Izentis offers gratings that utilize reflection from periodic surfaces, known as a reflection gratings. If the surfaces are flat, reflection gratings are similar to phase transmission gratings. Specifically much of the light is in the zeroth order. The key break-through for reflection gratings is to reflect the light on angled mirrors (often called grating facets) such that the diffraction orders coincide with the specular reflection angle. This effect is knows as blazing and it can significantly increase efficiency since the majority of the light is directed into a small number of non-zero diffraction orders. The angle α has to be designed such that the optical path length difference for two rays, that specularly reflect one period apart, is an integer multiple of the wavelength. Izentis LLC offers custom reflection gratings with facet angles ranging from 0.5 to 30 degrees, with pitches as low as 200 nm. The grating dimensions can be as large as 60 mm on a side. Please contact us for more information and quotes on reflection gratings.