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  • 1.
    Akram, Muhammad Nadeem
    et al.
    University of South-Eastern Norway, Norway.
    Baraas, Rigmor C.
    University of South-Eastern Norway, Norway.
    Baskaran, Karthikeyan
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Improved wide-field emmetropic human eye model based on ocular wavefront measurements and geometry-independent gradient index lens2018In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 35, no 11, p. 1954-1967Article in journal (Refereed)
    Abstract [en]

    There is a need to better understand the peripheral optics of the human eye and their correction. Current eye models have some limitations to accurately predict the wavefront errors for the emmetropic eye over a wide field. The aim here was to develop an anatomically correct optical model of the human eye that closely reproduces the wavefront of an average Caucasian-only emmetropic eye across a wide visual field. Using an optical design program, a schematic eye was constructed based on ocular wavefront measurements of the right eyes of thirty healthy young emmetropic individuals over a wide visual field (from 40° nasal to 40° temporal and up to 20° inferior field). Anatomical parameters, asymmetries, and dispersion properties of the eye’s different optical components were taken into account. A geometry-independent gradient index model was employed to better represent the crystalline lens. The RMS wavefront error, wavefront shapes, dominant Zernike coefficients, nasal-temporal asymmetries, and dispersion properties of the developed schematic eye closely matched the corresponding measured values across the visual field. The developed model can help in the design of wide-field ophthalmic instruments and is useful in the study and simulations of the peripheral optics of the human eye.

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  • 2.
    Cai, Yangjian
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Lin, Q.
    Zhu, S. Y.
    Coincidence subwavelength fractional Fourier transform2006In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 23, no 4, p. 835-841Article in journal (Refereed)
    Abstract [en]

    The coincidence subwavelength fractional Fourier transforms (FRTs) with entangled photon pairs and incoherent light radiation are introduced as an extension of the recently introduced coincidence FRT. Optical systems for implementing the coincidence subwavelength FRTs are designed. The width of the coincidence subwavelength FRT pattern is two times narrower than the width of the coincidence FRT. The coincidence subwavelength FRT with partially coherent light radiation is also studied numerically. Differences between the coincidence subwavelength FRT with entangled photon pairs and that with incoherent light radiation are discussed.

  • 3.
    Coppel, L.G.
    et al.
    RISE, Innventia.
    Neuman, M.
    Edström, P.
    Extension of the Stokes equation for layered constructions to fluorescent turbid media2012In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, no 4, p. 574-578Article in journal (Refereed)
  • 4.
    Doelman, Reinier
    et al.
    Delft Univ Technol, Netherlands.
    Klingspor, Måns
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Hansson, Anders
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Löfberg, Johan
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Verhaegen, Michel
    Delft Univ Technol, Netherlands.
    Identification of the dynamics of time-varying phase aberrations from time histories of the point-spread function2019In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 36, no 5, p. 809-817Article in journal (Refereed)
    Abstract [en]

    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 can be described by a vector-valued autoregressive (VAR) model. We propose an iterative method based on a convex heuristic for a rank-constrained optimization problem, to jointly estimate the parameters of the VAR model and the Zernike coefficients from a time series of measurements of the point-spread function (PSF) of the optical system. By assuming the phase aberration is small, the relation between aberration and PSF measurements can be approximated by a quadratic function. As such, our method is a blind identification method for linear dynamics in a stochastic Wiener system with a quadratic nonlinearity at the output and a phase retrieval method that uses a time-evolution-model constraint and a single image at every time step. (c) 2019 Optical Society of America.

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  • 5.
    Ekberg, Peter
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Su, Rong
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Chang, Ernest W.
    Yun, Seok Hyun
    Mattsson, Lars
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Fast and accurate metrology of multi-layered ceramic materials by an automated boundary detection algorithm developed for optical coherence tomography data2014In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 31, no 2, p. 217-226Article in journal (Refereed)
    Abstract [en]

    Optical coherence tomography (OCT) is useful for materials defect analysis and inspection with the additional possibility of quantitative dimensional metrology. Here, we present an automated image-processing algorithm for OCT analysis of roll-to-roll multilayers in 3D manufacturing of advanced ceramics. It has the advantage of avoiding filtering and preset modeling, and will, thus, introduce a simplification. The algorithm is validated for its capability of measuring the thickness of ceramic layers, extracting the boundaries of embedded features with irregular shapes, and detecting the geometric deformations. The accuracy of the algorithm is very high, and the reliability is better than 1 mu m when evaluating with the OCT images using the same gauge block step height reference. The method may be suitable for industrial applications to the rapid inspection of manufactured samples with high accuracy and robustness.

