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Sample records for optical bioimaging probes

  1. Chemical Address Tags of Fluorescent Bioimaging Probes

    PubMed Central

    Shedden, Kerby; Rosania, Gus R.

    2010-01-01

    Chemical address tags can be defined as specific structural features shared by a set of bioimaging probes having a predictable influence on cell-associated visual signals obtained from these probes. Here, using a large image dataset acquired with a high content screening instrument, machine vision and cheminformatics analysis have been applied to reveal chemical address tags. With a combinatorial library of fluorescent molecules, fluorescence signal intensity, spectral, and spatial features characterizing each one of the probes' visual signals were extracted from images acquired with the three different excitation and emission channels of the imaging instrument. With multivariate regression, the additive contribution from each one of the different building blocks of the bioimaging probes towards each measured, cell-associated image-based feature was calculated. In this manner, variations in the chemical features of the molecules were associated with the resulting staining patterns, facilitating quantitative, objective analysis of chemical address tags. Hierarchical clustering and paired image-cheminformatics analysis revealed key structure-property relationships amongst many building blocks of the fluorescent molecules. The results point to different chemical modifications of the bioimaging probes that can exert similar (or different) effects on the probes' visual signals. Inspection of the clustered structures suggests intramolecular charge migration or partial charge distribution as potential mechanistic determinants of chemical address tag behavior. PMID:20104576

  2. PPV-Based Conjugated Polymer Nanoparticles as a Versatile Bioimaging Probe: A Closer Look at the Inherent Optical Properties and Nanoparticle-Cell Interactions.

    PubMed

    Peters, Martijn; Zaquen, Neomy; D'Olieslaeger, Lien; Bové, Hannelore; Vanderzande, Dirk; Hellings, Niels; Junkers, Thomas; Ethirajan, Anitha

    2016-08-01

    Conjugated polymers have attracted significant interest in the bioimaging field due to their excellent optical properties and biocompatibility. Tailor-made poly(p-phenylenevinylene) (PPV) conjugated polymer nanoparticles (NPs) are in here described. Two different nanoparticle systems using poly[2-methoxy-5-(3',7'-dimethoxyoctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and a functional statistical copolymer 2-(5'-methoxycarbonylpentyloxy)-5-methoxy-1,4-phenylenevinylene (CPM-MDMO-PPV), containing ester groups on the alkoxy side chains, were synthesized by combining miniemulsion and solvent evaporation processes. The hydrolysis of ester groups into carboxylic acid groups on the CPM-MDMO-PPV NPs surface allows for biomolecule conjugation. The NPs exhibited excellent optical properties with a high fluorescent brightness and photostability. The NPs were in vitro tested as potential fluorescent nanoprobes for studying cell populations within the central nervous system. The cell studies demonstrated biocompatibility and surface charge dependent cellular uptake of the NPs. This study highlights that PPV-derivative based particles are a promising bioimaging probe and can cater potential applications in the field of nanomedicine. PMID:27345494

  3. Spectroscopic and nonlinear optical properties of new chalcone fluorescent probes for bioimaging applications: a theoretical and experimental study.

    PubMed

    Krawczyk, Przemysław; Pietrzak, Marek; Janek, Tomasz; Jędrzejewska, Beata; Cysewski, Piotr

    2016-06-01

    In this study, the newly synthesized non-centrosymmetric, 4-dimethylamino-3'-isothiocyanatochalcone (PKA) compound was presented. This compound belongs to the chalcone group, and its main purpose is to be used in biomedical imaging as a fluorescence dye. For this reason, the linear and nonlinear properties in solvents of different polarity were thoroughly studied. In accordance with the requirements for a fluorochrome, the PKA compound is characterized by strong absorption, large Stokes' shifts, relatively high fluorescence quantum yields and high nonlinear optical response. Moreover, the isothiocyanate reactive probe was conjugated with Concanavalin A. Conventional fluorescence microscopy imaging of Candida albicans cells incubated with the PKA-Concanavalin A, is presented. The results of this study show that the novel conjugate PKA-Concanavalin A could be a promising new probe for cellular labelling in biological and biomedical research. Graphical abstract Spectroscopic behavior of the PKA dye. PMID:27168200

  4. Carbon Nanoparticle-based Fluorescent Bioimaging Probes

    PubMed Central

    Bhunia, Susanta Kumar; Saha, Arindam; Maity, Amit Ranjan; Ray, Sekhar C.; Jana, Nikhil R.

    2013-01-01

    Fluorescent nanoparticle-based imaging probes have advanced current labelling technology and are expected to generate new medical diagnostic tools based on their superior brightness and photostability compared with conventional molecular probes. Although significant progress has been made in fluorescent semiconductor nanocrystal-based biological labelling and imaging, the presence of heavy metals and the toxicity issues associated with heavy metals have severely limited the application potential of these nanocrystals. Here, we report a fluorescent carbon nanoparticle-based, alternative, nontoxic imaging probe that is suitable for biological staining and diagnostics. We have developed a chemical method to synthesise highly fluorescent carbon nanoparticles 1–10 nm in size; these particles exhibit size-dependent, tunable visible emission. These carbon nanoparticles have been transformed into various functionalised nanoprobes with hydrodynamic diameters of 5–15 nm and have been used as cell imaging probes. PMID:23502324

  5. Optical probe

    DOEpatents

    Hencken, Kenneth; Flower, William L.

    1999-01-01

    A compact optical probe is disclosed particularly useful for analysis of emissions in industrial environments. The instant invention provides a geometry for optically-based measurements that allows all optical components (source, detector, rely optics, etc.) to be located in proximity to one another. The geometry of the probe disclosed herein provides a means for making optical measurements in environments where it is difficult and/or expensive to gain access to the vicinity of a flow stream to be measured. Significantly, the lens geometry of the optical probe allows the analysis location within a flow stream being monitored to be moved while maintaining optical alignment of all components even when the optical probe is focused on a plurality of different analysis points within the flow stream.

  6. Optically modulated fluorescence bioimaging: visualizing obscured fluorophores in high background.

    PubMed

    Hsiang, Jung-Cheng; Jablonski, Amy E; Dickson, Robert M

    2014-05-20

    Fluorescence microscopy and detection have become indispensible for understanding organization and dynamics in biological systems. Novel fluorophores with improved brightness, photostability, and biocompatibility continue to fuel further advances but often rely on having minimal background. The visualization of interactions in very high biological background, especially for proteins or bound complexes at very low copy numbers, remains a primary challenge. Instead of focusing on molecular brightness of fluorophores, we have adapted the principles of high-sensitivity absorption spectroscopy to improve the sensitivity and signal discrimination in fluorescence bioimaging. Utilizing very long wavelength transient absorptions of kinetically trapped dark states, we employ molecular modulation schemes that do not simultaneously modulate the background fluorescence. This improves the sensitivity and ease of implementation over high-energy photoswitch-based recovery schemes, as no internal dye reference or nanoparticle-based fluorophores are needed to separate the desired signals from background. In this Account, we describe the selection process for and identification of fluorophores that enable optically modulated fluorescence to decrease obscuring background. Differing from thermally stable photoswitches using higher-energy secondary lasers, coillumination at very low energies depopulates transient dark states, dynamically altering the fluorescence and giving characteristic modulation time scales for each modulatable emitter. This process is termed synchronously amplified fluorescence image recovery (SAFIRe) microscopy. By understanding and optically controlling the dye photophysics, we selectively modulate desired fluorophore signals independent of all autofluorescent background. This shifts the fluorescence of interest to unique detection frequencies with nearly shot-noise-limited detection, as no background signals are collected. Although the fluorescence brightness is

  7. Molecular spies for bioimaging--fluorescent protein-based probes.

    PubMed

    Miyawaki, Atsushi; Niino, Yusuke

    2015-05-21

    Convergent advances in optical imaging and genetic engineering have fueled the development of new technologies for biological visualization. Those technologies include genetically encoded indicators based on fluorescent proteins (FPs) for imaging ions, molecules, and enzymatic activities "to spy on cells," as phrased by Roger Tsien, by sneaking into specific tissues, cell types, or subcellular compartments, and reporting on specific intracellular activities. Here we review the current range of unimolecular indicators whose working principle is the conversion of a protein conformational change into a fluorescence signal. Many of the indicators have been developed from fluorescence resonance energy transfer- and single-FP-based approaches. PMID:26000848

  8. Spatial-scanning hyperspectral imaging probe for bio-imaging applications

    NASA Astrophysics Data System (ADS)

    Lim, Hoong-Ta; Murukeshan, Vadakke Matham

    2016-03-01

    The three common methods to perform hyperspectral imaging are the spatial-scanning, spectral-scanning, and snapshot methods. However, only the spectral-scanning and snapshot methods have been configured to a hyperspectral imaging probe as of today. This paper presents a spatial-scanning (pushbroom) hyperspectral imaging probe, which is realized by integrating a pushbroom hyperspectral imager with an imaging probe. The proposed hyperspectral imaging probe can also function as an endoscopic probe by integrating a custom fabricated image fiber bundle unit. The imaging probe is configured by incorporating a gradient-index lens at the end face of an image fiber bundle that consists of about 50 000 individual fiberlets. The necessary simulations, methodology, and detailed instrumentation aspects that are carried out are explained followed by assessing the developed probe's performance. Resolution test targets such as United States Air Force chart as well as bio-samples such as chicken breast tissue with blood clot are used as test samples for resolution analysis and for performance validation. This system is built on a pushbroom hyperspectral imaging system with a video camera and has the advantage of acquiring information from a large number of spectral bands with selectable region of interest. The advantages of this spatial-scanning hyperspectral imaging probe can be extended to test samples or tissues residing in regions that are difficult to access with potential diagnostic bio-imaging applications.

  9. Highly selective ratiometric fluorescent probe for Au3+ and its application to bioimaging.

    PubMed

    Choi, Ji Young; Kim, Gun-Hee; Guo, Zhiqian; Lee, Hye Yeon; Swamy, K M K; Pai, Jaeyoung; Shin, Seunghoon; Shin, Injae; Yoon, Juyoung

    2013-11-15

    The 4-propargylamino-1,8-naphthalimide based fluorescent probe 1 has been explored as a sensor for selective detection of Au(3+). 4-Amino-1,8-naphthalimides, that possess typical intramolecular charge transfer (ICT) electronic characteristics, have been widely used as versatile platforms for fluorescent probes. The newly designed probe 1 contains a propargylamine moiety at C-4 of the naphthalimide chromophore that reacts with Au(3+) to generate a product that has distinctly different electronic properties from 1. Specifically, the probe undergoes a remarkable change in its absorption spectrum upon addition of Au(3+) that is associated with a distinct color change from yellow to light pink. In addition, a blue shift of ca. 56 nm also takes place in the emission spectra of the probe. Consequently, 1 serves as a reaction-based sensor or so called chemodosimeter for Au(3+). Importantly, surfactants enhance the rate of reaction of 1 with Au(3+), thus, enhancing its use as a real time sensor. Finally, the results of studies probing its application to bioimaging of Au(3+) in live cells show that the probe 1 has a unique ability to sense Au(3+) in cells and, in particular, in lipid droplets within cells. PMID:23810913

  10. Fluorescent probes and bioimaging: alkali metals, alkaline earth metals and pH.

    PubMed

    Yin, Jun; Hu, Ying; Yoon, Juyoung

    2015-07-21

    All living species and life forms have an absolute requirement for bio-functional metals and acid-base equilibrium chemistry owing to the critical roles they play in biological processes. Hence, a great need exists for efficient methods to detect and monitor biometals and acids. In the last few years, great attention has been paid to the development of organic molecule based fluorescent chemosensors. The availability of new synthetic fluorescent probes has made fluorescence microscopy an indispensable tool for tracing biologically important molecules and in the area of clinical diagnostics. This review highlights the recent advances that have been made in the design and bioimaging applications of fluorescent probes for alkali metals and alkaline earth metal cations, including lithium, sodium and potassium, magnesium and calcium, and for pH determination within biological systems. PMID:25317749

  11. Folate receptor targeting silica nanoparticle probe for two-photon fluorescence bioimaging

    PubMed Central

    Wang, Xuhua; Yao, Sheng; Ahn, Hyo-Yang; Zhang, Yuanwei; Bondar, Mykhailo V.; Torres, Joseph A.; Belfield, Kevin D.

    2010-01-01

    Narrow dispersity organically modified silica nanoparticles (SiNPs), diameter ~30 nm, entrapping a hydrophobic two-photon absorbing fluorenyl dye, were synthesized by hydrolysis of triethoxyvinylsilane and (3-aminopropyl)triethoxysilane in the nonpolar core of Aerosol-OT micelles. The surface of the SiNPs were functionalized with folic acid, to specifically deliver the probe to folate receptor (FR) over-expressing Hela cells, making these folate two-photon dye-doped SiNPs potential candidates as probes for two-photon fluorescence microscopy (2PFM) bioimaging. In vitro studies using FR over-expressing Hela cells and low FR expressing MG63 cells demonstrated specific cellular uptake of the functionalized nanoparticles. One-photon fluorescence microscopy (1PFM) imaging, 2PFM imaging, and two-photon fluorescence lifetime microscopy (2P-FLIM) imaging of Hela cells incubated with folate-modified two-photon dye-doped SiNPs were demonstrated. PMID:21258480

  12. Bis-pyridinium quadrupolar derivatives. High Stokes shift selective probes for bio-imaging

    NASA Astrophysics Data System (ADS)

    Salice, Patrizio; Versari, Silvia; Bradamante, Silvia; Meinardi, Francesco; Macchi, Giorgio; Pagani, Giorgio A.; Beverina, Luca

    2013-11-01

    We describe the design, synthesis and characterization of five high Stokes shift quadrupolar heteroaryl compounds suitable as fluorescent probes in bio-imaging. In particular, we characterize the photophysical properties and the intracellular localization in Human Umbilical Vein Endothelial Cells (HUVEC) and Human Mesenchymal Stem Cells (HMSCs) for each dye. We show that, amongst all of the investigated derivatives, the 2,5-bis[1-(4-N-methylpyridinium)ethen-2-yl)]- N-methylpyrrole salt is the best candidates as selective mitochondrial tracker. Finally, we recorded the full emission spectrum of the most performing - exclusively mitochondrial selective - fluorescent probe directly from HUVEC stained cells. The emission spectrum collected from the stained mitochondria shows a remarkably more pronounced vibronic structure with respect to the emission of the free fluorophore in solution.

  13. Breathing laser as an inertia-free swept source for high-quality ultrafast optical bioimaging.

    PubMed

    Wei, Xiaoming; Xu, Jingjiang; Xu, Yiqing; Yu, Luoqin; Xu, Jianbing; Li, Bowen; Lau, Andy K S; Wang, Xie; Zhang, Chi; Tsia, Kevin K; Wong, Kenneth K Y

    2014-12-01

    We demonstrate an all-fiber breathing laser as inertia-free swept source (BLISS), with an ultra-compact design, for the emerging ultrafast bioimaging modalities. The unique feature of BLISS is its broadband wavelength-swept operation (∼60  nm) with superior temporal stability in terms of both long term (0.08 dB over 27 h) and shot-to-shot power variations (2.1%). More importantly, it enables a wavelength sweep rate of >10  MHz (∼7×10⁸  nm/s)—orders-of-magnitude faster than the existing swept sources based on mechanical or electrical tuning techniques. BLISS thus represents a practical and new generation of swept source operating in the unmet megahertz swept-rate regime that aligns with the pressing need for scaling the optical bioimaging speed in ultrafast phenomena study or high-throughput screening applications. To showcase its utility in high-speed optical bioimaging, we here employ BLISS for ultrafast time-stretch microscopy and multi-MHz optical coherence tomography of the biological specimen at a single-shot line-scan rate or A-scan rate of 11.5 MHz. PMID:25490629

  14. A two-photon fluorescent probe for bio-imaging of formaldehyde in living cells and tissues.

    PubMed

    Li, Jun-Bin; Wang, Qian-Qian; Yuan, Lin; Wu, Yong-Xiang; Hu, Xiao-Xiao; Zhang, Xiao-Bing; Tan, Weihong

    2016-05-23

    Formaldehyde (FA) plays an important role in living systems as a reactive carbonyl species (RCS). An abnormal degree of FA is known to induce neurodegeneration, cognitive decrease and memory loss owing to the formation of strong cross-link DNA and protein and other molecules. The development of efficient methods for biological FA detection is of great biomedical importance. Although a few one-photon FA fluorescent probes have been reported for imaging in living cells, probes excited by two photons are more suitable for bio-imaging due to their low background fluorescence, less photobleaching, and deep penetration depth. In this study, a two-photon fluorescent probe for FA detection and bio-imaging in living cells and tissues was reported. The detection is based on the 2-aza-Cope sigmatropic rearrangement followed by elimination to release the fluorophore, resulting in both one- and two-photon excited fluorescence increase. The probe showed a high sensitivity to FA with a detection limit of 0.2 μM. Moreover, enabled the two-photon bio-imaging of FA in live HEK-293 cells and tissues with tissue-imaging depths of 40-170 μm. Furthermore, could be applied for the monitoring of endogenous FA in live MCF-7 cells, presaging its practical applications in biological systems. PMID:27137921

  15. Stokes emission in GdF3:Nd3+ nanoparticles for bioimaging probes

    NASA Astrophysics Data System (ADS)

    Pokhrel, M.; Mimun, L. C.; Yust, B.; Kumar, G. A.; Dhanale, A.; Tang, L.; Sardar, D. K.

    2014-01-01

    There is increasing interest in rare earth (RE) doped nanoparticles (NPs) due to their sharp absorption and photoluminescence (PL) in the near infrared (NIR) spectral region. These NIR based nanoparticles (NPs) could allow biological imaging at substantial depths with enhanced contrast and high spatial resolution due to the absence of auto fluorescence in biological samples under infrared excitation. Here, we present the highly efficient infrared photoluminescence in GdF3:Nd3+ nanoparticles under 800 nm excitation within the hydrodynamic size limitations for bio-applications. The downconversion (Stokes emission) absolute quantum yields (QY) in powder, polymaleic anhydride-alt-1-octadicene (PMAO) coated powder and colloidal solutions have been investigated. QY measurements have revealed that downconversion (Stokes emission) QYs of approximately 5 +/- 2 nm sized GdF3:1% Nd3+ colloidal NPs are 2000 times higher than those of efficient upconversion (UC) particles NaYF4:20% Er/2% Yb of the same size. Furthermore, the utility of these NIR emitting nanoparticles for bioimaging probes has been demonstrated by confocal imaging and spectroscopic study.There is increasing interest in rare earth (RE) doped nanoparticles (NPs) due to their sharp absorption and photoluminescence (PL) in the near infrared (NIR) spectral region. These NIR based nanoparticles (NPs) could allow biological imaging at substantial depths with enhanced contrast and high spatial resolution due to the absence of auto fluorescence in biological samples under infrared excitation. Here, we present the highly efficient infrared photoluminescence in GdF3:Nd3+ nanoparticles under 800 nm excitation within the hydrodynamic size limitations for bio-applications. The downconversion (Stokes emission) absolute quantum yields (QY) in powder, polymaleic anhydride-alt-1-octadicene (PMAO) coated powder and colloidal solutions have been investigated. QY measurements have revealed that downconversion (Stokes emission) QYs

  16. Single-pulse CARS based multimodal nonlinear optical microscope for bioimaging.

    PubMed

    Kumar, Sunil; Kamali, Tschackad; Levitte, Jonathan M; Katz, Ori; Hermann, Boris; Werkmeister, Rene; Považay, Boris; Drexler, Wolfgang; Unterhuber, Angelika; Silberberg, Yaron

    2015-05-18

    Noninvasive label-free imaging of biological systems raises demand not only for high-speed three-dimensional prescreening of morphology over a wide-field of view but also it seeks to extract the microscopic functional and molecular details within. Capitalizing on the unique advantages brought out by different nonlinear optical effects, a multimodal nonlinear optical microscope can be a powerful tool for bioimaging. Bringing together the intensity-dependent contrast mechanisms via second harmonic generation, third harmonic generation and four-wave mixing for structural-sensitive imaging, and single-beam/single-pulse coherent anti-Stokes Raman scattering technique for chemical sensitive imaging in the finger-print region, we have developed a simple and nearly alignment-free multimodal nonlinear optical microscope that is based on a single wide-band Ti:Sapphire femtosecond pulse laser source. Successful imaging tests have been realized on two exemplary biological samples, a canine femur bone and collagen fibrils harvested from a rat tail. Since the ultra-broad band-width femtosecond laser is a suitable source for performing high-resolution optical coherence tomography, a wide-field optical coherence tomography arm can be easily incorporated into the presented multimodal microscope making it a versatile optical imaging tool for noninvasive label-free bioimaging. PMID:26074561

  17. Cyanine-based 1-amino-1-deoxyglucose as fluorescent probes for glucose transporter mediated bioimaging.

    PubMed

    Xu, Hu; Liu, Xinyu; Yang, Jinna; Liu, Ran; Li, Taoli; Shi, Yunli; Zhao, Hongxia; Gao, Qingzhi

    2016-05-27

    Two novel cyanine-based 1-amino-1-deoxy-β-glucose conjugates (Glu-1N-Cy3 and Glu-1N-Cy5) were designed, synthesized and their fluorescence characteristics were studied. Both Glu-1N-Cy3 and Glu-1N-Cy5 accumulate in living HT29 human colon cancer cells, which overexpress glucose transporters (GLUTs). The cellular uptake of the bioprobes was inhibited by natural GLUT substrate d-glucose and 2-deoxy-d-glucose. The GLUT specificity of the probes was validated with quercetin, which is both a permeant substrate via GLUTs and a high-affinity inhibitor of GLUT-mediated glucose transport. Competitive fluorometric assay for GLUT substrate cell uptake revealed that Glu-1N-Cy3 and Glu-1N-Cy5 are 5 and 10 times more sensitive than 2-NBDG, a leading fluorescent glucose bioprobe. This study provides fundamental data supporting the potential of these two conjugates as new powerful tools for GLUT-mediated theranostics, in vitro and in vivo molecular bioimaging and drug R&D. PMID:27033602

  18. Solution synthesis, optical properties, and bioimaging applications of silicon nanocrystals.

    PubMed

    McVey, Benjamin F P; Tilley, Richard D

    2014-10-21

    Understanding and unlocking the potential of semiconductor nanocrystals (NCs) is important for future applications ranging from biomedical imaging contrast agents to the next generation of solar cells and LEDs. Silicon NCs (Si NCs) have key advantages compared with other semiconductor NCs due to silicon's high natural abundance, low toxicity and strong biocompatibility, and unique size, and surface dependent optical properties. In this Account, we review and discuss the synthesis, surface modification, purification, optical properties, and applications of Si NCs. The synthetic methods used to make Si NCs have improved considerably in the last 5-10 years; highly monodisperse Si NCs can now be produced on the near gram scale. Scaled-up syntheses have allowed scientists to drive further toward the commercial utilization of Si NCs. The synthesis of doped Si NCs, through addition of a simple elemental precursor to a reaction mixture or by the production of a single source precursor, has shown great promise. Doped Si NCs have demonstrated unique or enhanced properties compared with pure Si NCs, for example, magnetism due to the presence of magnetic metals like Fe and Mn. Surface reactions have reached a new level of sophistication where organic (epoxidation and diol formation) and click (thiol based) chemical reactions can be carried out on attached surface molecules. This has led to a wide range of biocompatible functional groups as well as a degree of emission tuneability. The purification of Si NCs has been improved through the use of size separation columns and size selective precipitation. These purification approaches have yielded highly monodisperse and pure Si NCs previously unachieved. This has allowed scientists to study the size and surface dependent properties and toxicity and enabled the use of Si NCs in biomedical applications. The optical properties of Si NCs are complex. Using a combination of characterization techniques, researchers have explored the

  19. New Red-Emitting Conjugated Polyelectrolyte: Stabilization by Interaction with Biomolecules and Potential Use as Drug Carriers and Bioimaging Probes.

    PubMed

    Kahveci, Zehra; Vázquez-Guilló, Rebeca; Martínez-Tomé, Maria José; Mallavia, Ricardo; Mateo, C Reyes

    2016-01-27

    The design and development of fluorescent conjugated polyelectrolytes (CPEs) emitting in the red region of the visible spectrum is at present of great interest for bioimaging studies. However, despite the wide variety of CPEs available, stable bright red-emitters remain scarce due to their low solubility and instability in aqueous media, consequently limiting their applications. In this work, we have synthesized and characterized a new red-emitting cationic conjugated polyelectrolyte copoly-{[9,9-bis(6'-N,N,N-trimethylammonium)hexyl]-2,7-(fluorene)-alt-1,4-(naphtho[2,3c]-1,2,5-thiadiazole)} bromide (HTMA-PFNT), based on the incorporation of naphtha[2,3c][1,2,5] thiadiazole on fluorene backbone to increase the bathochromic emission, extending the conjugation length in the polymer backbone. Water stabilization was achieved by binding the polyelectrolyte to two different biological systems which are currently used as nanocarriers: human serum albumin (HSA) and lipid vesicles. Using both systems, stable nanostructures of different composition were obtained and their properties were characterized. The properties of the protein-based nanoparticles are consistent with polyelectrolyte aggregates covered with HSA molecules, while the liposome system is composed of lipid vesicles coated with polyelectrolyte chains partially inserted in the bilayer. Both protein and vesicle structural integrity were not affected after their interaction with HTMA-PFNT, as well as the carrier properties, allowing for the binding and transport of ligands. In addition, the nanoparticles displayed the ability of labeling the cell membrane of living cells. All these results extend the potential applications of these novel multifunctional nanoparticles as therapeutic carriers and bioimaging probes. PMID:26709951

  20. Fluorescent carbon nanoparticles derived from natural materials of mango fruit for bio-imaging probes

    NASA Astrophysics Data System (ADS)

    Jeong, Chan Jin; Roy, Arup Kumer; Kim, Sung Han; Lee, Jung-Eun; Jeong, Ji Hoon; Insik; Park, Sung Young

    2014-11-01

    Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials.Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04805a

  1. A fast-responsive fluorescent probe for sulfite and its bioimaging.

    PubMed

    Wang, Jiaoliang; Long, Liping; Xiao, Xiaoming

    2016-05-01

    A turn-on fluorescent probe Coumarin-SO2 based on a nucleophilic addition reaction was developed for the rapid detection of SO3 (2-) in aqueous media. The probe Coumarin-SO2 displays excellent water solubility, fast response, highly sensitivity and highly selectivity over other biological related species. More importantly, living cell imaging experiments indicate the feasibility of using the probe for the detection of SO3 (2-) in biological systems. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26377341

  2. Optic probe for semiconductor characterization

    DOEpatents

    Sopori, Bhushan L.; Hambarian, Artak

    2008-09-02

    Described herein is an optical probe (120) for use in characterizing surface defects in wafers, such as semiconductor wafers. The optical probe (120) detects laser light reflected from the surface (124) of the wafer (106) within various ranges of angles. Characteristics of defects in the surface (124) of the wafer (106) are determined based on the amount of reflected laser light detected in each of the ranges of angles. Additionally, a wafer characterization system (100) is described that includes the described optical probe (120).

  3. A chromenoquinoline-based fluorescent off-on thiol probe for bioimaging.

    PubMed

    Kand, Dnyaneshwar; Kalle, Arunasree Marasanapalli; Varma, Sreejith Jayasree; Talukdar, Pinaki

    2012-03-11

    A new chromenoquinoline-based fluorescent off-on thiol probe 2 is reported. In aqueous buffer solutions at physiological pH, the probe exhibited 223-fold enhancement in fluorescence intensity by a Michael addition of cysteine to the maleimide appended to a chromenoquinoline. Cell permeability and live cell imaging of thiols are also demonstrated. PMID:22301487

  4. An organic dye with very large Stokes-shift and broad tunability of fluorescence: Potential two-photon probe for bioimaging and ultra-sensitive solid-state gas sensor

    NASA Astrophysics Data System (ADS)

    He, Tingchao; Wang, Yue; Tian, Xiaoqing; Gao, Yang; Zhao, Xin; Grimsdale, Andrew C.; Lin, Xiaodong; Sun, Handong

    2016-01-01

    Light-emitting nonlinear optical molecules, especially those with large Stokes shifts and broad tunability of their emission wavelength, have attracted considerable attention for various applications including biomedical imaging and fluorescent sensors. However, most fluorescent chromophores have only limited potential for such applications due to small Stokes shifts, narrow tunability of fluorescence emissions, and small optical nonlinearity in highly polar solvents. In this work, we demonstrate that a two-photon absorbing stilbene chromophore exhibits a large two-photon absorption action cross-section (ηδ = 320 GM) in dimethylsulfoxide (DMSO) and shows broad fluorescence tunability (125 nm) by manipulating the polarity of the surrounding medium. Importantly, a very large Stokes shift of up to 227 nm is achieved in DMSO. Thanks to these features, this chromophore can be utilized as a two-photon probe for bioimaging applications and in an ultrasensitive solid-state gas detector.

  5. Reaction-based small-molecule fluorescent probes for chemoselective bioimaging

    NASA Astrophysics Data System (ADS)

    Chan, Jefferson; Dodani, Sheel C.; Chang, Christopher J.

    2012-12-01

    The dynamic chemical diversity of elements, ions and molecules that form the basis of life offers both a challenge and an opportunity for study. Small-molecule fluorescent probes can make use of selective, bioorthogonal chemistries to report on specific analytes in cells and in more complex biological specimens. These probes offer powerful reagents to interrogate the physiology and pathology of reactive chemical species in their native environments with minimal perturbation to living systems. This Review presents a survey of tools and tactics for using such probes to detect biologically important chemical analytes. We highlight design criteria for effective chemical tools for use in biological applications as well as gaps for future exploration.

  6. Dual-Emissive Cyclometalated Iridium(III) Polypyridine Complexes as Ratiometric Biological Probes and Organelle-Selective Bioimaging Reagents.

    PubMed

    Zhang, Kenneth Yin; Liu, Hua-Wei; Tang, Man-Chung; Choi, Alex Wing-Tat; Zhu, Nianyong; Wei, Xi-Guang; Lau, Kai-Chung; Lo, Kenneth Kam-Wing

    2015-07-01

    In this Article, we present a series of cyclometalated iridium(III) polypyridine complexes of the formula [Ir(N^C)2(N^N)](PF6) that showed dual emission under ambient conditions. The structures of the cyclometalating and diimine ligands were changed systematically to investigate the effects of the substituents on the dual-emission properties of the complexes. On the basis of the photophysical data, the high-energy (HE) and low-energy (LE) emission features of the complexes were assigned to triplet intraligand ((3)IL) and triplet charge-transfer ((3)CT) excited states, respectively. Time-dependent density functional theory (TD-DFT) calculations supported these assignments and indicated that the dual emission resulted from the interruption of the communication between the higher-lying (3)IL and the lower-lying (3)CT states by a triplet amine-to-ligand charge-transfer ((3)NLCT) state. Also, the avidin-binding properties of the biotin complexes were studied by emission titrations, and the results showed that the dual-emissive complexes can be utilized as ratiometric probes for avidin. Additionally, all the complexes exhibited efficient cellular uptake by live HeLa cells. The MTT and Annexin V assays confirmed that no cell death and early apoptosis occurred during the cell imaging experiments. Interestingly, laser-scanning confocal microscopy revealed that the complexes were selectively localized on the cell membrane, mitochondria, or both, depending on the nature of the substituents of the ligands. The results of this work will contribute to the future development of dual-emissive transition metal complexes as ratiometric probes and organelle-selective bioimaging reagents. PMID:26087119

  7. Reaction-based small-molecule fluorescent probes for chemoselective bioimaging.

    PubMed

    Chan, Jefferson; Dodani, Sheel C; Chang, Christopher J

    2012-12-01

    The dynamic chemical diversity of elements, ions and molecules that form the basis of life offers both a challenge and an opportunity for study. Small-molecule fluorescent probes can make use of selective, bioorthogonal chemistries to report on specific analytes in cells and in more complex biological specimens. These probes offer powerful reagents to interrogate the physiology and pathology of reactive chemical species in their native environments with minimal perturbation to living systems. This Review presents a survey of tools and tactics for using such probes to detect biologically important chemical analytes. We highlight design criteria for effective chemical tools for use in biological applications as well as gaps for future exploration. PMID:23174976

  8. Reaction-based small-molecule fluorescent probes for chemoselective bioimaging

    PubMed Central

    Chan, Jefferson; Dodani, Sheel C.; Chang, Christopher J.

    2014-01-01

    The dynamic chemical diversity of elements, ions and molecules that form the basis of life offers both a challenge and an opportunity for study. Small-molecule fluorescent probes can make use of selective, bioorthogonal chemistries to report on specific analytes in cells and in more complex biological specimens. These probes offer powerful reagents to interrogate the physiology and pathology of reactive chemical species in their native environments with minimal perturbation to living systems. This Review presents a survey of tools and tactics for using such probes to detect biologically important chemical analytes. We highlight design criteria for effective chemical tools for use in biological applications as well as gaps for future exploration. PMID:23174976

  9. A near-infrared multifunctional fluorescent probe with an inherent tumor-targeting property for bioimaging.

    PubMed

    Zhao, Xu; Li, Yang; Jin, Di; Xing, Yuzhi; Yan, Xilong; Chen, Ligong

    2015-07-25

    A mitochondria-targeting probe, by conjugating a quaternary ammonium cation with glucosamine modified pH-activated cyanine, was designed and synthesized. This probe has excellent selectivity and sensitivity toward pH, stability, cellular membrane permeability and low cytotoxicity. Owing to the acidic feature of tumors and the more negative mitochondrial membrane potential of tumor cells than that of normal cells, this probe can selectively accumulate in tumor cells and light up its fluorescence. It has been successfully applied for in vivo tumor imaging with a high signal-to-noise ratio. Moreover, this multifunctional switchable sensor was also employed for the fluorescent imaging of the fluctuation of intracellular pH in HeLa cells. PMID:26104217

  10. Transpiration purged optical probe

    DOEpatents

    VanOsdol, John; Woodruff, Steven

    2004-01-06

    An optical apparatus for clearly viewing the interior of a containment vessel by applying a transpiration fluid to a volume directly in front of the external surface of the optical element of the optical apparatus. The fluid is provided by an external source and transported by means of an annular tube to a capped end region where the inner tube is perforated. The perforation allows the fluid to stream axially towards the center of the inner tube and then axially away from an optical element which is positioned in the inner tube just prior to the porous sleeve. This arrangement draws any contaminants away from the optical element keeping it free of contaminants. In one of several embodiments, the optical element can be a lens, a viewing port or a laser, and the external source can provide a transpiration fluid having either steady properties or time varying properties.

  11. Serum-stable quantum dot--protein hybrid nanocapsules for optical bio-imaging

    NASA Astrophysics Data System (ADS)

    Lee, Jeong Yu; Nam, Dong Heon; Oh, Mi Hwa; Kim, Youngsun; Choi, Hyung Seok; Jeon, Duk Young; Beum Park, Chan; Nam, Yoon Sung

    2014-05-01

    We introduce shell cross-linked protein/quantum dot (QD) hybrid nanocapsules as a serum-stable systemic delivery nanocarrier for tumor-targeted in vivo bio-imaging applications. Highly luminescent, heavy-metal-free Cu0.3InS2/ZnS (CIS/ZnS) core-shell QDs are synthesized and mixed with amine-reactive six-armed poly(ethylene glycol) (PEG) in dichloromethane. Emulsification in an aqueous solution containing human serum albumin (HSA) results in shell cross-linked nanocapsules incorporating CIS/ZnS QDs, exhibiting high luminescence and excellent dispersion stability in a serum-containing medium. Folic acid is introduced as a tumor-targeting ligand. The feasibility of tumor-targeted in vivo bio-imaging is demonstrated by measuring the fluorescence intensity of several major organs and tumor tissue after an intravenous tail vein injection of the nanocapsules into nude mice. The cytotoxicity of the QD-loaded HSA-PEG nanocapsules is also examined in several types of cells. Our results show that the cellular uptake of the QDs is critical for cytotoxicity. Moreover, a significantly lower level of cell death is observed in the CIS/ZnS QDs compared to nanocapsules loaded with cadmium-based QDs. This study suggests that the systemic tumor targeting of heavy-metal-free QDs using shell cross-linked HSA-PEG hybrid nanocapsules is a promising route for in vivo tumor diagnosis with reduced non-specific toxicity.

  12. Tunable nanowire nonlinear optical probe

    SciTech Connect

    Nakayama, Yuri; Pauzauskie, Peter J.; Radenovic, Aleksandra; Onorato, Robert M.; Saykally, Richard J.; Liphardt, Jan; Yang, Peidong

    2008-02-18

    One crucial challenge for subwavelength optics has been thedevelopment of a tunable source of coherent laser radiation for use inthe physical, information, and biological sciences that is stable at roomtemperature and physiological conditions. Current advanced near-fieldimaging techniques using fiber-optic scattering probes1,2 have alreadyachieved spatial resolution down to the 20-nm range. Recently reportedfar-field approaches for optical microscopy, including stimulatedemission depletion (STED)3, structured illumination4, and photoactivatedlocalization microscopy (PALM)5, have also enabled impressive,theoretically-unlimited spatial resolution of fluorescent biomolecularcomplexes. Previous work with laser tweezers6-8 has suggested the promiseof using optical traps to create novel spatial probes and sensors.Inorganic nanowires have diameters substantially below the wavelength ofvisible light and have unique electronic and optical properties9,10 thatmake them prime candidates for subwavelength laser and imagingtechnology. Here we report the development of an electrode-free,continuously-tunable coherent visible light source compatible withphysiological environments, from individual potassium niobate (KNbO3)nanowires. These wires exhibit efficient second harmonic generation(SHG), and act as frequency converters, allowing the local synthesis of awide range of colors via sum and difference frequency generation (SFG,DFG). We use this tunable nanometric light source to implement a novelform of subwavelength microscopy, in which an infrared (IR) laser is usedto optically trap and scan a nanowire over a sample, suggesting a widerange of potential applications in physics, chemistry, materials science,and biology.

  13. High pressure optical combustion probe

    SciTech Connect

    Woodruff, S.D.; Richards, G.A.

