Publications related to Speckle (interference)

Validation of short-pulse reflectometry turbulence measurements with a synthetic diagnostic

Stefano Coda, Stephan Brunner, Oleg Krutkin, Umesh Kumar, Mackenzie Peter-Fulford Van Rossem, Samuele Mazzi

Experimental measurements of the turbulence amplitude utilizing a short pulse reflectometry method are presented. Two discharges with shaped plasma possessing opposite signs of triangularity are considered and a higher turbulence amplitude is found in the ...

IOP Publishing Ltd2024

Dual-shot approach for polarization retrieval through a scattering medium

Abhijit Roy

A dual-shot technique based on the field basis addition of two statistically independent speckle patterns is developed to recover an input polarization through a scattering layer. It is proposed theoretically, and demonstrated both numerically and experime ...

Iop Publishing Ltd2024

Confined spin waves in magnetochiral nanotubes with axial and circumferential magnetization

Dirk Grundler, Mohammad Hamdi, Andrea Mucchietto, Maria Carmen Giordano

We report experimental studies of spin-wave excitations in individual 22-nm-thick Ni80Fe20 nanotubes with diameters of about 150 nm. We apply Brillouin light-scattering spectroscopy under microwave irradiation, and we resolve sets of discrete resonances in ...

2023

Optical Diffraction Tomography Using Nearly In-Line Holography with a Broadband LED Source

Demetri Psaltis, Abhijit Roy, Ahmed Ayoub

We present optical tomography methods for a 3D refractive index reconstruction of weakly scattering objects using LED light sources. We are able to record holograms by minimizing the optical path difference between the signal and reference beams while sepa ...

MDPI2022

Temporal Talbot effect of optical dark pulse trains

Camille Sophie Brès, Jianqi Hu, Jiaye Wu

The temporal Talbot effect describes the periodic self-imaging of an optical pulse train along dispersive propagation. This is well studied in the context of bright pulse trains, where identical or multiplied pulse trains with uniform bright waveforms can ...

OPTICAL SOC AMER2022

Lock-in incoherent differential phase contrast imaging

Christophe Moser, Timothé Laforest, Damien Claude-Marie Loterie, Chiara Bonati

We introduce a lock-in method to increase the phase contrast in incoherent differential phase contrast (DPC) imaging. This method improves the phase sensitivity by the analog removal of the background. The use of a smart pixel detector with in-pixel signal ...

CHINESE LASER PRESS2022

Energy correlators of hadronically decaying electroweak bosons

Lorenzo Ricci, Marc Riembau Saperas

Energy correlators are field-theoretically clean and phenomenologically valuable probes of QCD dynamics. We explore the possibility of using the information encoded in the energy correlators of a hadronically decaying electroweak vector boson in order to e ...

American Physical Society2022

Shannon entropy and degree of polarization of a speckle pattern

Abhijit Roy

The dependence of the Shannon entropy (SE) of a speckle pattern on the degree of polarization (DoP) of the pattern is investigated both experimentally and numerically. The superposition of two uncorrelated speckle patterns with polarization diversity is ut ...

OPTICAL SOC AMER2021

Spatial statistics of superposition of two uncorrelated speckle patterns with polarization diversity

Abhijit Roy

A detailed theoretical and experimental study on the effect of the superposition of uncorrelated speckle patterns with polarization diversity on the spatial statistics of the superposed speckle pattern is presented. It is shown that depending on the mutual ...

Elsevier2021

Giant Brillouin Amplification in Gas Using Hollow-core Fiber

Luc Thévenaz, Flavien Gyger

Optical amplification in hollow core fibers has been achieved using stimulated Brillouin scattering directly in the gaseous medium. More than 50 dB optical gain is observed over 50 m of fiber using 200 mW of pump power. ...

Optical Society of America2021

Predicting optical transmission through complex scattering media from reflection patterns with deep neural networks

Demetri Psaltis, Eirini Kakkava

Deep neural networks (DNNs) are used to reconstruct transmission speckle intensity patterns from the respective reflection speckle intensity patterns generated by illuminated parafilm layers. The dependence of the reconstruction accuracy on the thickness o ...