  • 6.
    Freitag, Fabio Batista
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience. Univ Fed Rio Grande do Norte, Lab Sensory Ecol, BR-59072970 Natal, RN, Brazil; Univ Fed Rio Grande do Norte, Lab Adv Study Primates, BR-59072970 Natal, RN, Brazil.
    Pessoa, Daniel Marques Almeida
    Univ Fed Rio Grande do Norte, Lab Sensory Ecol, BR-59072970 Natal, RN, Brazil; Univ Fed Rio Grande do Norte, Lab Adv Study Primates, BR-59072970 Natal, RN, Brazil.
    Effect of luminosity on color discrimination of dichromatic marmosets (Callithrix jacchus)2012In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 29, no 2, p. A216-22Article in journal (Refereed)
    Abstract [en]

    Psychophysical data have shown that under mesopic conditions cones and rods can interact, improving color vision. Since electrophysiological data have suggested that rods of dichromatic marmosets appear to be active at higher luminance, we aimed to investigate the effect of different levels of sunlight on the foraging abilities of male dichromatic marmosets. Captive marmosets were observed under three different conditions, with respect to their performance in detecting colored food items against a green background. Compared to high and low light intensities, intermediate luminosities significantly increased detection of orange targets by male dichromats, an indication of rod intrusion.

  • 7.
    Gerosa, Rodrigo M.
    et al.
    Mackenzie Presbyterian University, Brazil.
    Sudirman, Aziza
    RISE, Swedish ICT, Acreo, Fiber Optics. KTH Royal Institute of Technology, Sweden.
    Menezes, Leonardo de S.
    Federal University of Pernambuco, Brazil.
    Margulis, Walter
    RISE, Swedish ICT, Acreo, Fiber Optics. KTH Royal Institute of Technology, Sweden.
    de Matos, Christiano J. S.
    Mackenzie Presbyterian University, Brazil.
    All-fiber high repetition rate dye laser2015In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 2, no 2, p. 186-193Article in journal (Refereed)
    Abstract [en]

    Optofluidic dye lasers may play a significant role in future laser applications in numerous areas, combining wavelength flexibility with integration and ease of operation. Nevertheless, no all-fiber integrated dye lasers have been demonstrated so far. In this paper, we report on a series of optofluidic all-fiber Rhodamine optical sources operating at a repetition rate as high as 1 kHz. Dye bleaching is avoided by circulating the Rhodamine dye during optical excitation. The laser radiation is extracted via conventional fibers that are spliced to the dye-filled capillary active medium. A tuneable amplified spontaneous emission source, a multimode laser, and a few transverse-mode laser are demonstrated by adjusting the setup. Threshold pump energies as low as similar to 1 mu J and slope efficiencies of up to mu 9% were obtained, indicating the potential for realworld applications in areas such as spectroscopy and biomedicine.

  • 8. Hegedues, Ramon
    et al.
    Akesson, Susanne
    Horvath, Gabor
    Polarization patterns of thick clouds: overcast skies have distribution of the angle of polarization similar to that of clear skies2007In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 24, no 8, p. 2347-2356Article in journal (Refereed)
    Abstract [en]

    The distribution of polarization in the overcast sky has been practically unknown. Earlier the polarization of light from heavily overcast skies (when the Sun’s disc was invisible) has been measured only sporadically in some celestial points by point-source polarimetry. What kind of patterns of the degree p and angle a of linear polarization of light could develop after transmission through a thick layer of ice or water clouds? To answer this question, we measured the p and a patterns of numerous totally overcast skies on the Arctic Ocean and in Hungary by full-sky imaging polarimetry. We present here our finding that depending on the optical thickness of the cloud layer, the pattern of a of light transmitted through the ice or water clouds of totally overcast skies is qualitatively the same as the a pattern of the clear sky. Under overcast conditions the value of a is determined predominantly by scattering on cloud particles themselves. Nevertheless, the degrees of linear polarization of light from overcast skies were rather low (p <= 16 %). Our results obtained under overcast conditions complete the earlier findings that the a pattern of the clear sky also appears in partly cloudy, foggy, and smoky skies. Our results show that the celestial distribution of the direction of polarization is a very robust pattern being qualitatively always the same under all possible sky conditions. This is of great importance for the orientation of polarization-sensitive animals based on sky polarization under conditions when the Sun is not visible. (c) 2007 Optical Society of America.