    1995-06-01

    The Department of Energy`s Morgantown Energy Technology Center has developed a combustion probe for monitoring flame presence and heat release. The technology involved is a compact optical detector of the OH radical`s UV fluorescence. The OH Monitor/Probe is designed to determine the flame presence and provide a qualitative signal proportional to the flame intensity. The probe can be adjusted to monitor a specific volume in the combustion zone to track spatial fluctuations in the flame. The probe is capable of nanosecond time response and is usually slowed electronically to fit the flame characteristics. The probe is a sapphire rod in a stainless steel tube which may be inserted into the combustion chamber and pointed at the flame zone. The end of the sapphire rod is retracted into the SS tube to define a narrow optical collection cone. The collection cone may be adjusted to fit the experiment. The fluorescence signal is collected by the sapphire rod and transmitted through a UV transmitting, fused silica, fiber optic to the detector assembly. The detector is a side window photomultiplier (PMT) with a 310 run line filter. A Hamamatsu photomultiplier base combined with a integral high voltage power supply permits this to be a low voltage device. Electronic connections include: a power lead from a modular DC power supply for 15 VDC; a control lead for 0-1 volts to control the high voltage level (and therefore gain); and a lead out for the actual signal. All low voltage connections make this a safe and easy to use device while still delivering the sensitivity required.

  14. Mesoporous persistent nanophosphors for in vivo optical bioimaging and drug-delivery.

    PubMed

    Maldiney, Thomas; Ballet, Benoit; Bessodes, Michel; Scherman, Daniel; Richard, Cyrille

    2014-11-21

    Based upon the ambitious idea that one single particle could serve multiple purposes at the same time, the combination and simultaneous use of imaging and therapeutics has lately arisen as one of the most promising prospects among nanotechnologies directed toward biomedical applications. Intended for both therapeutics and diagnostics in vivo, highly complex nanostructures were specifically designed to simultaneously act as optical imaging probes and delivery vehicles. Yet, such multifunctional photonic nanoplatforms usually exploit fluorescence phenomena which require constant excitation light through biological tissues and thus significantly reduce the detection sensitivity due to the autofluorescence from living animals. In order to overcome this critical issue, the present article introduces a novel multifunctional agent based on persistent luminescence mesoporous nanoparticles. Being composed of a hybrid chromium-doped zinc gallate core/mesoporous silica shell architecture, we show that this nanotechnology can be used as an efficient doxorubicin-delivery vehicle presenting a higher cytotoxicity toward U87MG cells than its unloaded counterpart in vitro. In addition, we demonstrate that a persistent luminescence signal from these doxorubicin-loaded mesoporous nanophosphors opens a new way to highly sensitive detection in vivo, giving access to the real-time biodistribution of the carrier without any autofluorescence from the animal tissues. This new persistent luminescence-based hybrid nanotechnology can be easily applied to the delivery of any therapeutic agent, thus constituting a versatile and sensitive optical nanotool dedicated to both therapeutic and diagnostic applications in vivo. PMID:25316201

  15. Mesoporous persistent nanophosphors for in vivo optical bioimaging and drug-delivery

    NASA Astrophysics Data System (ADS)

    Maldiney, Thomas; Ballet, Benoit; Bessodes, Michel; Scherman, Daniel; Richard, Cyrille

    2014-10-01

    Based upon the ambitious idea that one single particle could serve multiple purposes at the same time, the combination and simultaneous use of imaging and therapeutics has lately arisen as one of the most promising prospects among nanotechnologies directed toward biomedical applications. Intended for both therapeutics and diagnostics in vivo, highly complex nanostructures were specifically designed to simultaneously act as optical imaging probes and delivery vehicles. Yet, such multifunctional photonic nanoplatforms usually exploit fluorescence phenomena which require constant excitation light through biological tissues and thus significantly reduce the detection sensitivity due to the autofluorescence from living animals. In order to overcome this critical issue, the present article introduces a novel multifunctional agent based on persistent luminescence mesoporous nanoparticles. Being composed of a hybrid chromium-doped zinc gallate core/mesoporous silica shell architecture, we show that this nanotechnology can be used as an efficient doxorubicin-delivery vehicle presenting a higher cytotoxicity toward U87MG cells than its unloaded counterpart in vitro. In addition, we demonstrate that a persistent luminescence signal from these doxorubicin-loaded mesoporous nanophosphors opens a new way to highly sensitive detection in vivo, giving access to the real-time biodistribution of the carrier without any autofluorescence from the animal tissues. This new persistent luminescence-based hybrid nanotechnology can be easily applied to the delivery of any therapeutic agent, thus constituting a versatile and sensitive optical nanotool dedicated to both therapeutic and diagnostic applications in vivo.Based upon the ambitious idea that one single particle could serve multiple purposes at the same time, the combination and simultaneous use of imaging and therapeutics has lately arisen as one of the most promising prospects among nanotechnologies directed toward biomedical

  16. Fiber-Optic Probe For Laser Velocimetry

    NASA Technical Reports Server (NTRS)

    Lynch, Dana H.; Mcalister, Kenneth W.; Gunter, William D., Jr.

    1992-01-01

    Size and weight of optics reduced considerably. Proposed fiber-optic probe in laser velocimeter smaller (and, therefore, lighter in weight and more maneuverable) than previous probe. Proposed configuration is product of calculations and experiments showing virtual waists serve same purpose. Laser-velocimeter lens brought close to transfer lenses to focus on virtual waists, thereby shortening probe head considerably.

  17. Subwavelength optical probes for sensitive analysis

    NASA Astrophysics Data System (ADS)

    Tan, Weihong; Bang, Leng; Cordek, Julia; Liu, Xiaojing

    1998-04-01

    Near-field optics has been utilized for a variety of applications. Using near-field optical probe and microscopy, we have devised a method to introduce a near-field probe into live cultured vascular smooth muscle cell and NG108-15 neuroblastoma cells. We have effectively monitored cellular responses, with excellent spatial and fast temporal resolutions, to drug stimulation. Near-field optical probes enable the visualization of functional response in living cells. We have also nanofabricated the first single molecule optical probe. A single dye molecule, carbocyanine dye C18, is immobilized on a near-field optical probe by physical immobilization. We are able to control the preparation process by selecting the dye molecule concentrations and the interaction times of the probe with the DiI solution. The single DiI molecule probe's optical and spectroscopic properties have been characterized. Photobleaching of a single DiI molecule probe occurs as a discrete and total extinction of its fluorescence. We have also developed ultrasensitive detection schemes using near-field optical probes. Biomolecule immobilization has been carried out on optical fiber probes. Ultrasensitive biochemical sensors for glutamate and lactate have been prepared and characterized.

  18. Nanofabrication using near-field optical probes

    PubMed Central

    McLeod, Euan; Ozcan, Aydogan

    2012-01-01

    Nanofabrication using near-field optical probes is an established technique for rapid prototyping and automated maskless fabrication of nanostructured devices. In this review, we present the primary types of near-field probes and their physical processing mechanisms. Highlights of recent developments include improved resolution by optimizing the probe shape, incorporation of surface plasmonics in probe design, broader use in biological and magnetic storage applications, and increased throughput using probe arrays as well as high speed writing and patterning. PMID:22713756

  19. A novel fluorescent probe for Cr3 + based on rhodamine-crown ether conjugate and its application to drinking water examination and bioimaging

    NASA Astrophysics Data System (ADS)

    Diao, Quanping; Ma, Pinyi; Lv, Linlin; Li, Tiechun; Wang, Xinghua; Song, Daqian

    2016-03-01

    A trivalent chromium (Cr3 +) fluorescence probe (RhC) was designed and synthesized via Schiff base reaction based on rhodamine-crown ether conjugate. This probe displayed a favorable selectivity for Cr3 + over a range of other common metal ions in DMF/H2O (3:7, v/v; PBS buffer 50 mmol L- 1; pH = 6.8) solution, leading to prominent fluorescence "OFF-ON" switching of the rhodamine fluorophore. The limit of detection was calculated to be 1.5 μmol L- 1 (S/N = 3). The binding ratio of RhC-Cr3 + complex was determined to be 1:2 according to the Job's plot and HR-MS. The probe was successfully applied to examination of Cr3 + in drinking water spiked samples. The average recoveries ranged from 104.9% to 106.9% at spiked concentration level of 10.00 μmol L- 1, and the obtained results were consistent with those obtained using atomic absorption spectrometry (AAS). Moreover, bioimaging experiments showed that RhC can sense the Cr3 + in living cells with a fluorescence enhancement signal.

  20. A novel fluorescent probe for Cr(3+) based on rhodamine-crown ether conjugate and its application to drinking water examination and bioimaging.

    PubMed

    Diao, Quanping; Ma, Pinyi; Lv, Linlin; Li, Tiechun; Wang, Xinghua; Song, Daqian

    2016-03-01

    A trivalent chromium (Cr(3+)) fluorescence probe (RhC) was designed and synthesized via Schiff base reaction based on rhodamine-crown ether conjugate. This probe displayed a favorable selectivity for Cr(3+) over a range of other common metal ions in DMF/H2O (3:7, v/v; PBS buffer 50 mmol L(-1); pH=6.8) solution, leading to prominent fluorescence "OFF-ON" switching of the rhodamine fluorophore. The limit of detection was calculated to be 1.5 μmol L(-1) (S/N=3). The binding ratio of RhC-Cr(3+) complex was determined to be 1:2 according to the Job's plot and HR-MS. The probe was successfully applied to examination of Cr(3+) in drinking water spiked samples. The average recoveries ranged from 104.9% to 106.9% at spiked concentration level of 10.00 μmol L(-1), and the obtained results were consistent with those obtained using atomic absorption spectrometry (AAS). Moreover, bioimaging experiments showed that RhC can sense the Cr(3+) in living cells with a fluorescence enhancement signal. PMID:26641281

  1. Improved optical probe for monitoring dust explosions

    NASA Astrophysics Data System (ADS)

    Conti, R. S.; Cashdollar, K. L.; Liebman, I.

    1982-03-01

    An improved optical probe was developed to monitor dust-cloud concentration in explosions even in the presence of dust flame radiation. Principal features of the probe include a pulsed light-emitting diode and a photodetector with optical interference filter to reduce flame radiation. The probe has a U-shaped configuration and air jets to keep the windows dust free. Experimental data are presented for a coal dust explosion.

  2. Preparation of self-assembled core-shell nano structure of conjugated generation 4.5 poly (amidoamine) dendrimer and monoclonal Anti-IL-6 antibody as bioimaging probe.

    PubMed

    Mekuria, Shewaye Lakew; Tsai, Hsieh-Chih

    2015-11-01

    In this article, interleukin-6 (IL-6)-conjugated anionic generation 4.5 (G4.5) poly(amidoamine) (PAMAM) was synthesized through EDC/NHS coupling chemistry and evaluated for its optical properties in vitro. Conjugation was confirmed using Fourier-transformed infrared spectroscopy (FT-IR) and 2-dimensional nuclear magnetic resonance (2D NMR). After IL-6 conjugation, nanoparticle size increased to approximately 70 nm and zeta potential increased from -56.5 ± 0.2 to -19.1 ± 2.4 mV due to neutralization of negatively charged G4.5. Wide-angle X-ray scattering (WAXS) suggested that a layered nanoparticle structure was formed by the G4.5/IL-6 conjugate. Most interestingly, the intrinsic fluorescence of G4.5 significantly increased after IL-6 conjugation and underwent a blue shift as a result of H-aggregation. Furthermore, the cellular uptake of the conjugates by HeLa cells was significantly enhanced in comparison to free G4.5, as demonstrated by confocal microscopy and flow cytometry. These results indicated that the described system may be a potential bioimaging probe in vitro. PMID:26263213

  3. Optical probe with light fluctuation protection

    DOEpatents

    Da Silva, Luiz B.; Chase, Charles L.

    2003-11-11

    An optical probe for tissue identification includes an elongated body. Optical fibers are located within the elongated body for transmitting light to and from the tissue. Light fluctuation protection is associated with the optical fibers. In one embodiment the light fluctuation protection includes a reflective coating on the optical fibers to reduce stray light. In another embodiment the light fluctuation protection includes a filler with very high absorption located within the elongated body between the optical fibers.

  4. Characterization of Fiber Optic CMM Probe System

    SciTech Connect

    K.W.Swallow

    2007-05-15

    This report documents a study completed on the fiber optic probe system that is a part of the Werth optical CMM. This study was necessary due to a lack of documentation from the vendor for the proper use and calibration of the fiber probe, and was performed in support of the Lithographie Galvanoformung Abformung (LIGA) development program at the FM&T. As a result of this study, a better understanding of the fiber optic probe has been developed, including guidelines for its proper use and calibration.

  5. Graphene and graphene-like 2D materials for optical biosensing and bioimaging: a review

    NASA Astrophysics Data System (ADS)

    Zhu, Chengzhou; Du, Dan; Lin, Yuehe

    2015-09-01

    The increasing demands of bioassay and biomedical applications have significantly promoted the rational design and fabrication of a wide range of functional nanomaterials. Coupling these advanced nanomaterials with biomolecule recognition events leads to novel sensing and diagnostic platforms. Because of their unique structures and multifunctionalities, two-dimensional nanomaterials, such as graphene and graphene-like materials (e.g., graphitic carbon nitride, transition metal dichalcogenides, boron nitride, and transition metal oxides), have stimulated great interest in the field of optical biosensors and imaging because of their innovative mechanical, physicochemical and optical properties. Depending on the different applications, the graphene and graphene-like nanomaterials can be tailored to form either fluorescent emitters or efficient fluorescence quenchers, making them powerful platforms for fabricating a series of optical biosensors to sensitively detect various targets including ions, small biomolecules, DNA/RNA and proteins. This review highlights the recent progress in optical biosensors based on graphene and graphene-like 2D materials and their imaging applications. Finally, the opportunities and some critical challenges in this field are also addressed.

  6. Facile synthesis of N-rich carbon quantum dots by spontaneous polymerization and incision of solvents as efficient bioimaging probes and advanced electrocatalysts for oxygen reduction reaction.

    PubMed

    Lei, Zhouyue; Xu, Shengjie; Wan, Jiaxun; Wu, Peiyi

    2016-01-28

    In this study, uniform nitrogen-doped carbon quantum dots (N-CDs) were synthesized through a one-step solvothermal process of cyclic and nitrogen-rich solvents, such as N-methyl-2-pyrrolidone (NMP) and dimethyl-imidazolidinone (DMEU), under mild conditions. The products exhibited strong light blue fluorescence, good cell permeability and low cytotoxicity. Moreover, after a facile post-thermal treatment, it developed a lotus seedpod surface-like structure of seed-like N-CDs decorating on the surface of carbon layers with a high proportion of quaternary nitrogen moieties that exhibited excellent electrocatalytic activity and long-term durability towards the oxygen reduction reaction (ORR). The peak potential was -160 mV, which was comparable to or even lower than commercial Pt/C catalysts. Therefore, this study provides an alternative facile approach to the synthesis of versatile carbon quantum dots (CDs) with widespread commercial application prospects, not only as bioimaging probes but also as promising electrocatalysts for the metal-free ORR. PMID:26739885

  7. A new "off-on" fluorescent probe for Al3+ in aqueous solution based on rhodamine B and its application to bioimaging

    NASA Astrophysics Data System (ADS)

    Huang, Qi; Zhang, Qingyou; Wang, Enze; Zhou, Yanmei; Qiao, Han; Pang, Lanfang; Yu, Fang

    2016-01-01

    In this paper, a new fluorescent probe has been synthesized and applied as "off-on" sensor for the detection of Al3+ with a high sensitivity and excellent selectivity in aqueous media. The sensor was easily prepared by one step reaction between rhodamine B hydrazide and pyridoxal hydrochloride named RBP. The structure of the sensor has been characterized by nuclear magnetic resonance and electron spray ionization-mass spectrometry. The fluorescence intensity and absorbance for the sensor showed a good linearity with the concentration of Al3+ in the range of 0-12.5 μM and 8-44 μM, respectively, with detection limits of 0.23 μM and 1.90 μM. The sensor RBP was preliminarily applied to the determination of Al3+ in water samples from the lake of Henan University and tap water with satisfying results. Moreover, it can be used as a bioimaging reagent for imaging of Al3+ in living cells.

  8. A new "off-on" fluorescent probe for Al(3+) in aqueous solution based on rhodamine B and its application to bioimaging.

    PubMed

    Huang, Qi; Zhang, Qingyou; Wang, Enze; Zhou, Yanmei; Qiao, Han; Pang, Lanfang; Yu, Fang

    2016-01-01

    In this paper, a new fluorescent probe has been synthesized and applied as "off-on" sensor for the detection of Al(3+) with a high sensitivity and excellent selectivity in aqueous media. The sensor was easily prepared by one step reaction between rhodamine B hydrazide and pyridoxal hydrochloride named RBP. The structure of the sensor has been characterized by nuclear magnetic resonance and electron spray ionization-mass spectrometry. The fluorescence intensity and absorbance for the sensor showed a good linearity with the concentration of Al(3+) in the range of 0-12.5μM and 8-44μM, respectively, with detection limits of 0.23μM and 1.90μM. The sensor RBP was preliminarily applied to the determination of Al(3+) in water samples from the lake of Henan University and tap water with satisfying results. Moreover, it can be used as a bioimaging reagent for imaging of Al(3+) in living cells. PMID:26196932

  9. A TICT-based fluorescent probe for rapid and specific detection of hydrogen sulfide and its bio-imaging applications.

    PubMed

    Ren, Mingguang; Deng, Beibei; Kong, Xiuqi; Zhou, Kai; Liu, Keyin; Xu, Gaoping; Lin, Weiying

    2016-05-11

    By blocking the intramolecular twisted internal charge transfer (TICT) process, we designed and sythesized the first TICT-based fluorescent probe for hydrogen sulfide. The new probe exhibits high selectivity, good membrane-permeability and is suitable for visualization of exogenous and endogenous hydrogen sulfide in living cells. PMID:27090853

  10. A water-soluble colorimetric two-photon probe for discrimination of different palladium species and its application in bioimaging.

    PubMed

    Luo, Weifang; Liu, Weisheng

    2016-08-01

    A novel water-soluble colorimetric and fluorescent palladium probe with excellent selectivity and sensitivity has been designed. Notably, based on a palladium triggered terminal allyl ether cleavage reaction, the probe could detect and discriminate Pd(0) and Pd(2+)/Pd(4+) in about 2.5 min at room temperature with a low detection limit (0.29 ppb) and significant colour change (from light yellow to pink). The probe could serve as an excellent "naked-eye" colorimetric probe for selective and quantitative determination of palladium in aqueous solutions. Moreover, it could be used as a two-photon palladium probe for in vitro/vivo and three-dimensional imaging with low cytotoxicity and autofluorescence. PMID:27181987

  11. Rugged fiber optic probe for raman measurement

    DOEpatents

    O'Rourke, Patrick E.; Toole, Jr., William R.; Nave, Stanley E.

    1998-01-01

    An optical probe for conducting light scattering analysis is disclosed. The probe comprises a hollow housing and a probe tip. A fiber assembly made up of a transmitting fiber and a receiving bundle is inserted in the tip. A filter assembly is inserted in the housing and connected to the fiber assembly. A signal line from the light source and to the spectrometer also is connected to the filter assembly and communicates with the fiber assembly. By using a spring-loaded assembly to hold the fiber connectors together with the in-line filters, complex and sensitive alignment procedures are avoided. The close proximity of the filter assembly to the probe tip eliminates or minimizes self-scattering generated by the optical fiber. Also, because the probe can contact the sample directly, sensitive optics can be eliminated.

  12. Fast-Response Turn-on Fluorescent Probes Based on Thiolysis of NBD Amine for H2 S Bioimaging.

    PubMed

    Wang, Runyu; Li, Zhifei; Zhang, Changyu; Li, Yanyan; Xu, Guoce; Zhang, Qiang-Zhe; Li, Lu-Yuan; Yi, Long; Xi, Zhen

    2016-05-17

    Hydrogen sulfide (H2 S) is an important endogenous signaling molecule with multiple biological functions. New selective fluorescent turn-on probes based on fast thiolyling of NBD (7-nitro-1,2,3-benzoxadiazole) amine were explored for sensing H2 S in aqueous buffer and in living cells. The syntheses of both probes are simple and quite straightforward. The probes are highly sensitive and selective toward H2 S over other biologically relevant species. The fluorescein-NBD-based probe showed 65-fold green fluorescent increase upon H2 S activation. The rhodamine-NBD-based probe reacted rapidly with H2 S (t1/2 ≈1 min) to give a 4.5-fold increase in red fluorescence. Moreover, both probes were successfully used for monitoring H2 S in living cells and in mice. Based on such probe-based tools, we could observe H2 O2 -induced H2 S biogenesis in a concentration-dependent and time-dependent fashion in living cells. PMID:26952316

  13. Optical contacting for gravity probe star tracker

    NASA Technical Reports Server (NTRS)

    Wright, J. J.; Zissa, D. E.

    1984-01-01

    A star-tracker telescope, constructed entirely of fused silica elements optically contacted together, has been proposed to provide submilliarc-second pointing accuracy for Gravity Probe. A bibliography and discussion on optical contacting (the bonding of very flat, highly polished surfaces without the use of adhesives) are presented. Then results from preliminary experiments on the strength of optical contacts including a tensile strength test in liquid helium are discussed. Suggestions are made for further study to verify an optical contacting method for the Gravity Probe star-tracker telescope.

  14. Real-time optical fiber dosimeter probe

    NASA Astrophysics Data System (ADS)

    Croteau, André; Caron, Serge; Rink, Alexandra; Jaffray, David; Mermut, Ozzy

    2011-03-01

    There is a pressing need for a passive optical fiber dosimeter probe for use in real-time monitoring of radiation dose delivered to clinical radiation therapy patients. An optical fiber probe using radiochromic material has been designed and fabricated based on a thin film of the radiochromic material on a dielectric mirror. Measurements of the net optical density vs. time before, during, and after irradiation at a rate of 500cGy/minute to a total dose of 5 Gy were performed. Net optical densities increased from 0.2 to 2.0 for radiochromic thin film thicknesses of 2 to 20 μm, respectively.

  15. Construction of a Near-Infrared Fluorescent Turn-On Probe for Selenol and Its Bioimaging Application in Living Animals.

    PubMed

    Chen, Hua; Dong, Baoli; Tang, Yonghe; Lin, Weiying

    2015-08-10

    As selenocysteine (Sec) carries out the majority of the functions of the various Se-containing species in vivo, it is of high importance to develop reliable and rapid assays with biocompatibility to detect Sec. Herein, an NIR fluorescent turn-on probe for highly selective detection of selenol was designed and synthesized. The probe exhibits large turn-on signal upon treatment with selenocysteine (R-SeH), and it was further demonstrated that the new NIR fluorescent probe can be employed to image selenol in living animals. PMID:26177833

  16. 5-(Dimethylamino)-N-(4-ethynylphenyl)-1-naphthalenesulfonamide as a novel bifunctional antitumor agent and two-photon induced bio-imaging probe.

    PubMed

    Chui, C-H; Wang, Q; Chow, W-C; Yuen, M C-W; Wong, K-L; Kwok, W-M; Cheng, G Y-M; Wong, R S-M; Tong, S-W; Chan, K-W; Lau, F-Y; Lai, P B-S; Lam, K-H; Fabbri, E; Tao, X-M; Gambari, R; Wong, W-Y

    2010-05-28

    A novel compound, (5-(dimethylamino)-N-(4-ethynylphenyl)-1-naphthalenesulfonamide), was prepared and characterized; it shows dual functional roles as an effective antitumor and a two-photon induced bio-imaging agent. PMID:20379581

  17. Nonlinear Optical Properties of ZnO for BioimagingCell and Cell Destruction

    NASA Astrophysics Data System (ADS)

    Urban, Ben; Chakki, Samudyatha; Senthilkumar, Os; Senthilkumar, Kasilingam; Fujita, Yasuhisa; Neogi, Arup

    2011-03-01

    As of recent years nanotechnology has been at the forefront of scientific research. It promises to have a broad range of applications from turning unhealthy foods into health foods, making computers faster and curing cancer. We present results on using nonlinear optical processes of ZnO nano-crystals to detect, track and destroy cells. By incorporating ZnO into a hydrophobic nano-hydrogel matrix with trace amounts of H2 O2 , we can attach antibodies or microRNA for specific cell targeting and, using the heat generating properties of the third order nonlinear process, release H2 O2 in the cell causing instant cell death. Theoretically, with the appropriate sequence for microRNA or the appropriate antibodies, we could target cancer cells in the body and destroy them. This presentation gives our results until now.

  18. Probing plasmonic breathing modes optically

    SciTech Connect

    Krug, Markus K. Reisecker, Michael; Hohenau, Andreas; Ditlbacher, Harald; Trügler, Andreas; Hohenester, Ulrich; Krenn, Joachim R.

    2014-10-27

    The confinement of surface plasmon modes in flat nanoparticles gives rise to plasmonic breathing modes. With a vanishing net dipole moment, breathing modes do not radiate, i.e., they are optically dark. Having thus escaped optical detection, breathing modes were only recently revealed in silver nanodisks with electron energy loss spectroscopy in an electron microscope. We show that for disk diameters >200 nm, retardation induced by oblique optical illumination relaxes the optically dark character. This makes breathing modes and thus the full plasmonic mode spectrum accessible to optical spectroscopy. The experimental spectroscopy data are in excellent agreement with numerical simulations.

  19. Facile synthesis of N-rich carbon quantum dots by spontaneous polymerization and incision of solvents as efficient bioimaging probes and advanced electrocatalysts for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Lei, Zhouyue; Xu, Shengjie; Wan, Jiaxun; Wu, Peiyi

    2016-01-01

    In this study, uniform nitrogen-doped carbon quantum dots (N-CDs) were synthesized through a one-step solvothermal process of cyclic and nitrogen-rich solvents, such as N-methyl-2-pyrrolidone (NMP) and dimethyl-imidazolidinone (DMEU), under mild conditions. The products exhibited strong light blue fluorescence, good cell permeability and low cytotoxicity. Moreover, after a facile post-thermal treatment, it developed a lotus seedpod surface-like structure of seed-like N-CDs decorating on the surface of carbon layers with a high proportion of quaternary nitrogen moieties that exhibited excellent electrocatalytic activity and long-term durability towards the oxygen reduction reaction (ORR). The peak potential was -160 mV, which was comparable to or even lower than commercial Pt/C catalysts. Therefore, this study provides an alternative facile approach to the synthesis of versatile carbon quantum dots (CDs) with widespread commercial application prospects, not only as bioimaging probes but also as promising electrocatalysts for the metal-free ORR.In this study, uniform nitrogen-doped carbon quantum dots (N-CDs) were synthesized through a one-step solvothermal process of cyclic and nitrogen-rich solvents, such as N-methyl-2-pyrrolidone (NMP) and dimethyl-imidazolidinone (DMEU), under mild conditions. The products exhibited strong light blue fluorescence, good cell permeability and low cytotoxicity. Moreover, after a facile post-thermal treatment, it developed a lotus seedpod surface-like structure of seed-like N-CDs decorating on the surface of carbon layers with a high proportion of quaternary nitrogen moieties that exhibited excellent electrocatalytic activity and long-term durability towards the oxygen reduction reaction (ORR). The peak potential was -160 mV, which was comparable to or even lower than commercial Pt/C catalysts. Therefore, this study provides an alternative facile approach to the synthesis of versatile carbon quantum dots (CDs) with widespread

  20. A highly selective near-infrared fluorescent probe for carboxylesterase 2 and its bioimaging applications in living cells and animals.

    PubMed

    Jin, Qiang; Feng, Lei; Wang, Dan-Dan; Wu, Jing-Jing; Hou, Jie; Dai, Zi-Ru; Sun, Shi-Guo; Wang, Jia-Yue; Ge, Guang-Bo; Cui, Jing-Nan; Yang, Ling

    2016-09-15

    A near-infrared fluorescent probe (DDAB) for highly selective and sensitive detection of carboxylesterase 2 (CE2) has been designed, synthesized, and systematically studied both in vitro and in vivo. Upon addition of CE2, the ester bond of DDAB could be rapidly cleaved and then release a near-infrared (NIR) fluorophore DDAO, which brings a remarkable yellow-to-blue color change and strong NIR fluorescence emission in physiological solutions. The newly developed probe exhibits excellent properties including good specificity, ultrahigh sensitivity and high imaging resolution. Moreover, DDAB has been applied to measure the real activities of CE2 in complex biological samples, as well as to screen CE2 inhibitors by using tissue preparations as the enzymes sources. The probe has also been successfully used to detect endogenous CE2 in living cells and in vivo for the first time, and the results demonstrate that such detection is highly reliable. All these prominent features of DDAB make it holds great promise for further investigation on CE2-associated biological process and for exploring the physiological functions of CE2 in living systems. PMID:27129028

  1. Optical probing of cold trapped atoms

    NASA Technical Reports Server (NTRS)

    Fox, R. W.; Gilbert, S. L.; Hollberg, L.; Marquardt, J. H.; Robinson, H. G.

    1993-01-01

    Transitions between excited states of laser-cooled and laser-trapped rubidium and cesium atoms are probed by use of fiber and diode lasers. High-resolution Doppler-free spectra are detected by observation of the absorption and fluorescence of light from the intermediate level of two-step cascade systems. The optical double-resonance spectra show Autler-Townes splitting in the weak probe limit and more complicated spectra for a strongly coupled three-level system.

  2. Fiber optic probe for light scattering measurements

    DOEpatents

    Nave, Stanley E.; Livingston, Ronald R.; Prather, William S.

    1995-01-01

    A fiber optic probe and a method for using the probe for light scattering analyses of a sample. The probe includes a probe body with an inlet for admitting a sample into an interior sample chamber, a first optical fiber for transmitting light from a source into the chamber, and a second optical fiber for transmitting light to a detector such as a spectrophotometer. The interior surface of the probe carries a coating that substantially prevents non-scattered light from reaching the second fiber. The probe is placed in a region where the presence and concentration of an analyte of interest are to be detected, and a sample is admitted into the chamber. Exciting light is transmitted into the sample chamber by the first fiber, where the light interacts with the sample to produce Raman-scattered light. At least some of the Raman-scattered light is received by the second fiber and transmitted to the detector for analysis. Two Raman spectra are measured, at different pressures. The first spectrum is subtracted from the second to remove background effects, and the resulting sample Raman spectrum is compared to a set of stored library spectra to determine the presence and concentration of the analyte.

  3. Fiber optic probe for light scattering measurements

    DOEpatents

    Nave, S.E.; Livingston, R.R.; Prather, W.S.

    1993-01-01

    This invention is comprised of a fiber optic probe and a method for using the probe for light scattering analyses of a sample. The probe includes a probe body with an inlet for admitting a sample into an interior sample chamber, a first optical fiber for transmitting light from a source into the chamber, and a second optical fiber for transmitting light to a detector such as a spectrophotometer. The interior surface of the probe carries a coating that substantially prevents non-scattered light from reaching the second fiber. The probe is placed in a region where the presence and concentration of an analyte of interest are to be detected, and a sample is admitted into the chamber. Exciting light is transmitted into the sample chamber by the first fiber, where the light interacts with the sample to produce Raman-scattered light. At least some of the Raman- scattered light is received by the second fiber and transmitted to the detector for analysis. Two Raman spectra are measured, at different pressures. The first spectrum is subtracted from the second to remove background effects, and the resulting sample Raman spectrum is compared to a set of stored library spectra to determine the presence and concentration of the analyte.

  4. Ultrathin lensed fiber-optic probe for optical coherence tomography

    PubMed Central

    Qiu, Y.; Wang, Y.; Belfield, K. D.; Liu, X.

    2016-01-01

    We investigated and validated a novel method to develop ultrathin lensed fiber-optic (LFO) probes for optical coherence tomography (OCT) imaging. We made the LFO probe by attaching a segment of no core fiber (NCF) to the distal end of a single mode fiber (SMF) and generating a curved surface at the tip of the NCF using the electric arc of a fusion splicer. The novel fabrication approach enabled us to control the length of the NCF and the radius of the fiber lens independently. By strategically choosing these two parameters, the LFO probe could achieve a broad range of working distance and depth of focus for different OCT applications. A probe with 125μm diameter and lateral resolution up to 10μm was demonstrated. The low-cost, disposable and robust LFO probe is expected to have great potential for interstitial OCT imaging. PMID:27375934

  5. Ultrathin lensed fiber-optic probe for optical coherence tomography.

    PubMed

    Qiu, Y; Wang, Y; Belfield, K D; Liu, X

    2016-06-01

    We investigated and validated a novel method to develop ultrathin lensed fiber-optic (LFO) probes for optical coherence tomography (OCT) imaging. We made the LFO probe by attaching a segment of no core fiber (NCF) to the distal end of a single mode fiber (SMF) and generating a curved surface at the tip of the NCF using the electric arc of a fusion splicer. The novel fabrication approach enabled us to control the length of the NCF and the radius of the fiber lens independently. By strategically choosing these two parameters, the LFO probe could achieve a broad range of working distance and depth of focus for different OCT applications. A probe with 125μm diameter and lateral resolution up to 10μm was demonstrated. The low-cost, disposable and robust LFO probe is expected to have great potential for interstitial OCT imaging. PMID:27375934

  6. Designing Tripodal and Triangular Gadolinium Oxide Nanoplates and Self-Assembled Nanofibrils as Potential Multimodal Bioimaging Probes

    SciTech Connect

    Paik, T; Gordon, TR; Prantner, AM; Yun, H; Murray, CB

    2013-03-01

    Here, we report the shape-controlled synthesis of tripodal and triangular gadolinium oxide (Gd2O3) nanoplates. In the presence of lithium ions, the shape of the nanocrystals is readily controlled by tailoring reaction parameters such as temperature and time. We observe that the morphology transforms from an initial tripodal shape to a triangular shape with increasing reaction time or elevated temperatures. Highly uniform Gd2O3 nanoplates are self-assembled into nanofibril-like liquid-crystalline superlattices with long-range orientational and positional order. In addition, shape-directed self-assemblies are investigated by tailoring the aspect ratio of the arms of the Gd2O3 nanoplates. Due to a strong paramagnetic response, Gd2O3 nanocrystals are excellent candidates for MRI contrast agents and also can be doped with rare-earth ions to form nanophosphors, pointing to their potential in multimodal imaging. In this work, we investigate the MR relaxometry at high magnetic fields (9,4 and 14.1 T) and the optical properties including near-IR to visible upconversion luminescence and X-ray excited optical luminescence of doped Gd2O3 nanoplates. The complex shape of Gd2O3 nanoplates, coupled with their magnetic properties and their ability to phosphoresce under NIR or X-ray excitation which penetrate deep into tissue, makes these nanoplates a promising platform for multimodal imaging in biomedical applications.

  7. Quality Control Using Optical Probe Arrays

    NASA Astrophysics Data System (ADS)

    Stewart, Robert M.

    1989-01-01

    Low cost, optical probes, can be combined into an inspection array, and the go/no-go outputs can be analyzed by a high speed programmable logic controller (PLC). The PLC can be remotely addressed to change the desired level of quality control. The PLC can provide on-line data for blow-by-blow statistical process control (SPC).

  8. A Computational Framework for Bioimaging Simulation

    PubMed Central

    Watabe, Masaki; Arjunan, Satya N. V.; Fukushima, Seiya; Iwamoto, Kazunari; Kozuka, Jun; Matsuoka, Satomi; Shindo, Yuki; Ueda, Masahiro; Takahashi, Koichi

    2015-01-01

    Using bioimaging technology, biologists have attempted to identify and document analytical interpretations that underlie biological phenomena in biological cells. Theoretical biology aims at distilling those interpretations into knowledge in the mathematical form of biochemical reaction networks and understanding how higher level functions emerge from the combined action of biomolecules. However, there still remain formidable challenges in bridging the gap between bioimaging and mathematical modeling. Generally, measurements using fluorescence microscopy systems are influenced by systematic effects that arise from stochastic nature of biological cells, the imaging apparatus, and optical physics. Such systematic effects are always present in all bioimaging systems and hinder quantitative comparison between the cell model and bioimages. Computational tools for such a comparison are still unavailable. Thus, in this work, we present a computational framework for handling the parameters of the cell models and the optical physics governing bioimaging systems. Simulation using this framework can generate digital images of cell simulation results after accounting for the systematic effects. We then demonstrate that such a framework enables comparison at the level of photon-counting units. PMID:26147508

  9. Self-referencing remote optical probe

    DOEpatents

    O'Rourke, Patrick E.; Prather, William S.; Livingston, Ronald R.

    1991-01-01

    A probe for remote spectrometric measurements of fluid samples having a hollow probe body with a sliding reflective plug therein and a lens at one end, ports for admitting and expelling the fluid sample and a means for moving the reflector so that reference measurement can be made with the reflector in a first position near the lens and a sample measurement can be made with the reflector away from the lens and the fluid sample between the reflector and the lens. Comparison of the two measurements will yield the composition of the fluid sample. The probe is preferably used for remote measurements and light is carried to and from the probe via fiber optic cables.

  10. Self-referencing remote optical probe

    DOEpatents

    O'Rourke, P.E.; Prather, W.S.; Livingston, R.R.

    1991-08-13

    A probe is described for remote spectrometric measurements of fluid samples having a hollow probe body with a sliding reflective plug therein and a lens at one end, ports for admitting and expelling the fluid sample and a means for moving the reflector so that reference measurement can be made with the reflector in a first position near the lens and a sample measurement can be made with the reflector away from the lens and the fluid sample between the reflector and the lens. Comparison of the two measurements will yield the composition of the fluid sample. The probe is preferably used for remote measurements and light is carried to and from the probe via fiber optic cables. 3 figures.

