Spectral sampling of a soft X-ray tube emission by a lamellar multilayer grating in standard and conical mountings

A Lamellar Multilayer Amplitude Grating (LMAG) etched in a multilayer mirror was designed for an efficient use in the 1 keV region, through a multistep process involving sputtering coating, electron lithography and reactive ion etching. The multilayer structure has 115 W/B4C bilayers of 3.1 nm thickness, and the grating of period 1.33 μm has a small line-to-period ratio Γ equal to about 0.10. The properties of a LMAG illuminated in standard and conical mountings by a polychromatic radiation are given, and the concept of a “polychromator” based on a LMAG is presented. Taking benefit from the specific properties of a LMAG, the emission of a soft X-ray tube equipped with a copper target is spectrally analyzed with our LMAG in the Cu-L (930 eV) region in standard and conical mountings. This experiment shows that a LMAG could be an interesting spectral analyzer for short-duration X-ray sources.