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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.

4 division report from the annual report 2021 (german only)4 division report from the annual report 2021 (german only)

The Opens external link in new windowdivision report provides an overview of the most important news and events of the "Optics" division of the past year and thus complements the Opens internal link in current windowannual Report 2021 of the PTB. (german only)

News

PTB and NIST performed a comparison for high accuracy continuous wave optical power measurements in the kilowatt regime. The NIST carried out measurements with a power meter relying on photon momentum, while PTB performed the measurements with a modified off-the-shelf thermal power meter. The non-absorbing photon momentum measurement approach permits the two power meters to measure the same laser beam optical path simultaneously, resulting in a direct comparison of the meters supported by an optical system to accommodate differences in instrument settling times. The results show agreement within the expanded uncertainties for each instrument. NIST and PTB illustrate a degree of equivalence of 0.49% with an expanded uncertainty of 1.37% (k = 2) for an average result across all power levels.

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Single photon emitters in hexagonal boron nitride have gathered a lot of attention due
to their favourable emission properties and the manifold of possible applications. Despite
extensive scientic effort, the exact atomic origin of these emitters has remained unkown
thus far. Recently, several studies have tied the emission in the yellow spectral region
to carbon-related defects, but the exact atomic structure of the defects remains elusive.
In this study, photoluminescence emission and excitation spectroscopy is performed on a
large number of emitters within this region. By comparison of the experimental data with
theoretical predictions, the origin of yellow single photon emission in hexagonal boron nitride is determined. Knowledge of this atomic structure and its optical properties is crucial for the reliable implementation of these emitters in quantum technologies.

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Mithilfe von kurzwelliger und energiereicher UVC-Strahlung werden schon seit Jahrzehnten Oberflächen, Trinkwasser oder Raumluft desinfiziert. Dabei nutzt man aus, dass diese Strahlung Zellen schädigen kann – insbesondere diejenigen von Viren, Bakterien oder anderen Mikroorganismen. Allerdings kann sie auch Zellen in menschlichen Organen wie Haut und Auge schädigen. Die radiometrische Kalibrierung im Bereich der UV-Strahlung bei hohen Bestrahlungsstärken ist eine der Aufgaben im Fachbereich Photometrie und Spektroradiometrie der Physikalisch-Technischen Bundesanstalt (PTB). Das Hauptaugenmerk richtet sich dabei immer mehr auf sehr kurzwellige UVC-Strahlung. Verstärkt durch die Corona-Epidemie wird aktuell diskutiert, ob sogenannte Fern-UVC-Strahlung zwischen 200 nm und 240 nm, die nahezu nicht in Haut und Auge eindringt, auch offen strahlend und im öffentlichen Raum eingesetzt werden könnte. Allerdings lässt sich das Risiko für die...

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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.