Edouard Berrocal

Edouard Berrocal
Lund University | LU · Department of Physics

Ph.D.

About

117
Publications
27,684
Reads
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1,766
Citations
Citations since 2016
68 Research Items
1273 Citations
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2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250

Publications

Publications (117)
Article
Full-text available
Schlieren photography is widely used for visualizing phenomena within transparent media. The technique, which comes in a variety of configurations, is based on detecting or extracting the degree to which light is deflected whilst propagating through a sample. To date, high-speed schlieren videography can only be achieved using high-speed cameras, t...
Article
Full-text available
Droplets temperature is a key parameter for the study of heat and mass transfers in many spray applications. Time correlated single photons counting (TCSPC) is applied to monitor the fluorescence decay and determine the droplet temperature in the mixing zone of two sprays which are injected with significantly different temperatures. For some well-c...
Conference Paper
Full-text available
In this work, transmission measurements combined with high-speed imaging are performed using four different optical methods. Those methods are characterised by various types of illumination and filtering strategy: 1) a diffuse light without filtering, 2) a collimated homogeneous laser beam without filtering, 3) a collimated laser beam with structur...
Article
Full-text available
Light-sheet fluorescent microscopy (LSFM) has, in recent years, allowed for rapid 3D-imaging of cleared biomedical samples at larger and larger scale. However, even in cleared samples, multiple light scattering often degrades the imaging contrast and widens the optical sectioning. Accumulation of scattering intensifies these negative effects as lig...
Article
Full-text available
In this work, planar two-photon laser-induced fluorescence (2p-LIF) is applied for the first time to analyze the fluid dependent spray structure and atomization behavior of water and ethanol in a quantitative way. A commercial six-hole DISI (Direct-Injection Spark-Ignition) injector was studied at different injection pressures, operated with liquid...
Conference Paper
Full-text available
In this work, two-color laser-induced fluorescence (2c-LIF) is applied to measure the temperature in micrometric ethanol droplets, containing a novel dye mixture of fluorescein (FL) and sulforhodamine 101 (SRh). A monodisperse droplet generator is used to generate 100 µm sized droplets with temperatures from 293 K to 343 K. The addition and excitat...
Conference Paper
Meeting stricter legal emission limits and the simultaneous introduction of new synthetic fuels are key challenges for current and future research in the field of engine combustion. A deep knowledge of spray behavior is mandatory to address these problems, as air-fuel mixture and spray propagation in gasoline direct injection (GDI) are essential pr...
Article
Full-text available
Fast noninvasive probing of spatially varying decorrelating events, such as cerebral blood flow beneath the human skull, is an essential task in various scientific and clinical settings. One of the primary optical techniques used is diffuse correlation spectroscopy (DCS), whose classical implementation uses a single or few single-photon detectors,...
Article
Full-text available
Fast transient events, such as the disintegration of liquid bodies or chemical reactions between radical species, involve various processes that may occur at different time scales. Currently, there are two alternatives for monitoring such events: burst-or high-speed imaging. Burst imaging at ultrahigh speeds (∼100 MHz to THz) allows for the capture...
Article
Full-text available
We report, the use of laser-plasma-driven x rays to reveal the three-dimensional (3D) structure of a highly atomizing water spray. Soft x rays approximately 5 keV are generated by means of a laser-plasma accelerator. Transmission radiography measurements are performed at different angles, by rotating a multihole injector. Using computer tomography,...
Article
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Noninvasive optical imaging through dynamic scattering media has numerous important biomedical applications but still remains a challenging task. While standard diffuse imaging methods measure optical absorption or fluorescent emission, it is also well‐established that the temporal correlation of scattered coherent light diffuses through tissue muc...
Article
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In-situ quantification of particle concentration during the combustion of solid fuel powders is of importance for analyzing their combustion behaviors. Digital holography (DH) is applied here for studying iron powder combustion at high concentration. The performance of DH as a function of particle concentration is thoroughly studied with synthetic...
