Study of the Influence of Ion-Beam Etching on the Surface Roughness of Single-Crystal Sapphire

To increase the average and peak power of modern laser systems, a need appears for new materials or the possibility of modifying existing ones to create composites based on them. Such composite materials with the use of optical materials with a high thermal conductivity can serve to remove heat from the active medium. The substrates of X-ray optical elements operating under powerful synchrotron radiation beams should solve the same task. One of the promising materials for these purposes is single-crystal sapphire, since it has a fairly high thermal conductivity (~23–25 W/(m K) at 323 K) and a low temperature coefficient of linear expansion (~10–6 K–1 at Т = 323 K). In this work, the effect of energy and angles of incidence on the sample surface of argon ions on the surface roughness of the a cut of $$\left( {11\bar {2}0} \right)$$ single-crystal sapphire is studied. In the course of the study, the effect of smoothing the surface roughness by 30% relative to the initial value in the spatial frequency range from 0.049 to 63 µm–1 is demonstrated. The possibility of the ion processing of samples is also shown; in particular, at angles of incidence of ions on the sample surface within ±40°, the value of its effective roughness does not change much, which allows local correction of object shape errors without significant changes in the surface quality.