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Meng, P. (author), Pereira, S.F. (author), Dou, X. (author), Urbach, Paul (author)Improving the image quality of small particles is a classic problem and especially challenging when the distance between particles are below the optical diffraction limit. We propose a imaging system illuminated with radially polarized light combined with a suitable substrate that contains a thin dielectric layer to demonstrate that the...journal article 2020
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Xi, Z. (author), Konijnenberg, A.P. (author), Urbach, Paul (author)We introduce an optimal metagrating design for transverse-position metrology in presence of photon shot noise. The proposed working principle is closely related to the formation of a phase vortex in the diffraction orders in the parameter space. Using the topological robustness, we optimize the design and compress all the transverse-position...journal article 2020
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Wei, X. (author), Urbach, Paul (author), Coene, W.M.J.M. (author)We investigate the performance of ptychography with noisy data by analyzing the Cramér-Rao lower bound. The lower bound of ptychography is derived and numerically computed for both top-hat plane wave and structured illumination. The influence of Poisson noise on the ptychography reconstruction is discussed. The computation result shows that,...journal article 2020
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van der Sijs, T.A. (author), El Gawhary, O. (author), Urbach, Paul (author)Electromagnetic scattering is the main phenomenon behind all optical measurement methods where one aims to retrieve the shape or physical properties of an unknown object by measuring how it scatters an incident optical field. Such an inverse problem is often approached by solving, several times, the corresponding direct scattering problem and...journal article 2020
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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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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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- El Gawhary, O. (author), Van Mechelen, Todd (author), Urbach, Paul (author) journal article 2019
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Grillo Peternella, F. (author), Esselink, Thomas (author), Dorsman, S.A. (author), Harmsma, Peter (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, 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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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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Wei, X. (author), Urbach, Paul (author)For performing phase retrieval in the extreme ultraviolet (EUV) regime more efficiently, developing polychromatic ptychography is desirable. As an alternative to the existing ptychographic information multiplexing (PIM) method, we present an another scheme where all monochromatic exit waves are expressed in terms of the amplitude of the...journal article 2019
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Ansuinelli, P. (author), Coene, W.M.J.M. (author), Urbach, Paul (author)Scatterometry is an important nonimaging and noncontact method for optical metrology. In scatterometry certain parameters of interest are determined by solving an inverse problem. This is done by minimizing a cost functional that quantifies the discrepancy among measured data and model evaluation. Solving the inverse problem is mathematically...journal article 2019
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Meng, P. (author), Man, Z. (author), Konijnenberg, A.P. (author), Urbach, Paul (author)Optical angular momenta (AM) have attracted tremendous research interest in recent years. In this paper we theoretically investigate the electromagnetic field and angular momentum properties of tightly focused arbitrary cylindrical vortex vector (CVV) input beams. An absorptive particle is placed in focused CVV fields to analyze the optical...journal article 2019
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Chang, J. (author), Esmaeil Zadeh, I.Z. (author), Los, Johannes W.N. (author), Zichi, Julien (author), Fognini, Andreas (author), Gevers, Monique (author), Dorenbos, Sander (author), Pereira, S.F. (author), Urbach, Paul (author), Zwiller, Val (author)In the past decade, superconducting nanowire single-photon detectors (SNSPDs) have gradually become an indispensable part of any demanding quantum optics experiment. Until now, most SNSPDs have been coupled to single-mode fibers. SNSPDs coupled to multimode fibers have shown promising efficiencies but have yet to achieve high time resolution....journal article 2019
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Lu, Xingyuan (author), Shao, Y. (author), Zhao, C.L. (author), Konijnenberg, A.P. (author), Zhu, Xinlei (author), Tang, Y. (author), Cai, Yangjian (author), Urbach, Paul (author)We propose and experimentally demonstrate a noniterative diffractive imaging method for reconstructing the complex-valued transmission function of an object illuminated by spatially partially coherent light from the far-field diffraction pattern. Our method is based on a pinhole array mask, which is specially designed such that the...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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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
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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