  • 9. Hegedus, R.
    et al.
    Åkesson, S.
    Horvath, G.
    Polarization of "water-skies" above arctic open waters: how polynyas in the ice-cover can be visually detected from a distance2007In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 24Article in journal (Refereed)
    Abstract [en]

    The foggy sky above a white ice-cover and a dark water surface (permanent polynya or temporary lead) is white and dark gray, phenomena called the "ice-sky" and the "water-sky," respectively. Captains of icebreaker ships used to search for not-directly-visible open waters remotely on the basis of the water sky. Animals depending on open waters in the Arctic region may also detect not-directly-visible waters from a distance by means of the water sky. Since the polarization of ice-skies and water-skies has not, to our knowledge, been studied before, we measured the polarization patterns of water-skies above polynyas in the arctic ice-cover during the Beringia 2005 Swedish polar research expedition to the North Pole region. We show that there are statistically significant differences in the angle of polarization between the water-sky and the ice-sky. This polarization phenomenon could help biological and man-made sensors to detect open waters not directly visible from a distance. However, the threshold of polarization-based detection would be rather low, because the degree of linear polarization of light radiated by water-skies and ice-skies is not higher than 10%. (c) 2006 Optical Society of America.

  • 10. Huntley, J.M.
    et al.
    Saldner, Henrik O.
    Luleå University of Technology.
    Error-reduction methods for shape measurement by temporal phase unwrapping1997In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 14, no 12, p. 3188-3196Article in journal (Refereed)
    Abstract [en]

    Temporal phase unwrapping is a method of analyzing fringe patterns in which the fringe phase at each pixel is measured and unwrapped as a function of time t. We propose two methods for improving the signal-to-noise ratio of the total phase change by incorporating data from the intermediate phase values. The first involves fitting the expected curve to the measured phase history; the second involves Fourier transformation of the corresponding phasors. The performance of these methods is compared both experimentally, with data from a fringe projector based on a spatial-light modulator, and numerically. It is shown that the optimum performance is given by the Fourier transform method. The best way to use the first method is with decreasing exponentially with time from its maximum value to zero; this provides significant improvements in reliability, accuracy, and computation time compared with the original temporal unwrapping algorithm

  • 11.
    Hällstig, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Martin, Torleif
    Sjöqvist, Lars
    Lindgren, Mikael
    Polarization properties of a nematic liquid-crystal spatial light modulator for phase modulation2005In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 22, no 1, p. 177-184Article in journal (Refereed)
    Abstract [en]

    The polarization properties of a nematic zero-twist liquid-crystal (NLC) spatial light modulator (SLM) were studied. A large ratio between the liquid-crystal (LC) layer thickness and the pixel pitch combined with spatial variations in the applied electric field causes fringing fields between pixels. Depending on the LC alignment, the electric field components within the LC layer can result in a twist deformation. The produced inhomogeneous optical anisotropy affects the polarization of light propagating through the device. We experimentally examined polarization effects in different diffraction orders for both binary and blazed phase gratings. Simulations of the LC deformation together with finite-difference time-domain simulations for the optical propagation were used to calculate the corresponding far-field intensities. It was demonstrated how rigorous simulations of the NLC SLM properties can be used to understand the polarization features of different diffraction orders.

  • 12. Jaeken, Bart
    et al.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Artal, Pablo
    Peripheral aberrations in the human eye for different wavelengths: off-axis chromatic aberration2011In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 28, no 9, p. 1871-1879Article in journal (Refereed)
    Abstract [en]

    The interest in the eye's off-axis aberrations has increased strongly. On-axis the conversion of the aberration magnitude between different wavelengths is well known. We verified if this compensation is correct also for off-axis measurements by building a wavelength tunable peripheral Hartmann-Shack sensor and measuring 11 subjects out to +/- 30 degrees in the horizontal visual field. At the fovea, an average longitudinal chromatic aberration of 1D between red (671 nm) and blue (473 nm) light was found, and it increased slightly with eccentricity (up to 1.2D). A similar trend was measured for astigmatism as a function of wavelength (increase similar to 0.15D). Computational ray tracing in model eyes showed that the origin of the small increase of chromatic aberrations with eccentricity is the change of the oblique power of the refractive surfaces in the eye. Factors related to increase of axial length and refractive index of the eye were found to have a very small influence.