  11. Facile Synthesis of Amine-Functionalized Eu(3+)-Doped La(OH)3 Nanophosphors for Bioimaging.

    PubMed

    Sun, Conroy; Carpenter, Colin; Pratx, Guillem; Xing, Lei

    2011-12-01

    Here, we report a straightforward synthesis process to produce colloidal Eu(3+)-activated nanophosphors (NPs) for use as bioimaging probes. In this procedure, poly(ethylene glycol) serves as a high-boiling point solvent allowing for nanoscale particle formation as well as a convenient medium for solvent exchange and subsequent surface modification. The La(OH)3:Eu(3+) NPs produced by this process were ~3.5 nm in diameter as determined by transmission electron microscopy. The NP surface was coated with aminopropyltriethoxysilane to provide chemical functionality for attachment of biological ligands, improve chemical stability and prevent surface quenching of luminescent centers. Photoluminescence spectroscopy of the NPs displayed emission peaks at 597 and 615 nm (λex = 280 nm). The red emission, due to (5)D0 → (7)F1 and (5)D0 → (7)F2 transitions, was linear with concentration as observed by imaging with a conventional bioimaging system. To demonstrate the feasibility of these NPs to serve as optical probes in biological applications, an in vitro experiment was performed with HeLa cells. NP emission was observed in the cells by fluorescence microscopy. In addition, the NPs displayed no cytotoxicity over the course of a 48-h MTT cell viability assay. These results suggest that La(OH)3:Eu(3+) NPs possess the potential to serve as a luminescent bioimaging probe. PMID:27502647

  12. Facile Synthesis of Amine-Functionalized Eu3+-Doped La(OH)3 Nanophosphors for Bioimaging

    PubMed Central

    2011-01-01

    Here, we report a straightforward synthesis process to produce colloidal Eu3+-activated nanophosphors (NPs) for use as bioimaging probes. In this procedure, poly(ethylene glycol) serves as a high-boiling point solvent allowing for nanoscale particle formation as well as a convenient medium for solvent exchange and subsequent surface modification. The La(OH)3:Eu3+ NPs produced by this process were ~3.5 nm in diameter as determined by transmission electron microscopy. The NP surface was coated with aminopropyltriethoxysilane to provide chemical functionality for attachment of biological ligands, improve chemical stability and prevent surface quenching of luminescent centers. Photoluminescence spectroscopy of the NPs displayed emission peaks at 597 and 615 nm (λex = 280 nm). The red emission, due to 5D0 → 7F1 and 5D0 → 7F2 transitions, was linear with concentration as observed by imaging with a conventional bioimaging system. To demonstrate the feasibility of these NPs to serve as optical probes in biological applications, an in vitro experiment was performed with HeLa cells. NP emission was observed in the cells by fluorescence microscopy. In addition, the NPs displayed no cytotoxicity over the course of a 48-h MTT cell viability assay. These results suggest that La(OH)3:Eu3+ NPs possess the potential to serve as a luminescent bioimaging probe. PMID:27502647

  13. Impacts of quantum dots in molecular detection and bioimaging of cancer

    PubMed Central

    Mashinchian, Omid; Johari-Ahar, Mohammad; Ghaemi, Behnaz; Rashidi, Mohammad; Barar, Jaleh; Omidi, Yadollah

    2014-01-01

    Introduction: A number of assays have so far been exploited for detection of cancer biomarkers in various malignancies. However, the expression of cancer biomarker(s) appears to be extremely low, therefore accurate detection demands sensitive optical imaging probes. While optical detection using conventional fluorophores often fail due to photobleaching problems, quantum dots (QDs) offer stable optical imaging in vitro and in vivo. Methods: In this review, we briefly overview the impacts of QDs in biology and its applications in bioimaging of malignancies. We will also delineate the existing obstacles for early detection of cancer and the intensifying use of QDs in advancement of diagnostic devices. Results: Of the QDs, unlike the II-VI type QDs (e.g., cadmium (Cd), selenium (Se) or tellurium (Te)) that possess inherent cytotoxicity, the I-III-VI 2 type QDs (e.g., AgInS2, CuInS2, ZnS-AgInS2) appear to be less toxic bioimaging agents with better control of band-gap energies. As highly-sensitive bioimaging probes, advanced hybrid QDs (e.g., QD-QD, fluorochrome-QD conjugates used for sensing through fluorescence resonance energy transfer (FRET), quenching, and barcoding techniques) have also been harnessed for the detection of biomarkers and the monitoring of delivery of drugs/genes to the target sites. Antibody-QD (Ab-QD) and aptamer- QD (Ap-QD) bioconjugates, once target the relevant biomarker, can provide highly stable photoluminescence (PL) at the target sites. In addition to their potential as nanobiosensors, the bioconjugates of QDs with homing devices have successfully been used for the development of smart nanosystems (NSs) providing targeted bioimaging and photodynamic therapy (PDT). Conclusion: Having possessed great deal of photonic characteristics, QDs can be used for development of seamless multifunctional nanomedicines, theranostics and nanobiosensors. PMID:25337468

  14. Creating and Probing Graphene Electron Optics with Local Scanning Probes

    NASA Astrophysics Data System (ADS)

    Stroscio, Joseph

    Ballistic propagation and the light-like dispersion of graphene charge carriers make graphene an attractive platform for optics-inspired graphene electronics where gate tunable potentials can control electron refraction and transmission. In analogy to optical wave propagation in lenses, mirrors and metamaterials, gate potentials can be used to create a negative index of refraction for Veselago lensing and Fabry-Pérot interferometers. In circular geometries, gate potentials can induce whispering gallery modes (WGM), similar to optical and acoustic whispering galleries albeit on a much smaller length scale. Klein scattering of Dirac carriers plays a central role in determining the coherent propagation of electron waves in these resonators. In this talk, I examine the probing of electron resonators in graphene confined by linear and circular gate potentials with the scanning tunneling microscope (STM). The tip in the STM tunnel junction serves both as a tunable local gate potential, and as a probe of the graphene states through tunneling spectroscopy. A combination of a back gate potential, Vg, and tip potential, Vb, creates and controls a circular pn junction that confines the WGM graphene states. The resonances are observed in two separate channels in the tunneling spectroscopy experiment: first, by directly tunneling into the state at the bias energy eVb, and, second, by tunneling from the resonance at the Fermi level as the state is gated by the tip potential. The second channel produces a fan-like set of WGM peaks, reminiscent of the fringes seen in planar geometries by transport measurements. The WGM resonances split in a small applied magnetic field, with a large energy splitting approaching the WGM spacing at 0.5 T. These results agree well with recent theory on Klein scattering in graphene electron resonators. This work is done in collaboration with Y. Zhao, J. Wyrick, F.D. Natterer, J. F. Rodriquez-Nieva, C. Lewandoswski, K. Watanabe, T. Taniguchi, N. B

  15. Preparation, cytotoxicity and in vivo bioimaging of highly luminescent water-soluble silicon quantum dots

    NASA Astrophysics Data System (ADS)

    Fan, Jing-Wun; Vankayala, Raviraj; Chang, Chien-Liang; Chang, Chia-Hua; Chiang, Chi-Shiun; Hwang, Kuo Chu

    2015-05-01

    Designing various inorganic nanomaterials that are cost effective, water soluble, optically photostable, highly fluorescent and biocompatible for bioimaging applications is a challenging task. Similar to semiconducting quantum dots (QDs), silicon QDs are another alternative and are highly fluorescent, but non-water soluble. Several surface modification strategies were adopted to make them water soluble. However, the photoluminescence of Si QDs was seriously quenched in the aqueous environment. In this report, highly luminescent, water-dispersible, blue- and green-emitting Si QDs were prepared with good photostability. In vitro studies in monocytes reveal that Si QDs exhibit good biocompatibility and excellent distribution throughout the cytoplasm region, along with the significant fraction translocated into the nucleus. The in vivo zebrafish studies also reveal that Si QDs can be evenly distributed in the yolk-sac region. Overall, our results demonstrate the applicability of water-soluble and highly fluorescent Si QDs as excellent in vitro and in vivo bioimaging probes.

  16. Cone penetrometer fiber optic raman spectroscopy probe assembly

    DOEpatents

    Kyle, Kevin R.; Brown, Steven B.

    2000-01-01

    A chemically and mechanically robust optical Raman spectroscopy probe assembly that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via fiber optics to the light source and the detection system at the surface. A built-in broadband light source provides a strobe method for direct measurement of sample optical density. A mechanically stable sapphire window is sealed directly into the side-wall of the housing using a metallic, chemically resistant, hermetic seal design. This window permits transmission of the interrogation light beam and the resultant signal. The spectroscopy probe assembly is capable of accepting Raman, Laser induced Fluorescence, reflectance, and other optical probes with collimated output for CPT deployment.

  17. Cone penetrometer fiber optic Raman spectroscopy probe assembly

    SciTech Connect

    Kyle, K.R.; Brown, S.B.

    2000-01-25

    A chemically and mechanically robust optical Raman spectroscopy probe assembly is described that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via fiber optics to the light source and the detection system at the surface. A built-in broadband light source provides a strobe method for direct measurement of sample optical density. A mechanically stable sapphire window is sealed directly into the side-wall of the housing using a metallic, chemically resistant, hermetic seal design. This window permits transmission of the interrogation light beam and the resultant signal. The spectroscopy probe assembly is capable of accepting Raman, Laser induced Fluorescence, reflectance, and other optical probes with collimated output for CPT deployment.

  18. Probing the nano-bio interface with nanoplasmonic optical probes

    NASA Astrophysics Data System (ADS)

    Yu, X.; Wu, Linxi; Khanehzar, Ali; Feizpour, Amin; Xu, Fangda; Reinhard, Björn M.

    2014-08-01

    Noble metal nanoparticles have large cross-sections in both optical and electron microscopy and plasmon coupling between noble metal nanoparticles facilitate the characterization of subdiffraction limit separations through spectral analysis of the scattered light in Plasmon Coupling Microscopy (PCM). The size compatibility of noble metal nanoparticles together with the ability to encode specific functionality in a rational fashion by control of the nanoparticle surface makes noble metal nanoparticles unique probes for a broad range of biological processes. Recent applications of the technology include i.) characterization of cellular heterogeneity in nanomaterial uptake and processing through macrophages, ii.) testing the role of viral membrane lipids in mediating viral binding and trafficking, and iii.) characterizing the spatial organization of cancer biomarkers in plasma membranes. This paper reviews some of these applications and introduces the physical and material science principles underlying them. We will also introduce the use of membrane wrapped noble metal nanoparticles, which combine the superb photophysical properties of a nanoparticle core with the biological functionality of a membrane, as probes in PCM.

  19. Portable optical fiber probe for in vivo brain temperature measurements.

    PubMed

    Musolino, Stefan; Schartner, Erik P; Tsiminis, Georgios; Salem, Abdallah; Monro, Tanya M; Hutchinson, Mark R

    2016-08-01

    This work reports on the development of an optical fiber based probe for in vivo measurements of brain temperature. By utilizing a thin layer of rare-earth doped tellurite glass on the tip of a conventional silica optical fiber a robust probe, suitable for long-term in vivo measurements of temperature can be fabricated. This probe can be interrogated using a portable optical measurement setup, allowing for measurements to be performed outside of standard optical laboratories. PMID:27570698

  20. Portable optical fiber probe for in vivo brain temperature measurements

    PubMed Central

    Musolino, Stefan; Schartner, Erik P.; Tsiminis, Georgios; Salem, Abdallah; Monro, Tanya M.; Hutchinson, Mark R.

    2016-01-01

    This work reports on the development of an optical fiber based probe for in vivo measurements of brain temperature. By utilizing a thin layer of rare-earth doped tellurite glass on the tip of a conventional silica optical fiber a robust probe, suitable for long-term in vivo measurements of temperature can be fabricated. This probe can be interrogated using a portable optical measurement setup, allowing for measurements to be performed outside of standard optical laboratories. PMID:27570698

  1. Electro-optical Probing Of Terahertz Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Bhasin, K. B.; Romanofsky, R.; Whitaker, J. F.; Valdmanis, J. A.; Mourou, G.; Jackson, T. A.

    1990-01-01

    Electro-optical probe developed to perform noncontact, nondestructive, and relatively noninvasive measurements of electric fields over broad spectrum at millimeter and shorter wavelengths in integrated circuits. Manipulated with conventional intregrated-circuit-wafer-probing equipment and operated without any special preparation of integrated circuits. Tip of probe small electro-optical crystal serving as proximity electric-field sensor.

  2. Nonlinear optical properties and nonlinear optical probes of organic materials

    NASA Astrophysics Data System (ADS)

    Meredith, Gerald R.

    1992-02-01

    Nonlinear optical processes and electro-optical effects are expected to have increasing importance as the information age matures and photonics augment electronics in various high density and high bandwidth technologies. Whereas for electronics the emphasis is in construction of smaller device structures from a few parent materials, for organic materials the direction of materials research has been reversed. For some time it's been known that some molecular structures engender exceptionally large molecular nonlinear-polarization responses. If such molecules could be assembled in convenient, versatile, and reliable ways, the resulting materials would be very useful or even enabling in various photonics applications. The mature science and art of chemistry allows very good control over molecular composition and structure and, as will be illustrated in this talk, our knowledge of hyperpolarizability structure- property relationships is advancing rapidly. However, the science of fabrication and arrangement in molecular ensembles and polymers is rather primitive. Thus the goal to develop the appropriately structured materials for utilization in nonlinear and electro-optics has fostered the widespread use of nonlinear optical processes to probe the nature of supramolecular order and assembly. Examples of intrinsic and artificially assembled structures of crystals, molecular aggregates, polymeric orientational electrets and molecular mono- and multi-layer thin films will be shown. Nonlinear optical processes, primarily second-harmonic generation, provide unique probes of these structures, their assembly, and evolution.

  3. Micromachined photoplastic probe for scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Genolet, G.; Despont, M.; Vettiger, P.; Staufer, U.; Noell, W.; de Rooij, N. F.; Cueni, T.; Bernal, M.-P.; Marquis-Weible, F.

    2001-10-01

    We present a hybrid probe for scanning near-field optical microscopy (SNOM), which consists of a micromachined photoplastic tip with a metallic aperture at the apex that is attached to an optical fiber, thus combining the advantages of optical fiber probes and micromachined tips. The tip and aperture are batch fabricated and assembled to a preetched optical fiber with micrometer centering precision. Rectangular apertures of 50 nm×130 nm have been produced without the need of any postprocessing. Topographical and optical imaging with a probe having an aperture of 300 nm demonstrate the great potential of the photoplastic probe for SNOM applications.

  4. Probing the Casimir force with optical tweezers

    NASA Astrophysics Data System (ADS)

    Ether, D. S., Jr.; Pires, L. B.; Umrath, S.; Martinez, D.; Ayala, Y.; Pontes, B.; Araújo, G. R. de S.; Frases, S.; Ingold, G.-L.; Rosa, F. S. S.; Viana, N. B.; Nussenzveig, H. M.; Neto, P. A. Maia

    2015-11-01

    We propose to use optical tweezers to probe the Casimir interaction between microspheres inside a liquid medium for geometric aspect ratios far beyond the validity of the widely employed proximity force approximation. This setup has the potential for revealing unprecedented features associated to the non-trivial role of the spherical curvatures. For a proof of concept, we measure femtonewton double-layer forces between polystyrene microspheres at distances above 400 nm by employing very soft optical tweezers, with stiffness of the order of fractions of a fN/nm. As a future application, we propose to tune the Casimir interaction between a metallic and a polystyrene microsphere in saline solution from attraction to repulsion by varying the salt concentration. With those materials, the screened Casimir interaction may have a larger magnitude than the unscreened one. This line of investigation has the potential for bringing together different fields including classical and quantum optics, statistical physics and colloid science, while paving the way for novel quantitative applications of optical tweezers in cell and molecular biology.

  5. Design considerations for miniaturized optical neural probes

    NASA Astrophysics Data System (ADS)

    Rudmann, Linda; Ordonez, Juan S.; Stieglitz, Thomas

    2016-03-01

    Neural probes are designed to selectively record from or stimulate nerve cells. In optogenetics it is desirable to build miniaturized and long-term stable optical neural probes, in which the light sources can be directly and chronically implanted into the animals to allow free movement and behavior. Because of the size and the beam shape of the available light sources, it is difficult to target single cells as well as spatially localized networks. We therefore investigated design considerations for packages, which encapsulate the light source hermetically and have integrated hemispherical lens structures that enable to focus the light onto the desired region, by optical simulations. Integration of a biconvex lens into the package lid (diameter = 300 μm, material: silicon carbide) increased the averaged absolute irradiance ηA by 298 % compared to a system without a lens and had a spot size of around 120 μm. Solely integrating a plano-convex lens (same diameter and material) results in an ηA of up to 227 %.

  6. Hollow fiber-optic Raman probes for small experimental animals

    NASA Astrophysics Data System (ADS)

    Katagiri, Takashi; Hattori, Yusuke; Suzuki, Toshiaki; Matsuura, Yuji; Sato, Hidetoshi

    2007-02-01

    Two types of hollow fiber-optic probes are developed to measure the in vivo Raman spectra of small animals. One is the minimized probe which is end-sealed with the micro-ball lens. The measured spectra reflect the information of the sample's sub-surface. This probe is used for the measurement of the esophagus and the stomach via an endoscope. The other probe is a confocal Raman probe which consists of a single fiber and a lens system. It is integrated into the handheld microscope. A simple and small multimodal probe is realized because the hollow optical fiber requires no optical filters. The performance of each probe is examined and the effectiveness of these probes for in vivo Raman spectroscopy is shown by animal tests.

  7. Probing the Casimir force with optical tweezers

    NASA Astrophysics Data System (ADS)

    Maia Neto, Paulo; Ether, Diney; Pires, Luis; Ayala, Yareni; Rosa, Felipe; Umrath, Stefan; Ingold, Gert; Viana, Nathan; Nussenzveig, Moyses

    2015-03-01

    Optical tweezers (OT) are single-beam laser traps for neutral particles, usually applied to dielectric microspheres immersed in a fluid. The stiffness is proportional to the trapping beam power, and hence can be tuned to very small values, allowing one to measure femtonewton forces, once the device is carefully calibrated. We employ OT to measure the Casimir (or retarded van der Waals) force between polystyrene beads in ethanol, for distances between 50 nanometers and 1 micrometer. The spherical beads have diameters ranging from 3 to 7 micrometers. We find a rather large correction to the widely employed Proximity Force approximation (PFA), since the ratio between distances and sphere radii is much larger than the typical values probed in recent experiments. For the comparison with experimental data, we compute the Casimir force using the scattering approach applied to the spherical geometry, including the contribution of double-layer forces. We also present experimental results for the total force between a mercury microdroplet and a polystyrene bead immersed in ethanol, with similar distances and diameters. In short, we probe the Casimir force with different materials in a regime far from the validity of PFA, such that the spherical geometry plays a non-trivial role.

  8. Self optical motion-tracking for endoscopic optical coherence tomography probe using micro-beamsplitter probe

    NASA Astrophysics Data System (ADS)

    Li, Jiawen; Zhang, Jun; Chou, Lidek; Wang, Alex; Jing, Joseph; Chen, Zhongping

    2014-03-01

    Long range optical coherence tomography (OCT), with its high speed, high resolution, non-ionized properties and cross-sectional imaging capability, is suitable for upper airway lumen imaging. To render 2D OCT datasets to true 3D anatomy, additional tools are usually applied, such as X-ray guidance or a magnetic sensor. X-ray increases ionizing radiation. A magnetic sensor either increases probe size or requires an additional pull-back of the tracking sensor through the body cavity. In order to overcome these limitations, we present a novel tracking method using a 1.5 mm×1.5mm, 90/10-ratio micro-beamsplitter: 10% light through the beam-splitter is used for motion tracking and 90% light is used for regular OCT imaging and motion tracking. Two signals corresponding to these two split-beams that pass through different optical path length delays are obtained by the detector simultaneously. Using the two split beams' returned signals from the same marker line, the 2D inclination angle of each step is computed. By calculating the 2D inclination angle of each step and then connecting the translational displacements of each step, we can obtain the 2D motion trajectory of the probe. With two marker lines on the probe sheath, 3D inclination angles can be determined and then used for 3D trajectory reconstruction. We tested the accuracy of trajectory reconstruction using the probe and demonstrated the feasibility of the design for structure reconstruction of a biological sample using a porcine trachea specimen. This optical-tracking probe has the potential to be made as small as an outer diameter of 1.0mm, which is ideal for upper airway imaging.

  9. Optical brush: Imaging through permuted probes

    PubMed Central

    Heshmat, Barmak; Lee, Ik Hyun; Raskar, Ramesh

    2016-01-01

    The combination of computational techniques and ultrafast imaging have enabled sensing through unconventional settings such as around corners, and through diffusive media. We exploit time of flight (ToF) measurements to enable a flexible interface for imaging through permuted set of fibers. The fibers are randomly distributed in the scene and are packed on the camera end, thus making a brush-like structure. The scene is illuminated by two off-axis optical pulses. Temporal signatures of fiber tips in the scene are used to localize each fiber. Finally, by combining the position and measured intensity of each fiber, the original input is reconstructed. Unlike conventional fiber bundles with packed set of fibers that are limited by a narrow field of view (FOV), lack of flexibility, and extended coaxial precalibration, the proposed optical brush is flexible and uses off-axis calibration method based on ToF. The enabled brush form can couple to other types of ToF imaging systems. This can impact probe-based applications such as, endoscopy, tomography, and industrial imaging and sensing. PMID:26868954

  10. Optical brush: Imaging through permuted probes

    NASA Astrophysics Data System (ADS)

    Heshmat, Barmak; Lee, Ik Hyun; Raskar, Ramesh

    2016-02-01

    The combination of computational techniques and ultrafast imaging have enabled sensing through unconventional settings such as around corners, and through diffusive media. We exploit time of flight (ToF) measurements to enable a flexible interface for imaging through permuted set of fibers. The fibers are randomly distributed in the scene and are packed on the camera end, thus making a brush-like structure. The scene is illuminated by two off-axis optical pulses. Temporal signatures of fiber tips in the scene are used to localize each fiber. Finally, by combining the position and measured intensity of each fiber, the original input is reconstructed. Unlike conventional fiber bundles with packed set of fibers that are limited by a narrow field of view (FOV), lack of flexibility, and extended coaxial precalibration, the proposed optical brush is flexible and uses off-axis calibration method based on ToF. The enabled brush form can couple to other types of ToF imaging systems. This can impact probe-based applications such as, endoscopy, tomography, and industrial imaging and sensing.

  11. Use of a fiber optic probe for organic species determination

    DOEpatents

    Ekechukwu, Amy A.

    1996-01-01

    A fiber optic probe for remotely detecting the presence and concentration organic species in aqueous solutions. The probe includes a cylindrical housing with an organic species indicator, preferably diaminonaphthyl sulfonic acid adsorbed in a silica gel (DANS-modified gel), contained in the probe's distal end. The probe admits aqueous solutions to the probe interior for mixing within the DANS-modified gel. An optical fiber transmits light through the DANS-modified gel while the indicator reacts with organic species present in the solution, thereby shifting the location of the fluorescent peak. The altered light is reflected to a receiving fiber that carries the light to a spectrophotometer or other analysis device.

  12. Fiber Optic Biosensing Probes For Biomedically Important Compounds

    NASA Astrophysics Data System (ADS)

    Arnold, Mark A.

    1988-06-01

    Fiber optic biosensing probes for several bioanalytes of clinical and biomedical importance are described. The development of biosensors based on immobilization of a deaminating enzyme at the tip of a fiber optic ammonia sensor is illustrated with a biosensing probe for urea. In addition, biosensors based on the direct fluorometric detection of reduced nicotinamide adenine dinucleotide (NADH) at the tip of an optical fiber device are presented. Probes for lactate and pyruvate illustrate this concept. Finally, preliminary results from an investigation to prepare NADH sensing probes based on immobilized bacterial luciferase are given.

  13. Optimizing the synthesis of CdS/ZnS core/shell semiconductor nanocrystals for bioimaging applications.

    PubMed

    Liu, Li-Wei; Hu, Si-Yi; Pan, Ying; Zhang, Jia-Qi; Feng, Yue-Shu; Zhang, Xi-He

    2014-01-01

    In this study, we report on CdS/ZnS nanocrystals as a luminescence probe for bioimaging applications. CdS nanocrystals capped with a ZnS shell had enhanced luminescence intensity, stronger stability and exhibited a longer lifetime compared to uncapped CdS. The CdS/ZnS nanocrystals were stabilized in Pluronic F127 block copolymer micelles, offering an optically and colloidally stable contrast agents for in vitro and in vivo imaging. Photostability test exhibited that the ZnS protective shell not only enhances the brightness of the QDs but also improves their stability in a biological environment. An in-vivo imaging study showed that F127-CdS/ZnS micelles had strong luminescence. These results suggest that these nanoparticles have significant advantages for bioimaging applications and may offer a new direction for the early detection of cancer in humans. PMID:24991530

  14. Luminescent gold nanoparticles for bioimaging

    NASA Astrophysics Data System (ADS)

    Zhou, Chen

    Inorganic nanoparticles (NPs) with tunable and diverse material properties hold great potential as contrast agents for better disease management. Over the past decades, luminescent gold nanoparticles (AuNPs) with intrinsic emissions ranging from the visible to the near infrared have been synthesized and emerge as a new class of fluorophores for bioimaging. This dissertation aims to fundamentally understand the structure-property relationships in luminescent AuNPs and apply them as contrast agents to address some critical challenges in bioimaging at both the in vitro and in vivo level. In Chapter 2, we described the synthesized ~20 nm polycrystalline AuNPs (pAuNPs), which successfully integrated and enhanced plasmonic and fluorescence properties into a single AuNP through the grain size effect. The combination of these properties in one NP enabled AuNPs to serve as a multimodal contrast agent for in vitro optical microscopic imaging, making it possible to develop correlative microscopic imaging techniques. In Chapters 3-5, we proposed a feasible approach to optimize the in vivo kinetics and clearance profile of nanoprobes for multimodality in vivo bioimaging applications by using straightforward surface chemistry with luminescent AuNPs as a model. Luminescent glutathione-coated AuNPs of ~2 nm were synthesized. Investigation of the biodistribution showed that these glutathione-coated AuNPs (GS-AuNPs) exhibit stealthiness to the reticuloendothelial system (RES) organs and efficient renal clearance, with only 3.7+/-1.9% and 0.3+/-0.1% accumulating in the liver and spleen, and over 65% of the injection dose cleared out via the urine within the first 72 hours. In addition, ~2.5 nm NIR-emitting radioactive glutathione-coated [198Au]AuNPs (GS-[198Au]AuNPs) were synthesized for further evaluation of the pharmacokinetic profile of GS-AuNPs and potential multimodal imaging. The results showed that the GS-[198Au]AuNPs behave like small-molecule contrast agents in

  15. Fiber probes based optical techniques for biomedical diagnosis

    NASA Astrophysics Data System (ADS)

    Arce-Diego, José L.; Fanjul-Vélez, Félix

    2007-06-01

    Although fiber optics have been applied in optical communication and sensor systems for several years in a very successful way, their first application was developed in medicine in the early 20's. Manufacturing and developing of optical fibers for biomedical purposes have required a lot of research efforts in order to achieve a non-invasive, in-vivo, and real-time diagnosis of different diseases in human or animal tissues. In general, optical fiber probes are designed as a function of the optical measurement technique. In this work, a brief description of the main optical techniques for optical characterization of biological tissues is presented. The recent advances in optical fiber probes for biomedical diagnosis in clinical analysis and optical biopsy in relation with the different spectroscopic or tomographic optical techniques are described.

  16. Multimode-Optical-Fiber Imaging Probe

    NASA Technical Reports Server (NTRS)

    Jackson, Deborah

    1999-01-01

    Currently, endoscopic surgery uses single-mode fiber-bundles to obtain in vivo image information inside the orifices of the body. This limits their use to the larger natural orifices and to surgical procedures where there is plenty of room for manipulation. The knee joint, for example, can be easily viewed with a fiber optic viewer, but joints in the finger cannot. However, there are a host of smaller orifices where fiber endoscopy would play an important role if a cost effective fiber probe were developed with small enough dimensions (less than or equal to 250 microns). Examples of beneficiaries of micro-endoscopes are the treatment of the Eustatian tube of the middle ear, the breast ducts, tear ducts, coronary arteries, fallopian tubes, as well as the treatment of salivary duct parotid disease, and the neuro endoscopy of the ventricles and spinal canal. This work describes an approach for recovering images from tightly confined spaces using multimode. The concept draws upon earlier works that concentrated on image recovery after two-way transmission through a multimode fiber as well as work that demonstrated the recovery of images after one-way transmission through a multimode fiber. Both relied on generating a phase conjugated wavefront, which was predistorted with the characteristics of the fiber. The approach described here also relies on generating a phase conjugated wavefront, but utilizes two fibers to capture the image at some intermediate point (accessible by the fibers, but which is otherwise visually inaccessible).

  17. Design of fiber optic probes for laser light scattering

    NASA Technical Reports Server (NTRS)

    Dhadwal, Harbans S.; Chu, Benjamin

    1989-01-01

    A quantitative analysis is presented of the role of optical fibers in laser light scattering. Design of a general fiber optic/microlens probe by means of ray tracing is described. Several different geometries employing an optical fiber of the type used in lightwave communications and a graded index microlens are considered. Experimental results using a nonimaging fiber optic detector probe show that due to geometrical limitations of single mode fibers, a probe using a multimode optical fiber has better performance, for both static and dynamic measurements of the scattered light intensity, compared with a probe using a single mode fiber. Fiber optic detector probes are shown to be more efficient at data collection when compared with conventional approaches to measurements of the scattered laser light. Integration of fiber optic detector probes into a fiber optic spectrometer offers considerable miniaturization of conventional light scattering spectrometers, which can be made arbitrarily small. In addition static and dynamic measurements of scattered light can be made within the scattering cell and consequently very close to the scattering center.

  18. A miniature forward-imaging optical coherence tomography (OCT) probe

    NASA Astrophysics Data System (ADS)

    Joos, Karen M.; Shen, Jin-Hui

    2012-03-01

    Optical coherence tomography (OCT) has had a tremendous global health impact upon the current ability to diagnose, treat, and monitor multiple eye diseases. We propose that a miniature forward-imaging OCT probe can be developed for real-time ocular imaging. A miniature 25-gauge forward-imaging probe was designed and developed to use with an 850 nm spectral-domain optical coherence tomography (SDOCT) system (Bioptigen, Inc. Durham, NC). Imaging parameters were determined. Ocular tissues were examined with the miniature OCT probe. A miniature SDOCT probe was developed with the scanning driver within the hand piece. The SDOCT fiber-scanning probe maximally transmitted power of 800 μW. The scanning range was 3 mm when the probe tip was held 3 to 5 mm from the tissue surface. The axial resolution was 6 μm and the lateral resolution was 30-35 μm. The 25-gauge forward-imaging probe was used to image cellophane tape, eyelid skin, cornea, conjunctiva, sclera, iris, anterior lens, anterior chamber angle, retina, retinal tear, retinal detachment, optic nerve head, and optic nerve sheath. Images obtained from the miniature probe appeared similar to images from a 3 mm scanning range of a commercial large handheld OCT probe (Bioptigen, Inc. Durham, NC).

  19. Multimode-Optical-Fiber Imaging Probe

    NASA Technical Reports Server (NTRS)

    Jackson, Deborah

    2000-01-01

    Currently, endoscopic surgery uses single-mode fiber-bundles to obtain in vivo image information inside orifices of the body. This limits their use to the larger natural bodily orifices and to surgical procedures where there is plenty of room for manipulation. The knee joint, for example can be easily viewed with a fiber optic viewer, but joints in the finger cannot. However, there are a host of smaller orifices where fiber endoscopy would play an important role if a cost effective fiber probe were developed with small enough dimensions (< 250 microns). Examples of beneficiaries of micro-endoscopes are the treatment of the Eustatian tube of the middle ear, the breast ducts, tear ducts, coronary arteries, fallopian tubes, as well as the treatment of salivary duct parotid disease, and the neuro endoscopy of the ventricles and spinal canal. To solve this problem, this work describes an approach for recovering images from. tightly confined spaces using multimode fibers and analytically demonstrates that the concept is sound. The proof of concept draws upon earlier works that concentrated on image recovery after two-way transmission through a multimode fiber as well as work that demonstrated the recovery of images after one-way transmission through a multimode fiber. Both relied on generating a phase conjugated wavefront which was predistorted with the characteristics of the fiber. The described approach also relies on generating a phase conjugated wavefront, but utilizes two fibers to capture the image at some intermediate point (accessible by the fibers, but which is otherwise visually unaccessible).

  20. A Redox-Nucleophilic Dual-Reactable Probe for Highly Selective and Sensitive Detection of H2S: Synthesis, Spectra and Bioimaging.

    PubMed

    Zhang, Changyu; Wang, Runyu; Cheng, Longhuai; Li, Bingjie; Xi, Zhen; Yi, Long

    2016-01-01

    Hydrogen sulfide (H2S) is an important signalling molecule with multiple biological functions. The reported H2S fluorescent probes are majorly based on redox or nucleophilic reactions. The combination usage of both redox and nucleophilic reactions could improve the probe's selectivity, sensitivity and stability. Herein we report a new dual-reactable probe with yellow turn-on fluorescence for H2S detection. The sensing mechanism of the dual-reactable probe was based on thiolysis of NBD (7-nitro-1,2,3-benzoxadiazole) amine (a nucleophilic reaction) and reduction of azide to amine (a redox reaction). Compared with its corresponding single-reactable probes, the dual-reactable probe has higher selectivity and fluorescence turn-on fold with magnitude of multiplication from that of each single-reactable probe. The highly selective and sensitive properties enabled the dual-reactable probe as a useful tool for efficiently sensing H2S in aqueous buffer and in living cells. PMID:27440747

  1. Optical frequency domain imaging with a rapidly swept laser in the 1300nm bio-imaging window

    NASA Astrophysics Data System (ADS)

    Meleppat, Ratheesh Kumar; Vadakke Matham, Murukeshan; Seah, Leong Keey

    2015-07-01

    Optical frequency domain imaging system (OFDI) in the 1300nm biological imaging window is demonstrated by using a high speed frequency swept laser source. The output of the laser with central wave length of 1320nm is continuously tuned over a bandwidth of 100nm with a repetition rate of 16 KHz. The laser source has an instantaneous coherence length of 6mm and delivers an average power of 12mW. Axial resolution ~ 6μm in the biological tissue and peak sensitivity of 110dB are achieved. The experimentally determined values of the imaging parameters such as the axial resolution, sensitivity and depth range are found to be in good agreement with the theoretically estimated values. The developed system is capable of generating the images of size 512x1024 at a rate of 20 frames per second. High resolution and high contrast images of the finger nail and anterior chamber of a pig's eye acquired using the developed OFDI system are presented, which demonstrate the feasibility of the system for in-vivo biomedical imaging applications.

  2. Use of a fiber optic probe for organic species determination

    DOEpatents

    Ekechukwu, A.A.

    1996-12-10

    A fiber optic probe is described for remotely detecting the presence and concentration organic species in aqueous solutions. The probe includes a cylindrical housing with an organic species indicator, preferably diaminonaphthyl sulfonic acid adsorbed in a silica gel (DANS-modified gel), contained in the probe`s distal end. The probe admits aqueous solutions to the probe interior for mixing within the DANS-modified gel. An optical fiber transmits light through the DANS-modified gel while the indicator reacts with organic species present in the solution, thereby shifting the location of the fluorescent peak. The altered light is reflected to a receiving fiber that carries the light to a spectrophotometer or other analysis device. 5 figs.

  3. Novel fibre-optic-based ionization radiation probes

    NASA Astrophysics Data System (ADS)

    Jackson, David A.

    2004-06-01

    CsI ionization radiation probes interrogated via a fiber optic transceiver link for monitoring medical procedures such as Intensity Modulated Radiotherapy, Brachytherapy and Nuclear Medicine are presented together with potential industrial, environmental and military applications.

  4. Reflective fiber optic probe for surface finish survey

    NASA Astrophysics Data System (ADS)

    Wawrzyniuk, Leszek

    1995-06-01

    The Report relates to verification of the design of refractive fiber optic probes designed for checking surface finish condition and provides a description of tests on the models of such probes. Presented in the paper are the results of performance tests of a bifurcated probe to the concept of application of a non-random bundle of light guides for identification of surfaces representing different CLA values (0.32, 0.63, 1.25, 2.50 micrometers).

  5. A Redox-Nucleophilic Dual-Reactable Probe for Highly Selective and Sensitive Detection of H2S: Synthesis, Spectra and Bioimaging

    PubMed Central

    Zhang, Changyu; Wang, Runyu; Cheng, Longhuai; Li, Bingjie; Xi, Zhen; Yi, Long

    2016-01-01

    Hydrogen sulfide (H2S) is an important signalling molecule with multiple biological functions. The reported H2S fluorescent probes are majorly based on redox or nucleophilic reactions. The combination usage of both redox and nucleophilic reactions could improve the probe’s selectivity, sensitivity and stability. Herein we report a new dual-reactable probe with yellow turn-on fluorescence for H2S detection. The sensing mechanism of the dual-reactable probe was based on thiolysis of NBD (7-nitro-1,2,3-benzoxadiazole) amine (a nucleophilic reaction) and reduction of azide to amine (a redox reaction). Compared with its corresponding single-reactable probes, the dual-reactable probe has higher selectivity and fluorescence turn-on fold with magnitude of multiplication from that of each single-reactable probe. The highly selective and sensitive properties enabled the dual-reactable probe as a useful tool for efficiently sensing H2S in aqueous buffer and in living cells. PMID:27440747

  6. A Redox-Nucleophilic Dual-Reactable Probe for Highly Selective and Sensitive Detection of H2S: Synthesis, Spectra and Bioimaging

    NASA Astrophysics Data System (ADS)

    Zhang, Changyu; Wang, Runyu; Cheng, Longhuai; Li, Bingjie; Xi, Zhen; Yi, Long

    2016-07-01

    Hydrogen sulfide (H2S) is an important signalling molecule with multiple biological functions. The reported H2S fluorescent probes are majorly based on redox or nucleophilic reactions. The combination usage of both redox and nucleophilic reactions could improve the probe’s selectivity, sensitivity and stability. Herein we report a new dual-reactable probe with yellow turn-on fluorescence for H2S detection. The sensing mechanism of the dual-reactable probe was based on thiolysis of NBD (7-nitro-1,2,3-benzoxadiazole) amine (a nucleophilic reaction) and reduction of azide to amine (a redox reaction). Compared with its corresponding single-reactable probes, the dual-reactable probe has higher selectivity and fluorescence turn-on fold with magnitude of multiplication from that of each single-reactable probe. The highly selective and sensitive properties enabled the dual-reactable probe as a useful tool for efficiently sensing H2S in aqueous buffer and in living cells.

