scholarly journals Multispectral Depth-Resolved Fluorescence Lifetime Spectroscopy Using SPAD Array Detectors and Fiber Probes

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2678 ◽  
Author(s):  
João L. Lagarto ◽  
Caterina Credi ◽  
Federica Villa ◽  
Simone Tisa ◽  
Franco Zappa ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Single Photon ◽  
Single Point ◽  
Rabbit Aorta ◽  
Depth Information ◽  
Optical Scheme ◽  
Linear Arrangement ◽  
Excitation Light ◽  
Fluorescence Measurements ◽  
Array Detectors

Single Photon Avalanche Diode (SPAD) arrays are increasingly exploited and have demonstrated potential in biochemical and biomedical research, both for imaging and single-point spectroscopy applications. In this study, we explore the application of SPADs together with fiber-optic-based delivery and collection geometry to realize fast and simultaneous single-point time-, spectral-, and depth-resolved fluorescence measurements at 375 nm excitation light. Spectral information is encoded across the columns of the array through grating-based dispersion, while depth information is encoded across the rows thanks to a linear arrangement of probe collecting fibers. The initial characterization and validation were realized against layered fluorescent agarose-based phantoms. To verify the practicality and feasibility of this approach in biological specimens, we measured the fluorescence signature of formalin-fixed rabbit aorta samples derived from an animal model of atherosclerosis. The initial results demonstrate that this detection configuration can report fluorescence spectral and lifetime contrast originating at different depths within the specimens. We believe that our optical scheme, based on SPAD array detectors and fiber-optic probes, constitute a powerful and versatile approach for the deployment of multidimensional fluorescence spectroscopy in clinical applications where information from deeper tissue layers is important for diagnosis.

Assessment of In-Depth Degradation of Artificially Aged Triterpenoid Paint Varnishes Using Nonlinear Microscopy Techniques

2014 ◽  
Vol 21 (2) ◽  
pp. 510-517 ◽  
Author(s):  
George Filippidis ◽  
Meropi Mari ◽  
Lambrini Kelegkouri ◽  
Aggelos Philippidis ◽  
Aleksandros Selimis ◽  
...  
Keyword(s):  
Single Photon ◽  
Imaging Techniques ◽  
Depth Information ◽  
Aging Effects ◽  
Protective Layers ◽  
Fluorescence Measurements ◽  
Aging Studies ◽  
Nonlinear Imaging ◽  
Microscopy Techniques ◽  
Analytical Tools

AbstractThe present work investigates the applicability of nonlinear imaging microscopy for the precise assessment of degradation of the outer protective layers of painted artworks as a function of depth due to aging. Two fresh and artificially aged triterpenoid varnishes, dammar and mastic, were tested. Nonlinear imaging techniques have been employed as a new diagnostic tool for determination of the exact thickness of the affected region due to artificial aging of the natural varnishes. The measured thicknesses differ from the calculated mean penetration depths of the samples. These nondestructive, high resolution modalities are valuable analytical tools for aging studies and they have the potential to provide unique in-depth information. Single photon laser induced fluorescence measurements and Raman spectroscopy were used for the integrated investigation and analysis of aging effects in varnishes.

Increasing the information capacity of a fiber-optic multi-sensor converter of binary mechanical signals into electrical signals

2020 ◽  
pp. 15-23
Author(s):  
V. M. Grechishnikov ◽  
E. G. Komarov
Keyword(s):  
Fiber Optic ◽  
Information Capacity ◽  
Parallel Structure ◽  
Optical Scheme ◽  
Digital To Analog Converter ◽  
Electrical Signals ◽  
Mechanical Signals ◽  
Analog Converter ◽  
Output Code ◽  
Digital To Analog

The design and operation principle of a multi-sensor Converter of binary mechanical signals into electrical signals based on a partitioned fiber-optic digital-to-analog Converter with a parallel structure is considered. The digital-to-analog Converter is made from a set of simple and technological (three to five digit) fiber-optic digital-to-analog sections. The advantages of the optical scheme of the proposed. Converter in terms of metrological and energy characteristics in comparison with single multi-bit converters are justified. It is shown that by increasing the number of digital-analog sections, it is possible to repeatedly increase the information capacity of a multi-sensor Converter without tightening the requirements for its manufacturing technology and element base. A mathematical model of the proposed Converter is developed that reflects the features of its operation in the mode of sequential time conversion of the input code vectors of individual fiber-optic sections into electrical analogues and the formation of the resulting output code vector.

