The Laser Interferometer Space Antenna (LISA) observatory is a future L3 mission of the European Space Agency to detect gravitational waves, set to launch in 2035. The detector constellation will conduct interferometry to extreme precision over an unprecedented armlength of 2.5 million kms. In this paper, we present the development and testing results for the Zerodur interferometer (ZIFO), an optical demonstrator built to validate critical technology for the test setup of LISA's interferometric core. Optical pathlength stability measurements on the ZIFO demonstrate successful reduction of bench noise to maintain the 10 pm Hz-1 specification across the 1 mHz to 1 Hz frequency band. We also identify and characterize dominant noise sources from phasemeters and correlations of beam tilt into the pathlength that are observed during the test campaign.

This paper describes a setup aimed at measuring the so-called Tilt-To-Length (TTL) coupling in the optical benches of the LISA mission. The TTL is the coupling of the angular jitter of any optical setup into the optical path length between its input and output pupils. This might be deleterious in laser ranging experiments and must be evaluated for further compensation. The setup is made of two laser beams, one features an angular jitter that mimics the input beam as seen from the jittering bench under test (BUT), the other is aligned to the optical axis of the BUT and provides a phase reference for the jittering beam. The induced phase variations between both beams detected at the BUT's output pupil gives access to the TTL coupling. The "TTL probe" must feature a negligible residual TTL coupling which implies a micrometric accuracy in the centering of the setup pupil, the beams and the angular jitter associated pivot point. The setup integrates optical masks as a link between the setup optical reference frame to its mechanical reference frame, together with position memories and servo-loops for the beam's alignment. We show that the stability, the accuracy, and the noise floor of the setup is compliant with the LISA specifications for the TTL mitigation, although it makes use of off-the-shelf components and is operated in a standard environment laboratory.

TwinFocus (R) CPV system is a concentrator photovoltaic system developed in northern Italy by a spin-off between the University of Padova and a cluster of private companies. After 8 years of research and several adaptations a prototype installation was installed in Sicily, to test stability and performances. Here the obtained data are reported after the first year of operation. To positive aspects as good efficiency and production quality, some remained technical problems and degradation over time remains.

This article shows the first on-field data of a new CPV system, realized by a cluster of Italian companies and Padua University, in the framework of "Progetto Fotovoltaico a Concentrazione (CPV)" funded by Centro Ricerche "E. Fermi". TwinFocus (R) photovoltaic modules have been developed during the last 8 years, undergoing several modifications, and finally reached their final appearance. The first installation is now active in Sicily and mounts 24 modules, for a 3.5kWP production. Here we will describe the structure of the systems as well as performances, outlying its achievement in the first months of its life.

Concentrator photovoltaics (CPV) is a technology that offers an alternative to standard silicon modules, being more efficient and eco-friendlier. AtemEnergia is developing a CPV product with good characteristics of efficiency and reliability. To monitor the progresses of our prototypes, test their quality and discover potential defects in the devices and in the production lane, custom experimental setups were necessary, to investigate the peculiar characteristics of this technology, avoiding the huge costs of commercial instrumentation in this field. Here is an overview of the tests necessary to guarantee the correct production quality, along with the custom solutions we adopted for their implementation.

TwinFocus® is a CPV solution that adopts quasi-parabolic, off axis mirrors, to obtain a concentration of 760× on 3J solar cells (Azur space technology) with 44% efficiency. The adoption of this optical solution allows for a cheap, lightweight and space efficient system. In particular, the addition of a secondary optics to the mirror, grants an efficient use of space, with very low thicknesses and a compact modular design. Materials are recyclable and allow for reduction of weights to a minimum level. The product is realized through the cooperation of leading edge industries active in automotive lighting and plastic materials molding. The produced prototypes provide up to 27.6% efficiency according to tests operated on the field with non-optimal spectral conditions.

In this work we investigate the damage induced on a graphene–nickel interface after the exposure to Nd:YAG infrared laser radiation. The damage threshold has been experimentally determined. We observe that once the fluence exceeds the threshold value, both the morphology and the physical–chemical properties of the samples change. This has been verified by scanning probe microscopes measurements and near edge x-ray absorption fine structure spectroscopy analysis.

The optical constants of titanium dioxide (TiO2) have been experimentally determined at energies in the extreme ultraviolet and soft x-ray spectral regions, from 25.5 to 612 eV. Measuring angle-dependent reflectance of amorphous TiO2 thin films with synchrotron radiation at the BEAR beamline of Synchrotron ELETTRA. The experimental reflectivity profiles were fitted to the Fresnel equations using a genetic algorithm applied to a least-square curve fitting method, obtaining values for delta and beta. We compared our measurements with tabulated data. All samples were grown on Si (100) substrates by the electron-beam evaporation technique, with a substrate temperature of 150 degrees C and deposition rates of 0.3 to 0.5 angstrom/s. Complete films characterization have been carried out with structural (XRD, ellipsometry, and profilometry), compositional (x-ray photoelectron spectroscopy), and morphological (atomic force microscopy) analyses. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

Here, we show research innovation in radiation-matter interaction, with possible photonics and optoelectronics applications in building and maintenance of graphene-based devices, as well as a further confirmation for soft x-ray irradiation as a clean route towards graphene photoreduction. Thus, we have investigated the soft x-rays exposure effects on graphene/nickel samples damaged by nanosecond 1064nm Nd:YAG laser under laser fluence above the damage threshold. In this regard, NEXAFS analyses reveal the typical GO features in the C K edge spectra of the irradiated specimens. Moreover, the continuous exposures to soft x-rays radiation show the photo-reduction process monitored by NEXAFS in real time. Ten-hour soft x-ray exposure moves the spectra towards the typical one of the graphene.

