Binary gratings for CO2 laser-beam diagnostics

Propel-ties of binary gratings for beam diagnostics of high-power CO2 lasers are investigated. The layout uses a modal theory that includes absorption oi metallic surfaces by impedance boundary condition. Radiation-resistant gratings were fabricated in copper with photolithography combined with galvanic technology. In this Pray gratings have been realized in which the first-order diffraction efficiencies are polarization independent. Use of a second grating to reduce elliptical beam distortion is demonstrated. Finally it is shown that Rayleigh anomalies for binary diagnostic gratings are accompanied by high absorption. (C) 1996 Optical Society of America