Single Point PICA Probing with an Avalanche Photo-Diode

2001 ◽  
Author(s):  
Mike Bruce ◽  
Rama R. Goruganthu ◽  
Shawn McBride ◽  
David Bethke ◽  
J.M. Chin
Keyword(s):  
Single Photon ◽  
Single Point ◽  
Photon Counting ◽  
Ring Oscillator ◽  
Time Resolved ◽  
Single Photon Counting ◽  
Photo Diode ◽  
Avalanche Photo Diode ◽  
Photo Multiplier Tube ◽  
Channel Plate

Abstract For time resolved hot carrier emission from the backside, an alternate approach is demonstrated termed single point PICA. The single point approach records time resolved emission from an individual transistor using time-correlated-single-photon counting and an avalanche photo-diode. The avalanche photo-diode has a much higher quantum efficiency than micro-channel plate photo-multiplier tube based imaging cameras typically used in earlier approaches. The basic system is described and demonstrated from the backside on a ring oscillator circuit.

MODELING OF FIBER-OPTIC COMMUNICATION CHANNEL FOR QUANTUM CRYPTOGRAPHIC SYSTEMS

2019 ◽  
pp. 90-95
Author(s):  
V. A. Minaev ◽  
I. D. Korolev ◽  
O. A. Kulish ◽  
A. V. Mazin
Keyword(s):  
Information Transmission ◽  
Information Transfer ◽  
Fiber Optic ◽  
Single Photon ◽  
Optical Devices ◽  
Energy Losses ◽  
Integrated Optical ◽  
Integrated Optical Devices ◽  
Fiber Optic Communication ◽  
Optic Communication

The existing methods of information delivery to the strategic and tactical management of many government agencies are expensive, not always reliable and efficient. Therefore, quantum cryptographic systems (QCS) have been actively developed in recent years. However, there are problems with the use of the QCS associated with the reliability of information transfer. First, the existing fiber-optic communication channels (FOCC) are not designed to transmit single-photon signals, which leads to the complexity of their cryptographic protection. The second is insufficiently methodically developed calculation of energy losses and errors in the evaluation of the characteristics of information transfer in FOCC QCS. In article the analysis of the energy loss factors in the classical fiber-optic channel is carried out and the additive loss formula is discussed in detail. Then we consider the fiber-optic channel of quantum information transmission with the use of integrated optical devices. The additive formula of optical losses in such a channel is discussed. The features of losses in integrated optical devices are shown. The features of quantum cryptographic system of information transmission are considered. As a result, the model of FOCC QCS taking into account energy losses is presented, which allows competently in theoretical terms and visualize the passage of information through modern quantum cryptographically secure telecommunications while providing control in government structures.

scholarly journals Spectroscopic Studies of Dual Fluorescence in 2-(4-Fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole: Effect of Molecular Aggregation in a Micellar System

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2861 ◽  
Author(s):  
Grzegorz Czernel ◽  
Arkadiusz Matwijczuk ◽  
Dariusz Karcz ◽  
Andrzej Górecki ◽  
Agnieszka Niemczynowicz ◽  
...  
Keyword(s):  
Light Scattering ◽  
Fluorescence Spectra ◽  
Single Photon ◽  
Spectroscopic Studies ◽  
Fluorescence Probes ◽  
Molecular Aggregation ◽  
Micellar System ◽  
Dual Fluorescence ◽  
Fluorescence Measurements ◽  
Ionic Detergent