Extreme Ultraviolet (EUV) multilayer (ML) technology has been intensively applied in many scientific and technological fields such as solar physics and photolithography. More recently, the advent of free electron lasers (FEL) emitting bright sub-ps pulses with very high quality in term of intensity stability, coherence and temporal shape has encouraged the usage of multilayer coatings also in the transport and manipulation of FEL radiation. In fact, conventional single layers coated mirrors provide negligible reflectance in the EUV spectral range whereas ML mirrors can reach high efficiency at normal incidence without affecting the pulses characteristics. Such optical elements have been also exploited at FERMI@ELETTRA FEL where novel multilayer coatings specifically conceived for pump and probe experiment and ultrafast absorption spectroscopy have been designed. The main results are reported.

Graphene-metals interfaces are investigated in many subject areas both applicative and speculative. The interest mainly stems from the possibility for CVD synthesis of large area graphene on metals. In this case the metal acts as a catalyst for complete dehydrogenetaion of hydrocarbon precursors that leaves carbon behind at the surface. Such bilayer are also very appealing for surface plasmon resonance devices, since graphene acts both as a protective layer and biorecognition element. Several pairs of graphene-metal interfaces have been studied in terms of SPR performance and physical-chemical properties at the interface. With regard to this last aspect, NEXAFS spectroscopy is a powerful method to study single-, double-, and few-layers graphene and to illustrate any evolution of the electronic states.

The European Space Agency mission Solar Orbiter (SOLO) is dedicated to the study of the solar atmosphere and heliosphere. As a part of the payload, the instrument METIS (Multi Element Telescope for Imaging and Spectroscopy) will provide images of the corona, both in the visible range and at the hydrogen Lyman-a emission line (121.6 nm). The realization of optical coatings, based on Al and MgF2, able to reflect/transmit such spectral components is, therefore, necessary. Since optical characteristics of materials in the vacuum ultraviolet range are not well studied and vary greatly with the realization process, we implemented a study of their properties in different deposition conditions. This is aimed to the realization of a custom designed filter able to transmit the 121.6 nm wavelength while reflecting visible light, and thus separating visible from ultraviolet light paths in the METIS instrument. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

Probing of Hermean Exosphere By Ultraviolet Spectroscopy (PHEBUS) is a dual channels spectrometer working in the Extreme UltraViolet (EUV) and Far UltraViolet (FUV) range. It will be on board of ESA BepiColombo cornerstone mission and it will be devoted to investigate the composition, the dynamic, the formation and the feeding mechanisms of Mercury's exosphere system. A consistent interpretation of the observational data collected by PHEBUS requires a deeply knowledge of its radiometric behavior. The Mueller's matrix formalism can be adopted to derive an accurate radiometric model able to takes into account also the polarization state of the source observed by PHEBUS. Moreover, this theoretical model can be further verified and refined during an experimental ground calibration campaign. In this work we present the radiometric model derived for PHEBUS spectrometer together with some results obtained during the Flight Model (FM) ground calibration which is still ongoing. In particular, the obtained results employing this approach show that this is a complete and versatile method to perform the radiometric calibration of a generic space instrument.

The phase delay induced by multilayer (ML) mirrors is an important feature in many fields such as attosecond pulses compression, photolithography or in pump and probe experiments performed with Free Electron Laser (FEL) pulses. The experimental characterization of the ML phase delay can be obtained by the standing wave distribution measurement (by using Total Electron Yield (TEY) signal) combined to reflectance measurement. In this work, a ML structure with aperiodic capping-layers was designed and deposited for FEL applications and their reflectance and phase delay was characterized. The method adopted allows to retrieve the ML phase delay by using the TEY signals taken at different working configurations and it doesn't require the comparison with a bulk reference sample. The results obtained are presented and discussed.

Graphene Oxide and reduced Graphene Oxide are intriguing materials for photonics and electronic devices both for intrinsic characteristics and as precursors for the synthesis of graphene. Whatever the application and the engineering purpose, a fine control of the chemical and physical properties is required since the performances of graphene based systems depend on the reduction state of Graphene Oxide and can be strongly affected by interfaces interactions and neighboring effects. Then, a method for a local control of electric, electronic and chemical properties is required. The synergic application of Near Edge X ray Absorption Fine Structure Spectroscopy and Conductive Atomic Force Microscopy is a powerful way for such purpose allowing a full characterization of simple and composite samples, including specimens with dielectric discontinuities. Graphene Oxide/Gold (GO/Au) and Graphene Oxide/Silicon Oxide (GO/SiO2) have been selected as proof by example. The results show that the approach allow to relate chemical, electronic and physical properties to morphological features and local conductance behavior.

The practical use of graphene and graphene oxide beyond the research laboratories is strictly related to the fine tuning of new methodologies for processing and mass-production purposes. The photoreduction processing is an innovative route allowing exquisite control of the optoelectronic properties of graphene-like materials irradiated by coherent and incoherent light. We have investigated the effects induced by a mercury lamp on graphene/palladium bilayer; the change on the optical properties of the sample has been detected by using a surface plasmon resonance setup. The analysis, the perspectives and the preliminary results are shown thereafter.

Extreme ultraviolet Mo/Si multilayers protected by capping layers of different materials were exposed to 13.5 nm plasma source radiation generated with a table-top laser to study the irradiation damage mechanism. Morphology of single-shot damaged areas has been analyzed by means of atomic force microscopy. Threshold fluences were evaluated for each type of sample in order to determine the capability of the capping layer to protect the structure underneath.