Patterning of optical coatings by laser ablation for the fabrication of dielectric masks and diffractive phase elements

摘要

Excimer laser ablation is a versatile method to generate 2- or 3-D microstructured devices for mechanics, fluidics, and optics. Particularly, if in 1-D the structure is predefined by a layer design, and the other two dimensions are/defined in the layer ablation process by mask projection, very precise/structure definition in three dimensions and ablated surfaces with optical quality can be achieved. By patterning optical layers or layer stacks, a variety of applications is possible. Two examples are demonstrated. 1. Dielectric masks (amplitude masks) are fabricated by structuring a highly reflective dielectric layer stack.These masks can be used in high power laser machining systems. 2. Diffractive optical elements (phase elements) are generated by structured ablation of a transparent layer. The performance of these elements in shaping excimer laser beams is demonstrated.