RAPID FABRICATION OF DIFFRACTIVE OPTICAL-ELEMENTS BY USE OF IMAGE-BASED EXCIMER-LASER ABLATION

We describe a method of fabricating multilevel diffractive optics by e xcimer laser ablation. A portion of a chrome mask containing many patt erns is illuminated by 193-nm laser light and imaged by an objective l ens onto a poly(imide) substrate. Ablation of an entire single pattern is achieved in a single laser pulse. Multiple pulses are used to vary the ablation depth and multiple patterns are used Co create a variety of multilevel optics. We have successfully fabricated arrays of eight -level diffractive microlenses with varying focal lengths and decenter s. The optics performed with diffraction-limited focusing and near-the oretical diffraction efficiency (92%). (C) 1997 Optical Society of Ame rica.