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Polo, A. (author), Kutchoukov, V. (author), Bociort, F. (author), Pereira, S.F. (author), Urbach, H.P. (author)We apply a phase retrieval algorithm to the intensity pattern of a Hartmann wavefront sensor to measure with enhanced accuracy the phase structure of a Hartmann hole array. It is shown that the rms wavefront error achieved by phase reconstruction is one order of magnitude smaller than the one obtained from a typical centroid algorithm....journal article 2012
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Paris, R. (author), Thurner, T. (author), Berndorfer, T. (author), Yoo, H.W. (author), Schitter, G. (author)Due to their reconfigurability and sensor-near signal processing, smart cameras are ideally suited for applications in optical metrology. This article describes ongoing research activities in this area and demonstrates the efficient implementation of complex algorithms on limited hardware through intelligent systems integration. This enables the...journal article 2012
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Korkiakoski, V. (author), Keller, C.U. (author), Doelman, N. (author), Fraanje, P.R. (author), Verhaegen, M.H.G. (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...journal article 2011
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Ellenbroek, R.M.L. (author)The refractive index of air varies a.o. with temperature, humidity, pressure and the CO2 concentration. Due to atmospheric turbulence this refractive index varies both in space and in time, leading to aberrations in images of light having passed though it. These aberrations limit the achievable resolution of optical telescopes such that the...doctoral thesis 2011
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- Schutten, G.J.M. (author) master thesis 2011
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Ten Have, E.S. (author), Vdovin, G. (author)Closed-loop adaptive optical correction using a deformable mirror based on the total internal reflection (TIR) from an electrostatically deformed liquid-air interface was performed on a collimated beam of a HeNe-laser that was aberrated by a rotating phase disk. The frequency response of the system was measured and the influence of liquid...conference paper 2011
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Song, H. (author)Adaptive optics (AO), also called as Smart Optics, has received increasing attention in the past decades. The main idea behind AO is to actively sense and compensate the optical aberration in the system such that the image resolution is improved or the light beam is well focused. The applications of AO include ground-based telescopes, scanning...doctoral thesis 2011
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Fraanje, R. (author), Doelman, N. (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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Mahajan, V.N. (author), Aftab, M. (author)The theory of wavefront analysis of a noncircular wavefront is given and applied for a systematic comparison of the use of annular and Zernike circle polynomials for the analysis of an annular wavefront. It is shown that, unlike the annular coefficients, the circle coefficients generally change as the number of polynomials used in the expansion...journal article 2010
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Song, H. (author), Fraanje, R. (author), Schitter, G. (author), Kroese, H. (author), Vdovin, G. (author), Verhaegen, M. (author)In many scientific and medical applications, such as laser systems and microscopes, wavefront-sensor-less (WFSless) adaptive optics (AO) systems are used to improve the laser beam quality or the image resolution by correcting the wavefront aberration in the optical path. The lack of direct wavefront measurement in WFSless AO systems imposes a...journal article 2010
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Fraanje, P.R. (author), Rice, J. (author), Verhaegen, M. (author), Doelman, N. (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...journal article 2010
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Song, H. (author), Vdovin, G. (author), Fraanje, R. (author), Schitter, G. (author), Verhaegen, M. (author)In many scientific and medical applications wavefront-sensorless adaptive optics (AO) systems are used to correct the wavefront aberration by optimizing a certain target parameter, which is nonlinear with respect to the control signal to the deformable mirror (DM). Hysteresis is the most common nonlinearity of DMs, which can be corrected if the...journal article 2008
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Loktev, M. (author), Vdovin, G. (author), Soloviev, O. (author)We describe a compact integrated module implementing a low-cost adaptive optics system. It is targeted as a correction system for small telescopes with primary mirror diameter up to 1 m, operating on a natural guide star with magnitude at least 4 (for a 25 cm telescope). It is supposed to provide stable diffraction-limited imaging of stars,...conference paper 2008
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Hinnen, K. (author), Verhaegen, M. (author), Doelman, N. (author)Adaptive optics (AO) is used in ground-based astronomical telescopes to improve the resolution by counteracting the effects of atmospheric turbulence. Most AO systems are based on a simple control law that neglects the temporal evolution of the distortions introduced by the atmosphere. This paper presents a datadriven control design approach...journal article 2008
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Simonov, A.N. (author), Vdovine, G.V. (author), Loktev, M. (author)We present a prototype of an adaptive intraocular lens based on a modal liquid-crystal spatial phase modulator with wireless control. The modal corrector consists of a nematic liquid-crystal layer sandwiched between two glass substrates with transparent low- and high-ohmic electrodes, respectively. Adaptive correction of ocular aberrations is...journal article 2007
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Hinnen, K. (author), Verhaegen, M.H.G. (author), Doelman, N. (author)A recently proposed data-driven H2-optimal control approach is demonstrated on a laboratory setup. Most adaptive optics (AO) systems are based on a control law that neglects the temporal evolution of the wavefront. The proposed control approach is able to exploit the spatiotemporal correlation in the wavefront without assuming any form of...journal article 2007
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Loktev, M. (author), Vdovine, G.V. (author), Klimov, N. (author), Kotova, S. (author)A novel liquid crystal (LC) wavefront corrector with smooth modal influence functions is proposed and realized. The device consists of a thin layer of planar aligned nematic LC sandwiched between a glass plate with a conductive electrode and a plate made of ceramic material with a very high dielectric constant. Control electrodes are positioned...journal article 2007
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Hinnen, K.J.G. (author)Adaptive optics (AO) is a technique to actively correct the wavefront distortions introduced in a light beam as it propagates through a turbulent medium. Nowadays, it is commonly applied in ground-based telescopes to counteract the devastating effect of atmospheric turbulence. This thesis focuses on the control aspects of AO. Whereas most AO...doctoral thesis 2007
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Vuelban, E.M. (author)Abstract not availabledoctoral thesis 2006
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Hinnen, K. (author), Verhaegen, M. (author), Doelman, N. (author)Most adaptive optics systems (AO) are based on a simple control law that is unable to account for the temporal evolution of the wavefront. In this paper, a recently proposed data-driven H2-optimal control approach is demonstrated on an AO laboratory setup. The proposed control approach does not assume any form of decoupling and can therefore...conference paper 2006