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Accepted papers to appear in an upcoming issue

OSA now posts prepublication articles as soon as they are accepted and cleared for production. See the FAQ for additional information.

Beyond Fienup’s phase retrieval techniques:regularized inversion for in-line holography

Fabien Momey, Loïc Denis, Thomas Olivier, and Corinne Fournier

Doc ID: 374309 Received 30 Jul 2019; Accepted 16 Oct 2019; Posted 16 Oct 2019  View: PDF

Abstract: This paper includes a tutorial on how to reconstruct in-line holograms using aninverse problems approach, starting with modeling the observations, selecting regularizations andconstraints, and ending with the design of a reconstruction algorithm. A special focus is made onthe connections between the numerous alternating projection strategies derived from Fienup’sphase retrieval technique and the inverse problems framework. In particular, an interpretationof Fienup’s algorithm as iterates of a proximal gradient descent for a particular cost functionis given. Reconstructions from simulated and experimental holograms of micrometric beadsillustrate the theoretical developments. The results show that the transition from alternatingprojection techniques to the inverse problems formulation is straightforward and advantageous.

SNR advantage of anisotropy in oceanic opticalwireless communications links

Yahya Baykal

Doc ID: 375892 Received 28 Aug 2019; Accepted 15 Oct 2019; Posted 16 Oct 2019  View: PDF

Abstract: Signal-to-noise ratio (SNR) of an optical wireless communication (OWC) link that operates in anisotropic oceanic turbulence is evaluated.In order to find the SNR advantage of the anisotropy in the oceanic turbulent medium, SNR in anisotropic oceanic turbulence isnormalized by the SNR in isotropic oceanic turbulence. The dB values of this normalized SNR are examined versus the oceanicturbulence parameters of the ratio of temperature to salinity contributions to the refractive index spectrum, the rate of dissipation ofmean-squared temperature, the rate of dissipation of kinetic energy per unit mass of fluid at various oceanic anisotropic factors,avalanche multiplication factors, radii of receiver aperture, link lengths and detector responsivity values. It is found that as the oceanicturbulence becomes more anisotropic, at any link parameter, SNR of OWC link becomes advantageous over the isotropic counterpart.

Paraxial lens design of double-telecentricanamorphic zoom lenses with variablemagnifications or fixed conjugate

Zhang Jinkai, Xue Wang, Xiaobo Chen, Fajia Li, Haining Liu, Huanyong Cui, and Xuan Sun

Doc ID: 372675 Received 15 Jul 2019; Accepted 15 Oct 2019; Posted 15 Oct 2019  View: PDF

Abstract: This paper presents a paraxial lens design method for anamorphic zoom lenseswith double telecentricity. Four types of such lens systems are provided, which are the Y-XY-Y type, the Y-Y-Y-X type, the Y-X-Y-X type, and the Y-X-X-Y type. For each lens type,it can work in two different conditions: A. The distance between the object and the image isfixed during anamorphic zooming, or B. the magnifications in the tangential plane and thesagittal plane can be changed independently by changing the interval lens distances. For eachcondition, given the optical power of each lens component and the design parameters like thetotal length, the magnifications in the tangential plane and the sagittal plane, and theanamorphic ratio, formulas determining the interval distances between lens components, theobject position, and the stop position are provided. Eight examples of double-telecentricanamorphic zoom lenses are provided, and all the examples are tested in Zemax, which showsthe validity of the proposed design method.

Efficient Propagation of the Coherency MatrixInspired by Plenoptic Field Representations ofNonparaxial Wigner Functions

Jeremy Wittkopp and Jonathan Petruccelli

Doc ID: 371083 Received 26 Jun 2019; Accepted 14 Oct 2019; Posted 14 Oct 2019  View: PDF

Abstract: The angle-impact Wigner function (AIWF) is a tool that assigns weights to rays in away so that ray tracing can be used to exactly model the irradiance and polarization propertiesof nonparaxial, partially coherent, partially polarized electromagnetic fields. Although theAIWF offers computational advantages over more conventional wave propagation integrals, inpractice the large number of rays that must be traced has proved to be a significant bottleneck.We demonstrate an efficient method to implement AIWF propagation algorithms inspired by aplenoptic field representation. We illustrate method by computing irradiance and polarizationproperties of several paraxial and nonparaxial fields.

