Fabrication of beam homogenizers in quartz by laser micromachining

The combination of gray tone phase masks with a laser-based wet etching process can be applied as a one step micromachining process. This technique utilizes a XeCl excimer laser and an absorbing liquid which is in contact with quartz. Microstructures with continuous profiles, such as plano-convex microlenses in quartz, can be created with laser fluence well below the damage threshold of quartz.

The roughness of the etched features varies from several micrometers to below 10nm, depending on the laser fluence and applied absorbing solution. The etch rates of quartz using different organic solutions such as pyrene in acetone or pyrene in tetrahydrofurane reveal a complex behavior, suggesting that several processes dominate at various laser fluences.