  • 13.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Irreducible representations of finite groups in the T-matrix formulation of the electromagnetic scattering problem2005In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 22, no 6, p. 1187-1199Article in journal (Refereed)
    Abstract [en]

    For particles with discrete geometrical symmetries, a group-theoretical method is presented for transforming the matrix quantities in the T-matrix description of the electromagnetic scattering problem from the reducible basis of vector spherical wave functions into a new basis in which all matrix quantities become block diagonal. The notorious ill-conditioning problems in the inversion of the Q matrix are thus considerably alleviated, and the matrix inversion becomes numerically more expedient. The method can be applied to any point group. For the specific example of the D-6h group, it is demonstrated that computations in the new basis are faster by a factor of 3.6 as compared with computations that use the reducible basis. Most importantly, the method is capable of extending the range of size parameters for which convergent results can be obtained by 50%. (c) 2005 Optical Society of America

  • 14. Kellock, Henri
    et al.
    Setälä, Tero
    Shirai, Tomohiro
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Image quality in double- and triple-intensity ghost imaging with classical partially polarized light2012In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 29, no 11, p. 2459-2468Article in journal (Refereed)
    Abstract [en]

    Classical ghost imaging is a correlation-imaging technique in which the image of the object is found through intensity correlations of light. We analyze three different quality parameters, namely the visibility, the signal-to-noise ratio (SNR), and the contrast-to-noise ratio (CNR), to assess the performance of double-and triple-intensity correlation-imaging setups. The source is a random partially polarized beam of light obeying Gaussian statistics, and the image quality is evaluated as a function of the degree of polarization (DoP). We show that the visibility improves when the DoP and the order of imaging increase, while the SNR behaves oppositely. The CNR is for the most part independent of DoP and the imaging order. The results are important for the development of new imaging devices using partially polarized light.

  • 15.
    Laurell, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Hadi, K. E.
    Sundheimer, M.
    Ashieri, P.
    de Micheli, M. P.
    Ostrowsky, D.
    Quasi-phase-matchedparametric interacions in proton-exchanged lithium niobate waveguides1997In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532Article in journal (Refereed)
  • 16.
    Lenz, Reiner
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Eye movements and information geometry2016In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 33, no 8, p. 1598-1603Article in journal (Refereed)
    Abstract [en]

    The human visual system uses eye movements to gather visual information. They act as visual scanning processes and can roughly be divided into two different types: small movements around fixation points and larger movements between fixation points. The processes are often modeled as random walks, and recent models based on heavy tail distributions, also known as Lev\&\#x00FD; flights, have been used in these investigations. In contrast to these approaches we do not model the stochastic processes, but we will show that the step lengths of the movements between fixation points follow generalized Pareto distributions (GPDs). We will use general arguments from the theory of extreme value statistics to motivate the usage of the GPD and show empirically that the GPDs provide good fits for measured eye tracking data. In the framework of information geometry the GPDs with a common threshold form a two-dimensional Riemann manifold with the Fisher information matrix as a metric. We compute the Fisher information matrix for the GPDs and introduce a feature vector describing a GPD by its parameters and different geometrical properties of its Fisher information matrix. In our statistical analysis we use eye tracker measurements in a database with 15 observers viewing 1003 images under free-viewing conditions. We use Matlab functions with their standard parameter settings and show that a naive Bayes classifier using the eigenvalues of the Fisher information matrix provides a high classification rate identifying the 15 observers in the database.

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  • 17.
    Lundström, Linda
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Gustafsson, Jörgen
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Population distribution of wavefront aberrations in the peripheral human eye2009In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 26, no 10, p. 2192-2198Article in journal (Refereed)
    Abstract [en]

    We present a population study of peripheral wavefront aberrations in large off-axis angles in terms of Zernike coefficients. A laboratory Hartmann-Shack sensor was used to assess the aberrations in 0 degrees, 20 degrees, and 30 degrees in the nasal visual field of 43 normal eyes. The elliptical pupil meant that the quantification could be done in different ways. The three approaches used were (1) over a circular aperture encircling the pupil, (2) over a stretched version of the elliptical pupil, and (3) over a circular aperture within the pupil (MATLAB conversion code given). Astigmatism (c(2)(2)) increased quadratically and coma (c(3)(1)) linearly with the horizontal viewing angle, whereas spherical aberration (c(4)(0)) decreased slightly toward the periphery. There was no correlation between defocus and angle, although some trends were found when the subjects were divided into groups depending on refractive error. When comparing results of different studies it has to be kept in mind that the coefficients differ depending on how the elliptical pupil is taken into consideration.

