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Shao, Y. (author), Loktev, Mikhail (author), Tang, Y. (author), Bociort, F. (author), Urbach, Paul (author)
For advanced imaging systems, e.g., projection systems for optical lithography, spatially varying aberration calibration is of utmost importance to achieve uniform imaging performance over the entire field-of-view (FOV). Here we present an efficient, accurate, and robust spatially varying aberration calibration method using a pair of 2...
journal article 2019
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Dwivedi, P. (author), Pereira, S.F. (author), Urbach, Paul (author)
Wavefront aberration measurements are required to test an extreme ultraviolet (EUV) imaging system. For a high-NA EUV imaging system, where conventional wavefront-sensing techniques show limitations, ptychography can be used for this purpose. However, at the wavelength region of EUV (i.e., 13.5 nm), the position accuracy of the scanning mask...
journal article 2019
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Dwivedi, P. (author), Konijnenberg, A.P. (author), Pereira, S.F. (author), Meisner, J.A. (author), Urbach, Paul (author)
Ptychography is a form of coherent diffractive imaging; it employs far-field intensity patterns of the object to reconstruct the object. In ptychography, an important limiting factor for the reconstructed image quality is the uncertainty in the probe positions. Here, we propose a new approach which uses the hybrid input-output algorithm and...
journal article 2019
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el Gawhary, O. (author), Van Mechelen, T. (author), Urbach, Paul (author)
journal article 2019
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Grillo Peternella, F. (author), Esselink, Thomas (author), Dorsman, S.A. (author), Harmsma, PJ (author), Horsten, R.C. (author), Zuidwijk, T. (author), Urbach, Paul (author), Adam, A.J.L. (author)
In this paper, the design and the characterization of a novel interrogator based on integrated Fourier transform (FT) spectroscopy is presented. To the best of our knowledge, this is the first integrated FT spectrometer used for the interrogation of photonic sensors. It consists of a planar spatial heterodyne spectrometer, which is...
journal article 2019
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Lu, Xingyuan (author), Zhao, C.L. (author), Shao, Y. (author), Zeng, Yan-jun (author), Konijnenberg, A.P. (author), Zhu, Xinlei (author), Popov, Sergei (author), Urbach, Paul (author), Cai, Yangjian (author)
In the theory of partial coherence, coherence singularities can occur in the spectral degree of coherence (SDOC): in case the fields at two different points are completely uncorrelated, the phase of the SDOC is undefined. For a partially coherent vortex beam, the detection of coherence singularities is linked to the measurement of topological...
journal article 2019
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Mout, B.M. (author), Flesch, Andreas (author), Wick, Michael (author), Bociort, F. (author), Petschulat, Joerg (author), Urbach, Paul (author)
The electric field at the output of an optical system is in general affected by both aberrations and diffraction. Many simulation techniques treat the two phenomena separately, using a geometrical propagator to calculate the effects of aberrations and a wave-optical propagator to simulate the effects of diffraction. We present a ray-based...
journal article 2018
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Xi, Z. (author), Urbach, Paul (author)
We propose a scheme to retrieve the size parameters of a nanoparticle on a glass substrate at a scale much smaller than the wavelength. This is achieved by illuminating the particle using two plane waves to create rich and nontrivial local polarization distributions, and observing the far-field scattering pattern into the substrate. By using...
journal article 2018
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Ezerskaia, A. (author), Uzunbajakava, Natallia Eduarda (author), Puppels, Gerwin J. (author), De Sterke, Johanna (author), Caspers, Peter J. (author), Urbach, Paul (author), Varghese, Babu (author)
We demonstrate the feasibility of short wave infrared (SWIR) spectroscopy combined with tape stripping for depth profiling of lipids and water in the stratum corneum of human skin. The proposed spectroscopic technique relies on differential detection at three wavelengths of 1720, 1750, and 1770 nm, with varying ratio of the lipid-to-water...
journal article 2018
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Mout, B.M. (author), Wick, Michael (author), Bociort, F. (author), Petschulat, Joerg (author), Urbach, Paul (author)
We study a simulation method that uses the Wigner distribution function to incorporate wave optical effects in an established framework based on geometrical optics, i.e., a ray tracing engine. We use the method to calculate point spread functions and show that it is accurate for paraxial systems but produces unphysical results in the presence...