  7. Whispering Gallery Optical Resonator Spectroscopic Probe and Method

    NASA Technical Reports Server (NTRS)

    Anderson, Mark S. (Inventor)

    2014-01-01

    Disclosed herein is a spectroscopic probe comprising at least one whispering gallery mode optical resonator disposed on a support, the whispering gallery mode optical resonator comprising a continuous outer surface having a cross section comprising a first diameter and a second diameter, wherein the first diameter is greater than the second diameter. A method of measuring a Raman spectrum and an Infra-red spectrum of an analyte using the spectroscopic probe is also disclosed.

  8. Improved optical fiber probes for scanning near field optical microscopy

    NASA Astrophysics Data System (ADS)

    Wheaton, Bryan R.

    2004-12-01

    The motivation behind this work stems from a combination of my interest in atomic force microscopy (AFM) and the need to apply AFM to several areas of glass research. AFM was used as the main characterization tool in the study of near-field scanning optical microscopy (NSOM) tip formation, evaluation of phase separation in glasses and copper oxide semiconductor film formation. The use of atomic force microscopy (AFM) to evaluate the evolving tip structure of an optical fiber probe for NSOM was studied. This study demonstrates the feasibility of predicting the final tip cone angle, without taking the etching process to completion. Cone angles reported in this study ranged from 58 to 152 degrees, depending on the fiber type and etch conditions. The ability to vary the probe cone angle, and utilize AFM to evaluate the cone angle that results from a set of etch conditions, are valuable additions to the development of NSOM fiber tips. The chemical and spatial variation of phase separated morphologies in glasses can range from a few angstroms to microns, often requiring very high magnification for detection. Historically phase separated glasses have been characterized by transmission electron microscopy (TEM), a time consuming and costly technique. Atomic force microscopy (AFM) provides an inexpensive alternative to TEM and has proven to be a powerful tool in the evaluation of type, degree and scale of phase separation in glasses down to the nanometer level. AFM was used to show that the thickness and uniformity of the CuO films grown in-situ on the surface of copper containing alkali borosilicate glasses increased with time and temperature, however an upper time limit was reached in which no further thickness increases were realized. Tenorite, cuprite and copper metal films were produced depending on the heat treatment environment. XPS was utilized to confirm that copper oxide film formation during heat treatments of glasses near Tg results from the oxidation of copper

  9. Magnetic field concentrator for probing optical magnetic metamaterials.

    PubMed

    Antosiewicz, Tomasz J; Wróbel, Piotr; Szoplik, Tomasz

    2010-12-01

    Development of all dielectric and plasmonic metamaterials with a tunable optical frequency magnetic response creates a need for new inspection techniques. We propose a method of measuring magnetic responses of such metamaterials within a wide range of optical frequencies with a single probe. A tapered fiber probe with a radially corrugated metal coating concentrates azimuthally polarized light in the near-field into a subwavelength spot the longitudinal magnetic field component which is much stronger than the perpendicular electric one. The active probe may be used in a future scanning near-field magnetic microscope for studies of magnetic responses of subwavelength elementary cells of metamaterials. PMID:21164936

  10. Note: Folded optical system for narrow forward looking probe

    SciTech Connect

    Hou, Hsuan-Chao; Hah, Dooyoung; Kim, Jeonghwan; Feldman, M.

    2014-02-15

    An optical system is described in which a laser beam makes three passes through a single graded index lens, forming a focus along the optic axis. It has important applications in endoscopic probes, where the forward looking characteristic permits the avoidance of obstacles and the narrow structure makes it minimally invasive.

  11. Naked-eye and near-infrared fluorescence probe for hydrazine and its applications in in vitro and in vivo bioimaging.

    PubMed

    Zhang, Jianjian; Ning, Lulu; Liu, Jiting; Wang, Jianxi; Yu, Bianfei; Liu, Xiaoyan; Yao, Xiaojun; Zhang, Ziping; Zhang, Haixia

    2015-09-01

    Hydrazine has been applied diffusely in most of the chemical industry; however, it is a hazardous environmental pollutant and highly toxic to organisms. Selective, rapid, and sensitive detection of hydrazine thus becomes absolutely necessary in both biological and environmental sciences. Accordingly, fluorescence probes for hydrazine have been paid great attention in recent years. Disclosed here is the near-infrared (NIR) fluorescence probe with a turn-on fluorescent probe CyJ based on the structure-emission property relationships of the NIR dyes containing an acetyl group as the recognizing moiety. This new probe not only can be readily prepared, but also shows excellent sensing properties. First and most important of all, CyJ is highly selective for N2H4 over various anions, cations, and other amino compounds and has a low limit of detection (LOD) of hydrazine (5.4 ppb as fluorescence sensor and 6.1 ppb as UV sensor). Besides, CyJ exhibited a dramatic increase in fluorescence at λmax = 706 nm in the presence of N2H4, and it offers a rapid, colorimetric and vapor sensing detection process for N2H4 in both aqueous solution and diluted human serum. Furthermore, CyJ has good cell-membrane permeability and low cytotoxicity. In addition, we have successfully applied the CyJ to visualize N2H4 in live mouse and, for the first time, in tissues such as the liver, lung, kidney, heart, and spleen. PMID:26274784

  12. Solvent-dependent fluorescent-colorimetric probe for dual monitoring of Al(3+) and Cu(2+) in aqueous solution: an application to bio-imaging.

    PubMed

    Ghorai, Anupam; Mondal, Jahangir; Chowdhury, Shubhamoy; Patra, Goutam K

    2016-07-28

    A novel, quinoline-based smart probe L has been designed for the detection of Al(3+) and Cu(2+) at physiological range. The unprecedented solvent-dependent sensitivities of the probe L for simultaneous detection of Al(3+) and Cu(2+) ions with high selectivity and sensitivity have been observed for the first time. It displays quick responses through visible colorimetric as well as fluorogenic changes towards both Al(3+) and Cu(2+), as delineated by absorption and fluorescence titrations. The sensitivity of the fluorescence-based assay (12.6 nM) for Al(3+) and (18.4 nM) for Cu(2+) is far below the limit recommended in the World Health Organization (WHO) guidelines for drinking water. From (1)H NMR data, the Job plot and the ESI-MS spectrum, 1 : 2 stoichiometric complexations between L and both metals have been established. The geometry and spectral property of L and its metal complexes have been well rationalized by DFT calculations. This probe L has been tested as being highly suitable for mapping Al(3+) and Cu(2+) in human breast cancer cells, MCF7, thus providing a wonderful candidate for tracking Al(3+) and Cu(2+) in biological organisms and processes. The proposed chemosensor L has also been successfully applied for analysis of real samples. PMID:27353454

  13. Multi-function diamond film fiber optic probe and measuring system employing same

    DOEpatents

    Young, J.P.

    1998-11-24

    A fused fiber optic probe having a protective cover, a fiber optic probe system, and embodiments thereof for conducting electromagnetic spectral measurements are disclosed. The fused fiber optic probe comprises a probe tip having a specific geometrical configuration, an exciting optical fiber and at least one collection optical fiber fused within a housing, preferably silica, with a protective cover disposed over at least a portion of the probe tip. The specific geometrical configurations in which the probe tip can be shaped include a slanted probe tip with an angle greater than 0{degree}, an inverted cone-shaped probe tip, and a lens head. 9 figs.

  14. Optical probe, local fields, and Lorentz factor in ferroelectrics

    NASA Astrophysics Data System (ADS)

    Blinov, L. M.; Lazarev, V. V.; Palto, S. P.; Yudin, S. G.

    2014-06-01

    An optical probe is suggested that allows measurements of the local field and Lorentz factor ( L) in ferroelectric medium. The copolymer poly (vinylidene fluoride/trifluoroethylene) is mixed with Pd-tetraphenylporphyrin (TPP-Pd) that has a very narrow absorption band. Thus, TPP-Pd serves as a molecular optical probe of the local field. During the switching of the electric field lower than the coercive one the factor L of an unpolarized ferroelectric mixture is found to be of about 1/3 that corresponds to the random distribution of molecular dipoles in the ferroelectric. With increasing field, the dipole orientation acquires a lower symmetry and L tends to zero as predicted by lattice sum calculations for vinylidene fluoride. The knowledge of the field dependence of L and the usage of the optical probe makes it possible to measure directly the local and macroscopic fields in the individual elements of various ferroelectric-dielectric heterostructures.

  15. In Situ Proteome Profiling and Bioimaging Applications of Small-Molecule Affinity-Based Probes Derived From DOT1L Inhibitors.

    PubMed

    Zhu, Biwei; Zhang, Hailong; Pan, Sijun; Wang, Chenyu; Ge, Jingyan; Lee, Jun-Seok; Yao, Shao Q

    2016-06-01

    DOT1L is the sole protein methyltransferase that methylates histone H3 on lysine 79 (H3K79), and is a promising drug target against cancers. Small-molecule inhibitors of DOT1L such as FED1 are potential anti-cancer agents and useful tools to investigate the biological roles of DOT1L in human diseases. FED1 showed excellent in vitro inhibitory activity against DOT1L, but its cellular effect was relatively poor. In this study, we designed and synthesized photo-reactive and "clickable" affinity-based probes (AfBPs), P1 and P2, which were cell-permeable and structural mimics of FED1. The binding and inhibitory effects of these two probes against DOT1L protein were extensively investigated in vitro and in live mammalian cells (in situ). The cellular uptake and sub-cellular localization properties of the probes were subsequently studied in live-cell imaging experiments, and our results revealed that, whereas both P1 and P2 readily entered mammalian cells, most of them were not able to reach the cell nucleus where functional DOT1L resides. This offers a plausible explanation for the poor cellular activity of FED1. Finally with P1/P2, large-scale cell-based proteome profiling, followed by quantitative LC-MS/MS, was carried out to identify potential cellular off-targets of FED1. Amongst the more than 100 candidate off-targets identified, NOP2 (a putative ribosomal RNA methyltransferase) was further confirmed to be likely a genuine off-target of FED1 by preliminary validation experiments including pull-down/Western blotting (PD/WB) and cellular thermal shift assay (CETSA). PMID:27115831

  16. N, B-doped carbon dots as a sensitive fluorescence probe for Hg(2+) ions and 2,4,6-trinitrophenol detection for bioimaging.

    PubMed

    Ye, Qianghua; Yan, Fanyong; Shi, Dechao; Zheng, Tancheng; Wang, Yinyin; Zhou, Xuguang; Chen, Li

    2016-09-01

    Nitrogen and boron co-doped carbon dots (BCNDs1-3) were prepared from three kinds of borate via a facile hydrothermal method. The as-prepared BCNDs did not shift with the change of excitation wavelength and possess good water dispersibility, strong fluorescence emission with high fluorescent quantum yield of 29.01%, 51.42%, 68.28%, respectively. Subsequently, these BCNDs were exploited as excellent Hg(2+) ion and 2,4,6-trinitrophenol (TNP) probe. The efficient selective detection of Hg(2+) can be attributed to non-radiative electron/hole recombination annihilation through an effective electron transfer process and the detection of TNP can be attributed to the fluorescence resonance energy transfer process (FRET). The results show that the BCNDs2 is the most sensitive fluorescence probe for Hg(2+) ions and TNP detection as low as Hg(2+) 7.3nM and TNP 0.35μM compared with BCNDs1 and BCNDs3. The as-prepared BCNDs possess the advantages of good selectivity, fast response and a broad linear detection. They were applied to sensing and imaging of human umbilical vein endothelial cells, showing low cytotoxicity and good biocompatibility. PMID:27323236

  17. Infrared hollow optical fiber probes for reflectance spectral imaging.

    PubMed

    Huang, Chenhui; Kino, Saiko; Katagiri, Takashi; Matsuura, Yuji

    2015-05-10

    Systems for infrared reflectance imaging are built with an FT-IR spectrometer, hollow optical fibers, and a high-speed infrared camera. To obtain reflectance images of biological samples, an optical fiber probe equipped with a light source at the distal end and a hybrid fiber probe composed of fibers for beam radiation and ones for image detection have been developed. By using these systems, reflectance spectral images of lipid painted on biomedical hard tissue, which provides reflectance of around 4%, are successfully acquired. PMID:25967522

  18. Probing membrane potential with nonlinear optics.

    PubMed Central

    Bouevitch, O; Lewis, A; Pinevsky, I; Wuskell, J P; Loew, L M

    1993-01-01

    The nonlinear optical phenomenon of second harmonic generation is shown to have intrinsic sensitivity to the voltage across a biological membrane. Our results demonstrate that this second order nonlinear optical process can be used to monitor membrane voltage with excellent signal to noise and other crucial advantages. These advantages suggest extensive use of this novel approach as an important new tool in elucidating membrane potential changes in biological systems. For this first demonstration of the effect we use a chiral styryl dye which exhibits gigantic second harmonic signals. Possible mechanisms of the voltage dependence of the second harmonic signal are discussed. PMID:8218895

  19. Optical tweezer for probing erythrocyte membrane deformability

    NASA Astrophysics Data System (ADS)

    Khan, Manas; Soni, Harsh; Sood, A. K.

    2009-12-01

    We report that the average rotation speed of optically trapped crenated erythrocytes is direct signature of their membrane deformability. When placed in hypertonic buffer, discocytic erythrocytes are subjected to crenation. The deformation of cells brings in chirality and asymmetry in shape that makes them rotate under the scattering force of a linearly polarized optical trap. A change in the deformability of the erythrocytes, due to any internal or environmental factor, affects the rotation speed of the trapped crenated cells. Here we show how the increment in erythrocyte membrane rigidity with adsorption of Ca++ ions can be exhibited through this approach.

  20. Probing exoplanet clouds with optical phase curves.

    PubMed

    Muñoz, Antonio García; Isaak, Kate G

    2015-11-01

    Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve--from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the extent and location of the clouds. These considerations are relevant to the interpretation of optical phase curves with general circulation models. Finally, we estimate that the spherical albedo of Kepler-7b over the Kepler passband is in the range 0.4-0.5. PMID:26489652

  1. Probing exoplanet clouds with optical phase curves

    PubMed Central

    Muñoz, Antonio García; Isaak, Kate G.

    2015-01-01

    Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve—from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the extent and location of the clouds. These considerations are relevant to the interpretation of optical phase curves with general circulation models. Finally, we estimate that the spherical albedo of Kepler-7b over the Kepler passband is in the range 0.4–0.5. PMID:26489652

  2. Fiber optic detector probes for laser light scattering

    NASA Technical Reports Server (NTRS)

    Dhadwal, Harbans S.; Wu, Chi; Chu, Benjamin

    1989-01-01

    An experimental investigation of the role of fiber optic detector probes in laser light scattering is presented. A quantitative comparison between different detector configurations is accomplished by measuring the time taken for one million photocounts to be accumulated in the extrapolated zeroth delay channel of the net unnormalized intensity time correlation function. A considerable reduction in the accumulation time is achieved by relaxing a rather stringent requirement for the spatial coherence of the optical field.

  3. Photomultiplier for optically probing Comet Halley

    NASA Technical Reports Server (NTRS)

    Giovane, F.; Eichhorn, G.; Mckisson, J.; Weinberg, J. L.; Weisenberger, A.

    1991-01-01

    A low mass eight-color channel photopolarimeter was developed for the Giotto spacecraft. Utilizing the spin of the spacecraft, a multichannel plate photomultiplier, and a unique optical design, the instrument required no moving parts to measure color and linear polarization. The photopolarimeter collected data as the spacecraft passed through the coma of Comet Halley on March 13 and 14, 1986. This instrument's design, calibration, and reduction are discussed and some final results are presented.

  4. Bioimaging for quantitative phenotype analysis.

    PubMed

    Chen, Weiyang; Xia, Xian; Huang, Yi; Chen, Xingwei; Han, Jing-Dong J

    2016-06-01

    With the development of bio-imaging techniques, an increasing number of studies apply these techniques to generate a myriad of image data. Its applications range from quantification of cellular, tissue, organismal and behavioral phenotypes of model organisms, to human facial phenotypes. The bio-imaging approaches to automatically detect, quantify, and profile phenotypic changes related to specific biological questions open new doors to studying phenotype-genotype associations and to precisely evaluating molecular changes associated with quantitative phenotypes. Here, we review major applications of bioimage-based quantitative phenotype analysis. Specifically, we describe the biological questions and experimental needs addressable by these analyses, computational techniques and tools that are available in these contexts, and the new perspectives on phenotype-genotype association uncovered by such analyses. PMID:26850283

  5. Dynamic Force Sensing Using an Optically Trapped Probing System.

    PubMed

    Huang, Yanan; Cheng, Peng; Menq, Chia-Hsiang

    2011-12-01

    This paper presents the design of an adaptive observer that is implemented to enable real-time dynamic force sensing and parameter estimation in an optically trapped probing system. According to the principle of separation of estimation and control, the design of this observer is independent of that of the feedback controller when operating within the linear range of the optical trap. Dynamic force sensing, probe steering/clamping, and Brownian motion control can, therefore, be developed separately and activated simultaneously. The adaptive observer utilizes the measured motion of the trapped probe and input control effort to recursively estimate the probe-sample interaction force in real time, along with the estimation of the probing system's trapping bandwidth. This capability is very important to achieving accurate dynamic force sensing in a time-varying process, wherein the trapping dynamics is nonstationary due to local variations of the surrounding medium. The adaptive estimator utilizes the Kalman filter algorithm to compute the time-varying gain in real time and minimize the estimation error for force probing. A series of experiments are conducted to validate the design of and assess the performance of the adaptive observer. PMID:24382944

  6. Demonstration of a Fiber Optic Regression Probe

    NASA Technical Reports Server (NTRS)

    Korman, Valentin; Polzin, Kurt A.

    2010-01-01

    The capability to provide localized, real-time monitoring of material regression rates in various applications has the potential to provide a new stream of data for development testing of various components and systems, as well as serving as a monitoring tool in flight applications. These applications include, but are not limited to, the regression of a combusting solid fuel surface, the ablation of the throat in a chemical rocket or the heat shield of an aeroshell, and the monitoring of erosion in long-life plasma thrusters. The rate of regression in the first application is very fast, while the second and third are increasingly slower. A recent fundamental sensor development effort has led to a novel regression, erosion, and ablation sensor technology (REAST). The REAST sensor allows for measurement of real-time surface erosion rates at a discrete surface location. The sensor is optical, using two different, co-located fiber-optics to perform the regression measurement. The disparate optical transmission properties of the two fiber-optics makes it possible to measure the regression rate by monitoring the relative light attenuation through the fibers. As the fibers regress along with the parent material in which they are embedded, the relative light intensities through the two fibers changes, providing a measure of the regression rate. The optical nature of the system makes it relatively easy to use in a variety of harsh, high temperature environments, and it is also unaffected by the presence of electric and magnetic fields. In addition, the sensor could be used to perform optical spectroscopy on the light emitted by a process and collected by fibers, giving localized measurements of various properties. The capability to perform an in-situ measurement of material regression rates is useful in addressing a variety of physical issues in various applications. An in-situ measurement allows for real-time data regarding the erosion rates, providing a quick method for

  7. Endoscopic probe optics for spectrally encoded confocal microscopy

    PubMed Central

    Kang, DongKyun; Carruth, Robert W.; Kim, Minkyu; Schlachter, Simon C.; Shishkov, Milen; Woods, Kevin; Tabatabaei, Nima; Wu, Tao; Tearney, Guillermo J.

    2013-01-01

    Spectrally encoded confocal microscopy (SECM) is a form of reflectance confocal microscopy that can achieve high imaging speeds using relatively simple probe optics. Previously, the feasibility of conducting large-area SECM imaging of the esophagus in bench top setups has been demonstrated. Challenges remain, however, in translating SECM into a clinically-useable device; the tissue imaging performance should be improved, and the probe size needs to be significantly reduced so that it can fit into luminal organs of interest. In this paper, we report the development of new SECM endoscopic probe optics that addresses these challenges. A custom water-immersion aspheric singlet (NA = 0.5) was developed and used as the objective lens. The water-immersion condition was used to reduce the spherical aberrations and specular reflection from the tissue surface, which enables cellular imaging of the tissue deep below the surface. A custom collimation lens and a small-size grating were used along with the custom aspheric singlet to reduce the probe size. A dual-clad fiber was used to provide both the single- and multi- mode detection modes. The SECM probe optics was made to be 5.85 mm in diameter and 30 mm in length, which is small enough for safe and comfortable endoscopic imaging of the gastrointestinal tract. The lateral resolution was 1.8 and 2.3 µm for the single- and multi- mode detection modes, respectively, and the axial resolution 11 and 17 µm. SECM images of the swine esophageal tissue demonstrated the capability of this device to enable the visualization of characteristic cellular structural features, including basal cell nuclei and papillae, down to the imaging depth of 260 µm. These results suggest that the new SECM endoscopic probe optics will be useful for imaging large areas of the esophagus at the cellular scale in vivo. PMID:24156054

  8. Bioimage Informatics for Big Data.

    PubMed

    Peng, Hanchuan; Zhou, Jie; Zhou, Zhi; Bria, Alessandro; Li, Yujie; Kleissas, Dean Mark; Drenkow, Nathan G; Long, Brian; Liu, Xiaoxiao; Chen, Hanbo

    2016-01-01

    Bioimage informatics is a field wherein high-throughput image informatics methods are used to solve challenging scientific problems related to biology and medicine. When the image datasets become larger and more complicated, many conventional image analysis approaches are no longer applicable. Here, we discuss two critical challenges of large-scale bioimage informatics applications, namely, data accessibility and adaptive data analysis. We highlight case studies to show that these challenges can be tackled based on distributed image computing as well as machine learning of image examples in a multidimensional environment. PMID:27207370

  9. Probing ultrafast spin dynamics with optical pump-probe scanning tunnelling microscopy.

    PubMed

    Yoshida, Shoji; Aizawa, Yuta; Wang, Zi-han; Oshima, Ryuji; Mera, Yutaka; Matsuyama, Eiji; Oigawa, Haruhiro; Takeuchi, Osamu; Shigekawa, Hidemi

    2014-08-01

    Studies of spin dynamics in low-dimensional systems are important from both fundamental and practical points of view. Spin-polarized scanning tunnelling microscopy allows localized spin dynamics to be characterized and plays important roles in nanoscale science and technology. However, nanoscale analysis of the ultrafast dynamics of itinerant magnetism, as well as its localized characteristics, should be pursued to advance further the investigation of quantum dynamics in functional structures of small systems. Here, we demonstrate the optical pump-probe scanning tunnelling microscopy technique, which enables the nanoscale probing of spin dynamics with the temporal resolution corresponding, in principle, to the optical pulse width. Spins are optically oriented using circularly polarized light, and their dynamics are probed by scanning tunnelling microscopy based on the optical pump-probe method. Spin relaxation in a single quantum well with a width of 6 nm was observed with a spatial resolution of ∼ 1 nm. In addition to spin relaxation dynamics, spin precession, which provides an estimation of the Landé g factor, was observed successfully. PMID:24974938

  10. Probing ultrafast spin dynamics with optical pump-probe scanning tunnelling microscopy

    NASA Astrophysics Data System (ADS)

    Yoshida, Shoji; Aizawa, Yuta; Wang, Zi-Han; Oshima, Ryuji; Mera, Yutaka; Matsuyama, Eiji; Oigawa, Haruhiro; Takeuchi, Osamu; Shigekawa, Hidemi

    2014-08-01

    Studies of spin dynamics in low-dimensional systems are important from both fundamental and practical points of view. Spin-polarized scanning tunnelling microscopy allows localized spin dynamics to be characterized and plays important roles in nanoscale science and technology. However, nanoscale analysis of the ultrafast dynamics of itinerant magnetism, as well as its localized characteristics, should be pursued to advance further the investigation of quantum dynamics in functional structures of small systems. Here, we demonstrate the optical pump-probe scanning tunnelling microscopy technique, which enables the nanoscale probing of spin dynamics with the temporal resolution corresponding, in principle, to the optical pulse width. Spins are optically oriented using circularly polarized light, and their dynamics are probed by scanning tunnelling microscopy based on the optical pump-probe method. Spin relaxation in a single quantum well with a width of 6 nm was observed with a spatial resolution of ~1 nm. In addition to spin relaxation dynamics, spin precession, which provides an estimation of the Landé g factor, was observed successfully.

  11. Probing magnetic and electric optical responses of silicon nanoparticles

    SciTech Connect

    Permyakov, Dmitry; Sinev, Ivan; Markovich, Dmitry; Samusev, Anton; Belov, Pavel; Ginzburg, Pavel; Valuckas, Vytautas; Kuznetsov, Arseniy I.; Luk'yanchuk, Boris S.; Miroshnichenko, Andrey E.; Neshev, Dragomir N.; Kivshar, Yuri S.

    2015-04-27

    We study experimentally both magnetic and electric optically induced resonances of silicon nanoparticles by combining polarization-resolved dark-field spectroscopy and near-field scanning optical microscopy measurements. We reveal that the scattering spectra exhibit strong sensitivity of electric dipole response to the probing beam polarization and attribute the characteristic asymmetry of measured near-field patterns to the excitation of a magnetic dipole mode. The proposed experimental approach can serve as a powerful tool for the study of photonic nanostructures possessing both electric and magnetic optical responses.

  12. Optically Probed Laser-Induced Field-Free Molecular Alignment

    NASA Astrophysics Data System (ADS)

    Faucher, O.; Lavorel, B.; Hertz, E.; Chaussard, F.

    Molecular alignment induced by laser fields has been investigated in research laboratories for over two decades. It led to a better understanding of the fundamental processes at play in the interaction of strong laser fields with molecules, and also provided significant contributions to the fields of high harmonic generation, laser spectroscopy, and laser filamentation. In this chapter, we discuss molecular alignment produced under field-free conditions, as resulting from the interaction of a laser pulse of duration shorter than the rotational period of the molecule. The experimental results presented will be confined to the optically probed alignment of linear as well as asymmetric top molecules. Special care will be taken to describe and compare various optical methods that can be employed to characterize laser-induced molecular alignment. Promising applications of optically probed molecular alignment will be also demonstrated.

  13. Optically probing torsional superelasticity in spider silks

    NASA Astrophysics Data System (ADS)

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

    2013-11-01

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 102-3 rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

  14. Optically probing torsional superelasticity in spider silks

    SciTech Connect

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

    2013-11-11

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2−3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

  15. Miniature fibre optic probe for minimally invasive photoacoustic sensing

    NASA Astrophysics Data System (ADS)

    Mathews, Sunish J.; Zhang, Edward Z.; Desjardins, Adrien E.; Beard, Paul C.

    2016-03-01

    A miniature (175 μm) all-optical photoacoustic probe has been developed for minimally invasive sensing and imaging applications. The probe comprises a single optical fibre which delivers the excitation light and a broadband 50 MHz Fabry-Pérot (F-P) ultrasound sensor at the distal end for detecting the photoacoustic waves. A graded index lens proximal to the F-P sensor is used to reduce beam walk-off and thus increase sensitivity as well as confine the excitation beam in order to increase lateral spatial resolution. The probe was evaluated in non-scattering media and found to provide lateral and axial resolutions of < 100 μm and < 150 μm respectively for distances up to 1 cm from the tip of the probe. The ability of the probe to detect a blood vessel mimicking phantom at distances up to 7 mm from the tip was demonstrated in order to illustrate its potential suitability for needle guidance applications.

  16. Handheld probes and galvanometer scanning for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Duma, V.-F.; Dobre, G.; Demian, D.; Cernat, R.; Sinescu, C.; Topala, F. I.; Negrutiu, M. L.; Hutiu, Gh.; Bradu, A.; Rolland, J. P.; Podoleanu, A. G.

    2015-09-01

    As part of the ongoing effort of the biomedical imaging community to move Optical Coherence Tomography (OCT) systems from the lab to the clinical environment and produce OCT systems appropriate for multiple types of investigations in a medical department, handheld probes equipped with different types of scanners need to be developed. These allow different areas of a patient's body to be investigated using OCT with the same system and even without changing the patient's position. This paper reviews first the state of the art regarding OCT handheld probes. Novel probes with a uni-dimensional (1D) galvanometer-based scanner (GS) developed in our groups are presented. Their advantages and limitations are discussed. Aspects regarding the use of galvoscanners with regard to Micro-Electro- Mechanical Systems (MEMS) are pointed out, in relationship with our studies on optimal scanning functions of galvanometer devices in OCT. These scanning functions are briefly discussed with regard to their main parameters: profile, theoretical duty cycle, scan frequency, and scan amplitude. The optical design of the galvoscanner and refractive optics combination in the probe head, optimized for various applications, is considered. Perspectives of the field are pointed out in the final part of the paper.

  17. Biocompatible and Photostable AIE Dots with Red Emission for In Vivo Two-Photon Bioimaging

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Qian, Jun; Qin, Wei; Qin, Anjun; Tang, Ben Zhong; He, Sailing

    2014-03-01

    Bioimaging systems with cytocompatibility, photostability, red fluorescence, and optical nonlinearity are in great demand. Herein we report such a bioimaging system. Integration of tetraphenylethene (T), triphenylamine (T), and fumaronitrile (F) units yielded adduct TTF with aggregation-induced emission (AIE). Nanodots of the AIE fluorogen with efficient red emission were fabricated by encapsulating TTF with phospholipid. The AIE dots enabled three-dimensional dynamic imaging with high resolution in blood vessels of mouse brain under two-photon excitation.

  18. Plasmonic nanoprobes for SERS biosensing and bioimaging

    PubMed Central

    Vo-Dinh, Tuan; Wang, Hsin-Neng; Scaffidi, Jonathan

    2013-01-01

    This article provides an overview of the development and application of plasmonic nanoprobes developed in our laboratory for biosensing and bioimaging. We describe the use of plasmonics surface-enhanced Raman scattering (SERS) gene probes for the detection of diseases using DNA hybridization to target biospecies (HIV gene, breast cancer genes etc.). For molecular imaging, we describe a hyperspectral surface-enhanced Raman imaging (HSERI) system that combines imaging capabilities with SERS detection to identify cellular components using Raman dye-labeled silver nanoparticles in cellular systems The detection of specific target DNA sequences associated with breast cancer using “molecular sentinel” nanoprobes and the use of a plasmonic nanosensor to monitor pH in single cells are presented and discussed. Plasmonic nanosensors and nanoprobes have been developed as sensitive and selective tolls for environmental monitoring, cellular biosensing, medical diagnostics and high throughput screnning. PMID:19517422

  19. Magnetometer probe with low temperature rotation and optical fibers

    NASA Astrophysics Data System (ADS)

    Pajerowski, D. M.; Meisel, M. W.

    2009-02-01

    A new probe has been developed that allows for both optical irradiation and uniaxial rotation, all in the low temperature environment of a commercial superconducting quantum interference device (SQUID) magnetometer. As part of the design process, various materials were investigated and characterized for their low temperature structural and magnetic properties, including nylon, Vespel, Delrin, Spiderwire monofilament, and PowerPro braided microfilament. Using this information, a prototype was built and operated. Characteristics of the probe will be presented along with a summary of the low temperature (T >= 2 K) and high magnetic field (H <= 7 T) properties of the construction materials.

  20. Near-field optical microscopy based on microfabricated probes.

    PubMed

    Eckert, R; Freyland, J M; Gersen, H; Heinzelmann, H; Schürmann, G; Noell, W; Staufer, U; De Rooij, N F

    2001-04-01

    We demonstrate high resolution imaging with microfabricated, cantilevered probes, consisting of solid quartz tips on silicon levers. The tips are covered by a 60-nm thick layer of aluminium, which appears to be closed at the apex when investigated by transmission electron microscopy. An instrument specifically built for cantilever probes was used to record images of latex bead projection patterns in transmission as well as single molecule fluorescence. All images were recorded in constant height mode and show optical resolutions down to 32 nm. PMID:11298861

  1. Magneto-optical response of graphene: Probing substrate interactions

    NASA Astrophysics Data System (ADS)

    Chizhova, L. A.; Burgdörfer, J.; Libisch, F.

    2015-09-01

    Magneto-optical transitions between Landau levels can provide precise spectroscopic information on the electronic structure and excitation spectra of graphene, enabling probes of substrate and many-body effects. We calculate the magneto-optical conductivity of large-size graphene flakes using a tight-binding approach. Our method allows us to directly compare the magneto-optical response of an isolated graphene flake with one aligned on hexagonal boron nitride giving rise to a periodic superlattice potential. The substrate interaction induces band gaps away from the Dirac point. In the presence of a perpendicular magnetic field, Landau-level-like structures emerge from these zero-field band gaps. The energy dependence of these satellite structures is, however, not easily accessible by conventional probes of the density of states by varying the back-gate voltage. Here we propose the magneto-optical probing of the superlattice perturbed spectrum. Our simulation includes magneto-excitonic effects in first-order perturbation theory. Our approach yields a quantitative explanation of recently observed Landau-level-dependent renormalizations of the Fermi velocity.

  2. A Fiber Optic Probe for the Detection of Cataracts

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Dhadwal, Harbans S.

    1993-01-01

    A compact fiber optic probe developed for on-orbit science experiments was used to detect the onset of cataracts, a capability that could eliminate physicians' guesswork and result in new drugs to 'dissolve' or slow down the cataract formation before surgery is necessary. The probe is based upon dynamic light scattering (DLS) principles. It has no moving parts, no apertures, and requires no optical alignment. It is flexible and easy to use. Results are presented for excised but intact human eye lenses. In a clinical setting, the device can be easily incorporated into a slit-lamp apparatus (ophthalmoscope) for complete eye diagnostics. In this set-up, the integrated fiber optic probe, the size of a pencil, delivers a low power cone of laser light into the eye of a patient and guides the light which is backscattered by the protein molecules of the lens through a receiving optical fiber to a photo detector. The non-invasive DLS measurements provide rapid determination of protein crystalline size and its size distribution in the eye lens.

  3. Optically Levitated Microspheres as a Probe for New Interactions

    NASA Astrophysics Data System (ADS)

    Rider, Alexander; Moore, David; Blakemore, Charles; Lu, Marie; Gratta, Giorgio

    2016-03-01

    We are developing novel techniques to probe new interactions at micron distances using optically levitated dielectric microspheres. Levitated microspheres are an ideal probe for short-range interactions because they are suspended using the radiation pressure at the focus of a laser beam, which means that the microspheres can be precisely manipulated and isolated from the surrounding environment at high vacuum. We have performed a search for unknown charged particles bound within the bulk of the microspheres. Currently, we are searching for the presence of a Chameleon field postulated to explain the presence of dark energy in the universe. In the future we plan to use optically levitated microspheres to search for micron length-scale gravity like interactions that could couple between a microsphere and another mass. We will present resent results from these experiments and plans for future searches for new interactions.

  4. The design of optical fiber vortex flowmeter's probe

    NASA Astrophysics Data System (ADS)

    Lin, Xiaolin; Wang, Yutian; Ni, Yang; Li, Jianxia

    2009-07-01

    The vortex flowmeter works in a poor environment, therefore the stability and accuracy of the online testing system have become the core question for getting high accuracy. The optical probe is the main part of the system which produces and obtains the vortex signal. This paper designs the vortex shedder according to the hydromechanics principle, and it is proposed to be ringlike structures, also gives the test results which prove the effectiveness of the shedder on vortex decomposition. A liquid flow online testing system is designed according to the vortex signal characteristics, and the optical fiber is chosen as the sense organ. Then it designed the probe's parameters and the necessary important circuits of the system to further increase its accuracy. It also assembles the sensor system which is designed to insure the rationality, reliability, stability of the structure. Finally it proposed the methods on the coefficient revision and the liquid condition parameter compensation to get higher accuracy.

  5. Retroreflective Janus Microparticle as a Nonspectroscopic Optical Immunosensing Probe.

    PubMed

    Han, Yong Duk; Kim, Hyo-Sop; Park, Yoo Min; Chun, Hyeong Jin; Kim, Jae-Ho; Yoon, Hyun C

    2016-05-01

    We developed retroreflective Janus microparticles (RJPs) as a novel optical immunosensing probe for use in a nonspectroscopic retroreflection-based immunoassay. By coating the metals on the hemispherical surface of silica particles, highly reflective RJPs were fabricated. On the basis of the retroreflection principle, the RJPs responded to polychromatic white light sources, in contrast to conventional optical probes, which require specific monochromatic light. The retroreflection signals from RJPs were distinctively recognized as shining dots, which can be intuitively counted using a digital camera setup. Using the developed retroreflective immunosensing system, cardiac troponin I, a specific biomarker of acute myocardial infarction, was detected with high sensitivity. On the basis of the demonstrated features of the retroreflective immunosensing platform, we expect that our approach may be applied for various point-of-care-testing applications. PMID:27079154

  6. Using optical clock to probe quantum many-body physics

    NASA Astrophysics Data System (ADS)

    Ye, Jun

    2016-05-01

    The progress of optical lattice clock has benefited greatly from the understanding of atomic interactions. At the same time, the precision of clock spectroscopy has been applied to explore many-body spin interactions including SU(N) symmetry. Our recent work on this combined front of quantum metrology and many-body physics includes the probe of spin-orbital physics in the lattice clock and the investigation of a Fermi degenerate gas of 105 87Sr atoms in a three-dimensional magic-wavelength optical lattice.

  7. Near field optical probe for critical dimension measurements

    DOEpatents

    Stallard, Brian R.; Kaushik, Sumanth

    1999-01-01

    A resonant planar optical waveguide probe for measuring critical dimensions on an object in the range of 100 nm and below. The optical waveguide includes a central resonant cavity flanked by Bragg reflector layers with input and output means at either end. Light is supplied by a narrow bandwidth laser source. Light resonating in the cavity creates an evanescent electrical field. The object with the structures to be measured is translated past the resonant cavity. The refractive index contrasts presented by the structures perturb the field and cause variations in the intensity of the light in the cavity. The topography of the structures is determined from these variations.

  8. Near field optical probe for critical dimension measurements

    DOEpatents

    Stallard, B.R.; Kaushik, S.