  • 18.
    Marklund, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Noise-insensitive two-dimensional phase unwrapping method1998In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 15, no 1, p. 42-60Article in journal (Refereed)
    Abstract [en]

    A new two-dimensional phase unwrapping method, based on an iterative computational procedure, is proposed. The method, which is derived with the use of a global cost function to minimize the phase discontinuities in the unwrapped phase map, has shown to produce robust and reliable results on very noisy phase data. Preprocessing operations, such as noise cleaning or segmentation, will in many cases be superfluous but may be included

  • 19.
    Marklund, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Robust fringe density and direction estimation in noisy phase maps2001In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 18, no 11, p. 2717-2727Article in journal (Refereed)
    Abstract [en]

    A method for automated fringe analysis is presented. It robustly estimates local fringe density and direction in noisy wrapped phase maps. Such information can be used to improve the performance of two-dimensional phase unwrapping methods, to construct phase-jump-preserving filtering strategies, and also to perform robust segmentation of phase data. The method, which is highly insensitive to noise, is model based and performs the estimation in the Fourier domain.

  • 20.
    Mochizuki, Rika
    et al.
    NTT Solut Lab, Japan.
    Kojima, Takanori
    Chuo University, Japan.
    Lenz, Reiner
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Chao, Jinhui
    Chuo University, Japan.
    Color-weak compensation using local affine isometry based on discrimination threshold matching2015In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 32, no 11, p. 2093-2103Article in journal (Refereed)
    Abstract [en]

    We develop algorithms for color-weak compensation and color-weak simulation based on Riemannian geometry models of color spaces. The objective function introduced measures the match of color discrimination thresholds of average normal observers and a color-weak observer. The developed matching process makes use of local affine maps between color spaces of color-normal and color-weak observers. The method can be used to generate displays of images that provide color-normal and color-weak observers with a similar color difference experience. It can also be used to simulate the perception of a color-weak observer for color-normal observers. We also introduce a new database of measurements of color discrimination threshold data for color-normal and color-weak observers obtained at different lightness levels in CIELUV space. The compensation methods include compensations of chromaticity using local affine maps between chromaticity planes of color-normal and color-weak observers, and one-dimensional (1D) compensation on lightness. We describe how to determine correspondences between the origins of local coordinates in color spaces of color-normal and color-weak observers using a neighborhood expansion method. After matching the origins of the two coordinate systems, a local affine map is estimated by solving a nonlinear equation, or singular-value-decomposition (SVD). We apply the methods to natural images and evaluate their performance using the semantic differential (SD) method. (C) 2015 Optical Society of America

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  • 21.
    Papadogiannis, Petros
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Romashchenko, Dmitry
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. Johnson & Johnson Vis, R&D, Groningen, Netherlands..
    Vedhakrishnan, Shrilekha
    CSIC, Inst Opt Daza de Valdes, Madrid, Spain..
    Persson, Britta
    Karolinska Inst, Unit Optometry, Stockholm, Sweden..
    Pettersson, Anna Lindskoog
    Karolinska Inst, Unit Optometry, Stockholm, Sweden..
    Marcos, Susana
    CSIC, Inst Opt Daza de Valdes, Madrid, Spain.;Univ Rochester, Ctr Visual Sci, Inst Opt, Rochester, NY 14642 USA.;Univ Rochester, Flaum Eye Inst, Rochester, NY 14642 USA..
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Foveal and peripheral visual quality and accommodation with multifocal contact lenses2022In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 39, no 6, p. B39-B49, article id 060B39Article in journal (Refereed)
    Abstract [en]

    Multifocal contact lenses are increasingly popular interventions for controlling myopia. This study presents the short-termeffects of multifocal contact lenses on foveal and peripheral vision. TheMiSight contact lenses designed to inhibit myopia progression and the 1-Day Acuvue Moist contact lenses designed for presbyopia were investigated. The MiSight produced similar foveal results to spectacles despite the increased astigmatism and coma. The MiSight also reduced the low-contrast resolution acuity in the periphery, despite no clear change in relative peripheral refraction. When compared with spectacles, Acuvue Moist decreased accommodative response and reduced foveal high- and low-contrast resolution acuity, whereas peripheral thresholds were more similar to those of spectacles. The most likely treatment property for myopia control by theMiSight is the contrast reduction in the peripheral visual field and the changed accommodation.

