An elegant Breadboard of the optical bench for eLISA/NGO

The Laser Interferometer Space Antenna, as well as its reformulated European-only evolution, the New Gravitational-Wave Observatory, both employ heterodyne laser interferometry on million kilometer scale arm lengths in a triangular spacecraft formation, to observe gravitational waves at frequencies between 3 × 10−5 Hz and 1 Hz. The Optical Bench as central payload element realizes both the inter-spacecraft as well as local laser metrology with respect to inertial proof masses, and provides further functions, such as point-ahead accommodation, acquisition sensing, transmit beam conditioning, optical power monitoring, and laser redundancy switching. These functions have been combined in a detailed design of an Optical Bench Elegant Breadboard, which is currently under assembly and integration. We present an overview of the realization and current performances of the Optical Bench subsystems, which employ ultraprecise piezo mechanism, ultrastable assembly techniques, and shot noise limited RF detection to achieve translation and tilt metrology at Picometer and Nanoradian noise levels

Het ontwerp van een 2-assige scanspiegel voor de ruimtevaart

De ontworpen scanspiegel heeft een spiegel van 77 mm x 109 mm en een hoekbereik van +- 7,5 x +- 1 graden. De scanspiegel moet kleine hoekverstoringen tot 200 microradiaal met een frequentie van 100 Hz corrigeren. De hier besproken scanspiegel is als voorbeeld gekozen voor technologie ontwikkeling binnen TNO TPD met als toepassingsgebied de ruimtevaart. In het ontwerpproces is een ontwerpfilosofie gehanteerd waarbij nauw wordt samengewerkt tussen de gebieden: fijnmechanisch ontwerpen, dynamica en regeltechniek. Het doel van deze korte ontwerplus is het vroegtijdig optimaliseren van het ontwerpproces van complexe fijnmechanische systemen waarin dynamica en regeltechniek een belangrijke rol spelen

Interferometric Surface Characterisation of Laser Mirrors with Sub-Nanometer Reproducibility for Satellite-to-Satellite Optical Metrology

Path length errors caused by beamwalk over the surface topography of optical components can have a detrimental influence on the accuracy of highly sensitive translational metrology, that is of particular relevance for In-Field Pointing payload concepts, investigated for the LISA space mission. This paper presents the results of our experimental and theoretical investigations in surface induced path length errors with a detailed characterisation of their magnitudes

Interferometric characterization and modeling of pathlength errors resulting from beamwalk across mirror surfaces in LISA

An alternative payload concept with in-field pointing for the laser interferometer space antenna utilizes an actuated mirror in the telescope for beam tracking to the distant satellite. This actuation generates optical pathlength variations due to the resulting beamwalk over the surface of subsequent optical components, which could possibly have a detrimental influence on the accuracy of the measurement instrument. We have experimentally characterized such pathlength errors caused by a λ/10 mirror surface and used the results to validate a theoretical model. This model is then applied to predict the impact of this effect for the current optical design of the LISA off-axis wide-field telescope

Interferometric Characterisation of Path Length Errors Resulting from Mirror Surface Topography with Sub-nm Reproducibility

We present the results of our experimental characterisation of path length errors, caused by beamwalk over the surface topography of laser mirrors. These path length errors can have a major influence on the accuracy of the LISA measurement instrument in Astrium’s alternative payload concept with In-Field Pointing. Our measurement setup uses a highly sensitive heterodyne interferometer for measuring the path length error amplitudes, generated by the topography of a moving, λ/10 test mirror

Age- and disease-specific reference values for neurofilament light presented in an online interactive support interface

Interpretation of axonal damage biomarker Neurofilament Light chain (NfL) concentrations is difficult due to the lack of age-specific and disease-specific reference values. We here developed an interactive interface to support interpretation of NfL results in human body fluids. We used NfL values of 1698 individuals without a neurological disorder, aged 19–85 years, and patients with MS and dementias. Percentile regression estimates per diagnosis populate interactive graphs, alongside NfL background information (available on: https://mybiomarkers.shinyapps.io/Neurofilament). This accessible interface provides reference for interpretation of the individual patient results for clinicians. It showcases an adaptable method to support interpretation of age-dependent biomarkers in neurology