Phase estimation of a 2D fringe pattern using amonogenic-based multiscale analysis

Mohamed Kaseb, Guillaume Mercere, Hermine Bierme, Fabrice Brémand, and Philippe Carré

Doc ID: 370284 Received 01 Jul 2019; Accepted 11 Oct 2019; Posted 14 Oct 2019  View: PDF

Abstract: In this paper, a multiscale monogenic analysis is applied to 2D interference fringepatterns. The monogenic signal was originally developed as a 2D generalisation of the well-knownanalytic signal in the 1D case. The analytic and monogenic tools are both useful to extract aphase information, which can then be directly linked with physical quantities. Previous studiedhave already shown the interest of the monogenic signal in the field of interferometry. Thispaper presents theorical and numerical illustrations of the connexion between the physical phaseinformation and the phase estimated with the monogenic tool. More specifically, the ideal case ofpure cosine waves is deeply studied, and then the complexity of the fringe patterns is progressivelyincreased.One important weakness of the monogenic transform is its singularity at the null frequency,which makes the phase estimations of low frequency fringes diverge. Moreover, the monogenictransform is originally designed for narrowband signals, and encounters difficulties when dealingwith noised signals. These problems can be bypassed by performing a multiscale analysis basedon the monogenic wavelet transform. Moreover, this paper proposes a simple strategy to combinethe information extracted at different scales in order to get a better estimation of the phase. Thenumerical tests (synthetic and real signals) show how this approach provides a finer extraction ofthe geometrical structure of the fringe patterns.

A local model-based hyperspectral pansharpeningalgorithm via optimization constraint equation andsliding window

Wenqian Dong, SONG Xiao, and Jiahui Qu

Doc ID: 363015 Received 21 Mar 2019; Accepted 11 Oct 2019; Posted 14 Oct 2019  View: PDF

Abstract: The injection model-based algorithms have beenproved to be effective techniques to solve the pansharpeningproblem. However, the existing injectionmodel-based algorithms often face an imbalance betweenover-sharpened and image blurring in the fusedimage. This paper proposes a local model-based pansharpeningmethod to solve this problem from twoaspects. Firstly, an optimization constraint equationformed by the quality index is proposed to reduce thedifference between the details of hyperspectral (HS)images and panchromatic (PAN) images. Secondly, thesliding window-based fusion scheme is proposed forthe first time to adaptively fuse the details of HS andthat of PAN images to reduce redundancy. Simulationexperiments show that the proposed algorithm has theexcellent fusion performance from the aspects of subjectivityand objectivity.

Iterative phase retrieval for digital holography

Tatiana Latychevskaia

Doc ID: 372706 Received 16 Jul 2019; Accepted 10 Oct 2019; Posted 10 Oct 2019  View: PDF

Abstract: Iterative phase retrieval allows quantitatively correct and twin-image-free reconstructions of object amplitude and phase distributions from its in-line hologram. We show that for a sample which can be approximated as a 2D sample, a single-shot in-line hologram is sufficient to reconstruct the absorption and phase distributions of the sample. We also demonstrate that 3D samples, including 3D phase objects can be reconstructed from two and more holograms. Comparing the number of equations and unknowns, we show that in principle, two holograms are sufficient to recover the entire 3D sample distribution. In this method, the reconstruction is performed by applying iterative phase retrieval between the planes where intensity was measured. The recovered complex-valued wavefront is then propagated back to the sample planes, thus reconstructing 3D distribution of the sample. This method can be applied for 3D samples such as 3D distribution of particles, thick biological samples and other 3D phase objects. Examples of 3D objects reconstructions, including phase objects, are provided. Resolution enhancement obtained by iterative extrapolation of holograms is also discussed.

Linearly polarized laser beam with generalizedboundary condition and non-paraxial corrections

Huan Wang, LoÏc Amoudry, Kevin Cassou, Kevin Dupraz, Wenhui Huang, Aurelien Martens, Daniele Nutarelli, Chuanxiang Tang, Lixin Yan, and Fabian Zomer

Doc ID: 372194 Received 08 Jul 2019; Accepted 10 Oct 2019; Posted 11 Oct 2019  View: PDF

Abstract: Linearly polarized Gaussian beams, under the slowly varying envelope approximation, tightly focusedby a perfect parabola modeled with the integral formalism of Ignatovsky are found to be well approximatedwith a generalized Lax series expansion beyond the paraxial approximation. This allows to obtainsimple analytic formulae of the electromagnetic field both in the direct and momentum spaces. It significantlyreduces the computing time, especially when dealing with the problem of simulating direct laseracceleration. The series expansion formulation depends on integration constants that are linked to boundaryconditions. They were found to significantly depend on the region of space over which the integralformulation is fit. Consequently the net acceleration of electrons initially at rest is extremely sensitive tothe chosen set of initial parameters due to the extreme focusing investigated here. This suggests to avoidtoo tight focusing schemes in order to obtain reliable predictions when the process of interest is mainlysensitive to the field and not the intensity.