  • 22. Réfrégier, P.
    et al.
    Goudail, F.
    Chavel, P.
    Friberg, Ari
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Entropy of partially polarized light and application to statistical processing techniques2004In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 21, no 11, p. 2124-2134Article in journal (Refereed)
    Abstract [en]

    We have analyzed entropy properties of coherent and partially polarized light in an arbitrary number of spatial dimensions. We show that for Gaussian fields, the Shannon entropy is a simple function of the intensity and of the Barakat degree of polarization. In particular, we provide a probabilistic interpretation of this definition of the degree of polarization. Using information theory results, we also deduce some physical properties of partially polarized light such as additivity of the entropy and depolarization effects induced by mixing partially polarized states of light. Finally, we demonstrate that entropy measures can play an important role in segmentation and detection tasks.

  • 23.
    Schubert, Mathias
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. University of Nebraska, NE 68588 USA; Leibniz Institute Polymer Research IPF Dresden, Germany.
    Kuhne, Philipp
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Hofmann, Tino
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA.
    Optical Hall effect-model description: tutorial2016In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 33, no 8, p. 1553-1568Article in journal (Refereed)
    Abstract [en]

    The optical Hall effect is a physical phenomenon that describes the occurrence of magnetic-field-induced dielectric displacement at optical wavelengths, transverse and longitudinal to the incident electric field, and analogous to the static electrical Hall effect. The electrical Hall effect and certain cases of the optical Hall effect observations can be explained by extensions of the classic Drude model for the transport of electrons in metals. The optical Hall effect is most useful for characterization of electrical properties in semiconductors. Among many advantages, while the optical Hall effect dispenses with the need of electrical contacts, electrical material properties such as effective mass and mobility parameters, including their anisotropy as well as carrier type and density, can be determined from the optical Hall effect. Measurement of the optical Hall effect can be performed within the concept of generalized ellipsometry at an oblique angle of incidence. In this paper, we review and discuss physical model equations, which can be used to calculate the optical Hall effect in single- and multiple-layered structures of semiconductor materials. We define the optical Hall effect dielectric function tensor, demonstrate diagonalization approaches, and show requirements for the optical Hall effect tensor from energy conservation. We discuss both continuum and quantum approaches, and we provide a brief description of the generalized ellipsometry concept, the Mueller matrix calculus, and a 4 x 4 matrix algebra to calculate data accessible by experiment. In a follow-up paper, we will discuss strategies and approaches for experimental data acquisition and analysis. (C) 2016 Optical Society of America

  • 24.
    Shabbir, Saroosh
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Björk, Gunnar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Arbitrary interference curves by coincidence detection: Theory and experiment2013In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 30, no 10, p. 1921-1928Article in journal (Refereed)
    Abstract [en]

    We discuss how to use coincidence detection to generate unusual, nonsinusoidal interference curves by using not a single detector, but several in coincidence. The method works for both strong (classical) and weak (on the fewphoton level) light, although in the latter case the detection becomes probabilistic with low efficiency. Using the method, one can tailor the coincidence measurement setup to obtain essentially any interference pattern. We then use the method to experimentally demonstrate phase-difference state interference patterns in the few-photon regime that are highly nonsinusoidal. We also discuss optimal implementation of the method with regard to fluctuations and success probability, and we analyze the origin and magnitude of errors.

  • 25. Shirai, Tomohiro
    et al.
    Kellock, Henri
    Setälä, Tero
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Imaging through an aberrating medium with classical ghost diffraction2012In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 29, no 7, p. 1288-1292Article in journal (Refereed)
    Abstract [en]

    We describe a method for image transmission through an aberrating medium by means of a modified configuration for conventional ghost diffraction with classical incoherent beams. On the basis of optical coherence theory, we show that the effects of phase disturbances, be they deterministic or random, can be canceled out in our method and the squared modulus of the Fourier transform of the object is obtained in terms of intensity-correlation measurements. From the measurement data, the object can be reconstructed using standard phase retrieval algorithms.

