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van As, K. (author), Dellevoet, S. F.L.J. (author), Boterman, J. (author), Kleijn, C.R. (author), Bhattacharya, N. (author), Kenjeres, S. (author)The disease atherosclerosis causes stenosis inside the patient's arteries, which often eventually turns lethal. Our goal is to detect a stenosis in a non-invasive manner, preferably in an early stage. To that end, we study whether and how laser speckle contrast imaging (LSCI) can be deployed. We start out by using computational fluid dynamics...journal article 2022
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van As, K. (author), Simons, Bram A. (author), Kleijn, C.R. (author), Kenjeres, S. (author), Bhattacharya, N. (author)We study how the speckle contrast depends on scatterer velocity, with the goal of further developing laser speckle imaging as a quantitative measurement technique. To that end, we perform interferometric computer simulations on a dilute plug flow. The results of our numerical experiment, that we compare with known analytical expressions to...journal article 2022
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Hei, K. (author), Anandarajah, Kaszubowska (author), Martin, Eamonn P. (author), Shi, Guang (author), Anandarajah, Prince M. (author), Bhattacharya, N. (author)The measurement of distance plays an important role in many aspects of modern societies. In this paper, an absolute distance measurement method for arbitrary distance is proposed and demonstrated using mode-resolved spectral interferometry with a gain-switched dual comb. An accuracy of 12 µm, when compared to a He-Ne fringe counting laser...journal article 2021
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Shi, G. (author), Hei, K. (author), Wang, Wen (author), Bhattacharya, N. (author)Distance measurement using frequency sweeping interferometry is an absolute distance measurement technique that allows for high accuracy over long distances. Notwithstanding, the measurement accuracy is affected by laser sweeping nonlinearity and limited sweeping range. In this work, an optimized post-processing linearization method is...journal article 2020
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van As, K. (author), Boterman, Jorne (author), Kleijn, C.R. (author), Kenjeres, S. (author), Bhattacharya, N. (author)Laser speckle imaging (LSI) can be used to study dynamic processes in turbid media, such as blood flow. However, it is presently still challenging to obtain meaningful quantitative information from speckle, mainly because speckle is the interferometric summation of multiply scattered light. Consequently, speckle represents a convolution of...journal article 2019
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Hei, K. (author), Shi, Guang (author), Hänsel, A. (author), Deng, Z. (author), Latkowski, Sylwester (author), Van Den Berg, Steven A. (author), Bente, Erwin (author), Bhattacharya, N. (author)The measurement of distance plays an integral part in many aspects of modern societies. In this paper an integrated mode-locked laser on a chip is used for distance measurement based on mode-resolved interferometry. The emission from the on-chip source with a repetition rate of 2.5 GHz and a spectral bandwidth of 3 nm is coupled into a...journal article 2019
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- Bhattacharya, N. (author), Cui, M. (author), Zeitouny, M. (author), Urbach, Paul (author), van den Berg, S. (author) conference paper 2018
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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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Latkowski, S (author), Van Veldhoven, P. J. (author), Hänsel, A. (author), D'Agostino, D. (author), Rabbani-Haghighi, H. (author), Docter, B. (author), Bhattacharya, N. (author), Thijs, P. J A (author), Ambrosius, H. P M M (author), Smit, M (author), Williams, KA (author), Bente, E.A.J.M. (author)In this paper a generic monolithic photonic integration technology platform and tunable laser devices for gas sensing applications at 2 μm will be presented. The basic set of long wavelength optical functions which is fundamental for a generic photonic integration approach is realized using planar, but-joint, active-passive integration on...conference paper 2017
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- Hänsel, A. (author), Reyes Reyes, A. (author), Persijn, ST (author), Urbach, Paul (author), Bhattacharya, N. (author) journal article 2017
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Latkowski, S (author), Hänsel, A. (author), Van Veldhoven, P. J. (author), D’Agostino, D. (author), Rabbani-Haghighi, H. (author), Docter, B. (author), Bhattacharya, N. (author), Thijs, P. J A (author), Ambrosius, H. P M M (author), Smit, M (author), Bente, E.A.J.M. (author)We present a widely tunable extended cavity ring laser operating at 2 μm that is monolithically integrated on an indium phosphide substrate. The photonic integrated circuit is designed and fabricated within a multiproject wafer run using a generic integration technology platform. The laser features an intracavity tuning mechanism based on...journal article 2016
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Šmíd, R. (author), Hänsel, A. (author), Pravdová, L. (author), Sobota, J. (author), Cíp, O. (author), Bhattacharya, N. (author)In this work we present a design of an external optical cavity based on Fabry-Perot etalons applied to a 100 MHz Er-doped fiber optical frequency comb working at 1560 nm to increase its repetition frequency. A Fabry-Perot cavity is constructed based on a transportable cage system with two silver mirrors in plano-concave geometry including the...journal article 2016
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Nemati, M. (author), Kenjeres, S. (author), Urbach, Paul (author), Bhattacharya, N. (author)The scattering of coherent light from a system with underlying flow can be used to yield essential information about dynamics of the process. In the case of pulsatile flow, there is a rapid change in the properties of the speckle images. This can be studied using the standard laser speckle contrast and also the fractality of images. In this...journal article 2016
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- Nemati, M. (author), Urbach, Paul (author), Bhattacharya, N. (author) journal article 2016
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Somers, P.A.A.M. (author), Bhattacharya, N. (author)Speckle-based interferometry systems are useful tools for measuring vibration patterns at harmonically vibrating objects. The standard method for processing the speckle patterns acquired is to eliminate additive background noise and speckle phase, yielding Bessel-type fringe patterns whose values are proportional to the absolute value of the...journal article 2016
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Voigt, Dirk (author), Van Den Berg, Steven A. (author), Lešundák, Adam (author), van Eldik, S. (author), Bhattacharya, N. (author)Optical interferometry enables highly accurate non-contact displacement measurement. The optical phase ambiguity needs to be resolved for absolute distance ranging. In controlled laboratory conditions and for short distances it is possible to track a non-interrupted displacement from a reference position to a remote target. With large...conference paper 2016
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- Latkowski, S. (author), Hansel, A. (author), Bhattacharya, N. (author), De Vries, T. (author), Augustin, L. (author), Williams, K. (author), Smit, M. (author), Bente, E. (author) journal article 2015
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Van den Berg, S.A. (author), Van Eldik, S. (author), Bhattacharya, N. (author)Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved...journal article 2015
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Nemati, M. (author), Loozen, G.B. (author), Van der Wekken, N. (author), Van de Belt, G. (author), Urbach, H.P. (author), Bhattacharya, N. (author), Kenjeres, S. (author)A preliminary comparative measurement between particle imaging velocimetry (PIV) and laser speckle contrast analysis (LASCA) to study pulsatile flow using ventricular assist device in a patient-specific carotid artery phantom is reported. These full-field optical techniques have both been used to study flow and extract complementary parameters....journal article 2015
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Reyes Reyes, A. (author), Hou, Z. (author), Van Mastrigt, E. (author), Horsten, R.C. (author), De Jongste, J.C. (author), Pijnenburg, M.W. (author), Urbach, H.P. (author), Bhattacharya, N. (author)We present a broadband quantum cascade laser-based spectroscopic system covering the region between 850 and 1250 cm?1. Its robust multipass cavity ensures a constant interaction length over the entire spectral region. The device enables the detection and identification of numerous molecules present in a complex gas mixture without any pre...journal article 2014