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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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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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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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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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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

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Distributed control: A sequentially semi-separable approach for spatially heterogeneous linear systems

Rice, J.K. (author), Verhaegen, M. (author)

We consider the problem of designing controllers for spatially-varying interconnected systems distributed in one spatial dimension. The matrix structure of such systems can be exploited to allow fast analysis and design of centralized controllers with simple distributed implementations. Iterative algorithms are provided for stability analysis, H...

journal article 2009

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Distributed Control for Identical Dynamically Coupled Systems: A Decomposition Approach

Massioni, P. (author), Verhaegen, M. (author)

We consider the problem of designing distributed controllers for a class of systems which can be obtained from the interconnection of a number of identical subsystems. If the state space matrices of these systems satisfy a certain structural property, then it is possible to derive a procedure for designing a distributed controller which has the...

journal article 2009

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Extracting hysteresis from nonlinear measurement of wavefront-sensorless adaptive optics system

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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A Data-Driven H2-Optimal Control Approach for Adaptive Optics

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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Exploiting the spatiotemporal correlation in adaptive optics using data-driven H2-optimal control

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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Two-Stage Kalman Filtering via Structured Square-Root

Kanev, S. (author), Verhaegen, M. (author)

This paper considers the problem of estimating an unknown input (bias) by means of the augmented-state Kalman (AKF) filter. To reduce the computational complexity of the AKF, [12] recently developed an optimal two-stage Kalman filter (TS-AKF) that separates the bias estimation from the state estimation, and shows that his new two-stage estimator...

journal article 2005