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With the development of nanometer accuracy stitching interferometry, ion beam figuring (IBF) of x-ray mirrors can now be achieved with unprecedented performance. However, the process of producing x-ray diffraction gratings on these surfaces may degrade the figure quality due to process errors introduced during the ruling of the grating grooves. To address this challenge, we have investigated the post-production correction of gratings using IBF, where stitching interferometry is used to provide in-process feedback. A concern with ion beam correction in this case is that ions will induce enough surface mobility of atoms to cause smoothing of the grating structure and degradation of diffraction efficiency. In this study we found however that it is possible to achieve a nanometer-level planarity of the global grating surface with IBF, while preserving the grating structure. The preservation was so good, that we could not detect a change in the diffraction efficiency after ion beam correction. This is of major importance in achieving ultra-high spectral resolution, and the preservation of brightness for coherent x-ray beams.

We have developed a new method for the determination of photoabsorption at extreme ultraviolet wavelengths longer than 20 nm, where reliable refractive index values are sparse or non-existent. Our method overcomes the obstacle of multiple reflections that occur inside thin films in this spectral range, which up until now has prevented the accurate determination of photoabsorption from transmittance measurements. We have derived a mathematical expression that is independent of internal reflection amplitudes, while taking advantage of the transmittance oscillations stemming from such reflections. The method is validated on measurements of aluminum thin films. This advance will enable accurate refractive index values for many important materials for optical instrumentation, thus facilitating high-priority research on topics including coherent light sources, planetary and solar physics, and semiconductor manufacturing.

The influence of B 4 C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics is investigated. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization near Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.

We extend coherent diffraction imaging (CDI) to a high numerical aperture reflection mode geometry for the first time. We derive a coordinate transform that allows us to rewrite the recorded far-field scatter pattern from a tilted object as a uniformly spaced Fourier transform. Using this approach, FFTs in standard iterative phase retrieval algorithms can be used to significantly speed up the image reconstruction times. Moreover, we avoid the isolated sample requirement by imaging a pinhole onto the specimen, in a technique termed apertured illumination CDI. By combining the new coordinate transformation with apertured illumination CDI, we demonstrate rapid high numerical aperture imaging of samples illuminated by visible laser light. Finally, we demonstrate future promise for this technique by using high harmonic beams for high numerical aperture reflection mode imaging.

Ultra-high spectral resolution in the EUV and soft x-ray energy ranges requires the use of very high line density gratings with optimal design resulting in use of a Blazed Multilayer Grating (BMG) structure. Here we demonstrate the production of near-atomically perfect Si blazed substrates with an ultra-high groove density (10,000 l/mm) together with the measured and theoretical performance of an Al/Zr multilayer coating on the grating. A 1st order absolute efficiency of 13% and 24.6% was achieved at incidence angles of 11° and 36° respectively. Cross-sectional TEM shows the effect of smoothing caused by the surface mobility of deposited atoms and we correlate this effect with a reduction in peak diffraction efficiency. This work shows the high performance that can be achieved with BMGs based on small-period anisotropic etched Si substrates, but also the constraints imposed by the surface mobility of deposited species.

We investigated the damage mechanism of MoN/SiN multilayer XUV optics under two extreme conditions: thermal annealing and irradiation with single shot intense XUV pulses from the free-electron laser facility in Hamburg - FLASH. The damage was studied "post-mortem" by means of X-ray diffraction, interference-polarizing optical microscopy, atomic force microscopy, and scanning transmission electron microscopy. Although the timescale of the damage processes and the damage threshold temperatures were different (in the case of annealing it was the dissociation temperature of Mo2N and in the case of XUV irradiation it was the melting temperature of MoN) the main damage mechanism is very similar: molecular dissociation and the formation of N2, leading to bubbles inside the multilayer structure.

Magnesium/silicon carbide (Mg/SiC) multilayers have been fabricated with normal incidence reflectivity in the vicinity of 40% to 50% for wavelengths in the 25 to 50 nm wavelength range. However many applications, for example solar telescopes and ultrafast studies using high harmonic generation sources, desire larger bandwidths than provided by high reflectivity Mg/SiC multilayers. We investigate introducing a third material, Scandium, to create a tri-material Mg/Sc/SiC multilayer allowing an increase the bandwidth while maintaining high reflectivity.