The article presents the results of spectroscopic studies focused on a selected compound from the 1,3,4-thiadiazole group—2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thia-diazole (FABT)—in a micellar system formed by Triton X-100, a non-ionic detergent. Fluorescence measurements revealed the phenomenon of dual fluorescence whose emergence is related to the particular molecular organisation of the compound, which depends both on the concentration of the detergent and, most of all, the concentration of the compound itself. Dual fluorescence of FABT in a micellar system was observed for the compound dissolved in a methanol aqueous system, i.e., an environment wherein the dual fluorescence of the compound had never been reported before. Based on the interpretation of UV-Vis electronic absorption, resonance light scattering (RLS), emission and excitation fluorescence spectra, as well as measurements of dynamic light scattering (DLS) and Principal Component Analysis (PCA), we were able to relate the occurrence of this effect to the process of molecular aggregation taking place between FABT molecules in the micellar system in question. Results of fluorescence spectra measurements and time-correlated single photon counting (TCSPC) indicate that dual fluorescence occurs at detergent concentrations necessary to form micellar systems, which in turn facilitate the process of aggregation of FABT molecules. The correlation between the observed fluorescence effects and the previous measurements performed for analogues from this group suggests the possibility of charge transfer (CT) within the range of detergent concentrations wherein the aforementioned fluorescence effects are observed. It ought to be emphasised that this type of fluorescence effects are relatively easy to induce, which predisposes this groups of fluorophores as ideal fluorescence probes in the context of biological samples.

Single-photon imaging system with a fiber optic taper

2018 ◽  
Vol 14 (4) ◽  
pp. 267-270
Author(s):  
Tian-xiang Zheng ◽  
Guang-yue Shen ◽  
Zhao-hui Li ◽  
E. Wu ◽  
Xiu-liang Chen ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Imaging System ◽  
Single Photon ◽  
Photon Imaging

scholarly journals Development and Applications of Bioluminescent and Chemiluminescent Reporters and Biosensors

2019 ◽  
Vol 12 (1) ◽  
pp. 129-150 ◽  
Author(s):  
Hsien-Wei Yeh ◽  
Hui-Wang Ai
Keyword(s):  
Excited State ◽  
External Excitation ◽  
Excitation Light ◽  
Fluorescent Reporters ◽  
Fluorescence Measurements ◽  
Chemiluminescent Sensors ◽  
Biomedical Fields ◽  
Bioluminescent Reporters

Although fluorescent reporters and biosensors have become indispensable tools in biological and biomedical fields, fluorescence measurements require external excitation light, thereby limiting their use in thick tissues and live animals. Bioluminescent reporters and biosensors may potentially overcome this hurdle because they use enzyme-catalyzed exothermic biochemical reactions to generate excited-state emitters. This review first introduces the development of bioluminescent reporters, and next, their applications in sensing biological changes in vitro and in vivo as biosensors. Lastly, we discuss chemiluminescent sensors that produce photons in the absence of luciferases. This review aims to explore fundamentals and experimental insights and to emphasize the yet-to-be-reached potential of next-generation luminescent reporters and biosensors.

Imaging Spectroscopy Using Fiber Optics

1997 ◽  
Vol 3 (S2) ◽  
pp. 845-846
Author(s):  
S. Michael Angel ◽  
H. Trey Skinner ◽  
Brian J. Marquardt
Keyword(s):  
Optical Fiber ◽  
Fiber Optics ◽  
Optical Fibers ◽  
Fiber Optic ◽  
Imaging System ◽  
Single Point ◽  
Imaging Spectroscopy ◽  
Small Diameter ◽  
Imaging Spectrometer ◽  
Remote Spectroscopy

Optical fiber probes are routinely used with optical spectrometers to allow measurements to be made on remotely located samples. In most of these systems, however, the optical fibers are used as non-imaging “light pipes” for the transmission of laser light, and luminescence or Raman signals to and from the sample. Thus, while these systems are suitable for remote spectroscopy, they are limited to single-point measurements. In a recent paper, we showed that a small-diameter (i.e., 350 μm) coherent optical fiber bundle can be combined with an AOTF-based imaging spectrometer for fluorescence and Raman spectral micro-imaging with increased flexibility in terms of sample positioning and in-situ capabilities. The previous paper described the operation of the fiber-optic microimaging probe and AOTF imaging system and showed preliminary Raman and fluorescence images for model compounds with 4 μm resolution. We have extended this work to include a discussion of the lateral and vertical spatial resolution of the fiber-optic microprobe in a non-contact proximity-focused configuration.

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