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Wavefront coding with adaptive optics

Agbana, T.E. (author), Soloviev, O. (author), Bezzubik, V. (author), Patlan, V. (author), Verhaegen, M. (author), Vdovin, G.V. (author)

We have implemented an extended depth of field optical system by wavefront coding with a micromachined membrane deformable mirror. This approach provides a versatile extension to standard wavefront coding based on fixed phase mask. First experimental results validate the feasibility of the use of adaptive optics for variable depth wavefront...

conference paper 2015

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Automated spherical aberration correction in scanning confocal microscopy

Yoo, H.W. (author), Royen, M.E. (author), van Cappellen, W.A. (author), Houtsmuller, A.B. (author), Verhaegen, M.H.G. (author), Schitter, G. (author)

Mismatch between the refractive indexes of immersion media and glass coverslips introduces spherical aberrations in microscopes especially for high numerical aperture objectives. This contribution demonstrates an automated adjustment of the coverslip correction collar in scanning confocal microscopy to compensate for spherical aberrations due to...

journal article 2014

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Focal-plane wavefront sensing with high-order adaptive optics systems

Korkiakoski, V.A. (author), Keller, C.U. (author), Doelman, N. (author), Kenworthy, M. (author), Otten, G. (author), Verhaegen, M. (author)

We investigate methods to calibrate the non-common path aberrations at an adaptive optics system having a wavefront-correcting device working with an extremely high resolution (larger than 150x150 correcting elements). We use focal-plane images collected successively, the corresponding phase-diversity information and numerically efficient...

conference paper 2014

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Fast & Furious focal-plane wavefront sensing

Korkiakoski, V.A. (author), Keller, C.U. (author), Doelman, N. (author), Kenworthy, M. (author), Otten, G. (author), Verhaegen, M.H.G. (author)

We present two complementary algorithms suitable for using focal-plane measurements to control a wavefront corrector with an extremely high-spatial resolution. The algorithms use linear approximations to iteratively minimize the aberrations seen by the focal-plane camera. The first algorithm, Fast & Furious (FF), uses a weak-aberration...

journal article 2014

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Optimization-based wavefront sensorless adaptive optics for multiphoton microscopy

Antonello, J. (author), Van Werkhoven, T. (author), Verhaegen, M. (author), Truong, H.H. (author), Keller, C.U. (author), Gerritsen, H.C. (author)

Optical aberrations have detrimental effects in multiphoton microscopy. These effects can be curtailed by implementing model-based wavefront sensorless adaptive optics, which only requires the addition of a wavefront shaping device, such as a deformable mirror (DM) to an existing microscope. The aberration correction is achieved by maximizing a...

journal article 2014

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Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy

Van Werkhoven, T.I.M. (author), Antonello, J. (author), Truong, H.H. (author), Verhaegen, M. (author), Gerritsen, H.C. (author), Keller, C.U. (author)

Deep imaging in turbid media such as biological tissue is challenging due to scattering and optical aberrations. Adaptive optics has the potential to compensate the tissue aberrations. We present a wavefront sensing scheme for multi-photon scanning microscopes using the pulsed, near-infrared light reflected back from the sample utilising...

journal article 2014

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A class of efficient preconditioners with multilevel sequentially semiseparable matrix structure

Qiu, Y. (author), Van Gijzen, M.B. (author), Van Winderden, J.W. (author), Verhaegen, M.H.G. (author)

This paper presents a class of preconditioners for sparse systems arising from discretized partial differential equations (PDEs). In this class of preconditioners, we exploit the multilevel sequentially semiseparable (MSSS) structure of the system matrix. The off-diagonal blocks of MSSS matrices are of low-rank, which enables fast computations...

conference paper 2013

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Iterative linear focal-plane wavefront correction

Smith, C.S. (author), Marinica, R.M. (author), Den Dekker, A.J. (author), Verhaegen, M.H.G. (author), Korkiakoski, V. (author), Keller, C.U. (author), Doelman, N. (author)

We propose an efficient approximation to the nonlinear phase diversity (PD) method for wavefront reconstruction and correction from intensity measurements with potential of being used in real-time applications. The new iterative linear phase diversity (ILPD) method assumes that the residual phase aberration is small and makes use of a first...

journal article 2013

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Identification of a dynamical model of a thermally actuated deformable mirror

Haber, A. (author), Polo, A. (author), Ravensbergen, S. (author), Urbach, H.P. (author), Verhaegen, M.H.G. (author)

Using the subspace identification technique, we identify a finite dimensional, dynamical model of a recently developed prototype of a thermally actuated deformable mirror (TADM). The main advantage of the identified model over the models described by partial differential equations is its low complexity and low dimensionality. Consequently, the...

