Publications by Year

2023

  • High-resolution silicon photonics focused ultrasound transducer with a sub-millimeter aperture.

    High-resolution silicon photonics focused ultrasound transducer with a sub-millimeter aperture.

    2023 Optics Letters Vol. 48, Issue 10, pp. 2668-2671 Michael Nagli, Jürgen Koch, Yoav Hazan, Ahiad Levi, Orna Ternyak, Ludger Overmeyer, and Amir Rosenthal Abstract We present an all-optical focused ultrasound transducer with a sub-millimeter aperture and demonstrate its capability for high-resolution imaging of tissue ex vivo. The transducer is …Read More »
  • All-optical optoacoustic micro-tomography in reflection mode.

    All-optical optoacoustic micro-tomography in reflection mode.

    2023 Biomedical Engineering Letters Tamar Harary, Yoav Hazan & Amir Rosenthal Abstract High-resolution optoacoustic imaging at depths beyond the optical diffusion limit is conventionally performed using a microscopy setup where a strongly focused ultrasound transducer samples the image object point-by-point. Although recent advancements in miniaturized ultrasound detectors enables one to …Read More »
  • Homodyne time-of-flight acousto-optic imaging for low-gain photodetector.

    Homodyne time-of-flight acousto-optic imaging for low-gain photodetector.

    2023 Biomedical Engineering Letters volume 13, pages49–56  Ahiad R.Levi, Yoav Hazan, Aner Lev, Bruno G. Sfez & Amir Rosenthal Abstract Acousto-optics imaging (AOI) is a hybrid imaging modality that is capable of mapping the light fluence rate in deep tissue by local ultrasound modulation of the diffused photons. Since the …Read More »

2022

2021

  • Single pixel imaging at megahertz switching rates via cyclic Hadamard masks.

    Single pixel imaging at megahertz switching rates via cyclic Hadamard masks.

    2021 nature communications AbstractOptical imaging is commonly performed with either a camera and wide-field illumination or with a single detector and a scanning collimated beam; unfortunately, these options do not exist at all wavelengths. Single-pixel imaging offers an alternative that can be performed with a single detector and wide-field illumination, …Read More »
  • Single-pixel imaging of dynamic objects using multi-frame motion estimation.

    Single-pixel imaging of dynamic objects using multi-frame motion estimation.

    2021 Scientific Reports AbstractSingle-pixel imaging (SPI) enables the visualization of objects with a single detector by using a sequence of spatially modulated illumination patterns. For natural images, the number of illumination patterns may be smaller than the number of pixels when compressed-sensing algorithms are used. Nonetheless, the sequential nature of …Read More »

2020

  • Grüneisen-relaxation photoacoustic microscopy at 1.7 µm and its application in lipid imaging.

    Grüneisen-relaxation photoacoustic microscopy at 1.7 µm and its application in lipid imaging.

    © 2020 Optical Society of America AbstractWe report the first, to the best of our knowledge, demonstration of Grüneisen relaxation photoacoustic microscopy (GR-PAM) of lipid-rich tissue imaging at the 1.7 µm band, implemented with a high-energy thulium-doped fiber laser and a fiber-based delay line. GR-PAM enhances the image contrast by …Read More »
  • Increased SNR in acousto-optic imaging via coded ultrasound transmission.

    Increased SNR in acousto-optic imaging via coded ultrasound transmission.

    © 2020 Optical Society of America Abstract Acousto-optic imaging (AOI) is a non-invasive method that uses acoustic modulation to map the light fluence inside biological tissue. In many AOI implementations, ultrasound pulses are used in a time-gated measurement to perform depth-resolved imaging without the need for mechanical scanning. However, to …Read More »
  • Ultrasound Detection Arrays Via Coded Hadamard Apertures.

    Ultrasound Detection Arrays Via Coded Hadamard Apertures.

    © 2020 IEEE AbstractIn the medical fields, ultrasound detection is often performed with piezoelectric arrays that enable one to simultaneously map the acoustic fields at several positions. In this work, we develop a novel method for transforming a single-element ultrasound detector into an effective detectionarray by spatially filtering the incoming …Read More »

2019

2018

  • Algebraic determination of back-projection operators for optoacoustic tomography

    Algebraic determination of back-projection operators for optoacoustic tomography

    source: © 2018 Optical Society of America The simplicity and computational efficiency of back-projection formulae have made them a popular choice in optoacoustic tomography. Nonetheless, exact back-projection formulae exist for only a small set of tomographic problems. This limitation is overcome by algebraic algorithms, but at the cost of higher …Read More »
  • Ultrasound detection via low-noise pulse interferometry using a free-space Fabry-Pérot

    Ultrasound detection via low-noise pulse interferometry using a free-space Fabry-Pérot

    source: © 2018 Optical Society of America Coherence-restored pulse interferometry (CRPI) is a recently developed method for optical detection of ultrasound that achieves shot-noise-limited sensitivity and high dynamic range. In principle, the wideband source employed in CRPI may enable the interrogation of multiple detectors by using wavelength multiplexing. However, the …Read More »
  • Looking at sound: optoacoustics with all-optical ultrasound detection

