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Optics

Division 4

Division 4 which is responsible for optics is home to three base units: that of length, time and luminous intensity. On this basis, standards and measuring methods of highest accuracy are developed for various optical quantities.

 

Tasks

Division "Optics" supports industry, science and society by providing measurement services, research and development in the field of optical technology. Based on the SI units of length, time and luminous intensity different units are realized and disseminated. Further more, accurate standards and measurement techniques are developed.

The division realizes the time scale UTC (PTB), which is the legal time in the Federal Republic of Germany, performs precision measurements in different fields of optics and cooperates in international standardisation and certification.

News

Die Mikrowellensynthese ist ein essentieller Bestandteil der Fontänenuhren. Mit ihr werden die für die Zustandspräparation und die Anregung des Uhrenübergangs benötigten Mikrowellensignale erzeugt. Unsicherheiten in diesem Teilsystem wirken sich direkt auf die Gesamtunsicherheit der Fontänenuhren aus. Durch Anpassungen im Synthesizer-Design wurden die Unsicherheitsbeiträge der Mikrowellensynthese auf ein vernachlässigbares Niveau reduziert und im Rahmen einer neuen Evaluation verifiziert.

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Single‐photon sources (SPSs) based on quantum emitters hold promise in quantum radiometry as metrology standard for photon fluxes at the low light level. Ideally this requires control over the photon flux in a wide dynamic range, sub‐Poissonian photon statistics, and narrow‐band emission spectrum. In this work, a monochromatic SPS based on an organic dye molecule is presented, whose photon flux is traceably measured to be adjustable between 144 000 and 1320 000 photons per second at a wavelength of (785.6 ± 0.1) nm, corresponding to an optical radiant flux between 36.5 and 334 fW. The high purity of the single‐photon stream is verified, with a second‐order autocorrelation function at zero time delay below 0.1 throughout the whole range. Such molecule‐based SPS is hence used for the calibration of a single‐photon avalanche detector against a low‐noise analog photodiode traceable to the primary standard for optical radiant flux (i.e., the...

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Spectral responsivity (SR) measurements are a powerful technique to measure the opto-electronic properties of photovoltaic devices like solar cells or PV modules. Although the SR determination of solar cells is a common and established technique for many years, much more effort must be taken to determine the SR of PV modules due to their size. Significantly larger and more complex solar simulator must be used, which led to a variety of different measurement techniques, each with its own disadvantages. In this work we present SR and linearity measurements performed with an LED-based solar simulator, which is capable of measuring the SR of a whole PV module within a reasonable amount of time. The principal solar simulator characteristics with its advantages and challenges are presented, including the properties of the emitted spectrum and the homogeneity of the resulting light field. The evaluation of our method, which is performed at...

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