Double Multilayer

For some experiments the high resolution of perfect crystals is not required and higher flux is preferred to reduce exposure times and speed data collection. Double multilayer monochromators (DMM) use a matched pair of multilayer optics to select a relatively wide energy bandpass beam from a white beam source.

The ability to select different material combinations and lay down different thicknesses allows a large span of energy ranges from 2-100keV, with energy resolutions from 0.2-3%, whilst maintaining reflectivities of >75%.

Combination monochromators (DCM/DMM) can be used in a single beamline to provide the capability of rapidly switching between high resolution and high flux modes.

Example of multilayer optic with 2 stripes

Substrate materialSilicon
Active Optical Area300mm x 75mm
Slope Error< 1.5 µrad rms
Surface Roughness< 1Å rms
Energy Range2-8 keV8-20 keV
D spacing45 Å28 Å
Number of periods> 100> 150
Peak Reflectivity> 85% at 5 keV
> 75% at 12 keV
>90% at 8 keV
>90% at 20 keV