Fast Laser Micromachining of Micro-optics in Quartz and BaF2

Micro-lenses in quartz and BaF₂ are fabricated using a one step technique which utilizes Laser Induced Backside Wet Etching and the projection of a Diffractive Gray Tone Phase Mask. The structuring of quartz and BaF₂ is achieved using 308 nm irradiation and laser fluences well below the ablation threshold of these materials. The key element in this process is an organic liquid which is in contact with the quartz or BaF₂ substrate. The strong absorption of the laser light in a thin liquid layer at the substrate interface results in the creation of high temperature and pressure jumps, which are the key elements in the etching process.