RESUMO
We describe a method of fabricating multilevel diffractive optics by excimer laser ablation. A portion of a chrome mask containing many patterns is illuminated by 193-nm laser light and imaged by an objective lens 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 to create a variety of multilevel optics. We have successfully fabricated arrays of eight-level diffractive microlenses with varying focal lengths and decenters. The optics performed with diffraction-limited focusing and near-theoretical diffraction efficiency (92%).
RESUMO
We report the use of an integrated-optics wave-front measurement sensor to measure with 200-nsec temporal resolution the phase and intensity at the aperture of a high-power (3.5-MW peak power) flash-lamp-pumped pulsed dye laser. The measurements reveal large fluctuations of the dye-laser wave front during the 2-microsec duration of the laser pulse. The fluctuations and the resulting poor beam quality are attributed to inhomogeneous heating of the dye during the pulse. These high-temporal-resolution measurements, which are not possible with other state-of-the-art wave-front analyzers, explain the previously measured poor beam quality of the laser.
