International round-robin experiment for angle-resolved light scattering measurement

International audienc

Design, additive manufacturing, processing, and characterization of metal mirror made of aluminum silicon alloy for space applications

Metal mirrors are used for spaceborne optical systems, such as telescopes and spectrometers. In addition to the optical performance, the mechanical needs and the mass restrictions are important aspects during the design and manufacturing process. Using the additive manufacturing process, optimized internal lightweight structures are realized to reduce the weight of the system while keeping the mechanical stability. A mass reduction of ≈60.5  %   is achieved. Using the aluminum silicon alloy AlSi40, the thermal mismatch of the mirror base body to a necessary electroless nickel-polishing layer is minimized. Based on an exemplary mirror design, the optimization of the interior lightweight structure is described, followed by the manufacturing process from additive manufacturing to diamond turning, plating, and polishing. Finally, the results of surface metrology and light scattering measurements are presented. A final form deviation below 80 nm p  .    −  v  .   and a roughness of ∼1  nm rms could be demonstrated

Light scattering techniques for the characterization of optical components

The rapid developments in optical technologies generate increasingly higher and sometimes completely new demands on the quality of materials, surfaces, components, and systems. Examples for such driving applications are the steadily shrinking feature sizes in semiconductor lithography, nanostructured functional surfaces for consumer optics, and advanced optical systems for astronomy and space applications. The reduction of surface defects as well as the minimization of roughness and other scatter-relevant irregularities are essential factors in all these areas of application. Quality-monitoring for analysing and improving those properties must ensure that even minimal defects and roughness values can be detected reliably. Light scattering methods have a high potential for a non-contact, rapid, efficient, and sensitive determination of roughness, surface structures, and defects

Scatter reduction of calcium fluoride based DUV optics

Angle resolved scatter measurement was performed on uncoated and AR coated CaF2. Subsurface-damage-free CaF2 and AR coatings with smoothed capping led to 4-fold and 2-fold scatter reduction when compared to the corresponding super polished CaF2