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Andrei, R.M. (author), Fraanje, P.R. (author), Verhaegen, M. (author), Korkiakoski, V.A. (author), Keller, C.U. (author), Doelman, N.J. (author)We propose a new approach for the joint estimation of aberration parameters and unknown object from diversity images with applications in imaging systems with extended objects as astronomical ground-based observations or solar telescopes. The motivation behind our idea is to decrease the computational complexity of the conventional phase...conference paper 2012
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Korkiakoski, V. (author), Keller, C.U. (author), Doelman, N.J. (author), Fraanje, P.R. (author), Andrei, R. (author), Verhaegen, M. (author)We show experimental results demonstrating the feasibility of an extremely fast sequential phase-diversity (SPD) algorithm for point sources. The algorithm can be implemented on a typical adaptive optics (AO) system to improve the wavefront reconstruction beyond the capabilities of a wavefront sensor by using the information from the imaging...conference paper 2012
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Korkiakoski, V. (author), Venema, L. (author), Agocs, T. (author), Keller, C.U. (author), Doelman, N.J. (author), Fraanje, P.R. (author), Andrei, R. (author), Verhaegen, M. (author)We investigate the potential of phase-diversity (PD) and Gerchberg-Saxton (GS) algorithms in the calibration of active instruments. A set of images is recorded with the focal-plane scientific camera, each image having a known and unique defocus. The phase-retrieval algorithms are used, with those images, to estimate the non-common path...conference paper 2012
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Korkiakoski, V. (author), Keller, C.U. (author), Doelman, N.J. (author), Fraanje, P.R. (author), Verhaegen, M. (author)We study different possibilities to use adaptive optics (AO) and phase diversity (PD) together in a jointly optimized system. The potential of the joint system is demonstrated through numerical simulations. We find that the most significant benefits are obtained from the improved deconvolution of AO-corrected wavefronts and the additional...article 2012
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Andrei, R.M. (author), Smith, C.S. (author), Fraanje, P.R. (author), Verhaegen, M. (author), Korkiakoski, V.A. (author), Keller, C.U. (author), Doelman, N.J. (author)In this paper we give a new wavefront estimation technique that overcomes the main disadvantages of the phase diversity (PD) algorithms, namely the large computational complexity and the fact that the solutions can get stuck in a local minima. Our approach gives a good starting point for an iterative algorithm based on solving a linear system,...conference paper 2012
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Keller, C.U. (author), Korkiakoski, V. (author), Doelman, N.J. (author), Fraanje, P.R. (author), Andrei, R. (author), Verhaegen, M. (author)We present a promising approach to the extremely fast sensing and correction of small wavefront errors in adaptive optics systems. As our algorithm's computational complexity is roughly proportional to the number of actuators, it is particularly suitable to systems with 10,000 to 100,000 actuators. Our approach is based on sequential phase...conference paper 2012
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Korkiakoski, V. (author), Keller, C. (author), Doelman, N.J. (author), Fraanje, P.R. (author), Verhaegen, M. (author)We demonstrate the potential of joint-optimization of adaptive optics (AO) and phase-diversity (PD). The wavefront sensor information reduces computational costs by a factor of 20, and PD can reconstruct much better the AO corrected images.conference paper 2011
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Doelman, N.J. (author), Fraanje, P.R. (author), den Breeje, R. (author)An H2-optimal control approach for Adaptive Optics has been validated in an on-sky experiment on a solar telescope. A substantial performance improvement over the integrator control approach is demonstrated for control of the tip-tilt modes. The experimental results correspond reasonably well with simulations based on measured data.conference paper 2011
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Fraanje, P.R. (author), Massioni, P. (author), Verhaegen, M. (author), TNO Industrie en Techniek (author)Deformable mirrors with spatially invariant dynamic response can be considered as part of the class of decomposable systems. Such systems can be thought of as the interconnection of a number of identical subsystems, and they can be used to model certain classes of large scale systems. We show in this article that the technique allows the design...article 2010
