Logo der Physikalisch-Technischen Bundesanstalt

Nachrichten aus dem Jahresbericht 2020

Grundlagen der Metrologie

Photonic integrated circuits (PICs) are revolutionizing nanotechnology, with far-reaching applications in telecommunications, molecular sensing, and quantum information. PIC designs rely on mature nanofabrication processes and readily available and optimised photonic components (gratings, splitters, couplers). Hybrid plasmonic elements can enhance PIC functionality (e.g., wavelength-scale...

[ mehr ]

Planar plasmonic lenses have attracted a great deal of interest over the last few years for their super-resolution focusing capabilites. These highly compact structures with dimensions of only a few micrometres allow for the focusing of light to sub-wavelength-sized spots with focal lengths reaching into the far-field. This offers opportunities for new methods in nanometrology; for example,...

[ mehr ]

This paper reports on measurements of the transition frequency of a strontium-87 lattice clock with a record uncertainty of 1.5×10⁻¹⁶, by using two local caesium fountain clocks. This result is an important contribution to the decision processes concerning a redefinition of the SI base unit second based on optical clocks. With data spanning three years of observation, the authors set more...

[ mehr ]

Wir berichten über die Charakterisierung der winkelabhängigen Abstrahlung von Einzelphotonenemittern basierend auf einzelnen Stickstofffehlstellen-Zentren (NV-Zentren) in Nanodiamanten bei Raumtemperatur. Ein theoretisches Modell zur Berechnung der winkelabhängigen Abstrahlung eines solchen NV-Zentrums nahe einer dielektrischen Grenzfläche wird präsentiert. Zum ersten Mal wurde die Orientierung...

[ mehr ]

Traceable, highly accurate calibration of wavefront sensors such as Shack–Hartmann sensors is a challenging task and an active field of research. We have developed a measurement system for the traceable calibration of wavefront sensors employing spherical wavefronts and a point light source in combination with a three-axis linear stage. We obtain an absolute calibration of sensor errors, including...

[ mehr ]

Optische Atomuhren sollen die ungestörte Frequenz eines atomaren Übergangs realisieren.  Konsequente Weiterentwicklungen solcher Atomuhren machen sie zu den genauesten Messinstrumenten, die heutzutage zur Verfügung stehen. Ein Forschungsschwerpunkt bildet dabei die Entwicklung von Verfahren zur genauen Kontrolle oder Eliminierung von Frequenzverschiebungen durch äußere Störeinflüsse. In der...

[ mehr ]

Deep neural networks have been successfully applied in many different fields like computational imaging, healthcare, signal processing, or autonomous driving. In a proof-of-principle study, we demonstrate that computational optical form measurement can also benefit from deep learning. A data-driven machine-learning approach is explored to solve an inverse problem in the accurate measurement of...

[ mehr ]

A single-photon source is an essential tool for the emerging field of quantum technologies. Ideally, it should be spectrally compatible with other photonic devices while providing a high flux of narrow-band photons. The single organic dye molecule dibenzanthanthrene under cryogenic conditions possesses the given characteristics and therefore constitutes a prominent single-photon source....

[ mehr ]

The traceability of measurements of the parameters characterizing single-photon sources, such as photon flux and optical power, paves the way towards their reliable comparison and quantitative evaluation. In this paper, we present an absolute measurement of the optical power of a single-photon source based on an InGaAs quantum dot under pulsed excitation with a calibrated single-photon avalanche...

[ mehr ]

Das Protokoll NTP wird von Milliarden von Computern und smarten Geräten zur Synchronisation ihrer eingebauten digitalen Uhren verwendet. Bis vor kurzem konnten hierbei nicht die Identität der verwendeten Zeitquelle oder die Echtheit der ausgetauschten Zeitdaten sichergestellt werden. Andererseits wird in einer wachsenden Zahl von Anwendungen eine verlässliche, authentifizierbare Zeitquelle...

[ mehr ]

The Physikalisch-Technische Bundesanstalt has developed a reference setup for measuring the modulation transfer function (MTF) of camera lenses with the goal of reaching an expanded measurement uncertainty of 0.01 (coverage probability of 95%) for various measurement configurations. We present optomechanical simulations of the setup behavior, which are used to investigate the influence of the...

[ mehr ]

Accurate bidirectional measurements are performed at PTB using UV-microscopy. For this purpose, edge detection algorithms based on the rigorous calculation of the optical imaging problem are employed. Hence, all the parameters of the imaging system and the object must be considered due to their specific impact on theimage formation. In order to further improve the model-based edge detection the...

[ mehr ]

We demonstrate the retrieval of deep subwavelength structural information in nano-optical polarizers by scatterometry of quasi-bound states in the continuum (quasi-BICs). To this end, we investigate titanium dioxide wire grid polarizers for application wavelengths in the deep ultraviolet (DUV) spectral range fabricated with a self-aligned double-patterning process. In contrast to the...

[ mehr ]

Each mobile telecommunications network requires synchronization between its components. Deutsche Telekom Technik AG has decided to test a method developed by the AGH University of Science and Technology in Krakow, Poland, for the future monitoring of selected points in its network. It is based on optical time transmission (OTT), which has been tested in cooperation with PTB, among others on glass...

[ mehr ]

Für die Analyse von Messungen mit einem spektroskopischen Müller-matrix Ellipsometer wurde in der PTB kürzlich ein neuartiges Analyseverfahren entwickelt, welches den Einfluss von Depolarisation und anderen stochastischen Einflussgrößen adäquat in der Messunsicherheitsschätzung berücksichtigt. Dieses Verfahren wurde nun erstmalig auf die Messung der Dicken von SiO2-Schichten angewendet. Die...

[ mehr ]

Multiple Aperture Shear-Interferometry (MArS) is a shape measurement technique that uses multi-spot illumination to overcome the problem of a limited observation aperture of conventional interferometric techniques and thus considerably simplifies the measurement of optical aspheres and freeform surfaces. Using a shear interferometry setup, MArS measures the coherence function in order to obtain...

[ mehr ]

The challenges faced in a comparison of measuring the detection efficiency of free-running InGaAs/InP single-photon avalanche detectors (InGaAs/InP SPAD) were studied by four European National Metrology Institutes (NMIs) meeting at a single laboratory. The main purpose of this study is to develop a trustable measurement technique and to provide a snapshot of the methods used by the four NMIs for...

[ mehr ]

Annular subaperture stitching interferometry (ASSI) is a common approach for the measurement of aspherical surfaces. A common obstacle of ASSI is the occurrence of lateral displacement errors when the sensor or specimen is repositioned between the subaperture measurements. Our contribution focuses on modeling of the statistical displacement errors. Avirtual experiment is presented simulating the...

[ mehr ]

Metrologie für die Wirtschaft

Keine Nachrichten verfügbar.

Metrologie für die Gesellschaft

Keine Nachrichten verfügbar.

Internationale Angelegenheiten

Keine Nachrichten verfügbar.