Multilayer monochromators can be used for the monochromatisation of X-rays similar to crystals. Various wave lengths and band widths can be regulated by choosing the multilayer material, the period thickness and the thickness gradient.
Typical photon energies of laboratory X-ray sources:
Cu Ka
8041 eV Mo Ka
17444 eV
Cr Kα
5412 eV
Co Kα
6926 eV
Cu Kα
8040 eV
W Lα
8392 eV
Ga Kα
9241 eV
Mo Kα
17444 eV
Rh Kα
20167 eV
Ag Kα
22103 eV
Typical dimensions:
Multilayer monochromators can be produced in various sizes, from a few square millimeters (e.g. 6 x 4 mm² like shown in the picture) to a length of 500mm (typically synchronotron reflectors) or a diameter of 8" (wafer).
Typical parameters for multilayer monochromators:
Spectral range:
50 eV – 100 keV
Resolution:
0.25 % < ΔE/E < 2 % (periodic multilayers)
ΔE/E > 5% on request (aperiodic multilayers)
Thickness homogeneity:
Δd/d < 0.02%
Material systems optimized on maximum peak reflectivity or desired spectral band width with given wave length or on customer's request.
Applications:
Monochromators for laboratory X-ray sources and synchrotrons
Polarizers in supple X-ray range (e.g. O-K, Fe-L, Ni-L)
Integral reflectivity vs. resolution:
Integral reflectivity vs. resolution for crystals and various multilayer types. High resolution (HR) multilayer connect typical multilayer (resolution ~1-3%) and crystals (<0.1%), depth graded multilayers factor total reflecting optics.