Scattering from high efficiency diffraction gratings

This paper has characterized and measured scatter from high efficiency and reflective diffraction gratings. Three major types of scatter are identified: (1) random, which occurs over 27pi sr; (2) band or ghost scatter, which occurs in the plane of incidence; and (3) structured scatter, which is a symmetrical pattern repeated about each order. Measurements were taken at 10.6 Am on gratings made by ruling, ion etching, holography, or a combination of these techniques. We found that the characteristic scatter from these high efficiency gratings depends strongly on the way the gratings are fabricated.