Producing Optics

Fabricating multilayers

Incoatec produces X-ray optics using sputtering technologies. For this purpose an Argon plasma is ignited in a vacuum chamber. The charged Ar particles are then accelerated onto a target where they chip off target atoms. These target atoms then condense on the optical substrate forming a thin film. Multilayered films can be synthesized using two sputtering targets. Moving the substrate appropriately makes it possible to produce ultra precise thickness gradients as required for different optics. Deviations from specifications are lower than 1 %. The typical thickness of each single layer in a multilayer coating ranges from 1 - 10 nm. We are able to coat mirrors up to a maximum size of 6 inches in diameter or 150 cm in length.

Multilayer growth

The growth of our thin films is examined in selected cases using transmission electron microscopy (TEM), which is important when developing new multilayers, as insight is gained into the growth properties of the selected material combination. Extremely sharp and smooth interface boundaries are necessary in X-ray optical multilayers to achieve near-to-perfect performance. The long-term stability of the mirrors can be examined using annealing tests combined with TEM analyses. The TEM image (courtesy by Prof. W. Jäger, University Kiel) shows a La-B4C multilayer with amorphous layers where a single layer is 5 nm thick. The smooth interfaces demonstrate an optimal growth.

TEM micrograph of a La-B4C multilayer (courtesy by Prof. Jäger, Uni Kiel)

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