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An alternate multilayer (AML) grating is a 2 dimensional diffraction structure formed on an optical surface, having a 0.5 duty cycle in the in-plane and in the in-depth direction. It can be made by covering a shallow depth laminar grating with a multilayer stack. We show here that their 2D structure confer AML gratings a high angular and energetic selectivity and therefore enhanced diffraction properties, when used in grazing incidence. In the tender X-ray range (500eV – 5000 eV) they behave much like blazed gratings. Over 15% efficiency has been measured on a 1200 lines/mm Mo/Si AML grating in the 1.2 – 1.5 keV energy range. Computer simulations show that selected multilayer materials such as Cr/C should allow diffraction efficiency over 50% at photon energies over 3 keV. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

A Variable Groove Depth (VGD) grating is a laminar grating where the depth of the groove profile changes continuously along the grating lines. When illuminated by a narrow beam a few mm wide, they allow to adapt the depth of the groove profile the wavelength in use by simply translating the grating perpendicular to the dispersion plane. We show theoretically and experimentally that by varying the groove depth, either flux or harmonic contamination can be optimized. Low second harmonic contamination in the order of 5% at any energy should be obtained on SOLEIL monochromators equipped with VGD gratings. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]