Efficient full-vectorial modal analysis based onimmersed interface method for dielectric chiraloptical fibers

Yusheng Cao

Doc ID: 371959 Received 05 Jul 2019; Accepted 08 Oct 2019; Posted 08 Oct 2019  View: PDF

Abstract: This paper presents the application of immersed interface method in efficientmodal analysis of dielectric chiral optical fibers. Under the easily implemented finite differenceframework, developed are the second and fourth order accuracy formulations, which in principleare applicable for automatically computing various types of modes in dielectric chiral opticalfibers with an arbitrary, electromagnetic parameters piecewise constant profile. To validate thedeveloped formulations, numerical examples are given for the guided, leaky and surface modesin dielectric chiral step-profile and Bragg fibers.

Some theorems on “arctic mirages”; hillingar effectand superior mirages

Luc Dettwiller

Doc ID: 377469 Received 10 Sep 2019; Accepted 07 Oct 2019; Posted 08 Oct 2019  View: PDF

Abstract: In a stratified or a spherically symmetric atmosphere, we consider some cases where a curved light ray connectstwo points A and S on the sea or the ground, at the same height as in some cases of superior mirages or “arcticmirages”. We study the range D of this ray (i.e. the geodesic distance between A and S) as a function of S α , the rayinclination with respect to the vertical at A or S. The fundamental expression of D is an improper integral. We showthat a change of variables, also used to calculate the astronomical refraction, usually gives a well-behaved integral.In a spherically symmetric atmosphere, this happens when the refraction coefficient exceeds unity on the entireray, producing a hillingar effect (alias strong looming for an erect image) or superior mirages. We then find a niceexpression of dD dα S , which is usually negative. Inverted images (i.e. mirages in the strict sense) show up whendD dαS is positive; for this we find a necessary condition, in each atmospheric model. The strength of theseresults comes from not requiring a precise knowledge of the ray paths.

Gradient in spectral and color images:from the Di Zenzo initial construction to a genericproposition

Hermine Chatoux, Noël RICHARD, François Lecellier, and Christine Fernandez-Maloigne

Doc ID: 368981 Received 13 Jun 2019; Accepted 07 Oct 2019; Posted 14 Oct 2019  View: PDF

Abstract: In this paper, we define a generic gradient for color and spectral images, in regards to a proposed taxonomyof the state of the art. The full-vector gradient, taking into account the sensor’s characteristics,respects the metrological properties of genericity, robustness and reproducibility. We construct a protocolto compare gradients from different sensors. The comparison is developed simulating sensors using theirspectral characteristics. We develop three experiments using this protocol. The first one shows the resultsconsistency for similar sensors. The second one demonstrates the genericity of the approach, adapted toany kind of imaging sensors. The last one focuses on the channel inter-correlation considering sensors asin the color vision deficiency case.

Experimental method for measuring colorappearance shifts in high-dynamic-rangeluminance conditions

Jisoo Hwang, YEJIN HONG, Dong Lee, Youngshin Kwak, Seongchong Park, Jae-Keun Yoo, and YOUNGJOO CHAE

Doc ID: 370049 Received 13 Jun 2019; Accepted 06 Oct 2019; Posted 07 Oct 2019  View: PDF

Abstract: We present an experimental method to determine color appearance shifts underhigh-dynamic-range conditions. A couple of light booths with variable luminance providehigh-dynamic-range luminance conditions, and a perceptual color shift between the twobooths is determined using color appearance matching. For red, green, yellow, and bluegroups of four surface color samples, color shifts were measured for nine subjects under adual illumination at background luminance levels of 100 cd/m2 and 4,700 cd/m2. We observedsignificant perceptual hue shifts toward blue with magnitudes of 2.5 to 3.9 and 5.0 to 6.9CIELAB units, for the red and green samples, respectively, and decreases in chroma for mostsamples when changed from low to high luminances.