journal article 2013

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High precision wavelength estimation method for integrated optics

Oldenbeuving, R.M. (author), Song, H. (author), Schitter, G. (author), Verhaegen, M.H.G. (author), Klein, E.J. (author), Lee, C.J. (author), Offerhaus, H.L. (author), Boller, K.J. (author)

A novel and simple approach to optical wavelength measurement is presented in this paper. The working principle is demonstrated using a tunable waveguide micro ring resonator and single photodiode. The initial calibration is done with a set of known wavelengths and resonator tunings. The combined spectral sensitivity function of the resonator...

journal article 2013

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Modeling the Effect of Wave-front Aberrations in Fiber-based Scanning Optical Microscopy

Verstraete, H.R.G.W. (author), Verhaegen, M.H.G. (author), Kalkman, J. (author)

In scanning microscopy and optical coherence tomography, aberrations of the wave-front cause a loss in intensity and resolution. Intensity and resolution are quantified using Fresnel propagation, Fraunhofer diffraction, and the calculation of overlap integrals.

conference paper 2013

document

Real-time wavefront reconstruction from intensity measurements

Smith, C. (author), Marinica, R. (author), Verhaegen, M. (author)

We propose an efficient approximation to the nonlinear phase diversity method for wavefront reconstruction from intensity measurements. The new method, iterative linear phase diversity (ILPD), assumes that the residual phase aberration is small and makes use of a first order Taylor expansion of the point spread function (PSF) performed for an...

conference paper 2013

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Iterative learning control of a membrane deformable mirror for optimal wavefront correction

Haber, A. (author), Polo, A. (author), Smith, C.S. (author), Pereira, S.F. (author), Ubach, P. (author), Verhaegen, M. (author)

We present an iterative learning control (ILC) algorithm for controlling the shape of a membrane deformable mirror (DM). We furthermore give a physical interpretation of the design parameters of the ILC algorithm. On the basis of this insight, we derive a simple tuning procedure for the ILC algorithm that, in practice, guarantees stable and fast...

journal article 2013

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Semidefinite programming for model-based sensorless adaptive optics

Antonello, J. (author), Verhaegen, M.H.G. (author), Fraanje, R. (author), Van Werkhoven, T. (author), Gerritsen, H.C. (author), Keller, C.U. (author)

Wavefront sensorless adaptive optics methodologies are widely considered in scanning fluorescence microscopy where direct wavefront sensing is challenging. In these methodologies, aberration correction is performed by sequentially changing the settings of the adaptive element until a predetermined image quality metric is optimized. An efficient...

journal article 2012

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Joint optimization of phase diversity and adaptive optics: Demonstration of potential

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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Fault tolerant wind turbine production operation and shutdown (Sustainable Control)

Van Engelen, T. (author), Schuurmans, J. (author), Kanev, S. (author), Dong, J. (author), Verhaegen, M.H.G. (author), Hayashi, Y. (author)

Extreme environmental conditions as well as system failure are real-life phenomena. Especially offshore, extreme environmental conditions and system faults are to be dealt with in an effective way. The project Sustainable Control, a new approach to operate wind turbines (Agentschap NL, grant EOSLT02013) pro- vides the concepts for an integrated...

conference paper 2011

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Model-based aberration correction in a closed-loop wavefront-sensor-less adaptive optics system

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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Fast reconstruction and prediction of frozen flow turbulence based on structured Kalman filtering

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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A Decomposition-Based Approach to Linear Time-Periodic Distributed Control of Satellite Formations

Massioni, P. (author), Keviczky, T. (author), Gill, E.K.A. (author), Verhaegen, M. (author)

In this paper, we consider the problem of designing a distributed controller for a formation of spacecraft following a periodic orbit. Each satellite is controlled locally on the basis of information from only a subset of the others (the nearest ones). We describe the dynamics of each spacecraft by means of a linear time-periodic (LTP)...

journal article 2010

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Two-Degree-of-Freedom Active Vibration Control of a Prototyped “Smart” Rotor

Van Wingerden, J.W. (author), Hulskamp, A. (author), Barlas, A. (author), Houtzager, I. (author), Bersee, H. (author), Van Kuik, G. (author), Verhaegen, M. (author)

This paper studies the load reduction potential of a prototyped “smart” rotor. This is, a rotor where the blades are equipped with a number of control devices that locally change the lift profile on the blade, combined with appropriate sensors and controllers. Experimental models, using dedicated system identification techniques, are developed...

journal article 2010