Abstract

The output energy distribution of an excimer laser is typically asymmetric characterized by a nearly Gaussian distribution along the short axis and a flat-top distribution with Gaussian wings along the long axis. Many applications of UV lasers, however, call for a more homogeneous energy distribution with steep and well-defined edges. Diffractive optics provides powerful means for beam shaping. Simple, low-loss optical systems are possible, since multiple functions can be performed with a single element. Periodic elements, especially, are attractive, because they are not sensitive to lateral beam alignment or to variations in the incident beam shape. Their applicability to coherent beams, however, is limited due to the resulting rapidly-fluctuating, speckle-like intensity distribution. Here we demonstrate a periodic diffractive flat-top generator for an excimer laser. We make use of the partial coherence of the multi-spatial-mode laser source to smooth the output signal.¹

© 2000 IEEE