Preprint
Full-text available
Fast noninvasive probing of spatially varying decorrelating events, such as cerebral blood flow beneath the human skull, is an essential task in various scientific and clinical settings. One of the primary optical techniques used is diffuse correlation spectroscopy (DCS), whose classical implementation uses a single or few single-photon detectors,...
Article
Full-text available
Micron-sized iron powder is a promising energy carrier for the realization of large-scale storage and transportation. In-situ characterization of the combustion behaviors of iron particles is of great importance for understanding the combustion mechanism. In this work, magnified holographic imaging is employed to investigate the transient morpholog...
Article
Full-text available
This article, Part II of an article series on GPU-accelerated Monte Carlo simulation of photon transport through turbid media, focuses on the validation of the online software Multi-Scattering. While Part I detailed the implementation of the computational model, simulated and experimental results are now compared for the distribution of the scatter...
Article
Full-text available
As a promising carbon-free fuel, iron powder can directly combust with air and has great potential to provide clean and high-grad heat for various applications. The combustion characteristics of iron particles are of great significance for developing iron combustion model, designing efficient combustor, and optimizing combustion technologies. In th...
Conference Paper
Full-text available
Droplets generated by talking and coughing play a major role in the spreading of COVID-19. Thus, there is a need for accurate measurements of the physical properties of exhaled droplets just at the exit of the mouth, including their number and velocity. Several challenges are associated with imaging coughed droplets. First, large variation of dropl...
Article
Full-text available
To control the evolution of a pandemic such as COVID-19, knowing the conditions under which the pathogen is being transmitted represents a critical issue, especially when implementing protection strategies like social distancing and face masks wearing. For viruses and bacteria that spread via airborne and/or droplet pathways, this requires understa...
Conference Paper
Full-text available
In this work two-photon laser-induced fluorescence (2p-LIF) laser sheet imaging is used to analyze the structure and the atomization behavior of water and ethanol sprays. Multiple light scattering is reduced by 2p-LIF measurements using a femtosecond laser. This allows high-contrast spray imaging close to the nozzle resulting in an improved identif...
Article
Full-text available
In this work, the combustion behavior of seeded iron particles (d50 = 70 µm) in a laminar diffusion flame was studied in a modified Mckenna flat-flame burner. Two high speed cameras in stereo configuration allowed 3D position and 3D velocity measurements of burning iron particles as well as 3D evaluation of particle microexplosions. Microexplosive...
Article
Full-text available
This paper is Part II of a series of articles focusing on the disintegration of a cylindrical (Ø=0.60 mm diameter) water jet in a quiescent atmosphere, from Rayleigh to early atomization breakup regimes. Liquid fluorescence high-speed imaging is used here, instead of shadowgraphy, providing a more faithful representation of liquid jet breakup dynam...
Preprint
Full-text available
Noninvasive optical imaging through dynamic scattering media has numerous important biomedical applications but still remains a challenging task. While standard methods aim to form images based upon optical absorption or fluorescent emission, it is also well-established that the temporal correlation of scattered coherent light diffuses through tiss...
Article
Full-text available
This paper is Part I in a series of articles focused on a fundamental study on liquid jet disintegration. The main goal of this work is to provide an extensive open access database of high-speed images and videos for modelers and researchers in the field of fluid mechanics studying the dynamics of a liquid jet transiting from the Rayleigh to the at...
Article
Full-text available
Due to its low emission and high energy density, iron powder has been proposed as a promising recy-clable metal fuel for a future low-carbon society. The comprehensive understanding of combustion behavior of iron particles is crucial for studying fundamental mechanisms, developing suitable combustion technologies, and designing efficient iron powde...
Article
Full-text available
Diffuse correlation spectroscopy (DCS) is a well-established method that measures rapid changes in scattered coherent light to identify blood flow and functional dynamics within a tissue. While its sensitivity to minute scatterer displacements leads to a number of unique advantages, conventional DCS systems become photon-limited when attempting to...
Conference Paper
Tissue clearing allows 3D-imaging of large biomedical samples, but can be affected by blur effects limiting individual cells detection. Using a structured illumination light sheet we solve this issue, obtaining high-contrast images in turbid samples.