    1999-05-18

    A resonant planar optical waveguide probe for measuring critical dimensions on an object in the range of 100 nm and below is disclosed. The optical waveguide includes a central resonant cavity flanked by Bragg reflector layers with input and output means at either end. Light is supplied by a narrow bandwidth laser source. Light resonating in the cavity creates an evanescent electrical field. The object with the structures to be measured is translated past the resonant cavity. The refractive index contrasts presented by the structures perturb the field and cause variations in the intensity of the light in the cavity. The topography of the structures is determined from these variations. 8 figs.

  9. Compact piezoelectric transducer fiber scanning probe for optical coherence tomography.

    PubMed

    Zhang, Ning; Tsai, Tsung-Han; Ahsen, Osman O; Liang, Kaicheng; Lee, Hsiang-Chieh; Xue, Ping; Li, Xingde; Fujimoto, James G

    2014-01-15

    We developed a compact, optical fiber scanning piezoelectric transducer (PZT) probe for endoscopic and minimally invasive optical coherence tomography (OCT). Compared with previous forward-mount fiber designs, we present a reverse-mount design that achieves a shorter rigid length. The fiber was mounted at the proximal end of a quadruple PZT tube and scanned inside the hollow PZT tube to reduce the probe length. The fiber resonant frequency was 338 Hz using a 17-mm-long fiber. A 0.9 mm fiber deflection was achieved with a driving amplitude of 35 V. Using a GRIN lens-based optical design with a 1.3× magnification, a ∼6 μm spot was scanned over a 1.2 mm diameter field. The probe was encased in a metal hypodermic tube with a ∼25 mm rigid length and covered with a 3.2 mm outer diameter (OD) plastic sheath. Imaging was performed with a swept source OCT system based on a Fourier domain modelocked laser (FDML) light source at a 240 kHz axial scan rate and 8 μm axial resolution (in air). En face OCT imaging of skin in vivo and human colon ex vivo was demonstrated. PMID:24562102

  10. Raman Microscopy : A Versatile Approach to Bio-Imaging

    NASA Astrophysics Data System (ADS)

    McGarvey, J. J.; Renwick Beattie, J.

    Raman microscopy has become established as a key probe technique in biology and biomedicine. In combination with imaging and mapping it has been employed in the investigation of a diverse array of problems ranging from ex vivo and in vivo single cell studies to elucidation of the often complex, interacting structures which constitute human and animal tissues. This chapter emphasises the unique attributes of Raman microscopy as a bioimaging technique, including its non-invasive, spectral multiplexing ability, allied with high spatial resolution and underpinned by a range of multivariate data processing methods. A number of illustrative examples have been selected for discussion from the fields of molecular biology, ophthalmology, respiratory medicine as well as some non-medical examples. Recent advances and pointers to future activity in the uses of Raman microscopy as a structurally and functionally informative bioimaging technique are briefly considered.

  11. Transurethral optical laser knife and probe director for lateral firing laser probes

    NASA Astrophysics Data System (ADS)

    Malek, Reza S.

    1993-05-01

    Laser energy has been used by many for transurethral incision of small, obstructive prostates, vesical neck contractures, and urethral strictures. The customary techniques of moving the tip of the laser fiber through a cystoscope with a conventional laser guide, almost tangentially to the tissue to be incised, or drilling radially arranged holes in the scar, or both, have been cumbersome and imprecise. To provide exact control of the laser fiber and precise delivery of laser energy, a new guide was devised. It conducts the quartz fiber through the sheath and along the lens of an optical urethrotome. The tip of the quartz fiber contacts the tissue at an angle of 20 degree(s). KTP/532 laser energy is used to perform internal urethrotomy for urethral stricture, transurethral incision of postoperative contracture of the vesical neck, and transurethral incision of the small prostate under constant visual control. Recently, a straight version of this guide, called probe director, was devised to conduct the newly marketed lateral firing laser probes. This probe director allows precise control of such a probe within the prostatic urethral lumen and excellent maneuverability of the probe during transurethral laser prostatectomy.

  12. Optical injection probing of single ZnO tetrapod lasers

    SciTech Connect

    Szarko, Jodi M.; Song, Jae Kyu; Blackledge, Charles Wesley; Swart, Ingmar; Leone, Stephen R.; Li, Shihong; Zhao, Yiping

    2004-11-23

    The properties of zinc oxide (ZnO) nanotetrapod lasers are characterized by a novel ultrafast two-color pump/stimulated emission probe technique. Single legs of tetrapod species are isolated by a microscope objective, pumped by 267 nm pulses, and subjected to a time-delayed 400 nm optical injection pulse, which permits investigation of the ultrafast carrier dynamics in the nanosize materials. With the optical injection pulse included, a large increase in the stimulated emission at 400 nm occurs, which partially depletes the carriers at this wavelength and competes with the normal 390 nm lasing. At the 390 nm lasing wavelengths, the optical injection causes a decrease in the stimulated emission due to the energetic redistribution of the excited carrier depletion, which occurs considerably within the time scale of the subpicosecond duration of the injection pulse. The effects of the optical injection on the spectral gain are employed to probe the lasing dynamics, which shows that the full width at half maximum of the lasing time is 3 ps.

  13. Bioimage informatics for experimental biology

    PubMed Central

    Swedlow, Jason R.; Goldberg, Ilya G.; Eliceiri, Kevin W.

    2012-01-01

    Over the last twenty years there have been great advances in light microscopy with the result that multi-dimensional imaging has driven a revolution in modern biology. The development of new approaches of data acquisition are reportedly frequently, and yet the significant data management and analysis challenges presented by these new complex datasets remains largely unsolved. Like the well-developed field of genome bioinformatics, central repositories are and will be key resources, but there is a critical need for informatics tools in individual laboratories to help manage, share, visualize, and analyze image data. In this article we present the recent efforts by the bioimage informatics community to tackle these challenges and discuss our own vision for future development of bioimage informatics solution. PMID:19416072

  14. Design and fabrication of an optical probe with a phase filter for extended depth of focus.

    PubMed

    Xing, Jingchao; Kim, Junyoung; Yoo, Hongki

    2016-01-25

    The trade-off between spot size and depth of focus (DOF) often limits the performance of optical systems, such as optical coherence tomography and optical tweezers. Although researchers have proposed various methods to extend the DOF in free-space optics, many are difficult to implement in miniaturized optical probes due to space limitations. In this study, we present an optical probe with an extended DOF using a binary phase spatial filter (BPSF). The BPSF pattern was fabricated on the distal tip of an optical probe with a diameter of 1 mm by replica molding soft lithography, which can be easily implemented in a miniaturized optical probe due to its simple configuration. We optimized the BPSF pattern to enhance DOF, spot diameter, and light efficiency. To evaluate the fabricated endoscopic optical probe, we measured the three-dimensional point spread function of the BPSF probe and compared it with a probe without BPSF. The BPSF probe has a spot diameter of 3.56 μm and a DOF of 199.7 μm, while the probe without BPSF has a spot diameter of 3.69 μm and a DOF of 73.9 μm, representing a DOF gain of 2.7. We anticipate that this optical probe can be used in biomedical applications, including optical imaging and optical trapping techniques. PMID:26832486

  15. Development of an otolaryngological interferometric fiber optic diagnostic probe

    NASA Astrophysics Data System (ADS)

    Conerty, Michelle D.; Castracane, James; Saravia, Eduardo; Parnes, Steven M.; Cacace, Anthony T.

    1992-08-01

    Current medical instrumentation research at InterScience, Inc. is aimed at utilizing state of the art electro-optics in the development of a diagnostic fiber optic instrument capable of quantifying vibration patterns in real time. This work is in collaboration with the Division of Otolaryngology of the Albany Medical College. The innovative diagnostic probe system design involves the miniaturization of an electronic speckle pattern interferometry (ESPI) system through the use of fiber optic elements coupled with high speed image acquisition from a solid state matrix detector. Subsequent frame by frame processing produces a high quality three-dimensional spatial representation of the vibrational pattern. The diagnostic probe system is being developed for quantitative tympanic membrane and vocal cord vibration analysis. The significance of the introduction of this instrument to the medical community is the contribution it could make in the efficiency and effectiveness of the diagnosis of otolaryngological disorders. Specific applications include the evaluation of tympanosclerosis, stiffness related middle ear disorders, ossicular chain abnormalities, tympanic membrane replacement, vocal dysphonias, and early detection of laryngeal carcinomas, cysts, and phenomenological properties of mucosal wave dynamics. The current instrumentation research is focused on the production of a prototype system for clinical trials. This research is based in ESPI optical system development and miniaturization, system hardware and software development, and clinical design of the probe heads within anatomical limitations. Significant advantages of this diagnostic tool over currently used instrumentation and procedures are the real time capabilities of the instrument, the ability to quantify the vibrational pattern in time and space, and the possibility of establishing a database of patient history and disorder characteristics. Once fully developed and integrated into the clinical

  16. Preparation, Characterization and Application of Optical Switch Probes

    PubMed Central

    Petchprayoon, Chutima; Marriott, Gerard

    2011-01-01

    Optical switches represent a new class of molecular probe with applications in high contrast imaging and optical manipulation of protein interactions. Small molecule, organic optical switches based on nitrospirobenzopyran (NitroBIPS) and their reactive derivatives and conjugates undergo efficient, rapid and reversible, orthogonal optically-driven transitions between a colorless spiro (SP) state and a colored merocyanine (MC) state. The excited MC-state also emits fluorescence, which serves as readout of the state of the switch. Defined optical perturbations of SP and MC generate a defined waveform of MC-fluorescence that can be isolated against unmodulated background signals by using a digital optical lock-in detection approach or to control specific dipolar interactions on proteins. The protocols describe general procedures for the synthesis and spectroscopic characterization of NitroBIPS and specifically labeled conjugates along with methods for the manipulation of dipolar interactions on proteins and imaging of the MC-state of NitroBIPS within living cells. PMID:22140655

  17. Raman fiber optic probe assembly for use in hostile environments

    DOEpatents

    Schmucker, John E.; Falk, Jon C.; Archer, William B.; Blasi, Raymond J.

    2000-01-01

    This invention provides a device for Raman spectroscopic measurement of composition and concentrations in a hostile environment by the use of a first fiber optic as a means of directing high intensity monochromatic light from a laser to the hostile environment and a second fiber optic to receive the lower intensity scattered light for transmittal to a monochromator for analysis. To avoid damage to the fiber optics, they are protected from the hostile environment. A preferred embodiment of the Raman fiber optic probe is able to obtain Raman spectra of corrosive gases and solutions at temperatures up to 600.degree. F. and pressures up to 2000 psi. The incident exciting fiber optic cable makes an angle of substantially 90.degree. with the collecting fiber optic cable. This 90.degree. geometry minimizes the Rayleigh scattering signal picked up by the collecting fiber, because the intensity of Rayleigh scattering is lowest in the direction perpendicular to the beam path of the exciting light and therefore a 90.degree. scattering geometry optimizes the signal to noise ratio.

  18. Nanofabrication and applications of subwavelength optical probes: Chemical and biological sensors, light sources and exciton probes

    SciTech Connect

    Tan, W.

    1993-01-01

    The author has developed a new and controllable nanofabrication technique, photo-nanofabrication, based on near-field photo-chemical synthesis and nanometer optical sources. Photo-nanofabrication can produce subwavelength light and exciton probes with or without specific chemical or biological sensitivity. By applying near-field optics, the author has successfully demonstrated a new concept of near-field photochemical synthesis, in which the dimension of a product is solely determined by the size of the light source. The most successful application to date is the development of the smallest fiberoptic chemical sensors. Specifically, a thousandfold miniaturization of an immobilized fiberoptic pH sensor has been achieved, leading to at least a millionfold decrease in necessary sample volume and to at least a hundredfold shorter response time. The sensors have high fluorescence intensity and excellent detection limit. New internal calibration methods have also been developed for accurate pH quantification. The newly developed optical sensors have been used in real time measurements of pH on individual, viable, intact rat conceptuses during the period of organogenesis. The sensors can discriminate pH changes of less than 0.1 pH unit in the physiologic pH range. Static determinations of pH in rat conceptuses of varying gestational ages show decreasing pH with conceptal age. Chemical dynamic alterations in pH of intact rat conceptuses, in response to several variations in their environmental conditions, have been measured. Passive and active subwavelength light sources have been constructed with both micropipettes and fiberoptic tips. They have been used as exciton and light sources and in preliminary probe-to-sample distance regulated, Foerster energy transfer studies as well as in studies of the probe-to-sample interfacial Kasha effect. They were also used in supertip development for near-field scanning optical microscopy and for molecular exciton microscopy.

  19. A resonant scanning dipole-antenna probe for enhanced nanoscale imaging.

    PubMed

    Neumann, Lars; van 't Oever, Jorick; van Hulst, Niek F

    2013-11-13

    We present a scanning antenna probe that provides 35 nm optical hotspots with a 16-fold excitation enhancement. A resonant optical antenna, tuned to operation in the visible, is carved into the aluminum-coated scanning probe. The antenna resonances, field localization, excitation, and polarization response are probed in the near-field by scanning over single fluorescent nanobeads. At the same time, the distance-dependent coupling of the emission to the antenna mode is mapped. Good agreement with theory is obtained. The presented scanning antenna approach is useful for both nanoscale plasmonic mode imaging and (bio)imaging. PMID:24124987

  20. Optical depletion spectroscopy for probing evaporatively cooled OH

    NASA Astrophysics Data System (ADS)

    Hummon, Matthew; Wu, Hao; Stuhl, Benjamin; Reens, David; Yeo, Mark; Ye, Jun

    2013-05-01

    Pulsed laser induced fluorescence (PLIF) measurements provide a sensitive probe for the detection of molecular species. However, the broad linewidth of the pulsed lasers used for molecular excitation obscures spectral information useful for determination of molecule temperature. This limitation can be overcome by the use of a second, narrowband source of radiation that can deplete a subset of the molecules detected using PLIF, and a high resolution depletion spectrum can be obtained. In the past, we have demonstrated the use of microwave depletion spectroscopy to measure magnetically trapped, evaporatively cooled OH temperatures in the range of 5-50 mK. The lower limit of 5 mK is set by the details of the microwave transition. Here we present temperature measurements of trapped OH using an optical depletion technique, which is in principle capable of probing temperatures as low as 50 microkelvin. We acknowledge funding from the NSF Physics Frontier Center, NIST, DOE, and the AFOSR MURI on Cold Molecules.

  1. Probing molecular chirality by coherent optical absorption spectra

    SciTech Connect

    Jia, W. Z.; Wei, L. F.

    2011-11-15

    We propose an approach to sensitively probe the chirality of molecules by measuring their coherent optical-absorption spectra. It is shown that quantum dynamics of the cyclic three-level chiral molecules driven by appropriately designed external fields is total-phase dependent. This will result in chirality-dependent absorption spectra for the probe field. As a consequence, the charality-dependent information in the spectra (such as the locations and relative heights of the characteristic absorption peaks) can be utilized to identify molecular chirality and determinate enantiomer excess (i.e., the percentages of different enantiomers). The feasibility of the proposal with chiral molecules confined in hollow-core photonic crystal fiber is also discussed.

  2. Solids Fraction Measurement with a Reflective Fiber Optic Probe

    SciTech Connect

    Seachman, S.M.; Yue, P.C.; Ludlow, J.C.; Shadle, L.J.

    2006-11-01

    A method has been developed to extract solids fraction information from a reflective fiber optic probe. The commercially available reflective fiber optic probe was designed to measure axial particle velocity (both up and down directions). However, the reflected light intensity measured is related to particle size and particle concentration. A light reflection model is used to relate the reflected light intensity to solids fraction. In this model we assume that the reflected light intensity is a fixed fraction, K1, of the total light intensity lost in penetration of a solid layer. Also, the solids fraction is related to particle concentration, N, in the light path, by N = K2 (1- ε), where (1-ε) is the solids fraction. The parameters K1 and K2 are determined through a calibration and curve fitting procedure. This paper describes this procedure and the steps taken to derive the values of K1 and K2. It is proposed that the reflective fiber optic can be used for real time measurement of solids fraction in a circulating fluid bed.

  3. Micromachined fiber optic Fabry-Perot underwater acoustic probe

    NASA Astrophysics Data System (ADS)

    Wang, Fuyin; Shao, Zhengzheng; Hu, Zhengliang; Luo, Hong; Xie, Jiehui; Hu, Yongming

    2014-08-01

    One of the most important branches in the development trend of the traditional fiber optic physical sensor is the miniaturization of sensor structure. Miniature fiber optic sensor can realize point measurement, and then to develop sensor networks to achieve quasi-distributed or distributed sensing as well as line measurement to area monitoring, which will greatly extend the application area of fiber optic sensors. The development of MEMS technology brings a light path to address the problems brought by the procedure of sensor miniaturization. Sensors manufactured by MEMS technology possess the advantages of small volume, light weight, easy fabricated and low cost. In this paper, a fiber optic extrinsic Fabry-Perot interferometric underwater acoustic probe utilizing micromachined diaphragm collaborated with fiber optic technology and MEMS technology has been designed and implemented to actualize underwater acoustic sensing. Diaphragm with central embossment, where the embossment is used to anti-hydrostatic pressure which would largely deflect the diaphragm that induce interferometric fringe fading, has been made by double-sided etching of silicon on insulator. By bonding the acoustic-sensitive diaphragm as well as a cleaved fiber end in ferrule with an outer sleeve, an extrinsic Fabry-Perot interferometer has been constructed. The sensor has been interrogated by quadrature-point control method and tested in field-stable acoustic standing wave tube. Results have been shown that the recovered signal detected by the sensor coincided well with the corresponding transmitted signal and the sensitivity response was flat in frequency range from 10 Hz to 2kHz with the value about -154.6 dB re. 1/μPa. It has been manifest that the designed sensor could be used as an underwater acoustic probe.

  4. Optimized microviscosimeter using optical probing: application to biological membranes

    NASA Astrophysics Data System (ADS)

    Cretin, B.; Gaiffe, O.; Boireau, W.; Vairac, P.

    2008-06-01

    In this article, we report on studies aimed at sensing of the stiffness of membranes, particularly in the case of vesicles. A local approach could be done with AFM techniques but the local information is not pertinent for non homogeneous membranes. To solve this problem, we have developed and checked a specific sensor based on a vibrating sphere. The near-field acoustic wave enables to characterize biological particles which change the apparent viscosity and density of the surrounding fluid. The microsphere is well suited for very small volumes of liquid (typically about one microliter). Globally, the microsensor is based on a silicon cantilever which is glued on a piezoelectric transducer at its clamped end. The sphere is connected to the cantilever with a small glass rod (the core of an optical fiber). When operating, the sphere is immersed inside the investigated liquid and the piezoelectric actuator is excited with a low frequency generator. The vibration of the cantilever is sensed with a heterodyne laser probe. The plot of the response of the sensor (Bode plot) allows computing the properties of the liquid. When biological cells or vesicles are in the fluid, the effect of the biological elements is detectable and can be discriminated. We will present the microsensor and the optical probe which have allowed doing the described measurements. The theoretical study will show the influence of the different parameters and the crucial role of the optical probe to detect the low amplitude vibrations of the cantilever. The experimental results demonstrate the high sensitivity of the sensor to small variation of the composition of the fluid (water), particularly in the case of small vesicles of different kinds. Practically, this is a simulation of cells sensing.

  5. Refraction of narrow probing light beam in multilayer optical fiber

    NASA Astrophysics Data System (ADS)

    Mirovitskaya, S. D.; Kudryavtsev, D. L.

    1984-11-01

    For an experimental design and performance evaluation of optical fibers, it is necessary to establish an analytical relation between the refraction angle of a probing light beam and the geometrical parameters of the fiber. Here the problem is solved by application of Snell's law for a narrow light beam, first to a double-layer fiber consisting of a gradient core inside a homogeneous sheath and then to a triple-layer fiber consisting of a gradient core inside a double-layer sheath.

  6. A Call for Bioimaging Software Usability

    PubMed Central

    Carpenter, Anne E.; Kamentsky, Lee; Eliceiri, Kevin W.

    2013-01-01

    Bioimaging software developed in a research setting often fails to be widely used by the scientific community. We suggest that, to maximize both the public’s and researchers’ investments, usability should be a more highly valued goal. We describe specific characteristics of usability towards which bioimaging software projects should aim. PMID:22743771

  7. Interferometric strain measurements with a fiber-optic probe

    NASA Astrophysics Data System (ADS)

    Burnham-Fay, E. D.; Jacobs-Perkins, D. W.; Ellis, J. D.

    2015-09-01

    Experience at the Laboratory for Laser Energetics has shown that broadband base vibrations make it difficult to position cryogenic inertial confinement fusion targets. These effects must be mitigated for National Ignition Facility-scale targets; to this end an active vibration stabilization system is proposed. A single-mode optical fiber strain probe and a novel fiber contained heterodyne interferometer have been developed as a position feedback sensor for the vibration control system. A resolution limit of 54.5 nƐ; is measured with the optical strain gauge, limited by the lock-in amplifier. Experimental measurements of the sensor that show good agreement with reference resistive strain gauge measurements are presented.

  8. On the passive probing of fiber optic quantum communication channels

    SciTech Connect

    Korol'kov, A. V.; Katamadze, K. G.; Kulik, S. P.; Molotkov, S. N.

    2010-04-15

    Avalanche photodetectors based on InGaAs:P are the most sensitive and only detectors operating in the telecommunication wavelength range 1.30-1.55 {mu}m in the fiber optic quantum cryptography systems that can operate in the single photon count mode. In contrast to the widely used silicon photodetectors for wavelengths up to 1 {mu}m operating in a waiting mode, these detectors always operate in a gated mode. The production of an electron-hole pair in the process of the absorption of a photon and the subsequent appearance of an avalanche of carriers can be accompanied by the inverse processes of the recombination and emission of photons. Such a backward emission can present a potential serious problem for the stability of fiber optic quantum cryptography systems against passive probing. The results of analyzing the detection of backscattered radiation are reported. The probability of such an emission has been estimated.

  9. Local Optical Probe of Motion and Stress in a NEMS

    NASA Astrophysics Data System (ADS)

    Reserbat-Plantey, Antoine; Marty, Laëtitia; Arcizet, Olivier; Bendiab, Nedjma; Bouchiat, Vincent

    2012-02-01

    Nanoelectromechanical systems (NEMSs) are emerging nanoscale elements at the crossroads between mechanics, optics and electronics, with significant potential for actuation and sensing applications. The reduction of dimensions compared to their micronic counterparts brings new effects including sensitivity to very low mass, resonant frequencies in the radiofrequency range, mechanical non-linearities and observation of quantum mechanical effects. An important issue of NEMS is the understanding of fundamental physical properties conditioning dissipation mechanisms, known to limit mechanical quality factors and to induce aging due to material degradation. There is a need for detection methods tailored for these systems which allow probing motion and stress at the nanometer scale. Here, we show a non-invasive local optical probe for the quantitative measurement of motion and stress within a multilayer graphene NEMS provided by a combination of Fizeau interferences, Raman spectroscopy and electrostatically actuated mirror. Interferometry provides a calibrated measurement of the motion, resulting from an actuation ranging from a quasi-static load up to the mechanical resonance while Raman spectroscopy allows a purely spectral detection of mechanical resonance at the nanoscale. Such spectroscopic detection reveals the coupling between a strained nano-resonator and the energy of an inelastically scattered photon, and thus offers a new approach for optomechanics.

  10. Ultrafast Radiation Detection by Modulation of an Optical Probe Beam

    SciTech Connect

    Vernon, S P; Lowry, M E

    2006-02-22

    We describe a new class of radiation sensor that utilizes optical interferometry to measure radiation-induced changes in the optical refractive index of a semiconductor sensor medium. Radiation absorption in the sensor material produces a transient, non-equilibrium, electron-hole pair distribution that locally modifies the complex, optical refractive index of the sensor medium. Changes in the real (imaginary) part of the local refractive index produce a differential phase shift (absorption) of an optical probe used to interrogate the sensor material. In contrast to conventional radiation detectors where signal levels are proportional to the incident energy, signal levels in these optical sensors are proportional to the incident radiation energy flux. This allows for reduction of the sensor form factor with no degradation in detection sensitivity. Furthermore, since the radiation induced, non-equilibrium electron-hole pair distribution is effectively measured ''in place'' there is no requirement to spatially separate and collect the generated charges; consequently, the sensor risetime is of the order of the hot-electron thermalization time {le} 10 fs and the duration of the index perturbation is determined by the carrier recombination time which is of order {approx} 600 fs in, direct-bandgap semiconductors, with a high density of recombination defects; consequently, the optical sensors can be engineered with sub-ps temporal response. A series of detectors were designed, and incorporated into Mach Zehnder and Fabry-Perot interferometer-based detection systems: proof of concept, lower detection sensitivity, Mach-Zehnder detectors were characterized at beamline 6.3 at SSRL; three generations of high sensitivity single element and imaging Fabry-Perot detectors were measured at the LLNL Europa facility. Our results indicate that this technology can be used to provide x-ray detectors and x-ray imaging systems with single x-ray sensitivity and S/N {approx} 30 at x

  11. Fluorescent magnetic hybrid nanoprobe for multimodal bioimaging

    NASA Astrophysics Data System (ADS)

    Koktysh, Dmitry; Bright, Vanessa; Pham, Wellington

    2011-07-01

    A fluorescent magnetic hybrid imaging nanoprobe (HINP) was fabricated by the conjugation of superparamagnetic Fe3O4 nanoparticles and visible light emitting (~600 nm) fluorescent CdTe/CdS quantum dots (QDs). The assembly strategy used the covalent linking of the oxidized dextran shell of magnetic particles to the glutathione ligands of QDs. The synthesized HINP formed stable water-soluble colloidal dispersions. The structure and properties of the particles were characterized by transmission electron and atomic force microscopy, energy dispersive x-ray analysis and inductively coupled plasma optical emission spectroscopy, dynamic light scattering analysis, optical absorption and photoluminescence spectroscopy, and fluorescent imaging. The luminescence imaging region of the nanoprobe was extended to the near-infrared (NIR) (~800 nm) by conjugation of the superparamagnetic nanoparticles with synthesized CdHgTe/CdS QDs. Cadmium, mercury based QDs in HINP can be easily replaced by novel water-soluble glutathione stabilized AgInS2/ZnS QDs to present a new class of cadmium-free multimodal imaging agents. The observed NIR photoluminescence of fluorescent magnetic nanocomposites supports their use for bioimaging. The developed HINP provides dual-imaging channels for simultaneous optical and magnetic resonance imaging.

  12. Fluorescent magnetic hybrid nanoprobe for multimodal bioimaging

    PubMed Central

    Bright, Vanessa

    2011-01-01

    A fluorescent magnetic hybrid imaging nanoprobe (HINP) was fabricated by conjugation of superparamagnetic Fe3O4 nanoparticles and visible light-emitting (~600 nm) fluorescent CdTe/CdS quantum dots (QDs). The assembly strategy used the covalent linking of the oxidized dextran shell of magnetic particles to the glutathione ligands of QDs. Synthesized HINP formed stable water-soluble colloidal dispersions. The structure and properties of the particles were characterized by transmission electron and atomic force microscopy, energy dispersive X-ray analysis and inductively coupled plasma optical emission spectroscopy, dynamic light scattering analysis, optical absorption and photoluminescence spectroscopy, and fluorescent imaging. The luminescence imaging region of the nanoprobe was extended to the near-infrared (NIR) (~800 nm) by conjugation of superparamagnetic nanoparticles with synthesized CdHgTe/CdS QDs. Cadmium, mercury based QDs in HINP can be easily replaced by novel water soluble glutathione stabilized AgInS2/ZnS QDs to present a new class of cadmium-free multimodal imaging agents. Observed NIR photoluminescence of fluorescent magnetic nanocomposites supports their use for bioimaging. The developed HINP provides dual-imaging channels for simultaneous optical and magnetic resonance imaging. PMID:21597146

  13. Ultrafast dynamics in pentacene and tetracene probed using optical pump-probe spectroscopy

    NASA Astrophysics Data System (ADS)

    Thorsmølle, Verner; Averitt, Richard; Demsar, Jure; Chi, Xiaoliu; Tretiak, Sergie; Ramirez, Arthur; Taylor, Antoinette

    2004-03-01

    Here we present optical pump-probe measurements of photoinduced (PI) changes in the reflectivity and transmissivity of tetracene and pentacene single crystals. We studied the carrier relaxation dynamics as a function of probe photon energy aiming to elucidate the electronic structure and carrier dynamics in the singlet and triplet manifolds. We observe singlet exciton recombination, singlet fission, and triplet state absorption, which we can identify in the photoinduced (PI) absorption spectrum. In particular, both compounds display a broad long-lived (>>1ns) PI absorption. In tetracene this feature is centered at approximately 1.7 eV, while in pentacene it is centered around 1.4 eV and is very pronounced. The long relaxation time suggests that the state being probed is the triplet state T1 (i.e. T1->Tn). On the other hand, the width of the PI absorption band suggests that the final state is a band-like state at 1.7 eV (1.4 eV) above the triplet state in tetracene (pentacene). This observation supports the semiconductor band model.

  14. A fiber-optically coupled positron-sensitive surgical probe

    SciTech Connect

    Raylman, R.R.; Wahl, R.L.

    1994-05-01

    Positron-emitting radiopharmaceuticals such as {sup 18}F-labeled 2-deoxy-D-glucose (FDG) have considerable utility in the noninvasive imaging of cancers due to their rapid and excellent tumor-localizing properties. In addition, the relatively short range of positrons in tissue facilitates the precise delineation of FDG-avid tumors. Therefore, FDG used in conjunction with a positron-sensitive probe may be capable of guiding surgical procedures. Many of the current probe systems, however, are sensitive to the intense flux of background photons produced by positron annihilation. The authors describe the design, manufacture and initial in vitro and in vivo testing of a probe well-suited to the detection of positron-emitting isotopes in a high-photon background. The device consists of a small piece of plastic scintillator coupled by fiber-optic cable to a photomultiplier tube. Measurements of resolution and detector sensitivity were obtained. In addition, the reduction in resolution caused by the effects of various levels of background photon flux was determined. These measurements indicate that resolution is degraded minimally ({approximately}5% with a background-to-source ratio of 2:1) due to annihilation photon background. Sensitivity for positrons is good, detecting amounts of radioactivity as low as 10.2 nCi of FDG in vitro. In rats given FDG subcutaneously, lymph nodes containing as little as 11 nCi of FDG could be detected above the background activity levels present in normal surrounding tissues. A plastic scintillator probe system has been devised which may be highly suitable for intraoperative FDG-guided (or other positron or beta emitting-tracer) surgery. 29 refs., 7 figs.

  15. High-efficiency upconversion luminescent sensing and bioimaging of Hg(II) by chromophoric ruthenium complex-assembled nanophosphors.

    PubMed

    Liu, Qian; Peng, Juanjuan; Sun, Lining; Li, Fuyou

    2011-10-25

    A chromophoric ruthenium complex-assembled nanophosphor (N719-UCNPs) was achieved as a highly selective water-soluble probe for upconversion luminescence sensing and bioimaging of intracellular mercury ions. The prepared nanophosphors were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDXA), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Further application of N719-UCNPs in sensing Hg(2+) was confirmed by optical titration experiment and upconversion luminescence live cell imaging. Using the ratiometric upconversion luminescence as a detection signal, the detection limit of Hg(2+) for this nanoprobe in water was down to 1.95 ppb, lower than the maximum level (2 ppb) of Hg(2+) in drinking water set by the United States EPA. Importantly, the nanoprobe N719-UCNPs has been shown to be capable of monitoring changes in the distribution of Hg(2+) in living cells by upconversion luminescence bioimaging. PMID:21899309

  16. Deep-Probe Optical Waveguides for Chemical and Biosensors

    NASA Astrophysics Data System (ADS)

    Zourob, Mohammed; Skivesen, Nina; Horvath, Robert; Mohr, Stephan; Goddard, Nicholas J.

    Typical evanescent wave biosensors generate an electromagnetic wave at the sensor surface that penetrates 100-200 nm into the analysed medium. This has proven to be a highly sensitive tool to monitor refractive index changes in the close vicinity of the sensor surface. The sensitivity of such sensors can be enhanced significantly to monitor interactions caused by large micron scale objects such as bacterial and mammalian cells by increasing the penetration depth of the evanescent field. Recently, different formats of deep-probe optical waveguides including reverse waveguides (RW) based on low refractive index substrates (below 1.33) and metal-clad leaky waveguides (MCLW) have been developed for various sensing applications. These sensors are designed to maximize the overlap between the optical mode and the adlayer (superstrate layer) to be sensed. Increasing the penetration depth of the evanescent field opens up new perspectives for the detection of larger biological objects as it accommodates the majority of their body within the evanescent field. RWs use substrate materials with lower refractive index than that of the monitored superstrate layer (aqueous solution). In MCLWs, a thin metal layer is inserted between the substrate and the thicker waveguide layer. These sensor designs facilitate both increasing and tuning the penetration depth of the modes into the monitored aqueous solution and thereby significantly extend the range of possible application areas of optical waveguide sensors. The developed devices have been used for a range of biosensing applications, including the detection of bacteria, mammalian cells, organophosphorous pesticides and glucose using refractive index changes, absorbance and fluorescence monitoring. Integrating deep-probe sensors with an external electrical field or ultrasonic standing waves shortens analysis time significantly and reduces non-specific binding due to enhanced diffusion of analytes to the immobilized recognition

  17. A holographic improvement to traditional Optical Array Probes

    NASA Astrophysics Data System (ADS)

    Fugal, Jacob; Borrmann, Stephan

    2015-04-01

    Optical Array Probes have been used to measure cloud droplets and ice crystals in the size range of ~10 µm up to ~1 cm for about the last four decades. In this type of instrument, particles are swept past a focused laser sheet imaged onto a linear diode array. The resulting image has a single spatial axis and a time axis and thereby has shadowgraphs of the particles swept through and can then infer their size and shape, and therefrom size distributions, liquid water content, ice water content, and so on. One weakness inherent in the method is the difficulty in measuring small particles (~10 to 200µm in size) which appear out of focus or are not detected at all, depending on how far from the focus of the laser sheet they appear in the sensitive region. Out-of-focus small particles appear as a diffraction rings or doughnuts making the particles appear large than they actually are. Also the region in which the instrument is sensitive to small particles or depth-of-focus region is difficult to estimate making number concentrations and size distributions difficult to measure. On the other hand, holographic sample volumes are well defined as the sensitive region spans the entire area in which particles appear and the particles appearing in the holograms are reconstructed to their focus position. I.e. there is no depth-of-focus problem and the particles are sized in their focus position. Current holographic cloud particle probes use two-dimensional cameras that take snapshots of cloud particles having two spatial dimensions. These probes have also been high-resolution which requires high-performance servers to do the reconstruction and particle finding meaning the results of the measurements come long after the holograms are made. Of great advantage might be a low-resolution holographic probe with a spatial axis and a time axis with real-time results. Shown is that simple modifications to existing optical array probes such as a collimated laser sheet and a grayscale

  18. ‘Green’-synthesized near-infrared PbS quantum dots with silica-PEG dual-layer coating: ultrastable and biocompatible optical probes for in vivo animal imaging

    NASA Astrophysics Data System (ADS)

    Wang, D.; Qian, J.; Cai, F.; He, S.; Han, S.; Mu, Y.

    2012-06-01

    In this paper, PbS semiconductor quantum dots (QDs) with near-infrared (NIR) photoluminescence were synthesized in oleic acid and paraffin liquid mixture by using an easily handled and ‘green’ approach. Surface functionalization of the QDs was accomplished with a silica and polyethylene glycol (PEG) phospholipid dual-layer coating and the excellent chemical stability of the nanoparticles is demonstrated. We then successfully applied the ultrastable PbS QDs to in vivo sentinel lymph node (SLN) mapping of mice. Histological analyses were also carried out to ensure that the intravenously injected nanoparticles did not produce any toxicity to the organism of mice. These experimental results suggested that our ultrastable NIR PbS QDs can serve as biocompatible and efficient probes for in vivo optical bioimaging and has great potentials for disease diagnosis and clinical therapies in the future.

  19. Photothermal determination of optical coefficients of tissue phantoms using an optical fibre probe.

    PubMed

    Laufer, J G; Beard, P C; Walker, S P; Mills, T N

    2001-10-01

    The absorption and reduced scattering coefficients of turbid tissue phantoms have been determined from photothermal measurements made using an optical fibre probe. The thermal sensor was a thin polymer film positioned at the end of a multimode optical fibre. The film was illuminated by the output of a continuous-wave diode laser and formed the cavity of a low-finesse Fabry-Perot interferometer. Low energy laser pulses, launched into the fibre and passed through the film, produced an abrupt temperature rise in the target tissue, which was placed in contact with the film. The subsequent conduction of heat into the film caused a change in its optical thickness and hence the reflected intensity. The absorption and reduced scattering coefficients of gelatine tissue phantoms of known optical properties were determined from the measurements using a numerical model of photothermal signal generation and maximum a posteriori estimation. The determined optical coefficients were in good agreement with the known values. The results showed that the probe can be used for the determination of optical coefficients provided the thermal coefficients of the target tissue are known with low uncertainty. PMID:11686272

  20. Pigtailed electro-optic probes for vectorial electric field mapping

    NASA Astrophysics Data System (ADS)

    Warzecha, Adriana; Gaborit, Gwenaël; Ruaro, Mickael; Duvillaret, Lionel; Lassere, Jean-Louis

    2010-04-01

    Electro-optic measurement (EO) constitutes an efficient technique to characterize electrical (E) fields : indeed, the Pockel's effect properties (linear modification of refractive indices of some non-centrosymetric crystals induced by the E-field)1 leads to a vectorial measurement. Thus, it allows to map the E-field vector and its transient evolution, either in free space or inside guiding structures. Pigtailed EO sensors are naturally becoming a reliable and consistent mean of characterization for many applications, e.g. high power microwaves (HPM), electromagnetic interference (EMI), on chip diagnostic, bio-electromagnetism (e.g. influence of mobile phones on the human body). Even if these non-invasive sensors provide a greater temporal and spatial resolution (femtosecond and sub-millimeter, respectively) than commonly used sensors (antennas, bolometers), it remains temperature dependant and quite low sensitive. EO probes are based on the modification of a laser beam (either its polarization, phase or amplitude) crossing an EO crystal. We demonstrate here the last developments and improvements for EO probes as well as for whole EO setups, exploiting polarization state or amplitude modulation. The sensor is constituted by a polarization maintaining (PM) fiber carrying the beam to the crystal and taking it back once modulated, gradient index lense(s) managing the shape of the beam, half or quarter wave plate controlling the input and output polarizations and a crystal (either anisotropic: LiTaO3, LiNb03, DAST, KTP or isotropic : ZnTe, InP) converting the E-field into a modulation. Our probes are fully dielectric and cylindrically shaped (length ~ 1 cm and diameter ~ 2-3 mm). The setup is made of a 1.5 μm DFB laser, some photodiodes (low and high speed) added with a polarization state analyser arrangement in case of EO probes based on polarization state modulation scheme. The measurement bench is fully automated and compensate/measure the temperature deviation

  1. Enhanced vibrational spectroscopy, intracellular refractive indexing for label-free biosensing and bioimaging by multiband plasmonic-antenna array.

