Direct laser etching of transparent materials: High quality surface patterning and figuring for micro-optical applications

摘要

The etching of transparent materials with high precision and high quality is still a challenge for laser processing. Laser backside etching allows the processing of transparent materials with pulsed UV-lasers. The laser-etched structures in fused silica are characterized by a high fidelity and a low surface roughness. Different machining techniques were applied for laser etching of binary and three-dimensional microstructures with micron and sub-micron sizes. Applying contour mask technique micro sized cylindrical lens and prism array were fabricated. Using small spot laser written gratings with uniform or variable depth was machined with nanometer depth resolution and the etching of free-form surfaces with a size of 1 mm~2 and a P-V-value of less than 1 micron by means of laser scanning is demonstrated. Additionally, graded multilevel elements and submicron gratings were engraved with nanometer depth accuracy applying mask projection techniques.