Fabrication of micro-optical elements in quartz by laser induced backside wet etching

Micro-optical elements in quartz with continuous profiles were fabricated by laser induced backside wet etching, where the quartz plate is in contact with an organic solution, that strongly absorbs UV laser light. The absorption of the laser light by the organic molecules generates a temperature and pressure jump at the quartz-liquid interface, which results in etching of the quartz. This method allows microstructuring of quartz with an XeCl or KrF excimer laser at laser fluences well below the damage threshold of quartz for these wavelengths. The obtained structures in quartz vary from binary structures, as part of random phase plates, to complex three-dimensional structures, e.g., Fresnel lenses. The Fresnel lenses were created by applying diffractive grey tone phase masks fabricated by e-beam lithography. The roughness of the obtained structures varies from 50 to 500 nm, depending on the laser fluence and the applied substrate. (C) 2003 Elsevier Science B.V. All rights reserved.