    Looking at sound: optoacoustics with all-optical ultrasound detection

    source: © 2018 Light: Science & Applications Originally developed for diagnostic ultrasound imaging, piezoelectric transducers are the most widespread technology employed in optoacoustic (photoacoustic) signal detection. However, the detection requirements of optoacoustic sensing and imaging differ from those of conventional ultrasonography and lead to specifications not sufficiently addressed by piezoelectric …Read More »
  • Passive-demodulation pulse interferometry for ultrasound detection with a high dynamic range

    Passive-demodulation pulse interferometry for ultrasound detection with a high dynamic range

    source: © 2018 Optical Society of America In the optical detection of ultrasound, resonators with high Q-factors are often used to maximize sensitivity. However, increasing the Q-factor of a resonator may reduce the linear range of the interrogation scheme, making it more susceptible to strong external perturbations and incapable of …Read More »
  • Ultrasound Detection Using Acoustic Apertures

    Ultrasound Detection Using Acoustic Apertures

    source: © 2018 IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control Ultrasound detection is commonly performed by piezoelectric transducers that are optimized for a specific application. Since the piezoelectric technology is not configurable, transducers designed for one application may not be compatible with other applications. In addition, some designs of …Read More »

2017

  • Modeling the sensitivity dependence of silicon-photonics-based ultrasound detectors

    Modeling the sensitivity dependence of silicon-photonics-based ultrasound detectors

    source: © 2017 Optical Society of America With recent advances in optical technology, interferometric sensing has grown into a highly versatile approach for ultrasound detection, with many interferometric detectors relying on optical waveguides to achieve high levels of sensitivity and miniaturization. In this Letter, we establish a practical model for assessing …Read More »
  • Analysis of Negatively Focused Ultrasound Detectors in Optoacoustic Tomography

    Analysis of Negatively Focused Ultrasound Detectors in Optoacoustic Tomography

    source:© 2017 IEEE Transactions on Medical Imaging In optoacoustic tomography, negatively focused transducers may be used for improving the tangential image resolution while preserving a high signal-to-noise ratio. Commonly, image reconstruction in such scenarios is facilitated by the use of the virtual-detector approach. Although the validity of this approach has …Read More »
  • Fiber interferometer for hybrid optical and optoacoustic intravital microscopy

    Fiber interferometer for hybrid optical and optoacoustic intravital microscopy

    source: © 2017 Optical Society of America The addition of optoacoustic sensing to optical microscopy may supplement fluorescence contrast with label-free measurements of optical absorption, enhancing biological observation. However, the physical dimensions of many optoacoustic systems have restricted the implementation of hybrid optical and optoacoustic (O2A) microscopy to imaging thin samples …Read More »

2016

2015

2014

2013

  • Acoustic inversion in optoacoustic tomography : A review

    Acoustic inversion in optoacoustic tomography : A review

    source:© 2013 Current Medical Imaging Reviews Optoacoustic tomography enables volumetric imaging with optical contrast in biological tissue at depths beyond the optical mean free path by the use of optical excitation and acoustic detection. The hybrid nature of optoacoustic tomography gives rise to two distinct inverse problems: The optical inverse …Read More »
  • Optoacoustic determination of the spatial and temporal responses of ultrasound transducers

    Optoacoustic determination of the spatial and temporal responses of ultrasound transducers

    source:© 2013 IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control The characterization of the spatial and frequency response of acoustic detectors is important for enabling accurate optoacoustic imaging. In this work, we developed a hybrid method for the characterization of the spatially dependent response of ultrasound detectors. The method is …Read More »
  • Optoacoustic determination of spatio-temporal responses of ultrasound sensors

    Optoacoustic determination of spatio-temporal responses of ultrasound sensors

    source: © 2013 IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control The characterization of the spatial and frequency response of acoustic detectors is important for enabling accurate optoacoustic imaging. In this work, we developed a hybrid method for the characterization of the spatially dependent response of ultrasound detectors. The method …Read More »
  • Modeling the shape of cylindrically focused transducers in three-dimensional optoacoustic tomography

    Modeling the shape of cylindrically focused transducers in three-dimensional optoacoustic tomography

    source: © 2013 Journal of Biomedical Optics Cross sectional tomographic systems based on cylindrically focused transducers are widely used in optoacoustic (photoacoustic) imaging due to important advantages they provide such as high-cross sectional resolution, real-time imaging capacity, and high-throughput performance. Tomographic images in such systems are commonly obtained by means …Read More »
  • Weighted model-based optoacoustic reconstruction in acoustic scattering media

    Weighted model-based optoacoustic reconstruction in acoustic scattering media

    source: © 2013 Physics in Medicine & Biology Model-based optoacoustic inversion methods are capable of eliminating image artefacts associated with the widely adopted back-projection reconstruction algorithms. Yet, significant image artefacts might also occur due to reflections and scattering of optoacoustically-induced waves from strongly acoustically-mismatched areas in tissues. Herein, we modify …Read More »

2012

  • Improving quantification of intravascular fluorescence imaging using structural information