    PubMed

    Chen, Cheng-Kuang; Chang, Ming-Hsuan; Wu, Hsieh-Ting; Lee, Yao-Chang; Yen, Ta-Jen

    2014-10-15

    In this study, we report a multiband plasmonic-antenna array that bridges optical biosensing and intracellular bioimaging without requiring a labeling process or coupler. First, a compact plasmonic-antenna array is designed exhibiting a bandwidth of several octaves for use in both multi-band plasmonic resonance-enhanced vibrational spectroscopy and refractive index probing. Second, a single-element plasmonic antenna can be used as a multifunctional sensing pixel that enables mapping the distribution of targets in thin films and biological specimens by enhancing the signals of vibrational signatures and sensing the refractive index contrast. Finally, using the fabricated plasmonic-antenna array yielded reliable intracellular observation was demonstrated from the vibrational signatures and intracellular refractive index contrast requiring neither labeling nor a coupler. These unique features enable the plasmonic-antenna array to function in a label-free manner, facilitating bio-sensing and imaging development. PMID:24836017

  2. Thin Film Metal Coated Fiber Optic Hydrophone Probe

    PubMed Central

    Gopinath, R.; Arora, P.; Gandhi, G.; Daryoush, A.S.; El-Sherif, M.; Lewin, P.A.

    2010-01-01

    The purpose of this work was to improve on sensitivity performance of fiber sensor employed as Fiber Optic Hydrophone Probe (FOHP) by nano-scale thin film gold coating. The fiber is designed to provide a uniform and spatial averaging free response up to 100 MHz by etching down to an active diameter of about 9 μm. The sensitivity performance of straight cleaved (i.e. full size core and cladding) uncoated, tapered uncoated and tapered thin film gold coated fiber sensors were compared in the frequency range of 1.5 MHz to 20 MHz in the presence of acoustic pressure amplitude levels of up to 6 MPa. An unprecedented voltage sensitivity of −245 dB re 1V/uPa (560 mV/ MPa) was measured for thin film gold coated FOHP by optimizing the gold coating thickness. PMID:19881652

  3. Direct Optical Probing of Transverse Electric Mode in Graphene

    PubMed Central

    Menabde, Sergey G.; Mason, Daniel R.; Kornev, Evgeny E.; Lee, Changhee; Park, Namkyoo

    2016-01-01

    Unique electrodynamic response of graphene implies a manifestation of an unusual propagating and localised transverse-electric (TE) mode near the spectral onset of interband transitions. However, excitation and further detection of the TE mode supported by graphene is considered to be a challenge for it is extremely sensitive to excitation environment and phase matching condition adherence. Here for the first time, we experimentally prove an existence of the TE mode by its direct optical probing, demonstrating significant coupling to an incident wave in electrically doped multilayer graphene sheet at room temperature. We believe that proposed technique of careful phase matching and obtained access to graphene’s TE excitation would stimulate further studies of this unique phenomenon, and enable its potential employing in various fields of photonics as well as for characterization of graphene. PMID:26898892

  4. Direct Optical Probing of Transverse Electric Mode in Graphene

    NASA Astrophysics Data System (ADS)

    Menabde, Sergey G.; Mason, Daniel R.; Kornev, Evgeny E.; Lee, Changhee; Park, Namkyoo

    2016-02-01

    Unique electrodynamic response of graphene implies a manifestation of an unusual propagating and localised transverse-electric (TE) mode near the spectral onset of interband transitions. However, excitation and further detection of the TE mode supported by graphene is considered to be a challenge for it is extremely sensitive to excitation environment and phase matching condition adherence. Here for the first time, we experimentally prove an existence of the TE mode by its direct optical probing, demonstrating significant coupling to an incident wave in electrically doped multilayer graphene sheet at room temperature. We believe that proposed technique of careful phase matching and obtained access to graphene’s TE excitation would stimulate further studies of this unique phenomenon, and enable its potential employing in various fields of photonics as well as for characterization of graphene.

  5. Fiber-optic laser Doppler turbine tip clearance probe

    NASA Astrophysics Data System (ADS)

    Büttner, Lars; Pfister, Thorsten; Czarske, Jürgen

    2006-05-01

    A laser Doppler based method for in situ single blade tip clearance measurements of turbomachines with high precision is presented for what we believe is the first time. The sensor is based on two superposed fanlike interference fringe systems generated by two laser wavelengths from a fiber-coupled, passive, and therefore compact measurement head employing diffractive optics. Tip clearance measurements at a transonic centrifugal compressor performed during operation at 50,000 rpm (833 Hz, 586 m/s tip speed) are reported. At these speeds the measured uncertainty of the tip position was less than 20 μm, a factor of 2 more accurate than that of capacitive probes. The sensor offers great potential for in situ and online high-precision tip clearance measurements of metallic and nonmetallic turbine blades.

  6. Fiber-optic laser Doppler turbine tip clearance probe.

    PubMed

    Büttner, Lars; Pfister, Thorsten; Czarske, Jürgen

    2006-05-01

    A laser Doppler based method for in situ single blade tip clearance measurements of turbomachines with high precision is presented for what we believe is the first time. The sensor is based on two superposed fanlike interference fringe systems generated by two laser wavelengths from a fiber-coupled, passive, and therefore compact measurement head employing diffractive optics. Tip clearance measurements at a transonic centrifugal compressor performed during operation at 50,000 rpm (833 Hz, 586 m/s tip speed) are reported. At these speeds the measured uncertainty of the tip position was less than 20 microm, a factor of 2 more accurate than that of capacitive probes. The sensor offers great potential for in situ and online high-precision tip clearance measurements of metallic and nonmetallic turbine blades. PMID:16642064

  7. Molecular probes for nonlinear optical imaging of biological membranes

    NASA Astrophysics Data System (ADS)

    Blanchard-Desce, Mireille H.; Ventelon, Lionel; Charier, Sandrine; Moreaux, Laurent; Mertz, Jerome

    2001-12-01

    Second-harmonic generation (SHG) and two-photon excited fluorescence (TPEF) are nonlinear optical (NLO) phenomena that scale with excitation intensity squared, and hence give rise to an intrinsic 3-dimensional resolution when used in microscopic imaging. TPEF microscopy has gained widespread popularity in the biology community whereas SHG microscopy promises to be a powerful tool because of its sensitivity to local asymmetry. We have implemented an approach toward the design of NLO-probes specifically adapted for SHG and/or TPEF imaging of biological membranes. Our strategy is based on the design of nanoscale amphiphilic NLO-phores. We have prepared symmetrical bolaamphiphilic fluorophores combining very high two-photon absorption (TPA) cross-sections in the visible red region and affinity for cellular membranes. Their incorporation and orientation in lipid membranes can be monitored via TPEF anisotropy. We have also prepared amphiphilic push-pull chromophores exhibiting both large TPA cross-sections and very large first hyperpolarizabilities in the near-IR region. These NLO-probes have proved to be particularly useful for imaging of biological membranes by simultaneous SHG and TPEF microscopy and offer attractive prospects for real-time imaging of fundamental biological processes such as adhesion, fusion or reporting of membrane potentials.

  8. Proceedings of "Optical Probes of Dynamics in Complex Environments"

    SciTech Connect

    Sension, R; Tokmakoff, A

    2008-04-01

    This document contains the proceedings from the symposium on Optical Probes of Dynamics in Complex Environments, which organized as part of the 235th National Meeting of the American Chemical Society in New Orleans, LA from April 6 to 10, 2008. The study of molecular dynamics in chemical reaction and biological processes using time ƒresolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time resolved spectroscopy is central to all of DOEs grand challenges for fundamental energy science. This symposium brought together leaders in the field of ultrafast spectroscopy, including experimentalists, theoretical chemists, and simulators, to discuss the most recent scientific and technological advances. DOE support for this conference was used to help young US and international scientists travel to the meeting. The latest technology in ultrafast infrared, optical, and xray spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

  9. Fiber optic probe of free electron evanescent fields in the optical frequency range

    SciTech Connect

    So, Jin-Kyu MacDonald, Kevin F.; Zheludev, Nikolay I.

    2014-05-19

    We introduce an optical fiber platform which can be used to interrogate proximity interactions between free-electron evanescent fields and photonic nanostructures at optical frequencies in a manner similar to that in which optical evanescent fields are sampled using nanoscale aperture probes in scanning near-field microscopy. Conically profiled optical fiber tips functionalized with nano-gratings are employed to couple electron evanescent fields to light via the Smith-Purcell effect. We demonstrate the interrogation of medium energy (30–50 keV) electron fields with a lateral resolution of a few micrometers via the generation and detection of visible/UV radiation in the 700–300 nm (free-space) wavelength range.

  10. MEMS-based non-rotatory circumferential scanning optical probe for endoscopic optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Xu, Yingshun; Singh, Janak; Siang, Teo Hui; Ramakrishna, Kotlanka; Premchandran, C. S.; Sheng, Chen Wei; Kuan, Chuah Tong; Chen, Nanguang; Olivo, Malini C.; Sheppard, Colin J. R.

    2007-07-01

    In this paper, we present a non-rotatory circumferential scanning optical probe integrated with a MEMS scanner for in vivo endoscopic optical coherence tomography (OCT). OCT is an emerging optical imaging technique that allows high resolution cross-sectional imaging of tissue microstructure. To extend its usage to endoscopic applications, a miniaturized optical probe based on Microelectromechanical Systems (MEMS) fabrication techniques is currently desired. A 3D electrothermally actuated micromirror realized using micromachining single crystal silicon (SCS) process highlights its very large angular deflection, about 45 degree, with low driving voltage for safety consideration. The micromirror is integrated with a GRIN lens into a waterproof package which is compatible with requirements for minimally invasive endoscopic procedures. To implement circumferential scanning substantially for diagnosis on certain pathological conditions, such as Barret's esophagus, the micromirror is mounted on 90 degree to optical axis of GRIN lens. 4 Bimorph actuators that are connected to the mirror on one end via supporting beams and springs are selected in this micromirror design. When actuators of the micromirror are driven by 4 channels of sinusoidal waveforms with 90 degree phase differences, beam focused by a GRIN is redirected out of the endoscope by 45 degree tilting mirror plate and achieve circumferential scanning pattern. This novel driving method making full use of very large angular deflection capability of our micromirror is totally different from previously developed or developing micromotor-like rotatory MEMS device for circumferential scanning.

  11. Electric field and temperature measurement using ultra wide bandwidth pigtailed electro-optic probes.

    PubMed

    Bernier, Maxime; Gaborit, Gwenaël; Duvillaret, Lionel; Paupert, Alain; Lasserre, Jean-Louis

    2008-05-01

    We present pigtailed electro-optic probes that allow a simultaneous measurement of high frequency electric fields and temperature using a unique laser probe beam. This has been achieved by the development of a novel probe design associated with a fully automated servo-controlled optical bench, initially developed to stabilize the electric field sensor response. The developed electro-optic probes present a stable response in outdoors conditions over a time duration exceeding 1 h, a frequency bandwidth from kHz to tens of GHz with a sensitivity of 0.7 Vm(-1)Hz(-(1/2)), and a temperature accuracy of 40 mK. PMID:18449315

  12. Electroless silver plating for metallization of near-field optical fiber probes

    NASA Astrophysics Data System (ADS)

    Li, Chang'an; Xu, Lina; Gu, Ning

    2007-10-01

    By using mercaptopropyltrimethoxysilane (MPTS) self-assembled monolayers (SAMs), electroless silver plating is developed for the metallization of near-field optical fiber probes. This method has the advantages of controllability, no pinholes, convenience, low cost, and smooth tip surface. The metallized probes are characterized by optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDXS).

  13. Simulation of near-field scanning optical microscopy using a plasmonic gap probe

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuo; Tanaka, Masahiro; Katayama, Kiyofumi

    2006-10-01

    Imaging by near-field scanning optical microscopy (NSOM) with a plasmonic gap probe (PGP) is simulated to confirm the operation of the recently proposed PGP. The simulations demonstrate that the probe works in illumination, collection-reflection and collection mode, and that is it not necessary to vibrate the probe tip in order to remove background noise. The resolution of the scanned image is also shown to be approximately equal to the diameter of the probe tip. Furthermore, the throughput of the probe is much higher than conventional aperture probes providing similar resolution. The proposed probe thus has the advantages of both aperture probes and scattering probes, and is expected to have excellent characteristics for use as a scanning probe for NSOM.

  14. Chapter 17: bioimage informatics for systems pharmacology.

    PubMed

    Li, Fuhai; Yin, Zheng; Jin, Guangxu; Zhao, Hong; Wong, Stephen T C

    2013-04-01

    Recent advances in automated high-resolution fluorescence microscopy and robotic handling have made the systematic and cost effective study of diverse morphological changes within a large population of cells possible under a variety of perturbations, e.g., drugs, compounds, metal catalysts, RNA interference (RNAi). Cell population-based studies deviate from conventional microscopy studies on a few cells, and could provide stronger statistical power for drawing experimental observations and conclusions. However, it is challenging to manually extract and quantify phenotypic changes from the large amounts of complex image data generated. Thus, bioimage informatics approaches are needed to rapidly and objectively quantify and analyze the image data. This paper provides an overview of the bioimage informatics challenges and approaches in image-based studies for drug and target discovery. The concepts and capabilities of image-based screening are first illustrated by a few practical examples investigating different kinds of phenotypic changes caEditorsused by drugs, compounds, or RNAi. The bioimage analysis approaches, including object detection, segmentation, and tracking, are then described. Subsequently, the quantitative features, phenotype identification, and multidimensional profile analysis for profiling the effects of drugs and targets are summarized. Moreover, a number of publicly available software packages for bioimage informatics are listed for further reference. It is expected that this review will help readers, including those without bioimage informatics expertise, understand the capabilities, approaches, and tools of bioimage informatics and apply them to advance their own studies. PMID:23633943

  15. Dual-responsive aggregation-induced emission-active supramolecular nanoparticles for gene delivery and bioimaging.

    PubMed

    Dong, Ruijiao; Ravinathan, Screenath P; Xue, Lizhe; Li, Nan; Zhang, Yingjian; Zhou, Linzhu; Cao, Chengxi; Zhu, Xinyuan

    2016-06-28

    Dual-responsive aggregation-induced emission-active supramolecular fluorescent nanoparticles are reported, which have the ability to undergo a unique morphological transition combining with a cooperative optical variation in response to pH and light stimuli. The dynamic supramolecular nanoparticles show excellent biocompatibility and effective plasmid DNA condensation capability, further achieving efficient in vitro gene delivery and bioimaging. PMID:27251637

  16. Optical coherence tomography and optical coherence domain reflectometry for deep brain stimulation probe guidance

    NASA Astrophysics Data System (ADS)

    Jeon, Sung W.; Shure, Mark A.; Baker, Kenneth B.; Chahlavi, Ali; Hatoum, Nagi; Turbay, Massud; Rollins, Andrew M.; Rezai, Ali R.; Huang, David

    2005-04-01

    Deep Brain Stimulation (DBS) is FDA-approved for the treatment of Parkinson's disease and essential tremor. Currently, placement of DBS leads is guided through a combination of anatomical targeting and intraoperative microelectrode recordings. The physiological mapping process requires several hours, and each pass of the microelectrode into the brain increases the risk of hemorrhage. Optical Coherence Domain Reflectometry (OCDR) in combination with current methodologies could reduce surgical time and increase accuracy and safety by providing data on structures some distance ahead of the probe. For this preliminary study, we scanned a rat brain in vitro using polarization-insensitive Optical Coherence Tomography (OCT). For accurate measurement of intensity and attenuation, polarization effects arising from tissue birefringence are removed by polarization diversity detection. A fresh rat brain was sectioned along the coronal plane and immersed in a 5 mm cuvette with saline solution. OCT images from a 1294 nm light source showed depth profiles up to 2 mm. Light intensity and attenuation rate distinguished various tissue structures such as hippocampus, cortex, external capsule, internal capsule, and optic tract. Attenuation coefficient is determined by linear fitting of the single scattering regime in averaged A-scans where Beer"s law is applicable. Histology showed very good correlation with OCT images. From the preliminary study using OCT, we conclude that OCDR is a promising approach for guiding DBS probe placement.

  17. Probing the Active Galactic Nuclei using optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Vivek, M.

    Variability studies offer one of the best tools for understanding the physical conditions present in regions close to the central engine in an AGN. We probed the various properties of AGN through time variability studies of spectral lines in the optical wavelengths using the 2m telescope in IUCAA Girawali observatory. The absorption line variability studies are mainly concentrated in understanding the nature of outflows in quasars. Quasar outflows have a huge impact on the evolution of central supermassive blackholes, their host galaxies and the surrounding intergalactic medium. Studying the variability in these Broad Absorption Lines (BALs) can help us understand the structure, evolution, and basic physical properties of these outflows. We conducted a repeated Low ionization BAL monitoring program with 27 LoBALs (Low Ionization BALs) at z 0.3-2.1 covering timescales from 3.22 to 7.69 years in the quasar rest frame. We see a variety of phenomena, including some BALs that either appeared or disappeared completely and some BALs which do not vary over the observation period. In one case, the excited fine structure lines have changed dramatically. One source shows signatures of radiative acceleration. Here, we present the results from this program. Emission line studies are concentrated in understanding the peculiar characteristics of a dual-AGN source SDSS J092712.64+294344.0.

  18. Infrared fiber optic probes for evaluation of musculoskeletal tissue pathology

    NASA Astrophysics Data System (ADS)

    Padalkar, Mugdha; McGoverin, Cushla; Onigbanjo, Quam; Spencer, Richard; Barbash, Scott; Kropf, Eric; Pleshko, Nancy

    2014-03-01

    Musculoskeletal pathology of the knee commonly occurs with aging and as a result of injury. The incidence of anterior cruciate ligament (ACL) injuries continues to increase annually, and may precede the eventual onset of osteoarthritis (OA), a debilitating and prevalent disease characterized by cartilage degeneration. Early detection of OA remains elusive, with current imaging methods lacking adequate sensitivity to detect early pathologic cartilage changes. We used mid- and near- infrared (IR) spectroscopy through arthroscopic-based fiber-optic devices to assess cartilage damage and differentiate tendon from ligament. Mid-IR spectroscopy is characterized by distinct bands and low penetration depth (< 10 μm) and near-IR spectroscopy is characterized by complex overlapping bands and greater penetration depths (< 1 cm). We have found that combined mid- and near-IR analysis greatly extends the information available through either in the analysis of soft tissues, including cartilage, ligaments and tendons. We discuss here basic science studies and the potential for translation to clinical research with novel arthroscopic probes.

  19. Optically investigating Nd3+-Yb3+ cascade sensitized upconversion nanoparticles for high resolution, rapid scanning, deep and damage-free bio-imaging

    PubMed Central

    Zhao, Yuxiang; Zhan, Qiuqiang; Liu, Jing; He, Sailing

    2015-01-01

    The rapid development of upconversion nanoparticles (UCNPs) has been facing with a great challenge: intense emission, fast scanning, and deep imaging require high-power light irradiation with minimized heating effect (the intrinsic 975-nm excitation of Yb3+-sensitized UCNPs have overheating problem). By shifting the excitation peak from 975 nm to 795 nm, Nd3+-Yb3+ cascade sensitized upconversion nanoparticles (Nd-UCNPs) with minimized heating effect were reported as the new generation UCNPs. For the first time, within two optically modeled applications in vitro and in vivo, the damage outcomes under long time high power laser excitation were solidly calculated, complementing the damage-free study of Nd-UCNPs. The higher resolution (20% improvement) and five times faster scanning microscopy were successfully performed using Nd-UCNPs under safety laser power level. The computational results showed the Nd3+-Yb3+ energy transfer efficiency would not compromise the deep imaging ability, and the red (650-nm) emission is worth to be enhanced for deep tissue imaging. PMID:25798308

  20. A trifurcated fiber-optic-probe-based optical system designed for AGEs measurement

    NASA Astrophysics Data System (ADS)

    Wang, Yikun; Zhang, Long; Zhu, Ling; Liu, Yong; Zhang, Gong; Wang, An

    2011-11-01

    Advanced Glycation End-products (AGEs) are biochemical end-products of non-enzymatic glycation and are formed irreversibly in human serum and skin tissue. AGEs are thought to play an important role in the pathogenesis of diabetes and corresponding complications. All conventional methods for measuring AGEs must take sampling and measure in vitro. These methods are invasive and have the problem of relatively time-consuming. AGEs have fluorescent characteristics. Skin AGEs can be assessed noninvasively by collecting the fluorescence emitted from skin tissue when excited with proper light. However, skin tissue has absorption and scattering effects on fluorescence of AGEs, it is not reliable to evaluate the accumulation of AGEs according the emitted fluorescence but not considering optical properties of skin tissue. In this study, a portable system for detecting AGEs fluorescence and skin reflectance spectrum simultaneously has been developed. The system mainly consists of an ultraviolet light source, a broadband light source, a trifurcated fiber-optic probe, and a compact charge coupled device (CCD) spectrometer. The fiber-optic probe consists of 36 optical fibers which are connected to the ultraviolet light source, 6 optical fibers connected to the broadband light source, and a core fiber connected to the CCD spectrometer. Demonstrative test measurements with the system on skin tissue of 40 healthy subjects have been performed. Using parameters that are calculated from skin reflectance spectrum, the distortion effects caused by skin absorption and scattering can be eliminated, and the integral intensity of corrected fluorescence has a strong correlation with the accumulation of AGEs. The system looks very promising for both laboratory and clinical applications to monitor AGEs related diseases, especially for chronic diabetes and complications.

  1. A trifurcated fiber-optic-probe-based optical system designed for AGEs measurement

    NASA Astrophysics Data System (ADS)

    Wang, Yikun; Zhang, Long; Zhu, Ling; Liu, Yong; Zhang, Gong; Wang, An

    2012-03-01

    Advanced Glycation End-products (AGEs) are biochemical end-products of non-enzymatic glycation and are formed irreversibly in human serum and skin tissue. AGEs are thought to play an important role in the pathogenesis of diabetes and corresponding complications. All conventional methods for measuring AGEs must take sampling and measure in vitro. These methods are invasive and have the problem of relatively time-consuming. AGEs have fluorescent characteristics. Skin AGEs can be assessed noninvasively by collecting the fluorescence emitted from skin tissue when excited with proper light. However, skin tissue has absorption and scattering effects on fluorescence of AGEs, it is not reliable to evaluate the accumulation of AGEs according the emitted fluorescence but not considering optical properties of skin tissue. In this study, a portable system for detecting AGEs fluorescence and skin reflectance spectrum simultaneously has been developed. The system mainly consists of an ultraviolet light source, a broadband light source, a trifurcated fiber-optic probe, and a compact charge coupled device (CCD) spectrometer. The fiber-optic probe consists of 36 optical fibers which are connected to the ultraviolet light source, 6 optical fibers connected to the broadband light source, and a core fiber connected to the CCD spectrometer. Demonstrative test measurements with the system on skin tissue of 40 healthy subjects have been performed. Using parameters that are calculated from skin reflectance spectrum, the distortion effects caused by skin absorption and scattering can be eliminated, and the integral intensity of corrected fluorescence has a strong correlation with the accumulation of AGEs. The system looks very promising for both laboratory and clinical applications to monitor AGEs related diseases, especially for chronic diabetes and complications.

  2. High quality polyacrylic acid modified multifunction luminescent nanorods for tri-modality bioimaging, in vivo long-lasting tracking and biodistribution

    NASA Astrophysics Data System (ADS)

    Yi, Zhigao; Lu, Wei; Liu, Hongrong; Zeng, Songjun

    2014-12-01

    Polyacrylic acid (PAA) modified NaYF4:Gd/Yb/Er upconversion nanorods (denoted as PAA-UCNRs) are demonstrated for tri-modal upconversion (UC) optical, computed X-ray tomography (CT), and magnetic resonance imaging (MRI). The hydrophilic PAA-UCNRs were obtained from hydrophobic oleic acid (OA) capped UCNRs (denoted as OA-UCNRs) using a ligand exchange method. The as-prepared UCNRs with a hexagonal phase structure present high monodispersity. These PAA-UCNRs are successfully used as ideal probes for in vivo UC luminescence bioimaging and synergistic X-ray and UC bioimaging. Moreover, X-ray CT imaging reveals that PAA-UCNRs can act as contrast agents for improved detection of the liver and spleen. In addition, a significant signal enhancement in the liver is observed in in vivo MRI, indicating that PAA-UCNRs are ideal T1-weighted MRI agents. More importantly, in vivo long-term tracking based on these PAA-UCNRs in the live mice and the corresponding ex vivo bioimaging of isolated organs also verify the translocation of PAA-UCNRs from the liver to the spleen, and the observed intense UC signals from the feces reveal the biliary excretion mechanism of these UCNRs. These findings contribute to understanding of the translocation and potential route for excretion of PAA-UCNRs, which can provide an important guide for the diagnosis and detection of diseases based on these UCNRs.Polyacrylic acid (PAA) modified NaYF4:Gd/Yb/Er upconversion nanorods (denoted as PAA-UCNRs) are demonstrated for tri-modal upconversion (UC) optical, computed X-ray tomography (CT), and magnetic resonance imaging (MRI). The hydrophilic PAA-UCNRs were obtained from hydrophobic oleic acid (OA) capped UCNRs (denoted as OA-UCNRs) using a ligand exchange method. The as-prepared UCNRs with a hexagonal phase structure present high monodispersity. These PAA-UCNRs are successfully used as ideal probes for in vivo UC luminescence bioimaging and synergistic X-ray and UC bioimaging. Moreover, X-ray CT imaging

  3. Optofluidic needle probe integrating targeted delivery of fluid with optical coherence tomography imaging.

    PubMed

    Quirk, Bryden C; McLaughlin, Robert A; Pagnozzi, Alex M; Kennedy, Brendan F; Noble, Peter B; Sampson, David D

    2014-05-15

    We present an optofluidic optical coherence tomography (OCT) needle probe capable of modifying the local optical properties of tissue to improve needle-probe imaging performance. The side-viewing probe comprises an all-fiber-optic design encased in a hypodermic needle (outer diameter 720 μm) and integrates a coaxial fluid-filled channel, terminated by an outlet adjacent to the imaging window, allowing focal injection of fluid to a target tissue. This is the first fully integrated OCT needle probe design to incorporate fluid injection into the imaging mechanism. The utility of this probe is demonstrated in air-filled sheep lungs, where injection of small quantities of saline is shown, by local refractive index matching, to greatly improve image penetration through multiple layers of alveoli. 3D OCT images are correlated against histology, showing improvement in the capability to image lung structures such as bronchioles and blood vessels. PMID:24978229

  4. High speed 3D endoscopic optical frequency domain imaging probe for lung cancer diagnosis

    NASA Astrophysics Data System (ADS)

    Li, Jianan; Feroldi, Fabio; Mo, Jianhua; Helderman, Frank; de Groot, Mattijs; de Boer, Johannes F.

    2013-06-01

    We present a miniature motorized endoscopic probe for Optical Frequency Domain Imaging with an outer diameter of 1.65 mm and a rotation speed of 3,000 - 12,500 rpm. The probe has a motorized distal end which provides a significant advantage over proximally driven probes since it does not require a drive shaft to transfer the rotational torque to the distal end of the probe and functions without a fiber rotary junction. The probe has a focal Full Width at Half Maximum of 9.6 μm and a working distance of 0.47 mm. We analyzed the non-uniform rotation distortion and found a location fluctuation of only 1.87° in repeated measurements of the same object. The probe was integrated in a high-speed Optical Frequency Domain Imaging setup at 1310 nm. We demonstrated its performance with imaging ex vivo pig bronchial and in vivo goat lung.

  5. Core-shell designs of photoluminescent nanodiamonds with porous silica coatings for bioimaging and drug delivery II: application

    NASA Astrophysics Data System (ADS)

    Prabhakar, Neeraj; Näreoja, Tuomas; von Haartman, Eva; Karaman, Didem Şen; Jiang, Hua; Koho, Sami; Dolenko, Tatiana A.; Hänninen, Pekka E.; Vlasov, Denis I.; Ralchenko, Victor G.; Hosomi, Satoru; Vlasov, Igor I.; Sahlgren, Cecilia; Rosenholm, Jessica M.

    2013-04-01

    Recent advances within materials science and its interdisciplinary applications in biomedicine have emphasized the potential of using a single multifunctional composite material for concurrent drug delivery and biomedical imaging. Here we present a novel composite material consisting of a photoluminescent nanodiamond (ND) core with a porous silica (SiO2) shell. This novel multifunctional probe serves as an alternative nanomaterial to address the existing problems with delivery and subsequent tracing of the particles. Whereas the unique optical properties of ND allows for long-term live cell imaging and tracking of cellular processes, mesoporous silica nanoparticles (MSNs) have proven to be efficient drug carriers. The advantages of both ND and MSNs were hereby integrated in the new composite material, ND@MSN. The optical properties provided by the ND core rendered the nanocomposite suitable for microscopy imaging in fluorescence and reflectance mode, as well as super-resolution microscopy as a STED label; whereas the porous silica coating provided efficient intracellular delivery capacity, especially in surface-functionalized form. This study serves as a demonstration how this novel nanomaterial can be exploited for both bioimaging and drug delivery for future theranostic applications.Recent advances within materials science and its interdisciplinary applications in biomedicine have emphasized the potential of using a single multifunctional composite material for concurrent drug delivery and biomedical imaging. Here we present a novel composite material consisting of a photoluminescent nanodiamond (ND) core with a porous silica (SiO2) shell. This novel multifunctional probe serves as an alternative nanomaterial to address the existing problems with delivery and subsequent tracing of the particles. Whereas the unique optical properties of ND allows for long-term live cell imaging and tracking of cellular processes, mesoporous silica nanoparticles (MSNs) have proven

  6. Exciton dynamics in pentacene and tetracene studied using optical pump-probe spectroscopy

    NASA Astrophysics Data System (ADS)

    Thorsmølle, V. K.; Averitt, R. D.; Demsar, J.; Chi, X.; Smith, D. L.; Ramirez, A. P.; Taylor, A. J.

    We present room temperature photoinduced reflection and transmission measurements in pentacene and tetracene single crystals using optical pump-probe spectroscopy. Singlet exciton recombination, singlet-triplet fission, excited singlet, and triplet state absorption is observed.

  7. Optical Probe for Semiconductor: Cooperative Research and Development Final Report, CRADA Number CRD-06-206

    SciTech Connect

    Sopori, B.

    2011-02-01

    This CRADA involves development of a new semiconductor characterization tool, Optical Probe, which can be commercialized by GT Solar. GT Solar will participate in the design and testing of this instrument that will be developed under an IPP project.

  8. Exciton dynamics in pentacene and tetracene studied using optical pump-probe spectroscopy

    SciTech Connect

    Thorsmølle, V. K.; Averitt, R. D.; Demsar, J.; Chi, X.; Smith, D. L.; Ramirez, A. P.; Taylor, Antoinette J.,

    2004-01-01

    We present room temperature photoinduced reflection and transmission measurements in pentacene and tetracene single crystals using optical pump-probe spectroscopy. Singlet exciton recombination, singlet-triplet fission, excited singlet, and triplet state absorption is observed.

  9. Synthesis, Structure, Properties, and Bioimaging of a Fluorescent Nitrogen-Linked Bisbenzothiadiazole.

    PubMed

    Mota, Alberto A R; Corrêa, José R; Carvalho, Pedro H P R; de Sousa, Núbia M P; de Oliveira, Heibbe C B; Gatto, Claudia C; da Silva Filho, Demétrio A; de Oliveira, Aline L; Neto, Brenno A D

    2016-04-01

    This paper describes the synthesis, structure, photophysical properties, and bioimaging application of a novel 2,1,3-benzothiadiazole (BTD)-based rationally designed fluorophore. The capability of undergoing efficient stabilizing processes from the excited state allowed the novel BTD derivative to be used as a stable probe for bioimaging applications. No notable photobleaching effect or degradation could be observed during the experimental time period. Before the synthesis, the molecular architecture of the novel BTD derivative was evaluated by means of DFT calculations to validate the chosen design. Single-crystal X-ray analysis revealed the nearly flat characteristics of the structure in a syn conformation. The fluorophore was successfully tested as a live-cell-imaging probe and efficiently stained MCF-7 breast cancer cell lineages. PMID:26930300

  10. Triazole-based Zn²⁺-specific molecular marker for fluorescence bioimaging.

    PubMed

    Sinha, Sougata; Mukherjee, Trinetra; Mathew, Jomon; Mukhopadhyay, Subhra K; Ghosh, Subrata

    2014-04-25

    Fluorescence bioimaging potential, both in vitro and in vivo, of a yellow emissive triazole-based molecular marker has been investigated and demonstrated. Three different kinds of cells, viz Bacillus thuringiensis, Candida albicans, and Techoma stans pollen grains were used to investigate the intracellular zinc imaging potential of 1 (in vitro studies). Fluorescence imaging of translocation of zinc through the stem of small herb, Peperomia pellucida, having transparent stem proved in vivo bioimaging capability of 1. This approach will enable in screening cell permeability and biostability of a newly developed probe. Similarly, the current method for detection and localization of zinc in Gram seed sprouts could be an easy and potential alternative of the existing analytical methods to investigate the efficiency of various strategies applied for increasing zinc-content in cereal crops. The probe-zinc ensemble has efficiently been applied for detecting phosphate-based biomolecules. PMID:24725748

  11. Neurosurgical hand-held optical coherence tomography (OCT) forward-viewing probe

    NASA Astrophysics Data System (ADS)

    Sun, Cuiru; Lee, Kenneth K. C.; Vuong, Barry; Cusimano, Michael; Brukson, Alexander; Mariampillai, Adrian; Standish, Beau A.; Yang, Victor X. D.

    2012-02-01

    A prototype neurosurgical hand-held optical coherence tomography (OCT) imaging probe has been developed to provide micron resolution cross-sectional images of subsurface tissue during open surgery. This new ergonomic hand-held probe has been designed based on our group's previous work on electrostatically driven optical fibers. It has been packaged into a catheter probe in the familiar form factor of the clinically accepted Bayonet shaped neurosurgical non-imaging Doppler ultrasound probes. The optical design was optimized using ZEMAX simulation. Optical properties of the probe were tested to yield an ~20 um spot size, 5 mm working distance and a 3.5 mm field of view. The scan frequency can be increased or decreased by changing the applied voltage. Typically a scan frequency of less than 60Hz is chosen to keep the applied voltage to less than 2000V. The axial resolution of the probe was ~15 um (in air) as determined by the OCT system. A custom-triggering methodology has been developed to provide continuous stable imaging, which is crucial for clinical utility. Feasibility of this probe, in combination with a 1310 nm swept source OCT system was tested and images are presented to highlight the usefulness of such a forward viewing handheld OCT imaging probe. Knowledge gained from this research will lay the foundation for developing new OCT technologies for endovascular management of cerebral aneurysms and transsphenoidal neuroendoscopic treatment of pituitary tumors.

  12. Microemulsion characterization by the use of a noninvasive backscatter fiber optic probe

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Dhadwal, Harbans S.; Cheung, H. M.; Meyer, William V.

    1993-01-01

    This paper demonstrates the utility of a noninvasive backscatter fiber optic probe for dynamic light-scattering characterization of a microemulsion comprising sodium dodecyl sulfate/1-butanol/ brine/heptane. The fiber probe, comprising two optical fibers precisely positioned in a stainless steel body, is a miniaturized and efficient self-beating dynamic light-scattering system. Accuracy of particle size estimation is better than +/- 2 percent.

  13. Monte Carlo analysis on probe performance for endoscopic diffuse optical spectroscopy of tubular organ

    NASA Astrophysics Data System (ADS)

    Zhang, Yunyao; Zhu, Jingping; Cui, Weiwen; Nie, Wei; Li, Jie; Xu, Zhenghong

    2015-03-01

    We investigated the performance of endoscopic diffuse optical spectroscopy probes with circular or linear fiber arrangements for tubular organ cancer detection. Probe performance was measured by penetration depth. A Monte Carlo model was employed to simulate light transport in the hollow cylinder that both emits and receives light from the inner boundary of the sample. The influence of fiber configurations and tissue optical properties on penetration depth was simulated. The results show that under the same condition, probes with circular fiber arrangement penetrate deeper than probes with linear fiber arrangement, and the difference between the two probes' penetration depth decreases with an increase in the 'distance between source and detector (SD)' and the radius of the probe. Other results show that the penetration depths and their differences both decrease with an increase in the absorption coefficient and the reduced scattering coefficient but remain constant with changes in the anisotropy factor. Moreover, the penetration depth was more affected by the absorption coefficient than the reduced scattering coefficient. It turns out that in NIR band, probes with linear fiber arrangements are more appropriate for diagnosing superficial cancers, whereas probes with circular fiber arrangements should be chosen for diagnosing adenocarcinoma. But in UV-VIS band, the two probe configurations exhibit nearly the same. These results are useful in guiding endoscopic diffuse optical spectroscopy-based diagnosis for esophageal, cervical, colorectal and other cancers.