journal article 2018
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El Gawhary, O. (author), Van Mechelen, T. (author), Urbach, Paul (author)
Electromagnetic fields carry a linear and an angular momentum, the first being responsible for the existence of the radiation pressure and the second for the transfer of torque from electromagnetic radiation to matter. The angular momentum is considered to have two components, one due to the polarization state of the field, usually called...
journal article 2018
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Konijnenberg, A.P. (author), Coene, W.M.J.M. (author), Urbach, Paul (author)
A noise-robust extension of iterative phase retrieval algorithms that does not need to assume a noise model is proposed. It works by adapting the intensity constraints using the reconstructed object. Using a proof-of-principle ptychographic experiment with visible light and a spatial light modulator to create an object, the proposed method is...
journal article 2018
document
Dwivedi, P. (author), Konijnenberg, A.P. (author), Pereira, S.F. (author), Urbach, Paul (author)
Ptychography, a form of Coherent Diffractive Imaging, is used with short wavelengths (e.g. X-rays, electron beams) to achieve high-resolution image reconstructions. One of the limiting factors for the reconstruction quality is the accurate knowledge of the illumination probe positions. Recently, many advances have been made to relax the...
journal article 2018
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Konijnenberg, A.P. (author), Lu, Xingyuan (author), Liu, Leixin (author), Coene, W.M.J.M. (author), Zhao, C.L. (author), Urbach, Paul (author)
A novel non-iterative phase retrieval method is proposed and demonstrated with a
proof-of-principle experiment. The method uses a fixed specially designed mask and through-focus intensity measurements. It is demonstrated that this method is robust to spatial partial coherence in the illumination, making it suitable for coherent diffractive...
journal article 2018
document
Shao, Y. (author), Lu, Xingyuan (author), Konijnenberg, A.P. (author), Zhao, C.L. (author), Cai, Yangjian (author), Urbach, Paul (author)
The complete characterization of spatial coherence is extremely di cult because the mutual coherence function (MCF) is a complex-valued function of four independent Cartesian coordinates. This di culty limits the ability to control and to optimize the spatial coherence in a broad range of key applications. Here we propose an e cient and...
journal article 2018
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Meng, P. (author), Pereira, S.F. (author), Urbach, Paul (author)
Rigorous vectorial focusing theory is used to study the imaging of small adjacent particles with a confocal laser scanning system. We consider radially polarized illumination with an optimized amplitude distribution and an annular lens to obtain a narrower distribution of the longitudinal component of the field in focus. A polarization...
journal article 2018
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Strauch, M. (author), Somers, P.A.A.M. (author), Bociort, F. (author), Urbach, Paul (author)
A technique to create aspheric surface shapes on commercially available electrowetting liquid lenses is demonstrated. Based on a previously published surface oscillation model a technique using a Hankel transform is proposed and tested experimentally. An alternating actuation voltage is applied to the liquid lens to stimulate surface...
journal article 2018
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Xu, Xiaosi (author), Konijnenberg, A.P. (author), Pereira, S.F. (author), Urbach, Paul (author)
Coherent Fourier scatterometry is an optical metrology technique that utilizes the measured intensity of the scattered optical field to reconstruct certain parameters of test structures written on a wafer with nano-scale accuracy. The intensity of the scattered field is recorded with a camera and this information is used to retrieve the...
journal article 2017
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Xi, Z. (author), Urbach, Paul (author)
It is generally believed that when a single metallic nanowire is sufficiently small, it scatters like a point electric dipole. We show theoretically when a metallic nanowire is placed inside specially designed beams, the magnetic dipole contribution along with the electric dipole resonance can lead to unidirectional scattering in the far field,...
journal article 2017
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Wei, L. (author), Bhattacharya, N. (author), Urbach, Paul (author)
We describe a method to control the directional scattering of a high-index dielectric nanosphere, which utilizes the unique focusing properties of an azimuthally polarized phase vortex and a radially polarized beam to independently excite inside the nanosphere a spinning magnetic dipole and a linearly polarized electric dipole mode normal to the...
journal article 2017
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