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Optik

Abteilung 4

Gleich drei Basiseinheiten des internationalen Einheitensystems sind in der Optik beheimatet: die der Länge, Zeit und Lichtstärke. Darauf aufbauend werden für verschiedene optische Größen höchstgenaue Normale und Messmethoden entwickelt.

Aufgaben

Die Abteilung "Optik" unterstützt Industrie, Wissenschaft und Gesellschaft durch Bereitstellung von Messmöglichkeiten sowie Forschung und Entwicklung auf dem Gebiet optischer Technologien. Aufbauend auf den Basiseinheiten von Länge, Zeit und Lichtstärke werden verschiedene Einheiten dargestellt und weitergegeben sowie höchstgenaue Normale und Messmethoden entwickelt.

Die Abteilung realisiert mit der Zeitskala UTC (PTB) die gesetzliche Zeit in der Bundesrepublik Deutschland, führt Präzisionsmessungen auf unterschiedlichen Gebieten der Optik durch und arbeitet bei der Zertifizierung und der internationalen Normung mit.

4 Abteilungsbericht aus dem Jahresbericht 2019

Präzisions-Ionenfalle des neuen optischen Yb+-Frequenznormals.

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-2019 der PTB.

Nachrichten

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 propagation of the displacement errors through a cumulative and a global stitching algorithm to the retrieved surface form. For the considered experimental setup, the uncertainty in lateral position depends on the positioning uncertainties of the employed motion system and the uncertainty in the absolute distance measurement between the sensor and specimen. The lateral displacement uncertainty is determined experimentally employing a calibratable lateral grating. Thus, it is traceable to the SI unit of the length (meter). The experimental...

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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 measuring such photon-counting detectors at telecom wavelengths in order to establish proper procedures for characterising such devices. The detection efficiency measurements were performed using different experimental setups and reference standards with independent traceability chains at the wavelength of 1550 nm. A dedicated model to correct the dead time and dark count effects on the SPAD’s free-running counting process was developed, allowing the correct value of the photon rate impinging on the detector to be recovered from simple ratemeter...

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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 wave vector distributions created from multi-spot LED illumination reflected by the specimen. Based on the wave vectors we reconstruct the surface topography of aspheric lenses using an inverse ray tracing approach and prior knowledge about the individual source locations. We present the topographic measurement of two aspheric lenses with different global curvature radii measured with the same identical reflection setup. In addition, we examine the achievable accuracy of the wave vector measurement using a single light source to find physical...

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