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Rijnveld, N. (author), van den Braber, R. (author), Fraanje, P.R. (author), van den Dool, T.C. (author)TNO Science and Industry and MECAL have developed a six degree of freedom vibration isolation system that suppresses both floor vibrations and direct forces on a table top. The achieved reduction of transmissibility and compliance is 40 dB between 1 and 50 Hz in vertical direction, and 30 dB between 1 and 20 Hz in horizontal direction. Key...conference paper 2010
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Hamelinck, R.F.M.M. (author), Fraanje, P.R. (author), Doelman, N.J. (author)The resolving power of an optical system is often limited by the presence of timevarying wavefront distortions caused by heat flows. The aberrations do not only include tip/tilt and focus terms, but also higher spatial frequencies, due to the heat flow’s turbulent nature. TNO has built an adaptive optics (AO) breadboard, to demonstrate the...conference paper 2010
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Fraanje, P.R. (author), Rice, J. (author), Verhaegen, M. (author), Doelman, N.J. (author), TNO Industrie en Techniek (author)Efficient and optimal prediction of frozen flow turbulence using the complete observation history of the wavefront sensor is an important issue in adaptive optics for large ground-based telescopes. At least for the sake of error budgeting and algorithm performance, the evaluation of an accurate estimate of the optimal performance of a particular...article 2010
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TNO Industrie en Techniek (author), Fraanje, P.R. (author), Doelman, N.J. (author), Verhaegen, M. (author)Using a matching pursuit (MP) approach to solve least squares problems with a sparsity constraint sparse controllers are computed to compensate for atmospheric turbulence. The method has been validated by simulation of von Kármán turbulence with frozen flow for the case of prediction, reconstruction and control.conference paper 2010
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TNO Industrie en Techniek (author), Fraanje, P.R. (author), Doelman, N.J. (author)In recent years various researchers have proposed an optimal control approach for the rejection of turbulence-induced wavefront distortions in an AO system. The essential element in the design of an optimal controller is the choice for the turbulence model, which predicts the turbulence to compensate for the inherent delay in the AO control loop...conference paper 2010
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Doelman, N.J. (author), Fraanje, P.R. (author), Houtzager, I. (author), Verhaegen, M. (author), TNO Industrie en Techniek (author)An optimal control method to reject turbulence-induced wavefront distortions in an Adaptive Optics system is discussed. Details of a data-driven control approach are presented where the emphasis is put on the estimation of the optimal predictor of the wavefront disturbance. Several algorithms capable of finding the predictor parameters from the...conference paper 2009
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Fraanje, P.R. (author), Verhaegen, M. (author), Doelman, N.J. (author), TNO Industrie (author)This letter presents a robustification of the preconditioned Filtered-X LMS algorithm proposed by Elliott et al.. The method optimizes the average performance for probabilistic uncertainty in the secondary path and relaxes the SPR condition for global convergence. It also prevents large amplification in the pre-conditioning filters due to...article 2004
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Fraanje, P.R. (author), Verhaegen, M. (author), Doelman, N.J. (author), Berkhoff, A. (author), Technisch Physische Dienst TNO - TH (author)This paper presents a method to estimate the H2 optimal and a robust feedback controller by means of Subspace Model Identification using the internal model control (IMC) approach. Using IMC an equivalent feed forward control problem is obtained, which is solved by the Causal Wiener filter for the H2 optimal controller. The robust variant, called...article 2004
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Fraanje, P.R. (author), Verhaegen, M. (author), Doelman, N.J. (author), Technisch Physische Dienst TNO - TH (author)The Filtered-U LMS algorithm, proposed by Eriksson for active noise control applications, adapts the coefficients of an infinite-impulse response controller. Conditions for global convergence of the Filtered-U LMS algorithm were presented by Wang and Ren (Signal Processing, 73 (1999) 3) and Mosquera and Pérez-González (Signal Processing, 80 ...article 2003
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Fraanje, P.R. (author), Verhaegen, M. (author), Doelman, N.J. (author), Berkhoff, A.P. (author)Adaptive Active Control algorithms, such as the well known Filtered-X LMS and Filtered-U LMS algorithms, often do not yield optimal performance in practise, due to finite length impulse response of the controller (Filtered-X) or convergence to a local minimum (Filtered-U). In addition, especially for the MIMO case, these adaptive controllers...conference paper 2002