Nachrichten aus dem Jahresbericht 2021

Measuring the total momentum transfer of the absorbed and re-emitted photons from a highly reflective surface (reflection of the laser beam from an optical mirror) as a force provides the possibility of measuring the optical power with direct traceability to SI units.  PTB and the Technical University of Ilmenau (TUI) recently reviewed the viability and precision of the photon-momentum-based...

Im BxDiff JRP 18SIB03 Projekt (https://bxdiff.cmi.cz/), das im EU Programm EURAMET EMPIR Call 2018 - SI Broader Scope gefördert wird, entstehen u.a. Messplätze im Rang nationaler Normale für BTDF - (Bidirectional transmittance distribution function) und BSSRDF - (Bidirectional surface scattering distribution function) Untersuchungen. Die PTB unterstützt hierbei den Aufbau eines dezidierten BTDF...

Im nun abgeschlossene Projekt BiRD JRP 16NRM08 (https://www.birdproject.eu), gefördert im EU Programm EURAMET EMPIR Call 2016 – „Metrology Research for Pre‐ and Co‐normative projects“, wurden pränormative Grundlagen für solche Messgrößen erstellt, die zum optischen Erscheinungsbild von Produkten beitragen. Dies sind neben der Farbe und deren winkelabhängiger Abstrahlung auch Glanz, Sparkle und...

The Max-Planck-RIKEN-PTB Center for Time, Constants, and Fundamental Symmetries holds a workshop on recent advances on Tuesday March 9th, 2021, with the following speakers:

Ichiro Ushijima (RIKEN): Transportable optical lattice clocks with 18 digit precision
Richard Lange (PTB): Improved Limits for Violations of Local Position Invariance and Local Lorentz Invariance from Atomic Clocks
Peter Micke...

In quantum communication systems, the precise estimation of the detector´s response to the incoming light is necessary to avoid security breaches. The typical working regime uses a free-running single-photon avalanche diode in combination with attenuated laser pulses at telecom wavelength for encoding information. We demonstrate the validity of an analytical model for this regime which considers...

The aim of this project is to enable the SI-traceable measurement of column-integrated aerosol optical properties retrieved from the passive remote sensing of the atmosphere using solar and lunar radiation measurements.

The EMPIR Project “Single and entangled photon sources for quantum metrology (SEQUME)” is set to start on June 1st, 2021, for a three-year funding period. The aim of SEQUME project is to develop bright entangled photon sources based on different application-oriented platforms and to exploit high-purity single-photon sources to demonstrate the quantum advantage achieved by using these sources for...

The EMPIR Project “Quantum sensors for metrology based on single-atom-like device technology (QADeT)” is set to start on June 1st 2021 for a three-year funding period. The aim of the QADeT project is to realize single-atom-like systems (SALSs) in suitable materials, e.g. diamond, capable to perform nanoscale, high-sensitivity (electro-magnetic (EM) fields, temperature, stress, etc.) measurements. ...

Uncertainty quantification by ensemble learning is explored in terms of an application known from the field of computational optical form measurements. The application requires solving a large-scale, nonlinear inverse problem. Ensemble learning is used to extend the scope of a recently developed deep learning approach for this problem in order to provide an uncertainty quantification of the...

This contribution presents experimental and simulation results of a tiltable line scanning low coherence interferometer applied for form measurement of spherical and aspherical objects with a diameter of up to 300 mm.
The region of interest is sampled by multiple annular subapertures that are realigned employing stitching algorithms based on Cartesian- and Zernike polynomial fittings.
The paper...

Im Rahmen des BMBF-Projektes SiM4diM entwickelt die PTB zusammen mit den Firmen JCMwave und Carl Zeiss IMT sowie der Hochschule Aalen neue Verfahren zur vollständigen Modellierung mikroskopisch-bildgebender Messsysteme auf der Grundlage rigoroser Beugungsrechnungen. Ziel ist es, mit diesem „virtuellen Mikroskop“ die bildbasierte industrielle Messtechnik signifikant zu verbessern und die...

We apply an InGaAs quantum dot based single-photon source for the absolute detection efficiency calibration of a silicon single-photon avalanche diode operating in Geiger mode. The single-photon source delivers up to (2.55 ± 0.02) × 10⁶ photons per second inside a multimode fiber at the wavelength of 929.8 nm for above-band pulsed excitation with a repetition rate of 80 MHz. The purity of the...

The gravitational wave (GW) observatories calibrate interferometer displacement using photon momentum, with laser power serving as the measurand. These observatories are traceable to the International System of Units through a primary standard maintained by the US’s National Metrology Institute (NMI), the National Institute of Standards and Technology (NIST). The bilateral degree of equivalence of...

Im Forschungskonsortium "Quantum Repeater.Link" (QR.X), das vom Bundesministerium für Bildung und Forschung (BMBF) gefördert wird, entwickeln mehr als 20 Partner gemeinsam neuartige Quanten-Repeater und erforschen deren Einsatz in realen Szenarien.

The EMPIR Project “Supporting smart specialisation and stakeholder linkage in Photometry and Radiometry (Smart PhoRa)” has started on September 1st, 2021, for an 18-month funding period.

Das Phasenrauschen hochfrequenter Signale wird in der Regel durch einen Vergleich des zu untersuchenden Signals mit einem rauscharmen Referenzsignal gleicher Frequenz gemessen. Bei kommerziellen Phasenrauschmessplätzen wird dieses Referenzsignal durch einen über einen weiten Frequenzbereich abstimmbaren Oszillator erzeugt. Dadurch wird die Messung zum einen durch den Frequenzbereich des...

The tilted-wave interferometer is an interferometrical measurement system for the accurate optical form measurement of optical aspheres and freeform surfaces. Its evaluation procedure comprises a high-dimensional inverse problem to reconstruct the form of the surface under test from measured data. Recent work has used a deep learning hybrid approach to solve the inverse problem successfully in a...