  14. Aqueous synthesis and biostabilization of CdS@ZnS quantum dots for bioimaging applications

    NASA Astrophysics Data System (ADS)

    Chen, L.; Liu, Y.; Lai, C.; Berry, R. M.; Tam, K. C.

    2015-10-01

    Bionanohybrids, combining biocompatible natural polymers with inorganic materials, have aroused interest because of their structural, functional, and environmental advantages. In this work, we report on the stabilization of CdS@ZnS core-shell quantum dots (QDs) using carboxylated cellulose nanocrytals (CNCs) as nanocarrieers in aqueous phase. The high colloidal stability was achieved with sufficient negative charge on CNC surface and the coordination of Cd2+ to carboxylate groups. This coordination allows the in-situ nucleation and growth of QDs on CNC surface. The influences of QD to CNC ratio, pH and ZnS coating on colloidal stability and photoluminescence property of CNC/QD nanohybirds were also studied. The results showed that products obtained at pH 8 with a CdS to CNC weight ratio of 0.19 and a ZnS/CdS molar ratio of 1.5 possessed excellent colloidal stability and highest photoluminescence intensity. By anchoring QDs on rigid bionanotemplates, CNC/CdS@ZnS exhibited long-term colloidal and optical stability. Using biocompatible CNC as nanocarriers, the products have been demonstrated to exhibit low cytotoxicity towards HeLa cells and can serve as promising red-emitting fluorescent bioimaging probes.

  15. Single-body lensed-fiber scanning probe actuated by magnetic force for optical imaging.

    PubMed

    Min, Eun Jung; Na, Jihoon; Ryu, Seon Young; Lee, Byeong Ha

    2009-06-15

    We propose a fiber-based hand-held scanning probe suitable for the sample arm of an optical imaging system including optical coherence tomography. To achieve compactness, a single-body lensed-fiber and a solenoid actuator were utilized. The focusing lens of the probe was directly formed onto the distal end of a fiber, which eliminated the need for additional optical components and optical alignment. A ferromagnetic iron bead was glued onto the middle of the fiber to enable actuation by magnetic force, which allowed easy fabrication and good practicality. The fiber piece having the built-in fiber lens was forced to oscillate in its resonant frequency. With the implemented probe, optical coherence tomography images of a human fingertip and a pearl were obtained at an imaging speed of 30 frames/s over a scanning range of 4 mm. PMID:19529740

  16. Fabrication and characterization of a real-time optical fiber dosimeter probe

    NASA Astrophysics Data System (ADS)

    Croteau, André; Caron, Serge; Rink, Alexandra; Jaffray, David; Mermut, Ozzy

    2011-07-01

    There is a pressing need for a low cost, passive optical fiber dosimeter probe for use in real-time monitoring of radiation dose delivered to clinical radiation therapy patients. An optical fiber probe using radiochromic material has been designed and fabricated based on the deposition of a radiochromic thin film on a dielectric mirror. Measurements of the net optical density vs. time before, during, and after irradiation at a rate of 500 cGy/minute to a total dose of 5 Gy were performed. Net optical densities increased from 0.2 to 2.0 for radiochromic thin film thicknesses of 2 to 20 μm, respectively. An improved optical fiber probe fabrication method is presented.

  17. Few-cycle optical probe-pulse for investigation of relativistic laser-plasma interactions

    SciTech Connect

    Schwab, M. B.; Sävert, A.; Polz, J.; Schnell, M.; Rinck, T.; Möller, M.; Hansinger, P.; Jäckel, O.; Paulus, G. G.; Kaluza, M. C.; Veisz, L.

    2013-11-04

    The development of a few-cycle optical probe-pulse for the investigation of laser-plasma interactions driven by a Ti:sapphire, 30 Terawatt (TW) laser system is described. The probe is seeded by a fraction of the driving laser's energy and is spectrally broadened via self-phase modulation in a hollow core fiber filled with a rare gas, then temporally compressed to a few optical cycles via chirped mirrors. Shadowgrams of the laser-driven plasma wave created in relativistic electron acceleration experiments are presented with few-fs temporal resolution, which is shown to be independent of post-interaction spectral filtering of the probe-beam.

  18. In situ imaging of lung alveoli with an optical coherence tomography needle probe

    NASA Astrophysics Data System (ADS)

    Quirk, Bryden C.; McLaughlin, Robert A.; Curatolo, Andrea; Kirk, Rodney W.; Noble, Peter B.; Sampson, David D.

    2011-03-01

    In situ imaging of alveoli and the smaller airways with optical coherence tomography (OCT) has significant potential in the assessment of lung disease. We present a minimally invasive imaging technique utilizing an OCT needle probe. The side-facing needle probe comprises miniaturized focusing optics consisting of no-core and GRIN fiber encased within a 23-gauge needle. 3D-OCT volumetric data sets were acquired by rotating and retracting the probe during imaging. The probe was used to image an intact, fresh (not fixed) sheep lung filled with normal saline, and the results validated against a histological gold standard. We present the first published images of alveoli acquired with an OCT needle probe and demonstrate the potential of this technique to visualize other anatomical features such as bifurcations of the bronchioles.

  19. An optical gas temperature probe for high temperature fossil fuel process streams

    SciTech Connect

    Bauman, L.E.; Cook, R.L.; Lineberry, J.T.; Litchford, R.J.

    1995-12-31

    Reported here are the results of a feasibility study of a modular optical gas temperature probe for direct measurement of gas temperature in fossil-fueled combustion streams. A probe based upon the spectroscopic technique of line reversal would be superior to currently available gas temperature technology. The study concluded that a modular form of the line reversal optical temperature probe is feasible and, as such. the probe should be a commercially viable product with potential economic benefits from improved monitoring and control of utility furnaces. Such a probe will have the capability of making direct measurements of gas temperature in hot (>1500 K) process streams of coal combustion systems and large-scale power plant facilities.

  20. 3D visualization of tissue microstructures using optical coherence tomography needle probes

    NASA Astrophysics Data System (ADS)

    Kirk, Rodney W.; McLaughlin, Robert A.; Quirk, Bryden C.; Curatolo, Andrea; Sampson, David D.

    2011-05-01

    Optical coherence tomography (OCT) needle probes use miniaturized focusing optics encased in a hypodermic needle. Needle probes can scan areas of the body that are too deep to be imaged by other OCT systems. This paper presents an OCT needle probe-based system that is capable of acquiring three-dimensional scans of tissue structures. The needle can be guided to a target area and scans acquired by rotating and pulling-back the probe. The system is demonstrated using ex vivo human lymph node and sheep lung samples. Multiplanar reconstructions are shown of both samples, as well as the first published 3D volume rendering of lung tissue acquired with an OCT needle probe.

  1. Double-resonance probe for near-field scanning optical microscopy

    NASA Astrophysics Data System (ADS)

    Cherkun, A. P.; Serebryakov, D. V.; Sekatskii, S. K.; Morozov, I. V.; Letokhov, V. S.

    2006-03-01

    A surface-contact transducer is developed for scanning probe microscopes, whose operating principle is based on the coincidence between the resonance frequency of a 32kHz quartz tuning fork and that of the probe attached to it. This allows the transducer to have a high quality factor and, if the vibration amplitude of the probe tip exceeds that of the tuning fork prongs, materially improves its force sensitivity. The resonance transducer proposed by us has an experimentally verified force sensitivity of 8pN (rms) in the 300Hz frequency band, which is of the same order of magnitude as the sensitivity of atomic force microscope (AFM) cantilever sensors. The manufacture of such transducers equipped with optical-fiber probes for near-field scanning optical microscopy and with tungsten probes for AFM is described as an example.

  2. Field analysis of electro-optic probes for minimally invasive microwave sampling.

    PubMed

    Lee, Dong-Joon; Kwon, Jae-Yong; Kang, No-Weon

    2014-02-10

    We numerically and experimentally investigate the field invasiveness of microwave signals using an electro-optic technique. The distortion of the standing wave voltage and pulse waveform probed by the electro-optic technique is explored through both minimally invasive external and non-invasive internal sensing configurations. First, we analyzed the continuous wave microwave field imaging on a millimeter- scale coaxial transmission line using a highly accurate and stable electro- optic scanning system. The electric field images from the microwave device are attained virtually non-invasively using a miniaturized fiber-coupled electro-optic probe. The accuracy of the field imaging associated with various probe styles is investigated by numerical analysis and experiment. Then, we analyzed the waveform of the coaxial transmission line up to 50 GHz using a pulsed electro-optic system with an external probe set. Finally, the invasive analysis was extended to the sub-millimeter-scale on-wafer coplanar waveguides, where the voltage waveforms are measured using a minimally invasive external probe as well as an internal wafer probe for non-invasive sampling. PMID:24663582

  3. Phase-sensitive optical coherence reflectometer with differential phase-shift keying of probe pulses

    SciTech Connect

    Alekseev, A E; Vdovenko, V S; Sergachev, I A; Simikin, D E; Gorshkov, B G; Potapov, V T

    2014-10-31

    We report a new method for reconstructing the signal shape of the external dynamic perturbations along the entire length of the fibre of an optical coherence reflectometer. The method proposed is based on differential phase-shift keying of a probe pulse and demodulation of scattered light by the phase diversity technique. Possibilities of the method are demonstrated experimentally. (fibre-optic sensors)

  4. Determination of optical probe interrogation field of near-infrared reflectance: phantom and Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Bahadur, Ali N.; Giller, Cole A.; Kashyap, Dheerendra; Liu, Hanli

    2007-08-01

    An optical probe used to localize human brain tissues in vivo has been reported previously. It was able to sense the underlying tissue structure with an optical interrogation field, termed as "look ahead distance" (LAD). A new side-firing probe has been designed with its optical window along its side. We have defined the optical interrogation field of the new side probe as "look aside distance" (LASD). The purpose of this study is to understand the dependence of the LAD and LASD on the optical properties of tissue, the light source intensity, and the integration time of the detector, using experimental and computational methods. The results show that a decrease in light intensity does decrease the LAD and LASD and that an increase in integration time of detection may not necessarily improve the depths of LAD and LASD. Furthermore, Monte Carlo simulation results suggest that the LAD/LASD decreases with an increase in reduced scattering coefficient to a point, after which the LAD/LASD remains constant. We expect that an optical interrogation field of a tip or side probe is approximately 1-2 mm in white matter and 2-3.5 mm in gray matter. These conclusions will help us optimally manipulate the parameter settings during surgery and determine the spatial resolution of the probe.

  5. Quantitative optical coherence elastography based on fiber-optic probe for in situ measurement of tissue mechanical properties.

    PubMed

    Qiu, Yi; Wang, Yahui; Xu, Yiqing; Chandra, Namas; Haorah, James; Hubbi, Basil; Pfister, Bryan J; Liu, Xuan

    2016-02-01

    We developed a miniature quantitative optical coherence elastography (qOCE) instrument with an integrated Fabry-Perot force sensor, for in situ elasticity measurement of biological tissue. The technique has great potential for biomechanics modeling and clinical diagnosis. We designed the fiber-optic qOCE probe that was used to exert a compressive force to deform tissue at the tip of the probe. Using the space-division multiplexed optical coherence tomography (OCT) signal detected by a spectral domain OCT engine, we were able to quantify the probe deformation that was proportional to the force applied, and to quantify the tissue deformation corresponding to the external stimulus. Simultaneous measurement of force and displacement allowed us to extract Young's modulus of biological tissue. We experimentally calibrated our qOCE instrument, and validated its effectiveness on tissue mimicking phantoms and biological tissues. PMID:26977372

  6. Quantitative optical coherence elastography based on fiber-optic probe for in situ measurement of tissue mechanical properties

    PubMed Central

    Qiu, Yi; Wang, Yahui; Xu, Yiqing; Chandra, Namas; Haorah, James; Hubbi, Basil; Pfister, Bryan J.; Liu, Xuan

    2016-01-01

    We developed a miniature quantitative optical coherence elastography (qOCE) instrument with an integrated Fabry-Perot force sensor, for in situ elasticity measurement of biological tissue. The technique has great potential for biomechanics modeling and clinical diagnosis. We designed the fiber-optic qOCE probe that was used to exert a compressive force to deform tissue at the tip of the probe. Using the space-division multiplexed optical coherence tomography (OCT) signal detected by a spectral domain OCT engine, we were able to quantify the probe deformation that was proportional to the force applied, and to quantify the tissue deformation corresponding to the external stimulus. Simultaneous measurement of force and displacement allowed us to extract Young’s modulus of biological tissue. We experimentally calibrated our qOCE instrument, and validated its effectiveness on tissue mimicking phantoms and biological tissues. PMID:26977372

  7. Optical probe for the cytochrome P-450 cholesterol side chain cleavage enzyme

    DOEpatents

    Marrone, Babetta L.; Simpson, Daniel J.; Unkefer, Clifford J.; Whaley, Thomas W.

    1993-01-01

    An optical probe enables the study of enzyme activity by absorbance spectroscopy or by sensitive fluorescence methods. In particular, the probe provides the ability to monitor the activity of cytochrome P-450.sub.scc enzyme, the rate limiting enzyme for steroid biosynthesis. Located on the inner mitochondrial membrane, P-450.sub.scc catalyzes the conversion of cholesterol to pregnenolone and isocapraldehyde by sequential oxidations of the cholesterol side chain. The fluorogenic probe includes a cholesterol-like steroid linked to a chromophore through a linking group. The chromophore is selected to have little optical response when linked to the steroid substrate and an enhanced optical response when cleaved from the substrate and linking group. Thus, a fluorescent anion that can be optically detected is generated by the side-chain cleavage reaction during steroidogenesis.

  8. Optical probe for the cytochrome P-450 cholesterol side chain cleavage enzyme

    DOEpatents

    Marrone, Babetta L.; Simpson, Daniel J.; Unkefer, Clifford J.; Whaley, Thomas W.

    1992-01-01

    An optical probe enables the study of enzyme activity by absorbance spectroscopy or by sensitive fluorescence methods. In particular, the probe provides the ability to monitor the activity of cytochrome P-450.sub.scc enzyme, the rate limiting enzyme for steroid biosynthesis. Located on the inner mitochondrial membrane, P-450.sub.scc catalyzes the conversion of cholesterol to pregnenolone and isocapraldehyde by sequential oxidations of the cholesterol side chain. The fluorogenic probe includes a cholesterol-like steroid linked to a chromophore through a linking group. The chromophore is selected to have little optical response when linked to the steroid substrate and an enhanced optical response when cleaved from the substrate and linking group. Thus, a fluorescent anion that can be optically detected is generated by the side-chain cleavage reaction during steroidogenesis.

  9. Optical probe for the cytochrome P-450 cholesterol side chain cleavage enzyme

    SciTech Connect

    Marrone, B.L.; Simpson, D.J.; Unkefer, C.J.; Whaley, T.W.

    1993-05-04

    An optical probe enables the study of enzyme activity by absorbance spectroscopy or by sensitive fluorescence methods. In particular, the probe provides the ability to monitor the activity of cytochrome P-450[sub scc] enzyme, the rate limiting enzyme for steroid biosynthesis. Located on the inner mitochondrial membrane, P-450[sub scc] catalyzes the conversion of cholesterol to prednesolone and isocapraldehyde by sequential oxidations of the cholesterol side chain. The fluorogenic probe includes a cholesterol-like steroid linked to a chromophore through a linking group. The chromophore is selected to have little optical response when linked to the steroid substrate and an enhanced optical response when cleaved from the substrate and linking group. Thus, a fluorescent anion that can be optically detected is generated by the side-chain cleavage reaction during steroidogenesis.

  10. Miniaturized magnetic-driven scanning probe for endoscopic optical coherence tomography.

    PubMed

    Pang, Ziwei; Wu, Jigang

    2015-06-01

    We designed and implemented a magnetic-driven scanning (MDS) probe for endoscopic optical coherence tomography (OCT). The probe uses an externally-driven tiny magnet in the distal end to achieve unobstructed 360-degree circumferential scanning at the side of the probe. The design simplifies the scanning part inside the probe and thus allows for easy miniaturization and cost reduction. We made a prototype probe with an outer diameter of 1.4 mm and demonstrated its capability by acquiring OCT images of ex vivo trachea and artery samples from a pigeon. We used a spectrometer-based Fourier-domain OCT system and the system sensitivity with our prototype probe was measured to be 91 dB with an illumination power of 850 μW and A-scan exposure time of 1 ms. The axial and lateral resolutions of the system are 6.5 μm and 8.1 μm, respectively. PMID:26114041

  11. Activatable Optical Probes for the Detection of Enzymes

    PubMed Central

    Drake, Christopher R.; Miller, David C.; Jones, Ella F.

    2013-01-01

    The early detection of many human diseases is crucial if they are to be treated successfully. Therefore, the development of imaging techniques that can facilitate early detection of disease is of high importance. Changes in the levels of enzyme expression are known to occur in many diseases, making their accurate detection at low concentrations an area of considerable active research. Activatable fluorescent probes show immense promise in this area. If properly designed they should exhibit no signal until they interact with their target enzyme, reducing the level of background fluorescence and potentially endowing them with greater sensitivity. The mechanisms of fluorescence changes in activatable probes vary. This review aims to survey the field of activatable probes, focusing on their mechanisms of action as well as illustrating some of the in vitro and in vivo settings in which they have been employed. PMID:23519774

  12. Synthesis of Optical Molecular Probes for electric potential across a cell membrane

    NASA Astrophysics Data System (ADS)

    Lamichhane, Roshan

    Optical Imaging of neuronal activities is an attractive method, but the two widely used optical imaging methods based on Fluorescence Resonance Transfer (FRET) and electrochromism have some deficiencies that Photo Induced Electron Transfer (PeT) method has eliminated. In the paper we talk about the synthesis of optical molecular probes that rely on PeT mechanism, and which could possibly be used to measure the transmembrane potential across the neuronal cell membranes.

  13. Properties of contact pressure induced by manually operated fiber-optic probes.

    PubMed

    Bregar, Maksimilijan; Cugmas, Blaž; Naglic, Peter; Hartmann, Daniela; Pernuš, Franjo; Likar, Boštjan; Bürmen, Miran

    2015-12-01

    We assess the properties of contact pressure applied by manually operated fiber-optic probes as a function of the operator, probe contact area, and sample stiffness. First, the mechanical properties of human skin sites with different skin structures, thicknesses, and underlying tissues were studied by in vivo indentation tests. According to the obtained results, three different homogeneous silicone skin phantoms were created to encompass the observed range of mechanical properties. The silicon phantoms were subsequently used to characterize the properties of the contact pressure by 10 experienced probe operators employing fiber-optic probes with different contact areas. A custom measurement system was used to collect the time-lapse of diffuse reflectance and applied contact pressure. The measurements were characterized by a set of features describing the transient and steady-state properties of the contact pressure and diffuse reflectance in terms of rise time, optical coupling, average value, and variability. The average applied contact pressure and contact pressure variability were found to significantly depend on the probe operator, probe contact area, and surprisingly also on the sample stiffness. Based on the presented results, we propose a set of practical guidelines for operators of manual probes. PMID:26720880

  14. Probing Atomic Dynamics and Structures Using Optical Patterns

    NASA Astrophysics Data System (ADS)

    Schmittberger, Bonnie L.; Gauthier, Daniel J.

    2015-05-01

    Pattern formation is a widely studied phenomenon that can provide fundamental insights into nonlinear systems. Emergent patterns in cold atoms are of particular interest in condensed matter physics and quantum information science because one can relate optical patterns to spatial structures in the atoms. In our experimental system, we study multimode optical patterns generated from a sample of cold, thermal atoms. We observe this nonlinear optical phenomenon at record low input powers due to the highly nonlinear nature of the spatial bunching of atoms in an optical lattice. We present a detailed study of the dynamics of these bunched atoms during optical pattern formation. We show how small changes in the atomic density distribution affect the symmetry of the generated patterns as well as the nature of the nonlinearity that describes the light-atom interaction. We gratefully acknowledge the financial support of the National Science Foundation through Grant #PHY-1206040.

  15. Probing high quality pentacene monolayers by optical methods

    NASA Astrophysics Data System (ADS)

    He, Rui; Tassi, Nancy G.; Blanchet, Graciela B.; Pinczuk, Aron

    2006-05-01

    We report optical studies of pentacene monolayers grown on poly-alpha-methyl-styrene (PAMS) substrates of high uniformity that reaches into the micron length-scale in the lateral dimension. Raman scattering intensities from a two-monolayer pentacene film exhibit large resonance enhancements when incoming and outgoing photon energies overlap the free exciton measured in optical emission. The incoming and outgoing resonance enhancements are of about the same strength. The free exciton optical emission band is sharp and intense, and it blue-shifts by about 85 meV from that of the pentacene single crystal.

  16. Applications of graphene and its derivatives in intracellular biosensing and bioimaging.

    PubMed

    Zhu, Xiaohua; Liu, Yang; Li, Pei; Nie, Zhou; Li, Jinghong

    2016-08-01

    Graphene has a unique planar structure, as well as excellent electronic properties, and has attracted a great deal of interest from scientists. Graphene and its derivatives display advantageous characteristics as a biosensing platform due to their high surface area, good biocompatibility and ease of functionalization. Moreover, graphene and its derivatives exhibit excellent optical properties; thus they are considered to be promising and attractive candidates for bioimaging, mainly of cells and tissues. Following an introduction and a discussion of the optical properties of graphene, this review assesses the methods for engineering the functions of graphene and its derivatives. Specific examples are given on the use of graphene and its derivatives in fluorescence bioimaging, surface-enhanced Raman scattering (SERS) imaging, and magnetic resonance imaging (MRI). Finally, the prospects and further developments in this exciting field of graphene-based materials are suggested. PMID:27373227

  17. Intelligent spectral signature bio-imaging in vivo for surgical applications

    NASA Astrophysics Data System (ADS)

    Jeong, Jihoon; Frykman, Philip K.; Gaon, Mark; Chung, Alice P.; Lindsley, Erik H.; Hwang, Jae Y.; Farkas, Daniel L.

    2007-02-01

    Multi-spectral imaging provides digital images of a scene or object at a large, usually sequential number of wavelengths, generating precise optical spectra at every pixel. We use the term "spectral signature" for a quantitative plot of optical property variations as a function of wavelengths. We present here intelligent spectral signature bio-imaging methods we developed, including automatic signature selection based on machine learning algorithms and database search-based automatic color allocations, and selected visualization schemes matching these approaches. Using this intelligent spectral signature bio-imaging method, we could discriminate normal and aganglionic colon tissue of the Hirschsprung's disease mouse model with over 95% sensitivity and specificity in various similarity measure methods and various anatomic organs such as parathyroid gland, thyroid gland and pre-tracheal fat in dissected neck of the rat in vivo.

  18. Numerical method to compute optical conductivity based on pump-probe simulations

    NASA Astrophysics Data System (ADS)

    Shao, Can; Tohyama, Takami; Luo, Hong-Gang; Lu, Hantao

    2016-05-01

    A numerical method to calculate optical conductivity based on a pump-probe setup is presented. Its validity and limits are tested and demonstrated via concrete numerical simulations on the half-filled one-dimensional extended Hubbard model both in and out of equilibrium. By employing either a steplike or a Gaussian-like probing vector potential, it is found that in nonequilibrium, the method in the narrow-probe-pulse limit can be identified with variant types of linear-response theory, which, in equilibrium, produce identical results. The observation reveals the underlying probe-pulse dependence of the optical conductivity calculations in nonequilibrium, which may have applications in the theoretical analysis of ultrafast spectroscopy measurements.

  19. Tuning Localized Surface Plasmon Resonance in Scanning Near-Field Optical Microscopy Probes.

    PubMed

    Vasconcelos, Thiago L; Archanjo, Bráulio S; Fragneaud, Benjamin; Oliveira, Bruno S; Riikonen, Juha; Li, Changfeng; Ribeiro, Douglas S; Rabelo, Cassiano; Rodrigues, Wagner N; Jorio, Ado; Achete, Carlos A; Cançado, Luiz Gustavo

    2015-06-23

    A reproducible route for tuning localized surface plasmon resonance in scattering type near-field optical microscopy probes is presented. The method is based on the production of a focused-ion-beam milled single groove near the apex of electrochemically etched gold tips. Electron energy-loss spectroscopy and scanning transmission electron microscopy are employed to obtain highly spatially and spectroscopically resolved maps of the milled probes, revealing localized surface plasmon resonance at visible and near-infrared wavelengths. By changing the distance L between the groove and the probe apex, the localized surface plasmon resonance energy can be fine-tuned at a desired absorption channel. Tip-enhanced Raman spectroscopy is applied as a test platform, and the results prove the reliability of the method to produce efficient scattering type near-field optical microscopy probes. PMID:26027751

  20. Reflective optical probing of laser-driven plasmas at the rear surface of solid targets

    NASA Astrophysics Data System (ADS)

    Metzkes, J.; Zeil, K.; Kraft, S. D.; Rehwald, M.; Cowan, T. E.; Schramm, U.

    2016-03-01

    In this paper, a reflective optical pump-probe technique for laser-driven plasmas at solid density target surfaces is presented. The technique is termed high depth-of-field time-resolved microscopy and it exploits the angular redistribution of the probe beam intensity after the probe’s reflection from an expanded and hence non-planar iso-density surface in the plasma. The main application of the robust technique, which uses simple imaging of the probe beam, is the spatio-temporal resolution of the plasma formation and expansion at the target rear surface. Analytic and numerical modeling of the experimental setup are applied for the analysis of the experimental results. The relevance and potential of the optical plasma probing method is highlighted by the application to targets of different geometries, helping to understand the target shape-related differences in the ion acceleration performance.

  1. Rugged fiber optic probes and sampling systems for remote chemical analysis via the Raman technique

    SciTech Connect

    Nave, S.E.

    1996-07-01

    Recent advances in fiber optics, diode lasers, CCD detectors, dielectric and holographic optical filters, grating spectrometers, and chemometric data analysis have greatly simplified Raman spectroscopy. In order to make a rugged fiber optic Raman probe for solids/slurries like these at Savannah River, we have designed a probe that eliminates as many optical elements and surfaces as possible. The diffuse reflectance probe tip is modified for Raman scattering by installing thin dielectric in-line filters. Effects of each filter are shown for the NaNO{sub 3} Raman spectrum. By using a diode laser excitation at 780 nm, fluorescence is greatly reduced, and excellent spectra may be obtained from organic solids. At SRS, fiber optic Raman probes are being developed for in situ chemical mapping of radioactive waste storage tanks. Radiation darkening of silica fiber optics is negligible beyond 700 nm. Corrosion resistance is being evaluated. Analysis of process gas (off-gas from SRS processes) is investigated in some detail: hydrogen in nitrogen with NO{sub 2} interference. Other applications and the advantages of the method are pointed out briefly.

  2. Silicon nanomaterials platform for bioimaging, biosensing, and cancer therapy.

    PubMed

    Peng, Fei; Su, Yuanyuan; Zhong, Yiling; Fan, Chunhai; Lee, Shuit-Tong; He, Yao

    2014-02-18

    Silicon nanomaterials are an important class of nanomaterials with great potential for technologies including energy, catalysis, and biotechnology, because of their many unique properties, including biocompatibility, abundance, and unique electronic, optical, and mechanical properties, among others. Silicon nanomaterials are known to have little or no toxicity due to favorable biocompatibility of silicon, which is an important precondition for biological and biomedical applications. In addition, huge surface-to-volume ratios of silicon nanomaterials are responsible for their unique optical, mechanical, or electronic properties, which offer exciting opportunities for design of high-performance silicon-based functional nanoprobes, nanosensors, and nanoagents for biological analysis and detection and disease treatment. Moreover, silicon is the second most abundant element (after oxygen) on earth, providing plentiful and inexpensive resources for large-scale and low-cost preparation of silicon nanomaterials for practical applications. Because of these attractive traits, and in parallel with a growing interest in their design and synthesis, silicon nanomaterials are extensively investigated for wide-ranging applications, including energy, catalysis, optoelectronics, and biology. Among them, bioapplications of silicon nanomaterials are of particular interest. In the past decade, scientists have made an extensive effort to construct a silicon nanomaterials platform for various biological and biomedical applications, such as biosensors, bioimaging, and cancer treatment, as new and powerful tools for disease diagnosis and therapy. Nonetheless, there are few review articles covering these important and promising achievements to promote the awareness of development of silicon nanobiotechnology. In this Account, we summarize recent representative works to highlight the recent developments of silicon functional nanomaterials for a new, powerful platform for biological and

  3. In Situ Biosynthesis of Fluorescent Platinum Nanoclusters: Toward Self-Bioimaging-Guided Cancer Theranostics.

    PubMed

    Chen, Donghua; Zhao, Chunqiu; Ye, Jing; Li, Qiwei; Liu, Xiaoli; Su, Meina; Jiang, Hui; Amatore, Christian; Selke, Matthias; Wang, Xuemei

    2015-08-19

    Among the noble-metal clusters, very few reports about platinum clusters were used as bioimaging probes of tumors except as a reducing catalyst. It is first established herein that the biocompatible platinum nanoclusters are spontaneously biosynthesized by cancerous cells (i.e., HepG2 (human hepatocarcinoma), A549 (lung cancer), and others) rather than noncancerous cells (i.e., L02 (human embryo liver cells)) when incubated with micromolar chloroplatinic acid solutions. These in situ biosynthesized platinum nanoclusters could be readily realized in a biological environment and emit a bright fluorescence at 460 nm, which could be further utilized to facilitate an excellent cancer-cell-killing efficiency when combined with porphyrin derivatives for photothermal treatment. This raises the possibility of providing a promising and precise bioimaging strategy for specific fluorescent self-biomarking of tumor locations and realizing fluorescence imaging-guided photothermal therapy of tumors. PMID:26227621

  4. Probing Nearest-Neighbor Correlations of Ultracold Fermions in an Optical Lattice

    SciTech Connect

    Greif, Daniel; Tarruell, Leticia; Uehlinger, Thomas; Joerdens, Robert; Esslinger, Tilman

    2011-04-08

    We demonstrate a probe for nearest-neighbor correlations of fermionic quantum gases in optical lattices. It gives access to spin and density configurations of adjacent sites and relies on creating additional doubly occupied sites by perturbative lattice modulation. The measured correlations for different lattice temperatures are in good agreement with an ab initio calculation without any fitting parameters. This probe opens new prospects for studying the approach to magnetically ordered phases.

  5. Broadband miniature optical ultrasound probe for high resolution vascular tissue imaging

    PubMed Central

    Colchester, Richard J.; Zhang, Edward Z.; Mosse, Charles A.; Beard, Paul C.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2015-01-01

    An all-optical ultrasound probe for vascular tissue imaging was developed. Ultrasound was generated by pulsed laser illumination of a functionalized carbon nanotube composite coating on the end face of an optical fiber. Ultrasound was detected with a Fabry-Pérot (FP) cavity on the end face of an adjacent optical fiber. The probe diameter was < 0.84 mm and had an ultrasound bandwidth of ~20 MHz. The probe was translated across the tissue sample to create a virtual linear array of ultrasound transmit/receive elements. At a depth of 3.5 mm, the axial resolution was 64 µm and the lateral resolution was 88 µm, as measured with a carbon fiber target. Vascular tissues from swine were imaged ex vivo and good correspondence to histology was observed. PMID:25909031

  6. Broadband miniature optical ultrasound probe for high resolution vascular tissue imaging.

    PubMed

    Colchester, Richard J; Zhang, Edward Z; Mosse, Charles A; Beard, Paul C; Papakonstantinou, Ioannis; Desjardins, Adrien E

    2015-04-01

    An all-optical ultrasound probe for vascular tissue imaging was developed. Ultrasound was generated by pulsed laser illumination of a functionalized carbon nanotube composite coating on the end face of an optical fiber. Ultrasound was detected with a Fabry-Pérot (FP) cavity on the end face of an adjacent optical fiber. The probe diameter was < 0.84 mm and had an ultrasound bandwidth of ~20 MHz. The probe was translated across the tissue sample to create a virtual linear array of ultrasound transmit/receive elements. At a depth of 3.5 mm, the axial resolution was 64 µm and the lateral resolution was 88 µm, as measured with a carbon fiber target. Vascular tissues from swine were imaged ex vivo and good correspondence to histology was observed. PMID:25909031

  7. A simple one-step synthesis of melanin-originated red shift emissive carbonaceous dots for bioimaging.

    PubMed

    Hu, Chuan; Liu, Yongmei; Chen, Jiantao; He, Qin; Gao, Huile

    2016-10-15

    Carbonaceous dots (CDs) are superior nanomaterials owing to their promising luminescence properties and good biocompatibility. However, most CDs have relatively short excitation/emission, which restrict their application in bioimaging. In this study, a simple one-step procedure was developed for synthesis of melanin-originated CDs (MNPs). The MNPs showed two long red shift emissions at 570nm and 645nm with broad absorptions from 200nm to 400nm and 500nm to 700nm, suggesting the great potential of MNPs in bioimaging. Besides, several experiments indicated that MNPs possessed good serum stability and well blood compatibility. In vitro, MNPs could be taken up by C6 cell in a concentration- and time-dependent manner with endosomes involved. In conclusion, MNPs were prepared using a simple one-step method with unique optical and good biological properties and could be used for bioimaging. PMID:27416289

  8. Optical imaging of reporter gene expression using a positron-emission-tomography probe

    NASA Astrophysics Data System (ADS)

    Liu, Hongguang; Ren, Gang; Liu, Shuanglong; Zhang, Xiaofen; Chen, Luxi; Han, Peizhen; Cheng, Zhen

    2010-11-01

    Reporter gene/reporter probe technology is one of the most important techniques in molecular imaging. Lately, many reporter gene/reporter probe systems have been coupled to different imaging modalities such as positron emission tomography (PET) and optical imaging (OI). It has been recently found that OI techniques could be used to monitor radioactive tracers in vitro and in living subjects. In this study, we further demonstrate that a reporter gene/nuclear reporter probe system [herpes simplex virus type-1 thymidine kinase (HSV1-tk) and 9-(4-18F-fluoro-3-[hydroxymethyl] butyl) guanine ([18F]FHBG)] could be successfully imaged by OI in vitro and in vivo. OI with radioactive reporter probes will facilitate and broaden the applications of reporter gene/reporter probe techniques in medical research.

  9. The development and evaluation of head probes for optical imaging of the infant head

    NASA Astrophysics Data System (ADS)

    Branco, Gilberto

    The objective of this thesis was to develop and evaluate optical imaging probes for mapping oxygenation and haemodynamic changes in the newborn infant brain. Two imaging approaches are being developed at University College London (UCL): optical topography (surface mapping of the cortex) and optical tomography (volume imaging). Both have the potential to provide information about the function of the normal brain and about a variety of neurophysiologies! abnormalities. Both techniques require an array of optical fibres/fibre bundles to be held in contact with the head, for periods of time from tens of seconds to an hour or more. The design of suitable probes must ensure the comfort and safety of the subject, and provide measurements minimally sensitive to external sources of light and patient motion. A series of prototype adaptable helmets were developed for optical tomography of the premature infant brain using the UCL 32-channel time-resolved system. They were required to attach 32 optical fibre bundles over the infant scalp, and were designed to accommodate infants with a variety of head shapes and sizes, aged between 24-weeks gestational age and term. Continual improvements to the helmet design were introduced following the evaluation of each prototype on infants in the hospital. Data were acquired to generate images revealing the concentration and oxygenation of blood in the brain, and the response of the brain to sensory stimulation. This part of the project also involved designing and testing new methods of acquiring calibration data using reference phantoms. The second focus of the project was the development of probes for use with the UCL frequency-multiplexed near-infrared topography system. This is being used to image functional activation in the infant cortex. A series of probes were developed and experiments were conducted to evaluate their sensitivity to patient motion and to compression of the probe. The probes have been used for a variety of

  10. Miniature real-time intraoperative forward-imaging optical coherence tomography probe

    PubMed Central

    Joos, Karen M.; Shen, Jin-Hui

    2013-01-01

    Optical coherence tomography (OCT) has a tremendous global impact upon the ability to diagnose, treat, and monitor eye diseases. A miniature 25-gauge forward-imaging OCT probe with a disposable tip was developed for real-time intraoperative ocular imaging of posterior pole and peripheral structures to improve vitreoretinal surgery. The scanning range was 2 mm when the probe tip was held 3-4 mm from the tissue surface. The axial resolution was 4-6 µm and the lateral resolution was 25-35 µm. The probe was used to image cellophane tape and multiple ocular structures. PMID:24009997

  11. Micro sized implantable ball lens-based fiber optic probe design

    NASA Astrophysics Data System (ADS)

    Cha, Jaepyeong; Kang, Jin U.

    2014-02-01

    A micro sized implantable ball lens-based fiber optic probe design is described for continuous monitoring of brain activity in freely behaving mice. A prototype uses a 500-micron ball lens and a highly flexible 350-micron-diameter fiber bundle, which are enclosed by a 21G stainless steel sheath. Several types and thickness of brain tissue, consisting of fluorescent probes such as GFP, GCaMP3 calcium indicator, are used to evaluate the performance of the imaging probe. Measured working distance is approximately 400-μm, but is long enough to detect neural activities from cortical and cerebellar tissues of mice brain.

  12. Modified hyper-Ramsey methods for the elimination of probe shifts in optical clocks

    NASA Astrophysics Data System (ADS)

    Hobson, R.; Bowden, W.; King, S. A.; Baird, P. E. G.; Hill, I. R.; Gill, P.

    2016-01-01

    We develop a method of modified hyper-Ramsey spectroscopy in optical clocks, achieving complete immunity to the frequency shifts induced by the probing fields themselves. Using particular pulse sequences with tailored phases, frequencies, and durations, we can derive an error signal centered exactly at the unperturbed atomic resonance with a steep discriminant which is robust against variations in the probe shift. We experimentally investigate the scheme using the magnetically induced 1S0-3P0 transition in 88Sr, demonstrating automatic suppression of a sizable 2 ×10-13 probe Stark shift to below 1 ×10-16 even with very large errors in shift compensation.