    Improving quantification of intravascular fluorescence imaging using structural information

    source:© 2012 Physics in Medicine & Biology Intravascular near-infrared fluorescence (iNIRF) imaging can enable the in vivo visualization of biomarkers of vascular pathology, including high-risk plaques. The technique resolves the bio-distribution of systemically administered fluorescent probes with molecular specificity in the vessel wall. However, the geometrical variations that may occur …Read More »
  • Intravascular multispectral optoacoustic tomography of atherosclerosis: prospects and challenges

    Intravascular multispectral optoacoustic tomography of atherosclerosis: prospects and challenges

    source:©2012 Imaging Med. The progression of atherosclerosis involves complex changes in the structure, composition and biology of the artery wall. Currently, only anatomical plaque burden is routinely characterized in living patients, whereas compositional and biological changes are mostly inaccessible. However, anatomical imaging alone has proven to be insufficient for accurate …Read More »
  • Model-based optoacoustic imaging using focused detector scanning

    Model-based optoacoustic imaging using focused detector scanning

    source: © 2012 Optical Society of America Optoacoustic (photoacoustic) mesoscopic and microscopic imaging is often implemented by linearly scanning a spherically focused ultrasound transducer. In this case, the resolution and sensitivity along the scan direction are limited by diffraction and therefore degrade rapidly for imaging depths away from the focal …Read More »
  • Efficient framework for model-based tomographic image reconstruction using wavelet packets

    Efficient framework for model-based tomographic image reconstruction using wavelet packets

    source:© 2012 IEEE Transactions on Medical Imaging The use of model-based algorithms in tomographic imaging offers many advantages over analytical inversion methods. However, the relatively high computational complexity of model-based approaches often restricts their efficient implementation. In practice, many modern imaging modalities, such as computed-tomography, positron-emission tomography, or optoacoustic tomography, …Read More »
  • Spatial characterization of the response of a silica optical fiber to wideband ultrasound

    Spatial characterization of the response of a silica optical fiber to wideband ultrasound

    source: © 2012 Optical Society of America Optical fibers have long been recognized as a promising technology for remote sensing of ultrasound. Nonetheless, very little is known about the characteristics of their spatial response, which is significantly affected by the strong acoustic mismatches between the fiber and surrounding medium. In …Read More »
  • Wideband arbitrary-phase interferometer stabilization

    Wideband arbitrary-phase interferometer stabilization

    We report on a robust scheme for wideband variable-phase interferometer stabilization based on active modulation. In contrast to previous schemes, the correction signal is generated without using second harmonics, whose low amplitude often requires employing narrowband lock-in amplifiers. Resonances in the element modulating the phase are attenuated to enable high …Read More »
  • Wideband optical sensing using pulse interferometry

    Wideband optical sensing using pulse interferometry

    source: © 2012 Optics express Advances in fabrication of high-finesse optical resonators hold promise for the development of miniaturized, ultra-sensitive, wide-band optical sensors, based on resonance-shift detection. Many potential applications are foreseen for such sensors, among them highly sensitive detection in ultrasound and optoacoustic imaging. Traditionally, sensor interrogation is performed …Read More »
  • Wideband Fiber-Interferometer Stabilization With Variable Phase

    Wideband Fiber-Interferometer Stabilization With Variable Phase

    source: © 2012 IEEE Photonics Technology Letters We report on a robust scheme for wideband variable-phase interferometer stabilization based on active modulation. In contrast to previous schemes, the correction signal is generated without using second harmonics, whose low amplitude often requires employing narrowband lock-in amplifiers. Resonances in the element modulating …Read More »

2011

2010

2009

2008

2007

2006

2005

2004

2003

  • Measuring the structure of highly reflecting fiber Bragg gratings

    Measuring the structure of highly reflecting fiber Bragg gratings

    source: © 2003 IEEE Photonics Technology Letters We demonstrate a new technique that enables us to measure the structure of highly reflecting fiber Bragg gratings. The impulse response function is measured from both sides of the grating using a low-coherence spectral interferometry technique. An inverse scattering algorithm is used to …Read More »
  • Measuring temperature profiles in high-power optical fiber components

    Measuring temperature profiles in high-power optical fiber components

    source: © 2003 Optical Society of America We demonstrate a new method for measuring changes in temperature distribution caused by coupling a high-power laser beam into an optical fiber and by splicing two fibers. The measurement technique is based on interrogating a fiber Bragg grating by using low-coherence spectral interferometry. …Read More »
  • Inverse scattering algorithm for reconstructing strongly reflecting fiber Bragg gratings

    Inverse scattering algorithm for reconstructing strongly reflecting fiber Bragg gratings

    source: © 2003 IEEE Journal of Quantum Electronics We demonstrate a new inverse scattering algorithm for reconstructing the structure of highly reflecting fiber Bragg gratings. The method, called integral layer-peeling (ILP), is based on solving the Gel’fand-Levitan-Marchenko (GLM) integral equation in a layer-peeling procedure. Unlike in previously published layer-peeling algorithms, …Read More »