Concentrator of laser energy for thin vapor-cloud production near a surface

A novel scheme is presented for the production of a thin ( < 1 mm) uniform vapor layer over a large surface area ( > 100 cm2) by pulsed laser ablation of a solid surface. Instead of dispersing the laser energy uniformly over the surface, a modified Fabry–Perot interferometer is employed to concentrate the laser energy in very narrow closely spaced concentric rings. This approach may be optimized to minimum total laser energy for the desired vapor density. Furthermore, since the vapor is produced from a small fraction of the total surface area, the local ablation depth is large, which minimizes the fraction of surface contamination in the vapor.