Searched for: author:"Verhaegen, M.H.G."
(1 - 20 of 82)

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Piscaer, P.J. (author), Soloviev, O.A. (author), Verhaegen, M.H.G. (author)
This paper presents a computationally efficient framework in which a single focal-plane image is used to obtain a high-resolution reconstruction of dynamic aberrations. Assuming small-phase aberrations, a non-linear Kalman filter implementation is developed whose computational complexity scales close to linearly with the number of pixels of...
journal article 2021
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Nguyen, Hieu Thao (author), Bui, Hoa T. (author), Nguyen, Duy Cuong (author), Verhaegen, M.H.G. (author)
Motivated by a number of questions concerning transversality-type properties of pairs of sets recently raised by Ioffe and Kruger, this paper reports several new characterizations of the intrinsic transversality property in Hilbert spaces. New results in terms of normal vectors clarify the picture of intrinsic transversality, its variants and...
journal article 2020
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Yu, C. (author), Ljung, Lennart (author), Wills, Adrian (author), Verhaegen, M.H.G. (author)
In this paper, a unified identification framework called constrained subspace method for structured state-space models (COSMOS) is presented, where the structure is defined by a user specified linear or polynomial parametrization. The new approach operates directly from the input and output data, which differs from the traditional two-step...
journal article 2020
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Nguyen, Hieu Thao (author), Soloviev, O.A. (author), Verhaegen, M.H.G. (author)
We present an efficient phase retrieval approach for imaging systems with high numerical aperture based on the vectorial model of the point spread function. The algorithm is in the class of alternating minimization methods and can be adjusted for applications with either known or unknown amplitude of the field in the pupil. The algorithm...
journal article 2020
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Agbana, T.E. (author), Nijman, Patrick (author), Hoeboer, M.D.B. (author), van Grootheest, D.N. (author), van Diepen, Angela (author), van Lieshout, Lisette (author), Diehl, J.C. (author), Verhaegen, M.H.G. (author), Vdovin, Gleb (author)
We present a simple method for the diagnosis of urinary schistosomiasis using an in-line lensless holographic microscope combined with flow cytometry technique. Using simple image processing algorithms and binary image classifier, our system provides automated detection of Schistosoma haematobium eggs in infected urine samples. Registered...
conference paper 2020
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Haber, Aleksandar (author), Verhaegen, M.H.G. (author)
To develop high-performance controllers for adaptive optics (AO) systems, it is essential to first derive sufficiently accurate state-space models of deformable mirrors (DMs). However, it is often challenging to develop realistic large-scale finite element (FE) state-space models that take into account the system damping, actuator dynamics,...
journal article 2020
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Heemels, Alex (author), Agbana, T.E. (author), Pereira, S.F. (author), Diehl, J.C. (author), Verhaegen, M.H.G. (author), Vdovin, Gleb (author)
Fourier Ptychography is a computational imaging technique able to decouple high resolution from wide field of view, bypassing the diffraction limit of the microscope. Since it does not rely on high precision mechanics or fluorescent imaging, it is of practical interest for implementation in low scale devices. Despite its gains, realizing a...
conference paper 2020
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Pozzi, P. (author), Smith, C.S. (author), Carroll, E.C.M. (author), Wilding, D. (author), Soloviev, O.A. (author), Booth, Martin (author), Vdovin, Gleb (author), Verhaegen, M.H.G. (author)
Inhomogeneities in the refractive index of a biological microscopy sample can introduce phase aberrations, severely impairing the quality of images. Adaptive optics can be employed to correct for phase aberrations and improve image quality. However, conventional adaptive optics can only correct a single phase aberration for the whole field of...
journal article 2020
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Yu, Chengpu (author), Chen, Jie (author), Li, Shukai (author), Verhaegen, M.H.G. (author)
The identification of affinely parameterized state–space system models is quite popular to model practical physical systems or networked systems, and the traditional identification methods require the measurements of both the input and output data. However, in the presence of partial unknown input, the corresponding system identification...
journal article 2020
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Qiu, Yue (author), van Gijzen, M.B. (author), van Wingerden, J.W. (author), Verhaegen, M.H.G. (author), Vuik, Cornelis (author)
In this article, we study preconditioning techniques for the control of the Navier–Stokes equation, where the control only acts on a few parts of the domain. Optimization, discretization, and linearization of the control problem results in a generalized linear saddle-point system. The Schur complement for the generalized saddle-point system...