Article
Full-text available
In this article we present and describe an online freely accessible software called Multi-Scattering for the modeling of light propagation in scattering and absorbing media. Part II of this article series focuses on the validation of the model by rigorously comparing the simulated results with experimental data. The model is based on the use of the...
Article
Full-text available
Many important scientific questions in physics, chemistry and biology rely on high-speed optical imaging techniques for their investigations. These techniques are either passive, relying on the rapid readout of photoactive elements, or active, relying on the illumination properties of specially designed pulse trains. Currently, MHz imaging speeds a...
Preprint
Full-text available
Diffuse correlation spectroscopy (DCS) is a well-established method that measures rapid changes in scattered coherent light to identify blood flow and functional dynamics within tissue. While its sensitivity to minute scatterer displacements leads to a number of unique advantages, conventional DCS systems become photon-limited when attempting to pr...
Article
Full-text available
In contrast to static objects, liquid structures such as drops, blobs, as well as waves and ripples on water surfaces are challenging to image in 3D due to two main reasons: first, the transient nature of those phenomena requires snapshot imaging that is fast enough to freeze the motion of the liquid. Second, the transparency of liquids and the spe...
Article
Full-text available
Structured laser illumination planar imaging (SLIPI)-based techniques have been employed during the past decade for addressing multiple light scattering issues in spray imaging. In this article, SLIPI droplet sizing based on the intensity ratio of laser-induced fluorescence (LIF) over Mie scattering (SLIPI-LIF/Mie) and SLIPI-Scan for extinction-coe...
Article
Full-text available
This document provides supplementary information to "Simultaneous laser-driven X-ray and two-photon fluorescence imaging of atomizing sprays," https://doi.org/10.1364/optica.378063. First, we compare the different X-ray sources used for spray imaging. Then, different X-ray images are shown to illustrate the fluctuation of the spray. We also provide...
Conference Paper
This presentation will show our latest results on the use of soft X-rays emitted from a laser plasma accelerator for the visualization of an an atomizing spray used in the automotive industry.
Preprint
Full-text available
In this letter we report for the first time the possibility of visualizing an atomizing spray by simultaneously recording X-ray absorption and 2- photon laser-induced fluorescence imaging. This unique illumination/detection scheme was made possible thanks to the use of soft X-rays emitted from a laser-driven X-ray source. An 800 mJ laser pulse of 3...
Method
This document contains supplementary information to "Simultaneous laser-driven X-ray and two-photon fluorescence imaging of atomizing sprays". First, we compare the different X-ray sources used for spray imaging. Then, different X-ray images are shown to illustrate the fluctuation of the spray. We also provide details and discussion related to the...
Article
Full-text available
In this letter we report for the first time the possibility of visualizing an atomizing spray by simultaneously recording X-ray absorption and 2- photon laser-induced fluorescence imaging. This unique illumination/detection scheme was made possible thanks to the use of soft X-rays emitted from a laser-driven X-ray source. An 800 mJ laser pulse of 3...
Article
Full-text available
In this work, the possibility of using planar droplet sizing (PDS) based on laser-induced fluorescence (LIF) and Mie scattering was investigated within the framework of measuring the droplet Sauter mean diameter (SMD) of direct-injection spark-ignition (DISI) spray systems. For this purpose, LIF and Mie signals of monodisperse fuel droplets produce...
Article
Full-text available
In this study the structured laser illumination planar imaging (SLIPI) technique is combined with gas phase phosphor thermometry to measure quasi-instantaneously two-dimensional temperature fields with reduced bias from multiple scattering. Different reconstruction strategies are implemented, evaluated and compared, including a two-pulse and one-pu...
Article
In this study, we report on the 3D (three-dimensional) characterization of a spray in terms of its droplet SMD (Sauter Mean Diameter) using the LIF (Laser-Induced Fluorescence)/Mie ratio technique. The spray structure is analyzed for a multi-hole DISI (Direct-Injection Spark Ignition) injector. A calibration curve to convert LIF/Mie ratio to drople...
Article
Full-text available
Two-photon excitation laser induced fluorescence (2p-LIF) is used here for imaging an optically dense atomizing spray. The main advantage of the approach is that very little fluorescence interference originating from multiple light scattering is generated. This leads to high image contrast and a faithful description of the imaged fluid structures....
