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 single photon emission, expressed by the value of the 2^nd order correlation function g⁽²⁾(τ = 0), is between 0.14 and 0.24 depending on the excitation power applied to the quantum dot. The single-photon flux is sufficient to be measured with an analog low-noise reference detector, which is traceable to the national standard for optical radiant flux. The measured detection efficiency using the single-photon source remains constant within the measurement uncertainty for different photon fluxes. The corresponding weighted mean thus amounts to 0.3263...

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 Unsicherheit dimensionaler Metrologie auch im industriellen Umfeld um mehr als eine Größenordnung zu verringern.

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 addresses common challenges in the reduction and modeling of displacement errors associated with the motion of the interferometric sensor between subaperture measurements and compares the topography deviations of the experimental results with those simulated by a Monte Carlo based model.