Synthesis of fluid inclusions is made by the pre-formation of cavities with a diameter greater than 10 μm by laser ablation using a Nd-YAG pulsed laser focused through a Cassegrain objective. Ablation cavities inside the crystals are connected to the surface by microcracks, which serve as the fluid channels. In fluorite crystals, the microcracks heal at 200°C during four-week experiments and produce large inclusions corresponding to the ablation cavities and smaller ones in the microcracks. In quartz crystals, cavity sealing occurs by quartz overgrowths on faces perpendicular to the c axis at 300°C during four weeks. No cavity sealing occurs at 200°C in quartz. Micro-thermometric data demonstrate that fluid inclusions have trapped representative samples of the experimental fluids. Raman and infrared spectra indicate that fluid inclusions synthesised by our laser technique may be suitable for spectroscopic analysis.