Article
Full-text available
Imaging the interaction between different combustion species under turbulent flame conditions requires methods that both are extremely fast and provide means to spectrally separate different signals. Current experimental solutions to achieve this often rely on using several cameras that are time-gated and/or equipped with different spectral filters...
Article
Full-text available
Planar droplet sizing (PDS) is a technique relying on the assumption that laser-induced fluorescence (LIF) and Mie scattering optical signals from spherical droplets depend on their volume and surface area, respectively. In this article, we verify the validity of this assumption by experimentally analyzing the light intensity of the LIF and Mie opt...
Article
Full-text available
Imaging through turbid environments is experimentally challenging due to multiple light scattering. Structured laser illumination has proven to be effective to minimize errors arising from this phenomenon, allowing the interior of optically dense media to be observed. However, in order to preserve the image spatial resolution while suppressing the...
Conference Paper
This paper reports on the quantitative 2D and 3D droplet sizing based on the LIF/Mie ratio in ethanol DISI (Direct Injection Spark Ignition) sprays, where the required calibration is performed using quantitative micro and macro LIF/Mie ratio imaging of individual microdroplets. The droplets are generated from a monodisperse droplet generator in a d...
Article
Full-text available
This paper reports on the spray structure of the biofuels, ethanol, and butanol generated by a multihole direct-injection spark-ignition injector, which is studied in a constant volume chamber. The spray shape and structure are analyzed using two-phase structured laser illumination planar imaging where both laser-induced fluorescence and Mie-scatte...
Article
Full-text available
This paper describes the adaptation of the laser-induced fluorescence measurement technique for the investigation of the primary breakup of modern diesel and gasoline direct injection sprays. To investigate the primary breakup, a microscopic technique is required, and with the help of special tracer dyes, a high fluorescence signal can be achieved...
Article
Full-text available
In this study, the use of light sheet fluorescence microscopic imaging is demonstrated for viewing the dynamic of atomizing sprays with high contrast and resolution. The technique presents several advantages. First, liquid fluorescence gives a more faithful representation of the structure of liquid bodies, droplets, and ligaments than Mie scatterin...
Article
Full-text available
Imaging through optically dense sprays is challenging due to the detection of multiple light scattering, which blurs the recorded images and limits visibility. Structured laser illumination planar imaging (SLIPI) is a technique that is capable of reducing the intensity contribution that stems from multiple scattering in a light sheet imaging config...
Article
Full-text available
Structured laser illumination planar imaging (SLIPI) is combined with gas phase thermometry measurements using thermographic phosphor (TGP) particles. The technique is applied to a heated jet surrounded by a coflow which is operated at ambient temperature. The respective air flows are seeded with a powder of BaMgAl10O17:Eu²⁺ (BAM) which is used as...
Article
Full-text available
A comparison between the commonly used absorption spectrophotometry and a more recent approach known as structured laser illumination planar imaging (SLIPI) is presented for the characterization of scattering and absorbing liquids. Water solutions of milk and coffee are, respectively, investigated for 10 different levels of tur-bidity. For the milk...
Article
Full-text available
Many important scientific questions in physics, chemistry and biology require effective methodologies to spectroscopically probe ultrafast intra-and inter-atomic/molecular dynamics. However, current methods that extend into the femtosecond regime are capable of only point measurements or single snapshot visualizations and thus lack the capability t...
Article
Full-text available
We present an optical solution called DMD-PS to boost the dynamic range of 2D imaging spectroscopic measurements up to 22 bits by incorporating a digital micromirror device (DMD) prior to detection in combination with the periodic shadowing (PS) approach. In contrast to high dynamic range (HDR), where the dynamic range is increased by recording sev...
Article
Full-text available
We report in this Letter a two-phase structured laser illumination planar imaging [two-pulse SLIPI (2p-SLIPI)] optical setup where the "lines structure" is spatially shifted by exploiting the birefringence property of a calcite crystal. By using this optical component and two cross-polarized laser pulses, the shift of the modulated pattern is not "...