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We present a stability investigation of the Stockholm laboratory cryo soft x-ray microscope. The microscope operates at a wavelength of 2.48 nm and can image biological samples at liquid-nitrogen temperatures in order to mitigate radiation damage. We measured the stability of the two most critical components, sample holder and optics holder, in vacuo and at cryo temperatures at both short and long time scales with a fiber interferometer. Results revealed vibrations in the kHz range, originating mainly from a turbo pump, as well as long term drifts in connection with temperature fluctuations. With improvements in the microscope, earlier stability issues vanished and close-to diffraction-limited imaging could be achieved. Moreover, our investigation shows that fiber interferometers are a powerful tool in order to investigate position-sensitive setups at the nanometer level.

In this paper the latest efforts to improve our nanofabrication process for soft x‐ray zone plates is presented. The resolving power, which is proportional to the smallest outermost zone width of the zone plate, is increased by introducing cold development of the electron beam resist that is used for the patterning. With this process we have fabricated Ni zone plates with 13‐nm outermost zone and shown potential for making 11‐nm half‐pitch lines in the electron beam resist. Maintaining the diffraction efficiency of the zone plate is a great concern when the outermost zone width is decreased. To resolve this problem we have developed the so‐called Ni‐Ge zone plate in which the zone plate is build up by Ni and Ge, resulting in an increase of the diffraction efficiency. In a proof‐of‐principle experiment with 25‐nm Ni‐Ge zone plates, we have shown a doubling of the diffraction efficiency. When combined with cold development, the Ni‐Ge process has been shown to work down to 16‐nm half‐pitch. It is plausible that further refinement of the process will make it possible to go to 10‐nm outermost zone widths.

We demonstrate high-brightness operation of an electron-impact water-jet-anode soft x-ray source with an increased power loading of 15 times compared to our previously published results, with a cor ...

X‐ray wavefront propagation is a powerful technique when simulating the performance of x‐ray optical components. Using various numerical methods, interesting parameters such as focusing capability and efficiency can be investigated. Here we present the toolbox DiffractX, implemented in MATLAB. It contains many different wave propagation methods for the simulation of diffractive x‐ray optics, including Fresnel propagation, the finite difference method (FDM), the thin object approximation, the rigorous coupled wave theory (RCWT), and the finite element method (FEM). All tools are accessed through a graphical interface, making the design of simulations fast and intuitive, even for users with little or no programming experience. The tools have been utilized to characterize realistic as well as idealized optical components. This will aid further developments of diffractive x‐ray optics.

We describe an experimental and semi-quantitative theoretical investigation of the characteristics of two-photon-induced stimulated emission related to diagnostic applications. The laser power dependence, pressure dependence, and the spectral shape of the stimulated emission signal in CO are discussed and compared with those for laser-induced fluorescence. We also discuss decreases in the laser-induced fluorescence signal caused by the stimulated emission process, and propose a method for providing increased spatial resolution in measurements made using stimulated emission detection.

Soft X-ray microscopy is a powerful tool for investigations of, for example, polymers or soils in their natural liquid environment. This requires a wet-specimen chamber. Compact X-ray microscopy allows the horizontal mounting of such samples, thereby reducing the influence of gravitational forces. We have developed a wet-specimen chamber for such compact X-ray microscope. The chamber is vacuum compatible, which reduces the exposure time. The vacuum sealing is achieved by a combination of mechanical sealing and sealing by bio-compatible glue. With the wet-specimen chamber the specimens can be kept in an aqueous environment in a vacuum of 10(-4) mbar for several hours. Imaging of lipid droplets in water demonstrates the function of the wet-specimen chamber.

The 2-D intensity distributions of focused beams are determined by tomographic reconstruction of multiangular knife edge measurements. The µm-sized intensity distribution in the focal plane of the Stanford Table-Top Scanning Soft X-Ray Microscope is measured optically (633 nm) and with x-rays (13.5 nm). An iterative tomographic reconstruction algorithm is discussed.

We have previously demonstrated a liquid-metal-jet anode x-ray source concept with potential for a 100-1000× increase in brightness [1]. In the present paper we report on recent progress and demonstrate long-term operation of a high-brightness microfocus source based on this concept. The tube uses a Ga/In/Sn alloy with strong line emission at 9.25 keV (comparable to conventional copper anode sources) as well as significant continuum radiation up 100 keV, depending on settings. The spot size is 5-20 μm with an electron-beam power up to 200 W and a power density of ~10 W/μm. This is >10× more than current state-of-the-art microfocus tubes. This second generation prototype incorporates a continuous recycling system for uninterrupted operation as well as reduced footprint and enhanced reliability. This source shows promise to enable many laboratory-scale x-ray applications, today limited by source brightness. Also, for novel imaging modalities, like phase-contrast imaging [2], source brightness is crucial. Furthermore the system will enable faster and/or more accurate XRF and XRD analysis due to the increased source brightness. The system is now mature enough for scientific and industrial applications and long-term performance data will be presented.

The demand for sources of coherent blue light with milliwatt output powers has stimulated much research activity in guided-wave devices for second-harmonic generation (SHG). To address the inability of otherwise-suitable materials to phase-match birefringently, quasi-phase-matching (QPM) has been used for SHG of visible radiation in LiNbO3,1,2 polymer,3 and KTP4 waveguides. This paper reports blue light generated by quasi-phase-matched SHG in a periodically poled LiTaO3 waveguide.