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Fluorescence lifetime imaging through scattering media. Sci Rep 2023; 13:3066. [PMID: 36810512 PMCID: PMC9944959 DOI: 10.1038/s41598-023-30055-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 02/15/2023] [Indexed: 02/24/2023] Open
Abstract
Fluorescence lifetime determination has proven to be useful, e.g. identification of molecules, quantitative estimation of species concentration and determination of temperatures. Lifetime determination of exponentially decaying signals is challenging if signals of different decay rates are being mixed, resulting in erroneous results. Such issues occur when the contrast of the measurement object is low, which can be limiting in applied measurements due to spurious light scattering. A solution is presented here where structured illumination is used to enhance image contrast in fluorescence lifetime wide-field imaging. Lifetime imaging determination was carried out using Dual Imaging Modeling Evaluation (DIME), and spatial lock-in analysis was used for removing spurious scattered signal to enable fluorescence lifetime imaging through scattering media.
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Dorozynska K, Ek S, Kornienko V, Andersson D, Andersson A, Ehn A, Kristensson E. Snapshot multicolor fluorescence imaging using double multiplexing of excitation and emission on a single detector. Sci Rep 2021; 11:20454. [PMID: 34650144 PMCID: PMC8517015 DOI: 10.1038/s41598-021-99670-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 09/27/2021] [Indexed: 12/02/2022] Open
Abstract
Fluorescence-based multispectral imaging of rapidly moving or dynamic samples requires both fast two-dimensional data acquisition as well as sufficient spectral sensitivity for species separation. As the number of fluorophores in the experiment increases, meeting both these requirements becomes technically challenging. Although several solutions for fast imaging of multiple fluorophores exist, they all have one main restriction; they rely solely on spectrally resolving either the excitation- or the emission characteristics of the fluorophores. This inability directly limits how many fluorophores existing methods can simultaneously distinguish. Here we present a snapshot multispectral imaging approach that not only senses the excitation and emission characteristics of the probed fluorophores but also all cross term combinations of excitation and emission. To the best of the authors’ knowledge, this is the only snapshot multispectral imaging method that has this ability, allowing us to even sense and differentiate between light of equal wavelengths emitted from the same fluorescing species but where the signal components stem from different excitation sources. The current implementation of the technique allows us to simultaneously gather 24 different spectral images on a single detector, from which we demonstrate the ability to visualize and distinguish up to nine fluorophores within the visible wavelength range.
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Affiliation(s)
| | - Simon Ek
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden
| | - Vassily Kornienko
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden
| | - David Andersson
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden
| | | | - Andreas Ehn
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden
| | - Elias Kristensson
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden.
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Li Y, Tian J, Li DDU. Theoretical investigations of a modified compressed ultrafast photography method suitable for single-shot fluorescence lifetime imaging. APPLIED OPTICS 2021; 60:1476-1483. [PMID: 33690594 DOI: 10.1364/ao.415594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 01/15/2021] [Indexed: 06/12/2023]
Abstract
A single-shot fluorescence lifetime imaging (FLIM) method based on the compressed ultrafast photography (CUP) is proposed, named space-restricted CUP (srCUP). srCUP is suitable for imaging objects moving slowly (<∼150/Mmm/s, M is the magnification of the objective lens) in the field of view with the intensity changing within nanoseconds in a measurement window around 10 ns. We used synthetic datasets to explore the performances of srCUP compared with CUP and TCUP (a variant of CUP). srCUP not only provides superior reconstruction performances, but its reconstruction speed is also twofold and threefold faster than CUP and TCUP, respectively. The lifetime determination performances were assessed by estimating lifetime components, amplitude- and intensity-weighted average lifetimes (τA and τI), with the reconstructed scenes using the least squares method based on a bi-exponential model. srCUP has the best accuracy and precision for lifetime determinations with a relative bias less than 7% and a coefficient of variation less than 7% for τA, and a relative bias less than 10% and a coefficient of variation less than 11% for τI.
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Li Y, Jia H, Chen S, Tian J, Liang L, Yuan F, Yu H, Li DDU. Single-shot time-gated fluorescence lifetime imaging using three-frame images. OPTICS EXPRESS 2018; 26:17936-17947. [PMID: 30114076 DOI: 10.1364/oe.26.017936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 06/14/2018] [Indexed: 06/08/2023]
Abstract
Qualitative and quantitative measurements of complex flows demand for fast single-shot fluorescence lifetime imaging (FLI) technology with high precision. A method, single-shot time-gated fluorescence lifetime imaging using three-frame images (TFI-TGFLI), is presented. To our knowledge, it is the first work to combine a three-gate rapid lifetime determination (RLD) scheme and a four-channel framing camera to achieve this goal. Different from previously proposed two-gate RLD schemes, TFI-TGFLI can provide a wider lifetime range 0.6 ~ 13ns with reasonable precision. The performances of the proposed approach have been examined by both Monte-Carlo simulations and toluene seeded gas mixing jet diagnosis experiments. The measured average lifetimes of the whole excited areas agree well with the results obtained by the streak camera, and they are 7.6ns (N2 = 7L/min; O2 < 0.1L/min) and 2.6ns (N2 = 19L/min; O2 = 1L/min) with the standard deviations of 1.7ns and 0.8ns among the lifetime image pixels, respectively. The concentration distributions of the quenchers and fluorescent species were further analyzed, and they are consistent with the experimental settings.