2021

Deep Learning-Based Image Classification through a Multimode Fiber in the Presence of Wavelength Drift

Demetri Psaltis, Christophe Moser, Navid Borhani, Eirini Kakkava, Babak Rahmani, Ugur Tegin

Deep neural networks (DNNs) are employed to recover information after its propagation through a multimode fiber (MMF) in the presence of wavelength drift. The intensity distribution of the speckle patterns generated at the output of an MMF when an input wa ...

2020

Adaptive Regularization For Three-Dimensional Optical Diffraction Tomography

Michaël Unser, Demetri Psaltis, Thanh-An Michel Pham, Emmanuel Emilien Louis Soubies, Ahmed Ayoub, Ahmed Bassam Sayed Ayoub Mohamed Emam

Optical diffraction tomography (ODT) allows one to quantitatively measure the distribution of the refractive index of the sample. It relies on the resolution of an inverse scattering problem. Due to the limited range of views as well as optical aberrations ...

IEEE2020

Near-field phase profile and far-field contrast modulation for micro-lens arrays at the refraction limit

Toralf Scharf, Maryam Yousefi, Daniel Necesal

We investigate the far-field pattern generation for a micro-lens array (MLA) illuminated under different conditions. Plane wave and Gaussian beam illumination are considered for an MLA with a small diameter of 27 microns and 30 microns period. At these dim ...

2020

Spectral Properties of the Signal in Phase-Sensitive Optical Time-Domain Reflectometry with Direct Detection

Luc Thévenaz, Marcelo Alfonso Soto Hernandez, Li Zhang, Xin Lu

The spectral properties of the Rayleigh backscattered traces measured by a phase-sensitive optical time-domain reflectometer (øOTDR) with direct detection are theoretically and experimentally analyzed. The spectrum of the measured øOTDR signal is found to ...

IEEE Institute of Electrical and Electronics Engineers2020

Spatial coherence properties of an LED-based illumination system for mask-aligner lithography

Hans Peter Herzig, Toralf Scharf, Wilfried Noell, Raoul Kirner, Johana Bernasconi

A high-power LED-based illumination system has been developed as a replacement for the mercury arc lamps used in mask-aligner lithography. LEDs are arranged in a grid array and placed in the entrance aperture of individual reflectors. Those reflectors decr ...

SPIE2019

Deep Neural Networks for seeing through multimode fibers

Demetri Psaltis, Christophe Moser, Navid Borhani, Eirini Kakkava

Image delivery through multimode fibers (MMFs) suffers from modal scrambling which results in a speckle pattern at the fiber output. In this work, we use Deep Neural Networks (DNNs) for recovery and/or classification of the input image from the intensity-o ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Imaging through multimode fibers using deep learning: The effects of intensity versus holographic recording of the speckle pattern

Demetri Psaltis, Christophe Moser, Navid Borhani, Damien Claude-Marie Loterie, Eirini Kakkava, Babak Rahmani, Georgia Konstantinou, Ugur Tegin

Information transmission through multimode fibers (MMFs) has been a topic of great interest for many years. Deep learning algorithms have been applied successfully to MMFs in particular to fiber endoscopy. In this work, we show how Deep Neural Networks (DN ...

2019

Distributed hydrogen monitoring with phase-sensitive optical time-domain reflectometry

Luc Thévenaz, Li Zhang

We propose a distributed hydrogen sensing system based on ϕ-OTDR and a novel coating configuration with fiber adhesively bonding to palladium foils. An ultra-high sensitivedistributed hydrogen sensing with 5 cm spatial resolution is demonstrated ...

Optical Society of America2018

Distributed hydrostatic pressure measurement using phase-OTDR in a highly birefringent photonic crystal fibre

Luc Thévenaz, Li Zhang, Kenny Hey Tow

We demonstrate a distributed hydrostatic pressure measurement based on phase-sensitive optical time-domain reflectometry in a highly birefringent photonic crystal fibre with a 0.4 bar pressure resolution and a 10 cm spatial resolution. ...

Optical Society of America2018