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Delft, Netherlands

Cui M.,Technical University of Delft | Zeitouny M.G.,Technical University of Delft | Bhattacharya N.,Technical University of Delft | Van Den Berg S.A.,VSL | Urbach H.P.,Technical University of Delft
Optics Express | Year: 2011

We experimentally demonstrate long distance measurements with a femtosecond frequency comb laser using dispersive interferometry. The distance is derived from the unwrapped spectral phase of the dispersed interferometer output and the repetition frequency of the laser. For an interferometer length of 50 m this approach has been compared to an independent phase counting laser interferometer. The obtained mutual agreement is better than 1.5 μm (3 × 10-8), with a statistical averaging of less than 200 nm. Our experiments demonstrate that dispersive interferometry with a frequency comb laser is a powerful method for accurate and non-incremental measurement of long distances. © 2011 Optical Society of America. Source

Zeitouny M.G.,Technical University of Delft | Cui M.,Technical University of Delft | Janssen A.J.E.M.,TU Eindhoven | Bhattacharya N.,Technical University of Delft | And 2 more authors.
Optics Express | Year: 2011

We investigate general properties of the interferograms from a frequency comb laser in a non-linear dispersive medium. The focus is on interferograms at large delay distances and in particular on their broadening, the fringe formation and shape. It is observed that at large delay distances the interferograms spread linearly and that its shape is determined by the source spectral profile. It is also shown that each intensity point of the interferogram is formed by the contribution of one dominant stationary frequency. This stationary frequency is seen to vary as a function of the path length difference even within the interferogram. We also show that the contributing stationary frequency remains constant if the evolution of a particular fringe is followed in the successive interferograms found periodically at different path length differences. This can be used to measure very large distances in dispersive media. © 2011 Optical Society of America. Source

Vuelban E.M.,VSL
Measurement Science and Technology | Year: 2013

Recently a scanning method for determining the size-of-source effect (SSE) in radiation thermometry was proposed. It was shown that by scanning the radiation thermometer (RT) across a narrow slit with a slit width similar to the spot size of the RT, results comparable to the indirect method can be obtained. However, due to the low signal levels (almost at the noise level) detected by the RT, the method is susceptible to noise. We examine further this scanning method by determining the influence of the relative position of the slit, and slit size on the resulting SSE. We also present a simple model for the radiation propagation relevant to this method. Lastly, we compare the results of the scanning experiments to the conventional direct method for SSE and show that the scanning method is also comparable to the direct method, as long as the parameters of the scanning method (e.g., slit position, slit size) are adjusted properly. © 2013 IOP Publishing Ltd. Source

Rietveld G.,VSL
CPEM Digest (Conference on Precision Electromagnetic Measurements) | Year: 2010

An extremely sensitive vibrating reed electrometer is built, that is able to reach sub-aA current resolution within a one-minute measurement. The input leakage current of the set-up is -0.12 aA, that is less than 1 electron per second. Crucial for this extreme sensitivity and low leakage current is the development of an input stage with only vacuum gap capacitors. The stability and sensitivity of this new electrometer make it suitable for accurate low-frequency characterization of vacuum gap capacitors used in the electron counting capacitance standard experiment. ©2010 IEEE. Source

Wolf A.L.,VU University Amsterdam | Morgenweg J.,VU University Amsterdam | Koelemeij J.C.J.,VU University Amsterdam | Van Den Berg S.A.,VSL | And 2 more authors.
Optics Letters | Year: 2011

We demonstrate direct frequency-comb (FC) spectroscopy of the dipole-forbidden 4s2S1/2-3d2D5/2 transition in trapped 40Ca+ ions using an unamplified FC laser. The excitation is detected with nearly 100% efficiency using a shelving scheme in combination with single-ion imaging. The method demonstrated here has the potential to reach hertz-level accuracy, if a hertz-level linewidth FC is used in combination with confinement in the Lamb-Dicke regime. © 2010 Optical Society of America. Source

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