Object kinetics perception in auto-stereoscopic vision

Marie DEJEAN, Vincent Nourrit, and Jean Louis de Bougrenet de la Tocnaye

Doc ID: 360505 Received 19 Feb 2019; Accepted 04 Oct 2019; Posted 04 Oct 2019  View: PDF

Abstract: In this paper, we study the conditions for the perception of object kinetics, produced by a multi-view autostereoscopicsystem and a set of still images. We assess the capabilities and performances of such an optical systemto encode complex trajectories and kinetics of objects moving in depth. In particular, we set up rules to createmotions with non-uniform velocities, when obtained by motion parallax induced by the observer. We establish alink with plenoptic systems from where we derive some applicable scaling rules to ensure stereoscopic vision andto provide fluid motion perception with a satisfying visual comfort. Finally, we scale the optical system, thanks toobtained parameters, to emulate the perception of object motions in depth with a fluid kinetics and to createimpressive motion effects.

Influence of the CTAB surfactant layer on opticalproperties of single metallic nanospheres

Artur Movsesyan, Sylvie Marguet, Alina Muravitskaya, Jérémie Béal, Anne-Laure Baudrion, and Pierre-Michel Adam

Doc ID: 370184 Received 01 Jul 2019; Accepted 04 Oct 2019; Posted 04 Oct 2019  View: PDF

Abstract: We evaluate experimentally and theoretically the role of the residual ligandsand ambient environment refractive index on the optical response of a single spherical goldnanoparticle on a substrate and demonstrate the changes in the near and far-field propertiesof its hybridized modes in the presence of the CTAB layer. Particularly, we show that theconventional bilayer scheme for CTAB is not relevant for colloidal nanoparticles deposited on asubstrate. We show that this CTAB layer considerably changes the amplitude and localizationof the confinement of electric field which is of prime importance in the design of plasmoniccomplex systems coupled to emitters. Moreover, we numerically study the influence of CTABlayer on the modification of sensitivity of plasmonic resonances of a gold nanopshere to localrefractive index changes.

Beam propagation factor and kurtosis parameter of hollow vortex Gaussian beams: An alternative method

Guoquan Zhou, Shangshen Feng, Yiqing Xu, and Yimin Zhou

Doc ID: 375229 Received 12 Aug 2019; Accepted 04 Oct 2019; Posted 09 Oct 2019  View: PDF

Abstract: Based on the second-order moments, an analytical and concise expression of the beam propagation factor of a hollow vortex Gaussian beam has been derived, which is applicable for an arbitrary topological charge m. The beam propagation factor is determined by the beam order n and the topological charge m. With increasing the topological charge m, the beam propagation factor increases. However, the effect of the beam order n on the beam propagation factor is associated with the topological charge m. By using the transformation formula of higher-order intensity moments, an analytical expression of the kurtosis parameter of a hollow vortex Gaussian beam passing through a paraxial and real ABCD optical system has been presented. The kurtosis parameter is determined by the beam order n, the topological charge m, and the position of observation plane η. The influence of the beam order n on the kurtosis parameter is related with the topological charge m and the position parameter η. When the beam order n is larger than 1, the kurtosis parameter in different observation η-plane decreases and tends to a stable value with increasing the topological charge m. When m=±2n, the kurtosis parameter is independent of the position parameter η and keeps unvaried during the beam propagation. Regardless of the values of n and m, the kurtosis parameter must tend to a saturated value or a stable value as the position parameter η increases to a sufficiently large value. This research is beneficial to the practical application of a hollow vortex Gaussian beam.

Divide and conquer algorithm for nondiffracting beams

Alberto Martinez-Herrera, Armando Cespedes-Mota, and Servando Lopez-Aguayo

Doc ID: 374300 Received 01 Aug 2019; Accepted 04 Oct 2019; Posted 08 Oct 2019  View: PDF

Abstract: We put forward a robust technique to encode a plethoraof arbitrary images as nondiffracting beams by optimizingtheir respective phase component. This techniqueworks directly under the constraint of a ring of infinitesimalwidth in Fourier space. The procedure reported isbased on a stochastic direct search and global optimization:the differential evolution method. Unlike previousmethods reported, the present approach is also ableto optimize the spatial frequency of the image used. Remarkably,this technique also demonstrates that it ispossible to encode even more arbitrary images on demandinto nondiffracting forms by allowing a segmentationof the profile. We provide some codes to generatenondiffracting beams by using this algorithm.