  • 26.
    Tabernero, Juan
    et al.
    Univ Murcia, Murcia, Spain..
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Schwarz, Christina
    Univ Tubingen, Tubingen, Germany..
    Vohnsen, Brian
    Univ Coll Dublin, Dublin, Ireland..
    Visual and Physiological Optics: introduction to the joint feature issue in Biomedical Optics Express and Journal of the Optical Society of America A2023In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 40, no 7, p. VPO1-VPO2Article in journal (Other academic)
    Abstract [en]

    This feature issue collects articles presented at the tenth Visual and Physiological Optics meeting (VPO2022), held August 29-31, 2022, in Cambridge, UK. This joint feature issue between Biomedical Optics Express and Journal of the Optical Society of America A includes articles that cover the broad range of topics addressed at the meeting and examples of the current state of research in the field.

  • 27.
    Venkataraman, Abinaya Priya
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Papadogiannis, Petros
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Romashchenko, Dmitry
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Winter, Simon
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Peripheral resolution and contrast sensitivity: effects of monochromatic and chromatic aberrations2019In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 36, no 4, p. B52-B57Article in journal (Refereed)
    Abstract [en]

    Correction and manipulation of peripheral refractive errors are indispensable for people with central vision loss and in optical interventions for myopia control. This study investigates further enhancements of peripheral vision by compensating for monochromatic higher-order aberrations (with an adaptive optics system) and chromatic aberrations (with a narrowband green filter, 550 nm) in the 20 degrees nasal visual field. Both high-contrast detection cutoff and contrast sensitivity improved with optical correction. This improvement was most evident for gratings oriented perpendicular to the meridian due to asymmetric optical errors. When the natural monochromatic higher-order aberrations are large, resolution of 10% contrast oblique gratings can also be improved with correction of these errors. Though peripheral vision is mainly limited by refractive errors and neural factors, higher-order aberration correction beyond conventional refractive errors can still improve peripheral vision under certain circumstances.

  • 28. Voipio, Timo
    et al.
    Setälä, Tero
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Partial polarization theory of pulsed optical beams2013In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 30, no 1, p. 71-81Article in journal (Refereed)
    Abstract [en]

    We introduce a consistent matrix formalism for the characterization of partial polarization and coherence of random, nonstationary electromagnetic beams in time and frequency domains. We derive the temporal and spectral degrees of polarization and the Stokes parameters in terms of the time-domain and frequency-domain polarization matrices. The connections between temporal polarization and spectral coherence on the one hand and spectral polarization and temporal coherence on the other hand are discussed. Additionally, we establish equivalence theorems for fields with different temporal coherence properties to have the same spectral polarization states and for fields with different spectral coherence properties to possess identical temporal polarization. The theory is illustrated by analyzing specific examples of time-domain and frequency-domain electromagnetic Gaussian Schell-model pulsed beams.

  • 29.
    Wernersson, Erik L. G.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Boone, Matthieu N.
    Van den Bulcke, Jan
    Van Hoorebeke, Luc
    Luengo Hendriks, Cris L.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Postprocessing method for reducing phase effects in reconstructed microcomputed-tomography data2013In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 30, no 3, p. 455-461Article in journal (Refereed)
    Abstract [en]

    With increased resolution in x-ray computed tomography, refraction adds increasingly to the attenuation signal. Though potentially beneficial, the artifacts caused by refraction often need to be removed from the image. In this paper, we propose a postprocessing method, based on deconvolution, that is able to remove these artifacts after conventional reconstruction. This method poses two advantages over existing projection-based (preprocessing) phase-retrieval or phase-removal algorithms. First, evaluation of the parameters can be done very quickly, improving the overall speed of the method. Second, postprocessing methods can be applied when projection data is not available, which occurs in several commercial systems with closed software or when projection data has been deleted. It is shown that the proposed method performs comparably to state-of-the-art methods in terms of image quality.

