Publications associées à Cercle de confusion

Structured light engineering using a photonic nanojet

Toralf Scharf, Maryam Yousefi, Daniel Necesal

In this Letter, we present the photonic nanojet as a phenomenon in a structured light generator system that is implemented to modify the source focal spot size and emission angle. The optical system comprises a microlens array that is illuminated by a focu ...

OPTICAL SOC AMER2021

Structured light generation by refractive-diffractive micro optical array illuminators

Maryam Yousefi

Structured light generation having broad applications in different optical fields, is the topic of this thesis. Our structured light generation strategy is based on applying periodic microoptical elements at the refraction-diffraction limit, under a focuse ...

EPFL2021

Learning stereo reconstruction with deep neural networks

Stepan Tulyakov

Stereo reconstruction is a problem of recovering a 3d structure of a scene from a pair of images of the scene, acquired from different viewpoints. It has been investigated for decades and many successful methods were developed. The main drawback of these ...

EPFL2020

Solving the Depth Ambiguity in Single-Perspective Images

Sabine Süsstrunk, Majed El Helou, Marjan Shahpaski

Scene depth estimation is gaining in importance as more and more AR/VR and robot vision applications are developed. Conventional depth-from-defocus techniques can passively provide depth maps from a single image. This is especially advantageous for moving ...

2019

Fourier light scattering model for treating textures deeper than the wavelength

Christophe Ballif, Franz-Josef Haug, Matthias Wolfgang Bräuninger

We apply a Fourier-scattering model to describe light scattering in solar cells with textured surfaces. For the size and inclination angle of typical micro-textures, scattering may occur into large angles. This makes the model prone to paraxial errors. We ...

Optical Society of America2017

Refraction limit of miniaturized optical systems: a ball-lens example

Hans Peter Herzig, Roland Andreas Bitterli, Toralf Scharf, Wilfried Noell, Myun Sik Kim

We study experimentally and theoretically the electromagnetic field in amplitude and phase behind ball-lenses across a wide range of diameters, ranging from a millimeter scale down to a micrometer. Based on the observation, we study the transition between ...

Optical Society of America2016

Aberrations of the point spread function of a multimode fiber due to partial mode excitation

Adrien Charles-François Raymond Descloux

We investigate the point spread function of a multimode fiber. The distortion of the focal spot created on the fiber output facet is studied for a variety of the parameters. We develop a theoretical model of wavefront shaping through a multimode fiber and ...

Optical Society of America2016

Multiscale guided deblurring: Chromatic aberration correction in color and near-infrared imaging

Sabine Süsstrunk, Yue Lu, Zahra Sadeghipoor Kermani

Chromatic aberration, caused by photographic lens imperfections, results in the image of only one spectral channel being sharp, while the other channels are blurred depending on their wavelengths difference with the sharp channel. We study chromatic aberra ...

2015

A microfluidic flow-cell for the study of the ultrafast dynamics of biological systems

Majed Chergui, Adrien Alexis Paul Chauvet

The study of biochemical dynamics by ultrafast spectroscopic methods is often restricted by the limited amount of liquid sample available, while the high repetition rate of light sources can induce photodamage. In order to overcome these limitations, we de ...

American Institute of Physics2014

Simple and easily controllable parabolic-shaped microlenses printed on polymeric mesas

Jürgen Brugger, Joo Yeon Kim, Cristina Martin Olmos

A simple and easy shape-controllable approach is demonstrated for the fabrication of parabolic-shaped polymer microlenses (mu-lenses), which are widely used in bio-imaging systems such as microfluidic and lab-on-a-chip systems for improving the image quali ...

Royal Society of Chemistry2013

Joint Statistical Analysis of Images and Keywords with Applications in Semantic Image Enhancement

Sabine Süsstrunk, Albrecht Johannes Lindner, Appu Shaji

With the advent of social image-sharing communities, millions of images with associated semantic tags are now available online for free and allow us to exploit this abundant data in new ways. We present a fast non-parametric statistical framework designed ...

2012

Combining vernier acuity and visual backward masking as a sensitive test for visual temporal deficits in aging research

Michael Herzog, Maya Roinishvili

Performance in many everyday situations slows down when age increases. The causes of slowing down may be found on any stage of information processing. Here, we show that the combination of a vernier acuity task and the shine-through backward masking paradi ...

Elsevier2011

The perils of taxonomic inconsistency in quantitative palaeoecology: experiments with testate amoeba data

Edward Mitchell, Mariusz Lamentowicz

A fundamental requirement of quantitative palaeoecology is consistent taxonomy between a modern training set and palaeoecological data. In this study we assess the possible consequences of violation of this requirement by simulating taxonomic errors in tes ...

2011

Phase extraction in speckle interferometry by a circle fitting procedure in the complex plane

Pierre Jacquot, Sébastien Equis

In speckle interferometry (SI), temporal signals are amplitude- and frequency-modulated signals and exhibit a fluctuating background. Prior to phase computation, this background intensity must be eliminated. Here our approach is to build a complex signal f ...

Optical Society of America2011

On the Age of Pseudonyms in Mobile Ad Hoc Networks

Jean-Yves Le Boudec, Jean-Pierre Hubaux, Julien Freudiger

In many envisioned mobile ad hoc networks, nodes are expected to periodically beacon to advertise their presence. In this way, they can receive messages addressed to them or participate in routing operations. Yet, these beacons leak information about the n ...

2010

Extended depth-of-focus by digital holographic microscopy

Christian Depeursinge, Tristan Colomb, Etienne Cuche, Jonas Kühn, Nicolas Pavillon

A recurrent problem in microscopy is the finite depth-of-focus linked to the NA of microscope objectives. Digital holographic microscopy (DHM) has the unique feature of being able to numerically change the focus from a single hologram without the need of m ...

Optical Society of America2010

Perceived speed differences explain apparent compression in slit viewing

Michael Herzog

When a figure moves behind a stationary narrow slit, observers often report seeing the figure as an integrated whole, a phenomenon known as slit viewing or anorthoscopic perception. Interestingly, in slit viewing, the figure is perceived compressed along t ...

Elsevier2008

Efficient current injection scheme for nitride vertical cavity surface emitting lasers

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Julien Dorsaz, Eric Feltin, Antonino Francesco Castiglia, Dobri Simeonov

The authors report the realization of InGaN/GaN light emitting diodes (LEDs) with an electrical injection design suitable for vertical cavity surface emitting lasers. Controlled oxidation of an AlInN interlayer lattice matched to GaN allows confining the i ...

2007

Nanometer focusing properties of Fresnel zone plates described by dynamical diffraction theory

Christian David

The x-ray focusing properties of linear Fresnel zone plates have been derived by solving the Helmholtz equation for the field propagating through the zones. We consider the imaging of a point object into the first diffraction order of a volume zone plate h ...

2006