Fast computation and characterization ofperturbed Bessel-Gauss beams

Sebastian Merx, Johannes Stock, and Herbert Gross

Doc ID: 372368 Received 11 Jul 2019; Accepted 04 Oct 2019; Posted 07 Oct 2019  View: PDF

Abstract: In this paper, an extended definition of the Strehl-ratio is introduced for Bessel-Gaussbeams, which in contrast to classical beams is not defined at a single point but along the opticalaxis. For that purpose the Fresnel-diffraction integral is solved analytically to calculate theon-axis field of a Bessel-Gauss beam that is perturbed by spherical aberration, astigmatismand coma. Certain approximations are introduced, discussed and tested against a rigorouspropagation-method. The derived expression is applied to the tolerancing of an example system.

The energy transfer of the tightly focusedhybridly-polarized vector optical fields withelliptic symmetry in free space

Yue Pan, Meng-Shuai Wang, Xu-Zhen Gao, Xu Zhang, Rende Ma, Yongnan Li, Chenghou Tu, and Hui-Tian Wang

Doc ID: 372927 Received 17 Jul 2019; Accepted 04 Oct 2019; Posted 07 Oct 2019  View: PDF

Abstract: We theoretically and experimentally present the hybridly-polarized vector opticalfields (HP-VOFs) with elliptic symmetry in elliptic coordinate system. Compared with thetraditional cylindrical HP-VOFs, there is an additional degree of freedom for this new kind ofvector optical fields, as the interval between the two foci in the elliptic coordinate system. Exceptfor discussing the singularities of the HP-VOFs, we concentrate on studying the energy transferof the tightly focused HP-VOFs with elliptic symmetry in free space. We summarize the rules ofthe energy transfer, and introduce a reference optical field to explain them. We hope these resultscan provide a new way to flexibly modulate the tightly focused fields, which may be applied inrealms such as optical machining, optical trapping and information transmission.

A model for full-field optical coherencetomography in scattering media

Ugo Tricoli and Remi Carminati

Doc ID: 374615 Received 05 Aug 2019; Accepted 03 Oct 2019; Posted 04 Oct 2019  View: PDF

Abstract: We develop a model of full-field optical coherence tomography (FF-OCT) thatincludes a description of partial temporal and spatial coherence, together with a mean-fieldscattering theory going beyond the Born approximation. Based on explicit expressions of theFF-OCT signal, we discuss essential features of FF-OCT imaging, such as the influence ofpartial coherence on the optical transfer function, and on the decay of the signal with depth. Wederive the conditions under which the spatially averaged signal exhibits a pure exponential decay,providing a clear frame for the use of the Beer-Lambert law for quantitative measurements of theextinction length in scattering media.

Advancing Fourier: space-time concepts in ultrafastoptics, imaging and photonic neural networks

Luc Froehly, Francois Courvoisier, Daniel Brunner, Laurent Larger, Fabrice Devaux, Eric Lantz, John Dudley, and Maxime Jacquot

Doc ID: 370225 Received 18 Jun 2019; Accepted 03 Oct 2019; Posted 07 Oct 2019  View: PDF

Abstract: The concepts of Fourier optics were established in France in the 1940s by Pierre-Michel Duffieux, and laidthe foundations of an extensive series of activities in the French research community that have touched onnearly every aspect of contemporary optics and photonics. In this paper, we review a selection of resultswhere applications of the Fourier transform and transfer functions in optics have been applied to yieldsignificant advances in unexpected areas of optics, including the spatial shaping of complex laser beamsin amplitude and in phase, real-time ultrafast measurements, novel ghost imaging techniques, and thedevelopment of parallel processing methodologies for photonic artificial intelligence.

Topological complexity of photons’ paths in biologicaltissues

Tiziano Binzoni, Fabrizio Martelli, and david Cimasoni

Doc ID: 370183 Received 17 Jun 2019; Accepted 03 Oct 2019; Posted 03 Oct 2019  View: PDF

Abstract: In the present contribution three means of measuring the geometrical and topological complexity of photons’paths in random media are proposed. This is realized by investigating the behavior of the averagecrossing number, the mean writhe, and the minimal crossing number of photons’ paths generated byMonte Carlo (MC) simulations, for different sets of optical parameters. It is observed that the complexityof the photons’ paths increases for increasing light source/detector spacing, and that highly “knotted”paths are formed. Due to the particular rules utilized to generate the MC photons’ paths, the presentresults may have an interest not only for the biomedical optics community, but also from a pure mathematicalpoint of view.