  • 30.
    Winter, Simon
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Fathi, Mohammad Taghi
    Venkataraman, Abinaya Priya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Rosén, Robert
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Seidemann, Anne
    Esser, Gregor
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Effect of induced transverse chromatic aberration on peripheral vision2015In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 32, no 10, p. 1764-1771Article in journal (Refereed)
    Abstract [en]

    Transverse chromatic aberration (TCA) is one of the largest optical errors affecting the peripheral image quality in the human eye. However, the effect of chromatic aberrations on our peripheral vision is largely unknown. This study investigates the effect of prism-induced horizontal TCA on vision, in the central as well as in the 20 degrees nasal visual field, for four subjects. Additionally, the magnitude of induced TCA (in minutes of arc) was measured subjectively in the fovea with a Vernier alignment method. During all measurements, the monochromatic optical errors of the eye were compensated for by adaptive optics. The average reduction in foveal grating resolution was about 0.032 +/- 0.005 logMAR/arcmin of TCA (mean +/- std). For peripheral grating detection, the reduction was 0.057 +/- 0.012 logMAR/arcmin. This means that the prismatic effect of highly dispersive spectacles may reduce the ability to detect objects in the peripheral visual field.

  • 31. Yan, Wei
    et al.
    Yan, Min
    Laboratory of Optics, Photonics and Quantum Electronics, Department of Microelectronics and Applied Physics, Royal Institute of Technology (KTH), Kista, Electrum 229, Sweden.
    Qiu, Min
    Manipulation of light with α transformation media2011In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 28, no 6, p. 1058-1066Article in journal (Refereed)
    Abstract [en]

    A type of transformation media called α media is proposed by performing a direct transformation to the metric tensor of another kind of media, called seed media. Light rays in an α medium correlate to those in its seed medium through a simple displacement or rotation relation. Three types of commonly encountered anisotropic media are covered by the concept of α media: (1) media of slab shape, having continuous translational symmetry with respect to two Cartesian coordinate components; (2) media of cylindrical shape, having cylindrical rotational symmetry and continuous translational symmetry along the longitudinal direction; (3) media of spherical shape, having spherical rotational symmetry, with two principal axes along the symmetry directions, and with the material parameters in the same sign. Optical properties of such media can be effectively interpreted through recalling the properties of certain isotropic media, i.e., their seed media. Conversely, from simple isotropic media in which light trajectories are well known, one can design α media for manipulating light. Based on this fact, several optical devices, including frequency demultiplexers, beam splitters, focusing lenses, and radiation controllers, are designed and numerically verified. The famed invisibility cloak derived from a conventional coordinate transformation is revisited from the α media perspective.

  • 32.
    Yan, Wei
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Manipulation of light with α transformation media2011In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 28, no 6, p. 1058-1066Article in journal (Refereed)
    Abstract [en]

    A type of transformation media called α media is proposed by performing a direct transformation to the metric tensor of another kind of media, called seed media. Light rays in an α medium correlate to those in its seed medium through a simple displacement or rotation relation. Three types of commonly encountered anisotropic media are covered by the concept of α media: (1) media of slab shape, having continuous translational symmetry with respect to two Cartesian coordinate components; (2) media of cylindrical shape, having cylindrical rotational symmetry and continuous translational symmetry along the longitudinal direction; (3) media of spherical shape, having spherical rotational symmetry, with two principal axes along the symmetry directions, and with the material parameters in the same sign. Optical properties of such media can be effectively interpreted through recalling the properties of certain isotropic media, i.e., their seed media. Conversely, from simple isotropic media in which light trajectories are well known, one can design α media for manipulating light. Based on this fact, several optical devices, including frequency demultiplexers, beam splitters, focusing lenses, and radiation controllers, are designed and numerically verified. The famed invisibility cloak derived from a conventional coordinate transformation is revisited from the α media perspective.

  • 33.
    Yan, Wei
    et al.
    Department of Microelectronics and Applied Physics, Royal Institute of Technology (KTH), Electrum 229, Kista, Sweden.
    Yan, Min
    Department of Microelectronics and Applied Physics, Royal Institute of Technology (KTH), Electrum 229, Kista, Sweden.
    Ruan, Zhichao
    Department of Microelectronics and Applied Physics, Royal Institute of Technology (KTH), Electrum 229, Kista, Sweden.
    Qiu, Min
    Department of Microelectronics and Applied Physics, Royal Institute of Technology (KTH), Electrum 229, Kista, Sweden.
    Influence of geometrical perturbation at inner boundaries of invisibility cloaks2008In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 25, no 4, p. 968-973Article in journal (Refereed)
1 - 33 of 33
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