Evaluation of Area Scaling of the Reactive Ion-plasma Etched Astronomical Diffraction Gratings

Over the past three years, we have been developing the Reactive Ion-PLasma Etched (RIPLE) grating technology and have demonstrated it to be a highly predictive process that has resulted in near theoretical super-broadband DE from the prototype 1x1 sq. inch RIPLE grating. All measured DE scans from this prototype closely resembled those from model predictions within 2% at 1σ-level, indicating the highly predictive nature of the process and the presence of a non-significant level of defects in the device. The fabrication process has shown to be repeatable over the same area and grating parameters, and we extended it to larger grating areas with deeply-etched grating line features. We demonstrated the area scaling to 2x2 sq. inch via an iterative etching technique. We are about to reach the primary 4x4 sq. inch target with strong possibility to ramp up to 5x5 sq. inch. We discuss the evaluation of the area scaling effort.