High performance thin-film optical filters withstress compensation

Thomas Begou, Fabien Lemarchand, Frederic Lemarquis, Antonin MOREAU, and Julien Lumeau

Doc ID: 370156 Received 14 Jun 2019; Accepted 02 Oct 2019; Posted 03 Oct 2019  View: PDF

Abstract: We present a thorough description of high performance thin-film optical filterswith high flatness. These components can combine several tens or hundreds of layers and aremanufactured using plasma-assisted reactive magnetron sputtering. Stress compensation isachieved using dual side coatings with appropriate spectral function. Examples of highlyreflecting mirrors at 515 nm with 15 nm flatness peak-to-valley over up to 75 mm diameteraperture, narrow bandpass filters and filters with broadband controlled transmission aredescribed.

Large optics metrology for high power lasers

Stephane Bouillet, christel ameil, vincent beau, Odile Bonville, sandy cavaro, Roger Courchinoux, Jerome Daurios, Thierry Donval, Laure Eupherte, Sandrine Freville, Gael Gaborit, Isabelle Lebeaux, Christophe Leymarie, Sebastien Martin, Romain Parreault, Gerard Raze, Nadja Roquin, and Laurent Lamaignère

Doc ID: 369939 Received 25 Jun 2019; Accepted 30 Sep 2019; Posted 02 Oct 2019  View: PDF

Abstract: The Laser MégaJoule (LMJ) is a high power laser dedicated to laser-plasma experiments. At the beginning of the project in the mid-90s, an optical metrology laboratory was created at CEA to help accomplish all the steps of the construction of this laser. This paper proposes an overview of the capabilities of this metrology laboratory in four main fields: surface imperfections, photometry, laser damage measurement and wavefront measurement. The specificities for high power laser optics in each domain are highlighted as well as the specific features that make our instruments unique.

Calibration of high dynamic range images for applied colour and lighting research

Coralie Cauwerts, Sophie Boissard, and Bertrand Deroisy

Doc ID: 370052 Received 13 Jun 2019; Accepted 28 Sep 2019; Posted 30 Sep 2019  View: PDF

Abstract: The main objective of this work is to determine the most appropriate HDR picture calibration procedure for measuring luminance and colour, in a context of architecture. Three professional digital single-lens reflex cameras fitted with fisheye lenses were tested. Photometric and colorimetric accuracy was assessed in comparison with spectroradiometer measurements of 57 colour samples (Macbeth chart and additional Munsell samples). The results demonstrate that using a calibration model specific to the camera-lens association rather than the standardized RGB to XYZ colour transform matrix is necessary to achieve an acceptable colorimetric accuracy. Moreover, using a specific colour transform matrix reduces the error in luminance, especially for colourful elements. The study also shows the opportunity to share the same colour transform matrix between similar photographic materials (same brand and model). At last, among the three tested devices, one camera-lens association has higher performances and produces better quality QTVR panoramas.

Clinical evaluation of a device providingsimultaneous white-light and fluorescencevideo streams as well as panoramic imagingduring fluorescence assisted-transurethralresection of bladder cancer

Marine Amouroux, Julia SALLERON, Cécile HUIN-SCHOHN, Sharib ALI, Stéphane BERTHAUD, Philippe Rizo, Sylvain SCHNEIDER, Christine Vever-Bizet, Genevieve Bourg-Heckly, Francois Guillemin, Patricia Le Coupanec, Ernest GALBRUN, Joël DAOUK, Christian Daul, Walter Blondel, and Pascal ESCHWEGE

Doc ID: 369983 Received 14 Jun 2019; Accepted 25 Sep 2019; Posted 25 Sep 2019  View: PDF

Abstract: The current clinical study aimed at evaluating the clinical relevance of aninnovative device (called CyPaM2 device) that provides for the first time urologists with (i) Apanoramic image of the bladder inner wall within the surgery time, and with (ii) Asimultaneous (bimodal) display of fluorescence and white-light video streams during thefluorescence assisted - transurethral resection of bladder cancers (TURB) procedure. Theclinical relevance of this CyPaM2 device was evaluated on 10 patients according to threecriteria (image quality, fluorescent lesions detection relevance and ergonomics) comparedwith a reference medical device. Innovative features displayed by the CyPaM2 device wereevaluated without any possible comparison: (i) Simultaneous bimodal display of white-lightand fluorescence video streams, (ii) Remote light control, and (iii) Time delay for thepanoramic image building. The results highlight the progress to achieve in order to obtain afully mature device ready for commercialization and the relevance of the innovative featuresproposed by the CyPaM2 device confirming their interest.

