradients or tilt domains.