Low-Cost COTS GNSS Interference Monitoring, Detection, and Classification System.

Interference signals cause position errors and outages to global navigation satellite system (GNSS) receivers. However, to solve these problems, the interference source must be detected, classified, its purpose determined, and localized to eliminate it. Several interference monitoring solutions exist, but these are expensive, resulting in fewer nodes that may miss spatially sparse interference signals.

Synchronized beamline at FLASH2 based on high-order harmonic generation for two-color dynamics studies.

We present the design, integration, and operation of the novel vacuum ultraviolet (VUV) beamline installed at the free-electron laser (FEL) FLASH. The VUV source is based on high-order harmonic generation (HHG) in gas and is driven by an optical laser system synchronized with the timing structure of the FEL. Ultrashort pulses in the spectral range from 10 to 40 eV are coupled with the FEL in the beamline FL26, which features a reaction microscope (REMI) permanent endstation for time-resolved studies of ultrafast dynamics in atomic and molecular targets.

RNN-Aided Human Velocity Estimation from a Single IMU.

Pedestrian Dead Reckoning (PDR) uses inertial measurement units (IMUs) and combines velocity and orientation estimates to determine a position. The estimation of the velocity is still challenging, as the integration of noisy acceleration and angular speed signals over a long period of time causes large drifts. Classic approaches to estimate the velocity optimize for specific applications, sensor positions, and types of movement and require extensive parameter tuning.

UWB Channel Impulse Responses for Positioning in Complex Environments: A Detailed Feature Analysis.

Radio signal-based positioning in environments with complex propagation paths is a challenging task for classical positioning methods. For example, in a typical industrial environment, objects such as machines and workpieces cause reflections, diffractions, and absorptions, which are not taken into account by classical lateration methods and may lead to erroneous positions. Only a few data-driven methods developed in recent years can deal with these irregularities in the propagation paths or use them as additional information for positioning.

Sick Moves! Motion Parameters as Indicators of Simulator Sickness.

We explore motion parameters, more specifically gait parameters, as an objective indicator to assess simulator sickness in Virtual Reality (VR). We discuss the potential relationships between simulator sickness, immersion, and presence. We used two different camera pose (position and orientation) estimation methods for the evaluation of motion tasks in a large-scale VR environment: a simple model and an optimized model that allows for a more accurate and natural mapping of human senses.

XUV double-pulses with femtosecond to 650 ps separation from a multilayer-mirror-based split-and-delay unit at FLASH.

Extreme ultraviolet (XUV) and X-ray free-electron lasers enable new scientific opportunities. Their ultra-intense coherent femtosecond pulses give unprecedented access to the structure of undepositable nanoscale objects and to transient states of highly excited matter. In order to probe the ultrafast complex light-induced dynamics on the relevant time scales, the multi-purpose end-station CAMP at the free-electron laser FLASH has been complemented by the novel multilayer-mirror-based split-and-delay unit DESC (DElay Stage for CAMP) for time-resolved experiments.

Structured Mo/Si multilayers for IR-suppression in laser-produced EUV light sources.

Laser produced plasma sources are considered attractive for high-volume extreme-ultraviolet (EUV) lithography because of their high power at the target wavelength 13.5 nm. However, besides the required EUV light, a large amount of infrared (IR) light from the CO drive laser is scattered and reflected from the plasma as well as from the EUV mirrors in the optical system.

An extreme ultraviolet Michelson interferometer for experiments at free-electron lasers.

We present a Michelson interferometer for 13.5 nm soft x-ray radiation. It is characterized in a proof-of-principle experiment using synchrotron radiation, where the temporal coherence is measured to be 13 fs.

Compact x-ray microscope for the water window based on a high brightness laser plasma source.

We present a laser plasma based x-ray microscope for the water window employing a high-average power laser system for plasma generation. At 90 W laser power a brightness of 7.4 x 10(11) photons/(s x sr x μm(2)) was measured for the nitrogen Lyα line emission at 2.

Influence of the substrate finish and thin film roughness on the optical performance of Mo/Si multilayers.

Scattering resulting from interface imperfections critically affects the image contrast and optical throughput of multilayer coatings for 13.5 nm. To investigate the scattering mechanisms, at-wavelength scattering measurements in combination with atomic force microscopy are analyzed for an in-depth characterization of the roughness properties.

Extreme ultraviolet laser excites atomic giant resonance.

Exceptional behavior of light-matter interaction in the extreme ultraviolet is demonstrated. The photoionization of different rare gases was compared at the free-electron laser in Hamburg, FLASH, by applying ion spectroscopy at the wavelength of 13.7 nm and irradiance levels of thousands of terawatts per square centimeter.

Extreme-ultraviolet-induced oxidation of Mo/Si multilayers.

The extreme-ultraviolet (EUV)-induced oxidation of Mo/Si multilayer mirrors was characterized by several methods: EUV reflectivity, x-ray photoelectron spectroscopy, small-angle x-ray reflectometry, atomic force microscopy, and EUV scattering measurements. Based on the results of the different investigation techniques, an oxidation model was developed to explain the degradation of the mirrors under EUV radiation.

Photoelectric effect at ultrahigh intensities.

In the spectral range of the extreme ultraviolet at a wavelength of 13.3 nm, we have studied the photoionization of xenon at ultrahigh intensities. For our ion mass-to-charge spectroscopy experiments, irradiance levels from 10(12) to 10(16) W cm(-2) were achieved at the new free-electron laser in Hamburg FLASH by strong beam focusing with the aid of a spherical multilayer mirror.

EUV reflectance and scattering of Mo/Si multilayers on differently polished substrates.

Highly reflective Molybdenum/Silicon multilayer mirrors for 13.5 nm are characterized at-wavelength using a new laboratory size measurement system for EUV reflectance and scattering. Roughness analysis before and after coating by Atomic Force Microscopy indicates roughness enhancement as well as smoothing effects during thin film growth.

Chromium-scandium multilayer mirrors for the nitrogen K(alpha) line in the water window region.

Chromium-scandium (Cr-Sc) is a promising material combination for multilayer mirrors in the water window region. A possible x-ray source for laboratory use in this wavelength range is the nitrogen K(alpha) line at 3.16 nm.

Biophysical effects of high-energy pulsed ultrasound on human cells.

Human benign and malignant cells of different human origin (pancreas, liver, kidney, pharynx, tongue, lip) were exposed to high-energy pulsed ultrasound (HEPUS) in vitro to evaluate the effects of various physical parameters and sonication conditions on cell viability. This included the number of pulses, focal pressure, pulse repetition rate, pulse shape, cell suspension volume, water level of the basin and cell density. Cell viability was found to depend significantly on the number of pulses (exponential), the focal pressure (linear) and the pulse repetition rate (minimum at 1 Hz).

In vitro effects of high-energy pulsed ultrasound on human squamous cell carcinoma cells.

Human squamous cell carcinoma cells cloned from the hypopharynx (FaDu) and oral cavity (SCC-4) were exposed to high-energy pulsed ultrasound (HEPUS) in vitro to evaluate the effects of various physical parameters on cell viability. Such included the number of pulses, voltage applied, pulse repetition rate and cell density. The experimental piezoelectric ultrasound transducer used in the experiments generated pulses with a high negative pressure amplitude.