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Konijnenberg, A.P. (author), Adam, A.J.L. (author), Urbach, Paul (author)This book treats optics at the level of students in the later stage of their bachelor or the beginning of their master. It is assumed that the student is familiar with Maxwell’s equations. Although the book takes account of the fact that optics is part of electromagnetism, special emphasis is put on the usefulness of approximate models of optics...book 2024
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Zhu, Z. (author), Zhang, Yu Quan (author), Adam, A.J.L. (author), Min, Changjun (author), Urbach, Paul (author), Yuan, Xiaocong (author)Stable optical trapping of gold nanoparticles is essential and desirable because of its wide applications in nanotechnology. While several factors have been proposed to affect optical trapping stability, the sample's volume fraction during optical trapping has often been neglected. To address this, by utilizing the effective medium theory, we...journal article 2023
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Zhu, Z. (author), Zhang, Y. (author), Zhang, Shuoshuo (author), Adam, A.J.L. (author), Min, Changjun (author), Urbach, Paul (author), Yuan, Xiaocong (author)Nonlinear responses of nanoparticles induce enlightening phenomena in optical tweezers. With the gradual increase in optical intensity, effects from saturable absorption (SA) and reverse SA (RSA) arise in sequence and thereby modulate the nonlinear properties of materials. In current nonlinear optical traps, however, the underlying physical...journal article 2023
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Dou, X. (author), Pereira, S.F. (author), Min, Changjun (author), Zhang, Yuquan (author), Meng, P. (author), Urbach, Paul (author), Yuan, Xiaocong (author)The sidewall angle (SWA) of a nanostructure exerts influence on the performance of the nanostructure and plays an important role in processing nano-structural chips. It is still a great challenge to determine steep SWAs from far field measurements especially when the SWAs are close to 90°. Here, we propose a far-field detection system to...journal article 2021
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Konijnenberg, A.P. (author), Adam, A.J.L. (author), Urbach, Paul (author)This book treats optics at the level of students in the later stage of their bachelor or the beginning of their master. It is assumed that the student is familiar with Maxwell’s equations. Although the book takes account of the fact that optics is part of electromagnetism, special emphasis is put on the usefulness of approximate models of optics...book 2021
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Tang, Y. (author), Ha, S. (author), Begou, Thomas (author), Lumeau, Julien (author), Urbach, Paul (author), Dekker, N.H. (author), Adam, A.J.L. (author)The ability to apply force and torque directly to micro- and nanoscale particles in optical traps has a wide range of applications. While full control of both force and torque in three dimensions has been realized using top-down fabrication of rod-shaped particles composed of birefringent crystalline materials, widespread usage of such...journal article 2020
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Chen, P. (author), Engel, Philip (author), Mazur, Adam (author), Abélard, Clément (author), Urbach, Paul (author)Accurate optical modeling for design and optimization of liquid crystal on silicon spatial light modulators (LCoS SLMs) is important for phase-related applications. Traditional matrix method cannot accurately predict the optical performance when the LC distribution is complex, therefore the rigorous finite element method (FEM) is preferred....conference paper 2020
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Ezerskaia, A. (author), Ras, A. (author), Pereira, S.F. (author), Urbach, Paul (author), Varghese, B. (author)We report a low-cost optical method with high sensitivity for the quantitative assessment of the gloss of human skin in the low gloss regime relevant for physiological skin gloss conditions. Using Monte Carlo simulations, experiments on gloss calibration standards and in-vivo skin gloss experiments using an optical prototype, we demonstrate...conference paper 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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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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Strauch, M. (author), Shao, Y. (author), Bociort, F. (author), Urbach, Paul (author)The increased usage of liquid lenses motivates us to investigate surface waves on the liquid's surface. During fast focal switching, the surface waves decrease the imaging quality. We propose a model that describes the surface modes appearing on a liquid lens and predicts the resonance frequencies. The effects of those surface modes on a...journal article 2017
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Ezerskaia, A. (author), Ras, Arno (author), Bloemen, Pascal (author), Pereira, S.F. (author), Urbach, Paul (author), Varghese, Babu (author)We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between specular and diffuse reflection and on the other on...journal article 2017
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Wang, Haifeng (author), Lin, Jian (author), Zhang, Dawei (author), Wang, Yang (author), Gu, Min (author), Urbach, Paul (author), Gan, Fuxi (author), Zhuang, Songlin (author)We present a concealing method in which an anti-point spread function (APSF) is generated using binary optics, which produces a large-scale dark area in the focal region that can hide any object located within it. This result is achieved by generating two identical PSFs of opposite signs, one consisting of positive electromagnetic waves from...journal article 2016
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Mout, B.M. (author), Wick, Michael (author), Bociort, F. (author), Petschulat, Joerg (author), Urbach, Paul (author)We present a method for simulating multiple diffraction in imaging systems based on the Huygens–Fresnel principle. The method accounts for the effects of both aberrations and diffraction and is entirely performed using Monte Carlo ray tracing.We compare the results of this method to those of reference simulations for field propagation through...journal article 2016
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Li, X. (author), Wei, L. (author), Poelma, René H. (author), Vollebregt, S. (author), Wei, J. (author), Urbach, Paul (author), Sarro, Pasqualina M (author), Zhang, Kouchi (author)This paper presents a tuneable binary amplitude Fresnel lens produced by wafer-level microfabrication. The Fresnel lens is fabricated by encapsulating lithographically defined vertically aligned carbon nanotube (CNT) bundles inside a polydimethyl-siloxane (PDMS) layer. The composite lens material combines the excellent optical absorption...journal article 2016
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Ezerskaia, A. (author), Pereira, S.F. (author), Urbach, Paul (author), Varghese, Babu (author)Skin health characterized by a system of water and lipids in Stratum Corneum provide protection from harmful external elements and prevent trans-epidermal water loss. Skin hydration (moisture) and sebum (skin surface lipids) are considered to be important factors in skin health; a right balance between these components is an indication of...conference paper 2016
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Wei, L. (author), Urbach, Paul (author)The focal field properties of radially/azimuthally polarized Zernike polynomials are studied. A method to design the pupil field in order to shape the focal field of radially or azimuthally polarized phase vortex is introduced. With this method, we are able to obtain a pupil field to achieve a longitudinally polarized hollow spot with a depth of...journal article 2016
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Ezerskaia, A. (author), Pereira, S.F. (author), Urbach, Paul (author), Varghese, B. (author)Skin health is characterized by heterogeneous system of water and lipids in upper layers providing protection from external environment and preventing loss of vital components of the body. Skin hydration (moisture) and sebum (skin surface lipids) are considered to be important factors in skin health; a right balance between these components...conference paper 2016
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Mann, Daniel (author), Nascimento Duplat, D. (author), Keul, Helmut (author), Möller, Martin (author), Verheijen, Marcel (author), Xu, M. (author), Urbach, Paul (author), Adam, A.J.L. (author), Buskens, Pascal (author)Au and Ag nanoshells are of interest for a wide range of applications. The plasmon resonance of such nanoshells is the property of interest and can be tuned in a broad spectral regime, ranging from the ultraviolet to the mid-infrared. To date, a large number of manuscripts have been published on the optics of such nanoshells. Few of these,...journal article 2016
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Mout, B.M. (author), Wick, M. (author), Bociort, F. (author), Urbach, H.P. (author)The Wigner Distribution Function (WDF) forms an alternative representation of the optical field. It can be a valuable tool for understanding and classifying optical systems. Furthermore, it possesses properties that make it suitable for optical simulations: both the intensity and the angular spectrum can be easily obtained from the WDF and the...conference paper 2015