High-efficiency flat-top beam shaper fabricated by a nonlithographic technique

We report a compact flat-top beam shaper fabricated by laser-assisted chemi cal etching upon an ion-exchanged high-energy-beam-sensitive glass. The bea m shaper combines a phase filter element and a focusing lens element into a single diffractive optical element with a quasi-continuous surface relief profile. The fabrication takes advantage of the laser generation of gray-le vel patterns and one-step etching that are effective especially for such be am shaper fabrication. The demonstrated beam shaper with good flatness and edge features has an energy efficiency of 82%. (C) 1999 Society of Photo-Op tical Instrumentation Engineers. [S0091-3286(99)02202-3].