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Characterization of a lobster-eye type X-ray telescope
No full textLobster-eye type X-ray telescopes use reflecting plano mirrors under grazing incidence and can observe a large field of view. As part of a Bavarian-Czech cooperation, two telescopes were build, equipped with mirrors coated with gold and iridium. Their X-ray characterization was carried out at the PANTER test facility, which simulates parallel starlight incident on the telescopes. The telescopes have an angular resolution of about 4 arc minutes in X-rays and a focal length of about 2 meters. The used X-ray mirrors reflect and focus visible light as well; their functionality in the optical regime was checked in laboratory tests. Now another test campaign will be carried out to examine the telescope resolution for real objects of the visible night sky and the imaging properties for star constellations
Image Processing Algorithm for In Situ Monitoring Fiber Laser Remote Cutting by a High-Speed Camera
No full textWe present an in situ process monitoring approach for remote fiber laser cutting, which is based on evaluating images from a high-speed camera. A specifically designed image processing algorithm allows the distinction between complete and incomplete cuts by analyzing spectral and geometric information of the melt pool from the captured images of the high-speed camera. The camera-based monitoring system itself is fit to a conventional laser deflection unit for use with high-power fiber lasers, with the optical detection path being coaxially aligned to the incident laser. Without external illumination, the radiation of the melt from the process zone is recorded in the visible spectral range from the top view and spatially and temporally resolved. The melt pool size and emitted sparks are evaluated in dependence of machining parameters such as feed rate, cycles, and focus position during cutting electrical sheets
High speed melt flow monitoring and development of an image processing algorithm for laser fusion cutting
No full textThis contribution presents high-speed camera monitoring of melt pool dynamics for steel during laser fusion cutting and compares the images with recordings in aluminum. The experiments are performed by a 4 kW multimode fiber laser with an emission wavelength of 1070 nm. To visualize the thermal radiation from the process zone during the cutting process, the kerf is captured at sample rates of up to 170 000 frames per second without external illumination with a spectral response between 400 and 700 nm, allowing measurements of the melt flow dynamics from geometric image features. The dependencies of the melt flow dynamics on laser processing parameters, such as feed rate, gas pressure, and laser power, can be evaluated. The monitoring system is placed both off-axis and mounted to a conventional cutting head, with the monitoring path aligned to the processing laser for a coaxial and lateral view of the cut kerf. The measured signal characteristics of the images captured from the melt pool are examined in the visible spectral range of the emitted thermal radiation from the process zone. Moreover, a specifically developed image processing algorithm is developed that process and analyze the captured images and extract geometric information for a measurement of the melt flow
Effective areas of astronomical X-ray optics for cubesats and rocket experiments
No full textWe address the problem of estimation the sensitivity of astronomical X-ray telescopes of Lobster Eye type , with emphasis on calculation of effective areas for telescopes designed for rocket and CubeSat flights. This parameter is one of the principal parameters when justifying the real space application. Indeed, the larger the effective area is, the more efficient the optical system is, able to provide images of fainter and more distant celestial targets. We discuss the estimation of the effective collecting area of a X-ray telescope by two different methods and then compare the results: the analytical method and then the simulation algorithm.Poste
Sapphire Photonic Crystal Waveguides with Integrated Bragg Grating Structure
No full textAbstract: This contribution demonstrates photonic crystal waveguides generated within bulk planar sapphire substrates. A femtosecond laser is used to modify the refractive index in a hexagonal pattern around the pristine waveguide core. Near-field measurements reveal single-mode behavior at a wavelength of 1550 nm and the possibility to adapt the mode-field diameter. Based on farfield examinations, the effective refractive index contrast between the pristine waveguide core and depressed cladding is estimated to 3x10-4. Additionally, Bragg gratings are generated within the waveguide core. Due to the inherent birefringence of Al2O3, the gratings exhibit two distinct wavelengths of main reflection. Each reflection peak exhibits a narrow spectral full width at a half maximum of 130 pm and can be selectively addressed by exciting the birefringent waveguide with appropriately polarized light. Furthermore, a waveguide attenuation of 1 dB cm-1 is determined