journal article 2020
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Piscaer, P.J. (author), Soloviev, O.A. (author), Verhaegen, M.H.G. (author)
This paper discusses various practical problems arising in the design and simulation of predictive control methods for adaptive optics. Although there has been increased attention towards optimal prediction and control methods for AO systems, they are often tested in simplified simulation environments. The use of advanced AO simulators...
conference paper 2020
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Doelman, Reinier (author), Klingspor, Måns (author), Hansson, Anders (author), Löfberg, Johan (author), Verhaegen, M.H.G. (author)
To optimally compensate for time-varying phase aberrations with adaptive optics, a model of the dynamics of the aberrations is required to predict the phase aberration at the next time step. We model the time-varying behavior of a phase aberration, expressed in Zernike modes, by assuming that the temporal dynamics of the Zernike coefficients...
journal article 2019
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Doelman, R. (author), Verhaegen, M.H.G. (author)
A rank-constrained reformulation of the blind deconvolution problem on images taken with coherent illumination is proposed. Since in the reformulation the rank constraint is imposed on a matrix that is affine in the decision variables, we propose a novel convex heuristic for the blind deconvolution problem. The proposed heuristic allows for...
journal article 2019
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Pozzi, P. (author), Maddalena, L. (author), Ceffa, N.G. (author), Soloviev, O.A. (author), Vdovin, Gleb (author), Carroll, E.C.M. (author), Verhaegen, M.H.G. (author)
The use of spatial light modulators to project computer generated holograms is a common strategy for optogenetic stimulation of multiple structures of interest within a three-dimensional volume. A common requirement when addressing multiple targets sparsely distributed in three dimensions is the generation of a points cloud, focusing excitation...
journal article 2019
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Piscaer, P.J. (author), Soloviev, O.A. (author), Verhaegen, M.H.G. (author)
A new wavefront sensorless adaptive optics method is presented that can accurately correct for time-varying aberrations using a single focal plane image at each sample instance. The linear relation between the mean square of the aberration gradient and the change in second moment of the image forms the basis of the presented method. The new...
journal article 2019
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Gedon, Daniel (author), Piscaer, P.J. (author), Batselier, K. (author), Smith, C.S. (author), Verhaegen, M.H.G. (author)
An extension of the Tensor Network (TN) Kalman filter [2], [3] for large scale LTI systems is presented in this paper. The TN Kalman filter can handle exponentially large state vectors without constructing them explicitly. In order to have efficient algebraic operations, a low TN rank is required. We exploit the possibility to approximate the...
conference paper 2019
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Monchen, Guido (author), Sinquin, B. (author), Verhaegen, M.H.G. (author)
This brief presents an algorithm for the recursive identification of Vector AutoRegressive (VAR) models of large dimensions. We consider a VAR model where the coefficient matrices can be written as a sum of Kronecker products. The algorithm proposed consists of recursively updating the Kronecker factor matrices at each new time step using...
journal article 2018
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Quintavalla, M. (author), Pozzi, P. (author), Verhaegen, M.H.G. (author), Bijlsma, H.K. (author), Verstraete, H.R.G.W. (author), Bonora, S. (author)
Adaptive Optics (AO) has revealed as a very promising technique for high-resolution microscopy, where the presence of optical aberrations can easily compromise the image quality. Typical AO systems however, are almost impossible to implement on commercial microscopes. We propose a simple approach by using a Multi-actuator Adaptive Lens (MAL)...
conference paper 2018
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Pozzi, Paolo (author), Soloviev, O.A. (author), Wilding, Dean (author), Vdovin, Gleb (author), Verhaegen, M.H.G. (author)
We report on a universal sample-independent sensorless adaptive optics method, based on modal optimization of the second moment of the fluorescence emission from a point-like excitation. Our method employs a sample-independent precalibration, performed only once for the particular system, to establish the direct relation between the image...
journal article 2018
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Piscaer, P.J. (author), Gupta, A. (author), Soloviev, O.A. (author), Verhaegen, M.H.G. (author)
In this paper, we propose the use of Gaussian radial basis functions (GRBFs) to model the generalized pupil function for phase retrieval. The selection of the GRBF hyper-parameters is analyzed to achieve an increased accuracy of approximation. The performance of the GRBF-based method is compared in a simulation study with another modal-based...
journal article 2018
Searched for: author:"Verhaegen, M.H.G."
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