Modeling, Measuring, and using BRDFs: SignificantFrench Contributions

Lionel Simonot, Gael Obein, Benjamin Bringier, and Daniel Meneveaux

Doc ID: 370153 Received 17 Jun 2019; Accepted 25 Sep 2019; Posted 25 Sep 2019  View: PDF

Abstract: The scattering of light by a surface is described bythe Bidirectional Reflectance Distribution Function(BRDF). Unfortunately, this function cannot be straightforwardlyacquired nor modeled. French researchershave proposed interesting contributions in the field,with several models and accurate experimental systems.For instance, the National Metrological Institute (LNECNAM)has implemented the best angular resolutiongoniospectrophotometer (0.015o). Modeling the BRDFhas also been deeply studied in France, especially withthe microfacet theory these recent years, a better understandingof the shadowing/masking function, new generaldistribution functions, visible normals, interfacedLambertian microfacets and analysis concerning lightmultiple reflections. This paper proposes a state of theart concerning some significant French contributions inthese fields.

Large and extremely low loss, the unique challenges ofgravitational waves mirrors

Jerome Degallaix, Christophe MICHEL, Benoit SASSOLAS, Annalisa Allocca, Gianpetro Cagnoli, laurent balzarini, Vincent Dolique, Raffaele Flaminio, Daniele Forest, Massimo Granata, Bernard Lagrange, Nicolas Straniero, julien teillon, and Laurent Pinard

Doc ID: 370180 Received 18 Jun 2019; Accepted 25 Sep 2019; Posted 02 Oct 2019  View: PDF

Abstract: This article describes the making of the large mirrors of laser interferometer gravitational wave detectors.Those optics, working in the near infrared, are among the best optics ever made and have played a crucialrole for the first direct detection of the gravitational waves from black holes or neutron stars fusions.

Freeform lens design for a point source and far-fieldtarget

Lotte Romijn, Jan ten Thije Boonkkamp, and wilbert ijzerman

Doc ID: 372958 Received 25 Jul 2019; Accepted 23 Sep 2019; Posted 23 Sep 2019  View: PDF

Abstract: The field of freeform illumination design has surged since the introduction of new fabrication techniquesthat allow for the production of non-axially symmetric surfaces. Freeform surfaces aim to efficiently controlthe redistribution of light from a particular source distribution to a target irradiance, but designingsuch surfaces is a challenging problem in the field of nonimaging optics. Optical design strategies havebeen developed in both academia and industry. In this paper, we consider the design of a single freeformlens that converts the light from an ideal (zero-étendue) point source into a far-field target. We presenta mathematical approach and numerically solve the corresponding generalized Monge-Ampère equationof the optical system. We derive this equation using optimal transport theory and energy conservation.We use a generalized least-squares algorithm that can handle a non-quadratic cost function in the correspondingoptimal transport problem. The algorithm first computes the optical map and subsequentlyconstructs the optical surface. We demonstrate that the algorithm can generate a peanut-shaped lens forroadlighting purposes and a highly detailed lens that produces an image on a projection screen in the farfield.

Modeling and optimization of a geometricalcalibration procedure for stereoscopic videoendoscopes

Alexey Gorevoy, Alexander Machikhin, Demid Khokhlov, and Vladislav Batshev

Doc ID: 371893 Received 05 Jul 2019; Accepted 22 Sep 2019; Posted 23 Sep 2019  View: PDF

Abstract: Stereoscopic video endoscopes are widely used for remote visual inspection and precise three-dimensional (3D)measurements in industrial and biomedical applications. The reconstruction of 3D points from the correspondingimage points requires geometrical calibration procedure which accuracy affects the measurement uncertainty. Wepropose to perform an optimal choice of the calibration technique and the calibration target parameters using thecomputer simulation at the design stage. The effectiveness of this approach is demonstrated via the design of selfdevelopedminiature prism-based stereoscopic system. We simulated acquisition of calibration and measurementdata using optical design software. The conventional calibration technique requiring many positions of the flattarget with arbitrary displacements and rotations was compared with another one, which uses the translationstage to provide pure translation of the target. We analyzed the impact of the translation uncertainty, the numberof positions, the number of targets and the uncertainty of image point coordinates on the uncertainty of calibrationparameters and 3D measurements. We have shown that the second technique could provide the acceptablemeasurement accuracy using only two images. The results of computer simulation were confirmed experimentallyusing the prototype of the stereoscopic endoscope. The proposed approach may be used to optimize calibrationtechniques and reduce a cost of calibration equipment for various stereoscopic measurement systems.