Fabrication process for FEP piezoelectrets based on photolithographically structured thermoforming templates
No full textPiezoelectrets fabricated from fluoroethylenepropylene (FEP)-foils have shown drastic increase of their piezoelectric
properties during the last decade. This led to the development of FEP-based energy harvesters, which are about to evolve
into a technology with a power-generation-capacity of milliwatt per square-centimeter at their resonance frequency. Recent
studies focus on piezoelectrets with solely negative charges, as they have a better charge stability and a better suitability for
implementation in rising technologies, like the internet of things (IOT) or portable electronics. With these developments
heading towards applications of piezoelectrets in the near future, there is an urgent need to also address the fabrication
process in terms of scalability, reproducibility and miniaturization. In this study, we firstly present a comprehensive review
of the literature for a deep insight into the research that has been done in the field of FEP-based piezoelectrets. For the first
time, we propose the employment of microsystem-technology and present a process for the fabrication of thermoformed
FEP piezoelectrets based on thermoforming SU-8 templates. Following this process, unipolar piezoelectrets were fabri� cated with air void dimensions in the range of 300–1000 lm in width and approx. 90 lm in height. For samples with a void
size of 1000 lm, a d33-coefficient up to 26,508 pC/N has been achieved, depending on the applied seismic mass. Finally,
the properties as energy harvester were characterized. At the best, an electrical power output of 0.51 mW was achieved for
an acceleration of 1 � g with a seismic mass of 101 g. Such piezoelectrets with highly defined dimensions show good
energy output in relation to volume, with high potential for widespread applications
Die Modernisierung des chinesischen Normungssystems
No full textDas chinesische Normungssystem unterliegt seit Gründung der Volksrepublik 1949 einem kontinuierlichen Wandel. Mit der wirtschaftlichen Öffnung und wachsender Bedeutung am internationalen Handel wurde jedoch eine umfangreichere Modernisierung des chinesischen Normungssystems unausweichlich. Nachdem erste Versuche der Erneuerung des Normungssystems im Hauruckverfahren wenig Erfolg zeigten, geht China seit 2015 nun im Rahmen seiner Reformpläne für das Normungssystem einem
ganzheitlicheren Ansatz nach. Einem Ansatz, der den Anforderungen und Ansprüchen
einer führenden Wirtschaftsmacht in einem globalen Markt entspricht. Im Vergleich zu anderen führenden Normungsmächten wie Europa oder die USA gilt China als Nachzügler in der internationalen Normung. Das bietet jedoch den Vorteil, dass China aus den Erfahrungen anderer Nationen lernen und selbst ein Normungssystem etablieren kann, welches die besten Aspekte anderer Systeme aufgreift und gleichzeitig Chinas wirtschaftlichem Führungsanspruch gerecht wird
Identification of Motivated and Creative Highly Gifted People: Development of the CMAC-Test
No full textThe following contribution deals with the environmental conditions of highly gifted and
sensitive people (HGSP). Three researchers from different perspectives (physics, pedagogy,
and innovation management) empathize with the target group and try to understand their
experiences. From three interviews with adults, a first point of view is defined adopting the
Grounded Theory methodology. Adult interviews are compared with the perceptions of an
adolescent from today moving between state and private education systems. By comparing
both perspectives, differences and similarities are worked out. The discussions are used to
develop an online test focusing on creativity, motivation for achievement, and cognitive
capacities, as these are core categories identified that seem to be highly important in
combination. The empirical test is intended to provide the state education system with a simple
and interactive solution to identify a large group of people who need further support. To
achieve a high participation rate, the test will be designed for a maximum of one hour and the
implementation and evaluation will be carried out digitally. The authors' vision is to create an
adaptive environment that can effectively adjust to and educate diverse groups of learners
without over- or under burdening teachers and learners. A key finding of our case-based
research is that the existing school and higher education structures are not able to provide
sufficient support and challenge for HGSP. Support measures for HGSP are needed as well
as a new understanding of learning and teaching, so that new competencies can be built that
consider people's self-regulation, creativity, and motivation for achievement, in addition to
cognition and meta-cognition. Kuhl (2004, 18) explains why the capacities of self-regulation
are paramount for highly gifted students. When they want to meet a challenge, they face
problems that are more difficult and therefore need more persistence, resilience, and self� motivation. However, to support these special needs, teachers are often not ready or capable
to do so, nor do these needs fit with the performance requirements of the regular curriculum