Polar coordinate laser pattern generator for fabrication of diffractive optical elements with arbitrary structure

A precision laser pattern generator for writing arbitrary diffractive elements was developed as an alternative to Cartesian coordinate laser/electron-beam writers. This system allows for the fabrication of concentric continuous-relief and arbitrary binary patterns with minimum feature sizes of less than 0.6 mu m and position accuracy of 0.1 mu m over 300-mm substrates. Two resistless technologies of writing on chromium and on amorphous silicon films were developed and implemented. We investigated limit characteristics by writing special test structures. A 58-mm f/l.l zone plate written directly is demonstrated at a lambda/50 rms wave-front error corresponding to a 0.06-mu m pattern accuracy. Several examples of fabricated diffractive elements are presented. (C) 1999 Optical Society of America. OCIS codes: 050.1380, 090.1760, 050.1970, 220.3740, 230.4000.