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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.



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.

4 Abteilungsbericht aus dem Jahresbericht 2020

Der Initiates file downloadAbteilungsbericht gibt einen Überblick über die wichtigsten Nachrichten und Ereignisse der Abteilung „Optik“ des letzten Jahres und ergänzt somit den Opens internal link in current windowJahresbericht-2020 der PTB.


Single-photon detectors are a pivotal component in photonic quantum technologies. A precise and comprehensive calibration of the inherent detection efficiency is of utmost importance to ensure the proper evaluation of the performance in view of the specific technological application of interest, such as the protection against security breaches in quantum cryptographic solutions. Here we report on a systematic study on and comprehensive analysis of the estimation of the inherent detection efficiency of two commercial single-photon detectors based on single-photon avalanche diodes (SPADs) for various mean photon numbers and at high laser pulse repetition rates using different techniques. We observed an unexpected and significant drop in the inherent detection efficiency at detection rates of 10 % and higher relative to the maximum detection rate. It is demonstrated that for data analysis a statistical model for the detection rate...

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Solid immersion lenses (SILs) have the potential to enhance the single-photon emission properties of color centers in diamond, e.g., of germanium-vacancy (GeV-) centers, due to an increase of the photon extraction from the diamond. We present the successful generation of GeV-centers in bulk diamond, the fabrication of hemispherical SILs with GeV-centers using a focused ion beam (FIB) and the metrological characterization of the emission of the GeV-centers in SILs in terms of the spectral distribution, the single-photon purity, the saturation behavior, and the emitter’s excited state lifetime. We could verify a significant increase of the detector count rate for GeV-centers in SILs compared to those without a SIL. The singlephoton purity and detector count rate were measured for different excitation powers and were evaluated in a combined model. This allows the possibility to distinguish between the linear background emission and...

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Jan Spichtinger, a PhD student from PTB, won this year’s award for the best young scientist at the 12th High Level Expert Meeting on Asphere Metrology. The “Ultrapräzise Oberflächenbearbeitung” e.V. (Ultraprecise Surface Processing) Competence Center (CC UPOB) held this meeting virtually on 15-16 March 2022. The event was rounded off with the presentation of the Young Scientist Award (YSA) which honors young scientists in the fields of high-precision surface manufacturing and metrology. The meeting’s audience that was made up of experts from these fields selected the PTB doctoral student because of his work on the high-accuracy form measurement of moderately curved optical surfaces. He presented his research under the title of “Stitching interferometry for moderately curved freeform surfaces” and went on to introduce a new measurement method called SCaLA (stitching interferometry with cavity length and angle measurement). This method is...

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Offers for Students

As is the case at PTB in general, in Division Optics there is the possibility to write a student thesis, to complete an internship or to participate in research as a working student. If you are interested in the topics and projects of the working group, you can first contact the Opens external link in new windowcentral contact persons and mention the working group as a request.
Offers for Doctoral Candidates

As at PTB in general, Division Optics is active in many collaborations (with link to new Div. collaboration page) with universities, research institutions, industry and other metrology institutes worldwide. These collaborations support many exciting third-party funding opportunities for PhD students to become involved in PTB research. If you are interested in the topics and projects of the working groups, you can first inquire at the Opens external link in new windowjob postings.