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Ehn A, Bood J, Li Z, Berrocal E, Aldén M, Kristensson E. FRAME: femtosecond videography for atomic and molecular dynamics. LIGHT, SCIENCE & APPLICATIONS 2017; 6:e17045. [PMID: 30167293 PMCID: PMC6062331 DOI: 10.1038/lsa.2017.45] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 03/02/2017] [Accepted: 03/10/2017] [Indexed: 05/18/2023]
Abstract
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 to perform ultrafast spectroscopic videography of dynamic single events. Here we present a laser-probe-based method that enables two-dimensional videography at ultrafast timescales (femtosecond and shorter) of single, non-repetitive events. The method is based on superimposing a structural code onto the illumination to encrypt a single event, which is then deciphered in a post-processing step. This coding strategy enables laser probing with arbitrary wavelengths/bandwidths to collect signals with indiscriminate spectral information, thus allowing for ultrafast videography with full spectroscopic capability. To demonstrate the high temporal resolution of our method, we present videography of light propagation with record high 200 femtosecond temporal resolution. The method is widely applicable for studying a multitude of dynamical processes in physics, chemistry and biology over a wide range of time scales. Because the minimum frame separation (temporal resolution) is dictated by only the laser pulse duration, attosecond-laser technology may further increase video rates by several orders of magnitude.
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Affiliation(s)
- Andreas Ehn
- Division of Combustion Physics, Department of Physics, Lund University, Lund SE-223 63, Sweden
| | - Joakim Bood
- Division of Combustion Physics, Department of Physics, Lund University, Lund SE-223 63, Sweden
| | - Zheming Li
- Division of Combustion Physics, Department of Physics, Lund University, Lund SE-223 63, Sweden
| | - Edouard Berrocal
- Division of Combustion Physics, Department of Physics, Lund University, Lund SE-223 63, Sweden
| | - Marcus Aldén
- Division of Combustion Physics, Department of Physics, Lund University, Lund SE-223 63, Sweden
| | - Elias Kristensson
- Division of Combustion Physics, Department of Physics, Lund University, Lund SE-223 63, Sweden
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Larsson K, Aldén M, Bood J. Simultaneous Visualization of Hydrogen Peroxide and Water Concentrations Using Photofragmentation Laser-Induced Fluorescence. APPLIED SPECTROSCOPY 2017; 71:2118-2127. [PMID: 28447477 DOI: 10.1177/0003702817702386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A concept based on photofragmentation laser-induced fluorescence (PFLIF) is for the first time demonstrated for simultaneous detection of hydrogen peroxide (H2O2) and water (H2O) vapor in various mixtures containing the two constituents in a bath of argon gas. A photolysis laser pulse at 248 nm dissociates H2O2 into OH fragments, whereupon a probe pulse, delayed 100 ns and tuned to an absorption line in the A2Σ+ (v = 1) ← X2Π(v = 0) band of OH near 282 nm, induces fluorescence. The total OH fluorescence reflects the H2O2 concentration, while its spectral shape is utilized to determine the H2O concentration via a model predicting the ratio between the fluorescence intensities of the A2Σ+ (v = 1) → X2Π(v = 1) and the A2Σ+ (v = 0) → X2Π(v = 0) bands. The H2O detection scheme requires that the bath gas has a collisional cross-section with OH(A) that is significantly lower than that of H2O, which is the case for argon. Spectrally dispersed OH fluorescence spectra were recorded for five different H2O2/H2O/Ar mixtures; the H2O2 concentration in the range of 30-500 ppm and the H2O concentration in the range of 0-3%. Fluorescence intensity ratios predicted by the model for these mixtures agree very well with corresponding experimental data, which thus validates the model. The concept was also demonstrated for two-dimensional imaging, using two intensified charge-coupled device (CCD) cameras for signal detection. Water content was here sensed through the different temporal characteristics of the two fluorescence bands by triggering the two cameras so that one captures the total OH fluorescence while the other one captures only the early part, which mainly stems from A2Σ+ (v = 1) → X2Π(v = 1) fluorescence. Hence, the H2O2 concentration is reflected by the image of the camera recording the total OH fluorescence, whereas H2O concentration is extracted from the ratio between the two camera images. Quantification of the concentrations was carried out based on calibration measurements performed in known mixtures of H2O2 (30-500 ppm) and H2O (0-3%) in bulk argon. The detection limits for single-shot imaging are estimated to be 20 ppm for H2O2 and 0.05% for H2O. The authors believe that the concept provides a valuable asset in, for example, pharmaceutical or aseptic food packaging applications, where H2O2/H2O vapor is routinely used for sterilization.
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Affiliation(s)
- Kajsa Larsson
- Division of Combustion Physics, Lund University, Lund, Sweden
| | - Marcus Aldén
- Division of Combustion Physics, Lund University, Lund, Sweden
| | - Joakim Bood
- Division of Combustion Physics, Lund University, Lund, Sweden
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Ehn A, Zhu J, Li X, Kiefer J. Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering. APPLIED SPECTROSCOPY 2017; 71:341-366. [PMID: 28155328 DOI: 10.1177/0003702817690161] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.
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Affiliation(s)
- Andreas Ehn
- 1 Combustion Physics, Lund University, Lund, Sweden
| | - Jiajian Zhu
- 2 Science and Technology on Scramjet Laboratory, National University of Defense Technology, Changsha, China
| | - Xuesong Li
- 3 Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Johannes Kiefer
- 4 Technische Thermodynamik and MAPEX Center for Materials and Processes, Universität Bremen, Bremen, Germany
- 5 School of Engineering, University of Aberdeen, Aberdeen, UK
- 6 Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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