Angular reflectance model for ridged specularsurfaces, with comprehensive calculation ofinterreflections and polarization

Dorian Saint-Pierre, Pierre Chavel, Lionel Simonot, and Mathieu Hébert

Doc ID: 370710 Received 21 Jun 2019; Accepted 18 Sep 2019; Posted 19 Sep 2019  View: PDF

Abstract: The color of a surface structured at the mesoscopic scale differs from the one of a flat surface of the same materialbecause of the light interreflections taking place in the concavities of the surface, as well as shadowing effects. Thecolor variation does not only arise in scattering materials, but also in absence of scattering, e.g. in metals and cleardielectrics, just as a consequence of multiple specular reflections between neighboring flat facets of the surface. Inthis paper, we investigate such color variation in the case of an infinitely long V-shaped groove, having in mind thevisual appearance of a surface composed of many structures of that sort, all parallel and identical. We develop a fullmodel of multiple specular reflections, accounting for ray position and orientation and polarization effectsoccurring at each reflection. We compare that situation with two approximate models, more usual and easier tocompute, where light is assumed to remain unpolarized all along, or where the p- and s-polarized components aretreated separately. Spectral reflectances were predicted for various materials and angles of cavities, under diffuseillumination. In most cases, the three models predict very similar bi-hemispherical reflectances, but thehemispherical-directional reflectances can vary noticeably in certain observation directions. This study might helpachieving more physically-realistic rendering of dielectric or metallic ridged surfaces in computer graphics.

Analysis of Volume-Phase-grating-characteristics thatarbitrary refractive index distributions influencePart I: Derivation of coupling coefficients and grating thickness, andcharacteristics of the G-factors

Kaoru Nakajima

Doc ID: 370941 Received 27 Jun 2019; Accepted 16 Sep 2019; Posted 17 Sep 2019  View: PDF

Abstract: The equations for the coupling coefficient and the grating thickness of volume phase gratings are derived fromMaxwell’s equations this time. The equations cover all graded types of refractive index distributions (RIDs) whichchange continuously from a triangular type to a rectangular type. The functions expressed as arbitrary gradedtypes of RIDs, which are proposed this time, are used among them. Furthermore, the new idea, the correlativecoupling-length coefficient is devised for the first time as arbitrary RID function “G-factor”. The results based on thecoupled-mode theory this time show a very close agreement under 0.2 % with the results of the rigorous coupledwave analysis method. The values of the grating thickness and the G-factor are confirmed with validity. By means ofthe new method, not only can the grating thickness of any graded type of VP-grating which is under the Braggcondition be obtained very easily, but the spectral bandwidths and the angular bandwidths which are not underthe Bragg condition can be controlled very easily and the configuration of RID can be estimated as well.

Pseudo-differential representation of the metaplectictransform and its application to fast algorithms

Nicolas Lopez and Ilya Dodin

Doc ID: 371561 Received 02 Jul 2019; Accepted 12 Sep 2019; Posted 13 Sep 2019  View: PDF

Abstract: The metaplectic transform (MT), also known as the linear canonical transform, is a unitary integral mappingwhich is widely used in signal processing and can be viewed as a generalization of the Fouriertransform. For a given function y on an N-dimensional continuous space q, the MT of y is parameterizedby a rotation (or more generally, a linear symplectic transformation) of the 2N-dimensional phase space(q, p), where p is the wavevector space dual to q. Here, we derive a pseudo-differential form of the MT.For small-angle rotations, or near-identity transformation of the phase space, it readily yields asymptoticdifferential representations of the MT, which are easy to compute numerically. Rotations by larger anglesare implemented as successive applications of K 1 small-angle MTs. The algorithm complexity scalesas O(KN3Np), where Np is the number of grid points. We present a numerical implementation of thisalgorithm and discuss how to mitigate the associated numerical instabilities.

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