  13. Swept-source common-path optical coherence tomography with a MEMS endoscopic imaging probe

    NASA Astrophysics Data System (ADS)

    Duan, Can; Wang, Donglin; Zhou, Zhengwei; Liang, Peng; Samuelson, Sean; Pozzi, Antonio; Xie, Huikai

    2014-03-01

    A MEMS-based common-path endoscopic imaging probe for 3D swept-source optical coherence tomography (SSOCT) has been developed. The common path is achieved by setting the reference plane at the rear surface of the GRIN lens inside the probe. MEMS devices have the advantages of low cost, small size and fast speed, which are suitable for miniaturizing endoscopic probes. The aperture size of the two-axis MEMS mirror employed in this endoscopic probe is 1 mm by 1 mm and the footprint of the MEMS chip is 1.55 mm by 1.7 mm. The MEMS mirror achieves large two dimensional optical scan angles up to 34° at 4.0 V. The endoscopic probe using the MEMS mirror as the scan engine is only 4.0 mm in diameter. Additionally, an optimum length of the GRIN lens is established to remove the artifacts in the SSOCT images generated from the multiple interfaces inside the endoscopic imaging probe. The MEMS based commonpath probe demonstrates real time 3D OCT images of human finger with 10.6 μm axial resolution, 17.5 μm lateral resolution and 1.0 mm depth range at a frame rate of 50 frames per second.

  14. High speed miniature motorized endoscopic probe for 3D optical frequency domain imaging

    NASA Astrophysics Data System (ADS)

    Li, Jianan; Feroldi, Fabio; Mo, Jianhua; Helderman, Frank; de Groot, Mattijs; de Boer, Johannes F.

    2013-03-01

    We present a miniature motorized endoscopic probe for Optical Frequency Domain Imaging with an outer diameter of 1.65 mm and a rotation speed of 3,000 - 12,500 rpm. This is the smallest motorized high speed OCT probe to our knowledge. The probe has a motorized distal end which provides a significant advantage over proximally driven probes since it does not require a drive shaft to transfer the rotational torque to the distal end of the probe and functions without a fiber rotary junction. The probe has a focal Full Width at Half Maximum of 9.6 μm and a working distance of 0.47 mm. We analyzed the non-uniform rotation distortion and found a location fluctuation of only 1.87° in repeated measurements of the same object. The probe was integrated in a high-speed Optical Frequency Domain Imaging setup at 1310 nm We demonstrated its performance with imaging ex vivo pig bronchial and in vivo goat lung.

  15. Probing DNA with micro- and nanocapillaries and optical tweezers

    NASA Astrophysics Data System (ADS)

    Steinbock, L. J.; Otto, O.; Skarstam, D. R.; Jahn, S.; Chimerel, C.; Gornall, J. L.; Keyser, U. F.

    2010-11-01

    We combine for the first time optical tweezer experiments with the resistive pulse technique based on capillaries. Quartz glass capillaries are pulled into a conical shape with tip diameters as small as 27 nm. Here, we discuss the translocation of λ-phage DNA which is driven by an electrophoretic force through the nanocapillary. The resulting change in ionic current indicates the folding state of single λ-phage DNA molecules. Our flow cell design allows for the straightforward incorporation of optical tweezers. We show that a DNA molecule attached to an optically trapped colloid is pulled into a capillary by electrophoretic forces. The detected electrophoretic force is in good agreement with measurements in solid-state nanopores.

  16. Optical coherence tomography probe design for reduced artifact generation and manufacturability

    NASA Astrophysics Data System (ADS)

    Staloff, Daniel; Comstock, Lovell; Miller, William; Schreiber, Horst

    2016-03-01

    Many fiber based probes used in Optical Coherence Tomography (OCT) are comprised of a spacer, GRIN lens, fiber, and a microprism. This design form suffers from many material interfaces, which induce back reflections into the sample arm of the interferometer. With so many interfaces, these probes can produce artifacts in the system's imaging window. We present a design which has just two interfaces to minimize image artifacts. The two components of this design are the fiber endface and a reflective optic. With optimization, these two components can produce back reflections below -90dB which will minimize image artifacts. This will results in high fidelity imaging for medical diagnostics.

  17. Towards better scanning near-field optical microscopy probes--progress and new developments.

    PubMed

    Heinzelmann, H; Freyland, J M; Eckert, R; Huser, T; Schürmann, G; Noell, W; Staufer, U; De Rooij, N F

    1999-01-01

    Several approaches are described with the aim of producing near-field optical probes with improved properties. Focused ion beam milling allows the fabrication of small apertures in a controlled fashion, resulting in probes with excellent polarization properties and increased transmission. Microfabrication processes are described that allow the production of apertures of 30-50 nm, facilitating the mass-fabrication of apertured tip structures that can be used in a combined force/near-field optical microscope. Finally, possible future developments are outlined. PMID:11388268

  18. Generating and probing entangled states for optical atomic clocks

    NASA Astrophysics Data System (ADS)

    Braverman, Boris; Kawasaki, Akio; Vuletic, Vladan

    2016-05-01

    The precision of quantum measurements is inherently limited by projection noise caused by the measurement process itself. Spin squeezing and more complex forms of entanglement have been proposed as ways of surpassing this limitation. In our system, a high-finesse asymmetric micromirror-based optical cavity can mediate the atom-atom interaction necessary for generating entanglement in an 171 Yb optical lattice clock. I will discuss approaches for creating, characterizing, and optimally utilizing these nonclassical states for precision measurement, as well as recent progress toward their realization. This research is supported by DARPA QuASAR, NSF, and NSERC.

  19. Non-Invasive Optical Biosensor for Probing Cell Signaling

    PubMed Central

    Fang, Ye

    2007-01-01

    Cell signaling mediated through a cellular target is encoded by spatial and temporal dynamics of downstream signaling networks. The coupling of temporal dynamics with spatial gradients of signaling activities guides cellular responses upon stimulation. Monitoring the integration of cell signaling in real time, if realized, would provide a new dimension for understanding cell biology and physiology. Optical biosensors including resonant waveguide grating (RWG) biosensor manifest a physiologically relevant and integrated cellular response related to dynamic redistribution of cellular matters, thus providing a non-invasive means for cell signaling study. This paper reviews recent progresses in biosensor instrumentation, and theoretical considerations and potential applications of optical biosensors for whole cell sensing.

  20. Transpiration-purged optical probe: a novel sensor for high temperature harsh environments

    SciTech Connect

    VanOsdol, J.G.; Woodruff, S.D.; Straub, D.L.

    2007-10-05

    Typical control systems that are found in modern power plants must control the many physical aspects of the complex processes that occur inside the various components of the power plant. As detection and monitoring of pollutants becomes increasingly important to plant operation, these control systems will become increasingly complex, and will depend upon accurate monitoring of the concentration levels of the various chemical species that are found in the gas streams. In many cases this monitoring can be done optically. Optical access can also be used to measure thermal emissions and the particulate loading levels in the fluid streams. Some typical environments were optical access is needed are combustion chambers, reactor vessels, the gas and solid flows in fluidized beds, hot gas filters and heat exchangers. These applications all have harsh environments that are at high temperatures and pressures. They are often laden with products of combustion and other fine particulate matter which is destructive to any optical window that could be used to monitor the processes in these environments in order to apply some control scheme over the process. The dust and char that normally collects on the optical surfaces reduces the optical quality and thus impairs the ability of the optical surface to transmit data. Once this has occurred, there is generally no way to clean the optical surface during operation. The probe must be dismounted from the vessel, disassembled and cleaned or replaced, then remounted. This would require the shutdown of the particular component of the plant where optical monitoring is required. This renders the probe ineffective to be used as the monitoring part of any control system application. The components of optical monitoring equipment are usually built in supporting structures that require precise alignment. This is almost always accomplished using fine scale adjustments to specialized mounting hardware that is attached to the reactor vessel. When

  1. Bases for time-resolved probing of transient carrier dynamics by optical pump-probe scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Yokota, Munenori; Yoshida, Shoji; Mera, Yutaka; Takeuchi, Osamu; Oigawa, Haruhiro; Shigekawa, Hidemi

    2013-09-01

    The tangled mechanism that produces optical pump-probe scanning tunneling microscopy spectra from semiconductors was analyzed by comparing model simulation data with experimental data. The nonlinearities reflected in the spectra, namely, the excitations generated by paired laser pulses with a delay time, the logarithmic relationship between carrier density and surface photovoltage (SPV), and the effect of the change in tunneling barrier height depending on SPV, were examined along with the delay-time-dependent integration process used in measurement. The optimum conditions required to realize reliable measurement, as well as the validity of the microscopy technique, were demonstrated for the first time.

  2. Homodyne displacement measuring interferometer probe for optical coordinate measuring machine with tip and tilt sensitivity

    NASA Astrophysics Data System (ADS)

    Butler, Sam C.; Ricci, Michael A.; Wang, Chen; Wei, Qun; Ellis, Jonathan D.

    2015-10-01

    In this proceedings, we present a 3DoF (one linear, two angular) optical probe for measuring freeform optics in conjunction with an optical coordinate measuring machine (OCMM). This probe uses homodyne interferometry in a Michelson configuration and position sensing detection to simultaneously measure displacement, tip, and tilt. The goal of this work is to investigate point-to-point methods for measuring freeform optics and establish a probing methodology that can perform self-alignment with respect to the local optical surface. We present the design and preliminary benchtop validation of the probe's performance. Benchtop validation shows successful measurements with 5 nm linear and 20 μrad angular noise levels, with a 15 μm spot size. A CMOS sensor is used for visual confirmation of proper focus on measurement surface to minimize initial defocus error. A PSD detects linear horizontal and vertical displacement of the reflected beam from the measurement surface using autocollimation. In-phase and quadrature signals are measured by two photodetectors and post-processed to obtain displacement information. Periodic error caused by polarization effects and beam mixing is compensated by FPGA-based signal processing.

  3. Integrated Fiber-Optic Light Probe: Measurement of Static Deflections in Rotating Turbomachinery

    NASA Technical Reports Server (NTRS)

    Kurkov, Anatole P.

    1998-01-01

    At the NASA Lewis Research Center, in cooperation with Integrated Fiber Optic Systems, Inc., an integrated fiber-optic light probe system was designed, fabricated, and tested for monitoring blade tip deflections, vibrations, and to some extent, changes in the blade tip clearances of a turbomachinery fan or a compressor rotor. The system comprises a set of integrated fiber-optic light probes that are positioned to detect the passing blade tip at the leading and trailing edges. In this configuration, measurements of both nonsynchronous blade vibrations and steady-state blade deflections can be made from the timing information provided by each light probe-consisting of an integrated fiber-optic transmitting channel and numerical aperture receiving fibers, all mounted in the same cylindrical housing. With integrated fiber-optic technology, a spatial resolution of 50 mm is possible while the outer diameter is kept below 2.5 mm. To evaluate these probes, we took measurements in a single-stage compressor facility and an advanced fan rig in Lewis' 9- by 15-Foot Low-Speed Wind Tunnel.

  4. Probing myocardium biomechanics using quantitative optical coherence elastography

    NASA Astrophysics Data System (ADS)

    Wang, Shang; Lopez, Andrew L.; Morikawa, Yuka; Tao, Ge; Li, Jiasong; Larina, Irina V.; Martin, James F.; Larin, Kirill V.

    2015-03-01

    We present a quantitative optical coherence elastographic method for noncontact assessment of the myocardium elasticity. The method is based on shear wave imaging optical coherence tomography (SWI-OCT), where a focused air-puff system is used to induce localized tissue deformation through a low-pressure short-duration air stream and a phase-sensitive OCT system is utilized to monitor the propagation of the induced tissue displacement with nanoscale sensitivity. The 1-D scanning of M-mode OCT imaging and the application of optical phase retrieval and mapping techniques enable the reconstruction and visualization of 2-D depth-resolved shear wave propagation in tissue with ultra-high frame rate. The feasibility of this method in quantitative elasticity measurement is demonstrated on tissue-mimicking phantoms with the estimated Young's modulus compared with uniaxial compression tests. We also performed pilot experiments on ex vivo mouse cardiac muscle tissues with normal and genetically altered cardiomyocytes. Our results indicate this noncontact quantitative optical coherence elastographic method can be a useful tool for the cardiac muscle research and studies.

  5. An integrated fiber-optic probe combined with support vector regression for fast estimation of optical properties of turbid media.

    PubMed

    Zhou, Yang; Fu, Xiaping; Ying, Yibin; Fang, Zhenhuan

    2015-06-23

    A fiber-optic probe system was developed to estimate the optical properties of turbid media based on spatially resolved diffuse reflectance. Because of the limitations in numerical calculation of radiative transfer equation (RTE), diffusion approximation (DA) and Monte Carlo simulations (MC), support vector regression (SVR) was introduced to model the relationship between diffuse reflectance values and optical properties. The SVR models of four collection fibers were trained by phantoms in calibration set with a wide range of optical properties which represented products of different applications, then the optical properties of phantoms in prediction set were predicted after an optimal searching on SVR models. The results indicated that the SVR model was capable of describing the relationship with little deviation in forward validation. The correlation coefficient (R) of reduced scattering coefficient μ'(s) and absorption coefficient μ(a) in the prediction set were 0.9907 and 0.9980, respectively. The root mean square errors of prediction (RMSEP) of μ'(s) and μ(a) in inverse validation were 0.411 cm(-1) and 0.338 cm(-1), respectively. The results indicated that the integrated fiber-optic probe system combined with SVR model were suitable for fast and accurate estimation of optical properties of turbid media based on spatially resolved diffuse reflectance. PMID:26092344

  6. Design of a compact laparoscopic probe for optical stimulation of the cavernous nerves

    NASA Astrophysics Data System (ADS)

    Tozburun, Serhat; Fried, Nathaniel M.

    2009-02-01

    The cavernous nerves are responsible for erectile function and course along the prostate surface, varying in size and location among patients, making preservation of sexual function challenging after prostate cancer surgery. Electrical stimulation has proven inconsistent and unreliable in identifying these nerves and evaluating nerve function. Optical stimulation of the rat cavernous nerves has recently been reported as a alternative to electrical stimulation, with potential advantages including noncontact stimulation and improved spatial selectivity. This study describes the design of a compact laparoscopic probe for future clinical use in optical nerve stimulation. The 10-Fr (3.4-mm-OD) prototype laparoscopic probe includes an aspheric lens for collimation of the laser beam with a 0.8- mm-diameter spot, coupled with a 200-μm-core optical fiber. A 45° gold-coated rod mirror in the probe tip provides side-firing delivery of the laser radiation. The probe handle houses a miniature linear motorized stage for lateral scanning of the probe tip over a 25-mm line along the prostate surface. A 5.5-W Thulium fiber laser with tunable wavelength range of 1850-1880 nm was tested with the probe. The probe fits through a standard 5-mm-ID laparoscopic port and is capable of delivering pulse energies up to 8 mJ (1.6 J/cm2) at a 2.5-ms pulse duration, well above the threshold (~ 0.35 J/cm2) for optical stimulation of the cavernous nerves.

  7. Asteroid (4179) Toutatis size determination via optical images observed by the Chang'e-2 probe

    NASA Astrophysics Data System (ADS)

    Liu, P.; Huang, J.; Zhao, W.; Wang, X.; Meng, L.; Tang, X.

    2014-07-01

    This work is a physical and statistical study of the asteroid (4179) Toutatis using the optical images obtained by a solar panel monitor of the Chang'e-2 probe on Dec. 13, 2012 [1]. In the imaging strategy, the camera is focused at infinity. This is specially designed for the probe with its solar panels monitor's principle axis pointing to the relative velocity direction of the probe and Toutatis. The imaging strategy provides a dedicated way to resolve the size by multi-frame optical images. The inherent features of the data are: (1) almost no rotation was recorded because of the 5.41-7.35 Earth-day rotation period and the small amount of elapsed imaging time, only minutes, make the object stay in the images in a fixed position and orientation; (2) the sharpness of the upper left boundary and the vagueness of lower right boundary resulting from the direction of SAP (Sun-Asteroid-Probe angle) cause a varying accuracy in locating points at different parts of Toutatis. A common view is that direct, accurate measurements of asteroid shapes, sizes, and pole positions are now possible for larger asteroids that can be spatially resolved using the Hubble Space Telescope or large ground-based telescopes equipped with adaptive optics. For a quite complex planetary/asteroid probe study, these measurements certainly need continuous validation via a variety of ways [2]. Based on engineering parameters of the probe during the fly-by, the target spatial resolving and measuring procedures are described in the paper. Results estimated are optical perceptible size on the flyby epoch under the solar phase angles during the imaging. It is found that the perceptible size measured using the optical observations and the size derived from the radar observations by Ostro et al.~in 1995 [3], are close to one another.

  8. Common path ball lens probe for optical coherence tomography (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Singh, Kanwarpal; Yamada, Daisuke; Tearney, Guillermo J.

    2016-02-01

    Background: Common path probes are highly desirable for optical coherence tomography (OCT) as they reduce system complexity and cost. In this work we report an all-fiber common path side viewing monolithic probe for coronary artery imaging. Methods: Our common path probe was designed for spectrometer based Fourier domain OCT at 1310 nm wavelength. Light from the fiber expands in the coreless fiber region and then focussed by the ball lens. Reflection from ball lens-air interface served as reference signal. The monolithic ball lens probe was assembled within a 560 µmouter diameter drive shaft which was attached to a rotary junction. The drive shaft was placed inside an outer, transparent sheath of 800 µm diameter. Results: With a source input power of 25 mW, we could achieve sensitivity of 100.5 dB. The axial resolution of the system was found to be 15.6 µm in air and the lateral resolution (full width half maximum) was approximately 49 µm. As proof of principal, images of skin acquired using this probe demonstrated clear visualization of the stratum corneum, epidermis, and papillary dermis, along with sweat ducts. Conclusion: In this work we have demonstrated a monolithic, ball lens common, path probe for OCT imaging. The designed ball lens probe is easy to fabricate using a laser splicer. Based on the features and capability of common path probes to provide a simpler solution for OCT, we believe that this development will be an important enhancement for certain types of catheters.

  9. CTU Optical probes for liquid phase detection in the 1000 MW steam turbine

    NASA Astrophysics Data System (ADS)

    Kolovratník, Michal; Bartoš, Ondřej

    2015-05-01

    The aim of this paper is to introduce the measurement capacity of a new generation of CTU's optical probes to determine the liquid phase distribution in steam turbines and other energy systems. At the same time the paper presents the first part of the results concerning output wetness achieved through the use of experimental research performed with the probes in a new low pressure (LP) part of the steam turbine 1000MW in the Temelin nuclear power plant (ETE). Two different probes were used. A small size extinction probe with a diameter of 25mm which was developed for measuring in a wider range of turbines in comparison with the previous generation with a diameter of 50mm. The second probe used was a photogrammetric probe developed to observe the coarse droplets. This probe is still under development and this measurement was focused on verifying the capabilities of the probe. The data processing technique is presented together with yielded examples of the wetness distribution along the last blade of the 1000MW steam turbine. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o. (DSP).

  10. All-reflective femtosecond optical pump-probe setup for transient grating spectroscopy.

    PubMed

    Cucini, R; Bencivenga, F; Masciovecchio, C

    2011-04-01

    We developed a pump-probe setup that can be used for free electron lasers based four-wave mixing experiments in the extreme ultraviolet/soft x-ray spectral range. The main feature of the proposed optical layout is the absence of transmission optics. Test measurements on liquid and solid samples carried out using the transient grating technique in both transmission and reflection geometry demonstrate the reliability of the setup. PMID:21478973

  11. Pump-probe quantum state tomography in a semiconductor optical amplifier.

    PubMed

    Grosse, N B; Owschimikow, N; Aust, R; Lingnau, B; Koltchanov, A; Kolarczik, M; Lüdge, K; Woggon, U

    2014-12-29

    Pump-probe quantum state tomography was applied to the transmission of a coherent state through an In(Ga)As based quantum dot optical amplifier during the interaction with an optical pump pulse. The Wigner function and the statistical moments of the field were extracted and used to determine the degree of population inversion and the signal-to-noise ratio in a sub-picosecond time window. PMID:25607214

  12. Facilitation at single synapses probed with optical quantal analysis.

    PubMed

    Oertner, Thomas G; Sabatini, Bernardo L; Nimchinsky, Esther A; Svoboda, Karel

    2002-07-01

    Many synapses can change their strength rapidly in a use-dependent manner, but the mechanisms of such short-term plasticity remain unknown. To understand these mechanisms, measurements of neurotransmitter release at single synapses are required. We probed transmitter release by imaging transient increases in [Ca(2+)] mediated by synaptic N-methyl-D-aspartate receptors (NMDARs) in individual dendritic spines of CA1 pyramidal neurons in rat brain slices, enabling quantal analysis at single synapses. We found that changes in release probability, produced by paired-pulse facilitation (PPF) or by manipulation of presynaptic adenosine receptors, were associated with changes in glutamate concentration in the synaptic cleft, indicating that single synapses can release a variable amount of glutamate per action potential. The relationship between release probability and response size is consistent with a binomial model of vesicle release with several (>5) independent release sites per active zone, suggesting that multivesicular release contributes to facilitation at these synapses. PMID:12055631

  13. Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application.

    PubMed

    Huang, Zhulin; Lei, Xing; Liu, Ye; Wang, Zhiwei; Wang, Xiujuan; Wang, Zhaoming; Mao, Qinghe; Meng, Guowen

    2015-08-12

    Optical fiber-Raman devices integrated with plasmonic nanostructures have promising potentials for in situ probing remote liquid samples and biological samples. In this system, the fiber probe is required to simultaneously demonstrate stable surface enhanced Raman scattering (SERS) signals and high sensitivity toward the target species. Here we demonstrate a generic approach to integrate presynthesized plasmonic nanostructures with tapered fiber probes that are prepared by a dipping-etching method, through reversed electrostatic attraction between the silane couple agent modified silica fiber probe and the nanostructures. Using this approach, both negatively and positively charged plasmonic nanostructures with various morphologies (such as Au nanosphere, Ag nanocube, Au nanorod, Au@Ag core-shell nanorod) can be stably assembled on the tapered silica fiber probes. Attributed to the electrostatic force between the plasmonic units and the fiber surface, the nanostructures do not disperse in liquid samples easily, making the relative standard deviation of SERS signals as low as 2% in analyte solution. Importantly, the detection sensitivity of the system can be optimized by adjusting the cone angle (from 3.6° to 22°) and the morphology of nanostructures assembled on the fiber. Thus, the nanostructures-sensitized optical fiber-Raman probes show great potentials in the applications of SERS-based environmental detection of liquid samples. PMID:26186260

  14. MatMix 1.0: Using optical mixing to probe visual material perception.

    PubMed

    Zhang, Fan; de Ridder, Huib; Fleming, Roland W; Pont, Sylvia

    2016-04-01

    MatMix 1.0 is a novel material probe we developed for quantitatively measuring visual perception of materials. We implemented optical mixing of four canonical scattering modes, represented by photographs, as the basis of the probe. In order to account for a wide range of materials, velvety and glittery (asperity and meso-facet scattering) were included besides the common matte and glossy modes (diffuse and forward scattering). To test the probe, we conducted matching experiments in which inexperienced observers were instructed to adjust the modes of the probe to match its material to that of a test stimulus. Observers were well able to handle the probe and match the perceived materials. Results were robust across individuals, across combinations of materials, and across lighting conditions. We conclude that the approach via canonical scattering modes and optical mixing works well, although the image basis of our probe still needs to be optimized. We argue that the approach is intuitive, since it combines key image characteristics in a "painterly" approach. We discuss these characteristics and how we will optimize their representations. PMID:27089066

  15. NEAR-INFRARED DYES: Probe Development and Applications in Optical Molecular Imaging

    PubMed Central

    Nolting, Donald D.; Gore, John C.; Pham, Wellington

    2010-01-01

    The recent emergence of optical imaging has brought forth a unique challenge for chemists: development of new biocompatible dyes that fluoresce in the near-infrared (NIR) region for optimal use in biomedical applications. This review describes the synthesis of NIR dyes and the design of probes capable of noninvasively imaging molecular events in small animal models. PMID:21822405

  16. Use of a fiber-optic probe during CO2 laser drilling

    NASA Astrophysics Data System (ADS)

    Yilbas, Bekir S.; Sahin, Ahmet Z.; Ciftlikli, Cebrail

    1993-09-01

    The present study examines the effect of plasma on CO2 laser drilling of mild steel samples using oxygen assisting gas at different pressures. A fiber optic probe was used to detect the plasma on the surface of the workpiece. Mild steel samples at different thicknesses were used as workpieces. Oxygen was introduced coaxially with the laser beam.

  17. Local measurement in Freon R123 two-phase vertical upflow using bi-optical probe

    SciTech Connect

    Saito, T.; Matsutani, K.; Iwase, T.; Sunami, T.; Tomomatsu, K.; Ueno, T.; Osaki, T.

    1995-12-31

    In the U-bend region of steam generator of PWR plant, the authors have experienced some tube failures due to flow induced vibration. In this project, the thermal hydraulic and flow induced vibration tests are planned using the model steam generator equipped with the large scale U-bend tube bundle and the Freon two-phase flow loop. The objectives of this project are to verify the reliability of U-bend tubes and to upgrade the technologies to evaluate the thermal hydraulic behaviors in U-bend region and the flow induced vibration of U-bend tubes. The void fraction and interfacial velocity are key parameters for the flow induced vibration phenomena. So, it is important to measure the void fraction and interfacial velocity precisely. In order to confirm the capability of bi-optical probe for the measurement of those key parameters in the Freon two-phase flow, the authors performed the verification test of bi-optical probe. This paper describes the results of the verification test of bi-optical probe. The verification test has been performed using a single pipe. The void fractions and interfacial velocities have been measured at some local positions in the single pipe using bi-optical probe.

  18. Optical signaling in biofluids: a nondenaturing photostable molecular probe for serum albumins.

    PubMed

    Dey, Gourab; Gaur, Pankaj; Giri, Rajanish; Ghosh, Subrata

    2016-01-31

    The systematic investigation of the interaction of a new class of molecular materials with proteins through structure-optical signaling relationship studies has led to the development of efficient fluorescent probes that can detect and quantify serum albumins in biofluids without causing any denaturation. PMID:26675447

  19. Bimodal endoscopic probe combining white-light microscopy and optical coherence tomography.

    PubMed

    Blattmann, M; Kretschmer, S; Thiele, S; Ataman, C; Zappe, H; Herkommer, A; Seifert, A

    2016-05-20

    We present a novel bimodal endoscopic imaging probe that can simultaneously provide full-field white-light video microscopy and confocal optical coherence tomography (OCT) depth scans. The two modalities rely on spectrally separated optical paths that run partially in parallel through a micro-optical bench system, which has a cross-section of only 2  mm×2.76  mm and is realized via standard silicon micromachining techniques. With a numerical aperture of 0.061, the video modality has a resolution and field of view of 9.3 and 1240  μm×1080  μm, respectively. The resolution is limited by the pixel spacing of the coherent fiber bundle, which relays the acquired image from the distal to the proximal end. A custom-designed diffractive optical element placed within the video imaging path significantly improves the image contrast by up to 45% in the medium frequency range. The OCT modality is optimized for 830 nm center wavelength, and works in a confocal arrangement with an NA of 0.018. It provides single-point depth probing at the center of the video image with a lateral resolution of 20 μm. Through its compact footprint and enhanced functionality, the probe can provide depth-resolved guiding capability for existing laparoscopes and represents a major step toward a new class of multimodal endoscopic imaging probes. PMID:27411158

  20. A New Generation Fiber Optic Probe: Characterization of Biological Fluids, Protein Crystals and Ophthalmic Diseases

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Suh, Kwang I.

    1996-01-01

    A new fiber optic probe developed for determining transport properties of sub-micron particles in fluids experiments in a microgravity environment has been applied to characterize particulate dispersions/suspensions in various challenging environments which have been hitherto impossible. The probe positioned in front of a sample delivers a low power light (few nW - 3mW) from a laser and guides the light which is back scattered by the suspended particles through a receiving optical fiber to a photo detector and to a digital correlator. The probe provides rapid determination of macromolecular diffusivities and their respective size distributions. It has been applied to characterize various biological fluids, protein crystals, and ophthalmic diseases.

  1. Field-hardened optical waveguide hybrid integrated-circuit multisensor chemical probe and its chemistry

    NASA Astrophysics Data System (ADS)

    Pollina, Richard J.; Himka, Roger L.; Saini, Devinder P.; McGibbon, Alan; Klainer, Stanley M.

    1997-05-01

    A single probe containing three hybrid integrated-circuit, optical waveguide, chemical-biochemical sensors (chip sensors) has been developed. Each chip sensor contains two hybrid waveguides -- one for sensing and one for reference. The sense waveguide is coated with a species-specific or group-specific chemistry or biochemistry. The reference waveguide is coated with a version of the sense chemistry or biochemistry, which is not sensitive to the analyte. The integrated structure is encapsulated and contains a single fixed light source, two detectors (reference and sense), and an optical train. The design is amenable to fluorescence, absorption, and refraction measurements. The three chip sensors are individually mounted in a probe that contains all of the electronics and computing capability necessary to collect and process the output information from each chip sensor. Only the surface of the individual chips are exposed to the target analytes. The probe is rugged, intrinsically safe, and can operate under 75 m (250 ft) of water.

  2. Optical properties of microfabricated fully-metal-coated near-field probes in collection mode.

    PubMed

    Descrovi, Emiliano; Vaccaro, Luciana; Aeschimann, Laure; Nakagawa, Wataru; Staufer, Urs; Herzig, Hans-Peter

    2005-07-01

    A study of the optical properties of microfabricated, fully-metal-coated quartz probes collecting longitudinal and transverse optical fields is presented. The measurements are performed by raster scanning the focal plane of an objective, focusing azimuthally and radially polarized beams by use of two metal-coated quartz probes with different metal coatings. A quantitative estimation of the collection efficiencies and spatial resolutions in imaging both longitudinal and transverse fields is made. Longitudinally polarized fields are collected with a resolution approximately 1.5 times higher as compared with transversely polarized fields, and this behavior is almost independent of the roughness of the probe's metal coating. Moreover, the coating roughness is a critical parameter in the relative collection efficiency of the two field orientations. PMID:16053165

  3. Single-crystal sapphire tubes as economical probes for optical pyrometry in harsh environments

    SciTech Connect

    Ruzicka, Jakub; Houzvicka, Jindrich; Bok, Jiri; Praus, Petr; Mojzes, Peter

    2011-12-20

    One-end-sealed single-crystal sapphire tubes are presented as a simple, robust, and economical alternative for bulky lightpipe probes. Thermal radiation from a blackbody cavity created at the inner surface of the sealed end is gathered by a simple lens-based collecting system and transmitted via optical fiber to the remote detection unit. Simplicity and applicability of the concept are demonstrated by the combination of commercially available sapphire tubes with a common optical pyrometer. Radiation thermometers with sapphire tubes as invasive probes can be useful for applications requiring immunity to electromagnetic interference, resistance to harsh environments, simple replacement in the case of failure, and enhanced mechanical firmness, enabling wider range probe positioning inside the medium of interest.

  4. Fiber optic cone penetrometer raman probe for in situ chemical characterization of the Hanford underground waste tanks

    SciTech Connect

    Kyle, K.R.; Brown, S.B.

    1997-03-03

    A field hardened fiber optic Raman probe has been developed for cone penetrometer deployment in the Hanford underground chemical waste storage tanks. The corrosive chemical environment of the tanks, as well as Hanford specific deployment parameters, provide unique challenges for the design of an optical probe.

  5. Nanostructure materials for biosensing and bioimaging applications

    NASA Astrophysics Data System (ADS)

    Law, Wing Cheung

    not fully understand, three possible factors are concluded after systematic researches: (i) an increase of the absolute mass in each binding event, (ii) an increase in the bulk refractive index of the analyte, and (iii) coupling between the localized surface plasmon resonance (LSPR) of metallic nanoparticles and surface plasmon resonance (SPR) of the sensing film. Indeed, the role of plasmonic coupling in sensitivity enhancement is still an open question. In order to obtain a better understanding of this phenomenon, at the end of part I, extended studies were performed to investigate how the LSPR properties of metallic nanoparticle labels correlate with the enhancement factor. For this purpose, gold nanorods (Au-NRs) were chosen as the amplification labels because of the easy tunability of LSPR peak of Au-NR. After reading the "Result and Discussion" section, the readers will have better understanding of "plasmonic coupling" between the sensing film and the metallic labels with suitable operating laser source. In the second part of the thesis, the bioimaging part, the application of nanostructure materials in live cancer cell imaging and small animal imaging were demonstrated. There are different types of imaging technique available in laboratories and clinics: optical imaging, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), thermography and ultrasound imaging. Although such imaging techniques have been well developed and used over a decade, improving the sensitivity, enhancing the contrast, decreasing the acquisition time and reducing the toxicity of the contrast agent are highly desirable. For optical imaging, the scientists discovered that the use of near infrared fluorescence materials can assist the surgeon to locate the tumor, the nerve and the lymph node more accurately. For CT scan, the use of Au-NR as the contrast agent can improve the sensitivity. Iron oxide nanoparticle or gadolinium ion containing

  6. Probing graphene defects and estimating graphene quality with optical microscopy

    SciTech Connect

    Lai, Shen; Kyu Jang, Sung; Jae Song, Young; Lee, Sungjoo

    2014-01-27

    We report a simple and accurate method for detecting graphene defects that utilizes the mild, dry annealing of graphene/Cu films in air. In contrast to previously reported techniques, our simple approach with optical microscopy can determine the density and degree of dislocation of defects in a graphene film without inducing water-related damage or functionalization. Scanning electron microscopy, confocal Raman and atomic force microscopy, and X-ray photoelectron spectroscopy analysis were performed to demonstrate that our nondestructive approach to characterizing graphene defects with optimized thermal annealing provides rapid and comprehensive determinations of graphene quality.

  7. Upconverting and NIR emitting rare earth based nanostructures for NIR-bioimaging

    NASA Astrophysics Data System (ADS)

    Hemmer, Eva; Venkatachalam, Nallusamy; Hyodo, Hiroshi; Hattori, Akito; Ebina, Yoshie; Kishimoto, Hidehiro; Soga, Kohei

    2013-11-01

    In recent years, significant progress was achieved in the field of nanomedicine and bioimaging, but the development of new biomarkers for reliable detection of diseases at an early stage, molecular imaging, targeting and therapy remains crucial. The disadvantages of commonly used organic dyes include photobleaching, autofluorescence, phototoxicity and scattering when UV (ultraviolet) or visible light is used for excitation. The limited penetration depth of the excitation light and the visible emission into and from the biological tissue is a further drawback with regard to in vivo bioimaging. Lanthanide containing inorganic nanostructures emitting in the near-infrared (NIR) range under NIR excitation may overcome those problems. Due to the outstanding optical and magnetic properties of lanthanide ions (Ln3+), nanoscopic host materials doped with Ln3+, e.g. Y2O3:Er3+,Yb3+, are promising candidates for NIR-NIR bioimaging. Ln3+-doped gadolinium-based inorganic nanostructures, such as Gd2O3:Er3+,Yb3+, have a high potential as opto-magnetic markers allowing the combination of time-resolved optical imaging and magnetic resonance imaging (MRI) of high spatial resolution. Recent progress in our research on over-1000 nm NIR fluorescent nanoprobes for in vivo NIR-NIR bioimaging will be discussed in this review.In recent years, significant progress was achieved in the field of nanomedicine and bioimaging, but the development of new biomarkers for reliable detection of diseases at an early stage, molecular imaging, targeting and therapy remains crucial. The disadvantages of commonly used organic dyes include photobleaching, autofluorescence, phototoxicity and scattering when UV (ultraviolet) or visible light is used for excitation. The limited penetration depth of the excitation light and the visible emission into and from the biological tissue is a further drawback with regard to in vivo bioimaging. Lanthanide containing inorganic nanostructures emitting in the near

  8. Ball lens based lensed patch cord probes for optical coherence tomography in the field of dentistry

    NASA Astrophysics Data System (ADS)

    Eom, J. B.; Kim, Y.; Lee, S. J.; Min, E. J.; Park, S. J.; Lee, B. H.

    2012-10-01

    A lensed patch cord probe has been made with a ball lens packaged in a metal cylinder. By simply placing a ball lens directly in front of a fiber patch cord, a compact and potentially disposable sampling probe for optical coherence tomography (OCT) could be implemented. To achieve a sufficiently long working distance and a good transverse resolution simultaneously, the proper ball lens diameter and the distance between the ball lens and the fiber patch cord were investigated. Experimentally, a working distance of up to 5.2 mm, 3 dB bandwidth of 2 mm, and transverse resolution of 16 μm were achieved. With the patch cord probe, a common path swept source OCT system was implemented and used to demonstrate the feasibility as the dedicated probe for dentistry.

  9. Common-path optical coherence tomography using a microelectromechanical-system-based endoscopic probe.

    PubMed

    Wang, Donglin; Duan, Can; Zhang, Xiaoyang; Yun, Zhao; Pozzi, Antonio; Xie, Huikai

    2016-09-01

    This paper presents a common-path (CP) swept-source optical coherence tomography (SSOCT) system based on a special endoscopic probe design with an in-line internal reflection as the reference and a two-axis electrothermal microelectromechanical system mirror for image scanning. The rear surface of a gradient reflective index (GRIN) lens inside the probe is set as the reference reflection plane. The length of the GRIN lens is optimized to eliminate the artifacts in SSOCT images successfully. Doppler OCT is also demonstrated based on the CP endoscopic probe. The diameter of the probe is only 2.5 mm, so it can be easily inserted into the biopsy channel of traditional endoscopes to access human internal organs for in vivo diagnoses. PMID:27607267

  10. Probing vacuum birefringence using x-ray free electron and optical high-intensity lasers

    NASA Astrophysics Data System (ADS)

    Karbstein, Felix; Sundqvist, Chantal

    2016-07-01

    Vacuum birefringence is one of the most striking predictions of strong field quantum electrodynamics: Probe photons traversing a strong field region can indirectly sense the applied "pump" electromagnetic field via quantum fluctuations of virtual charged particles which couple to both pump and probe fields. This coupling is sensitive to the field alignment and can effectively result in two different indices of refraction for the probe photon polarization modes giving rise to a birefringence phenomenon. In this article, we perform a dedicated theoretical analysis of the proposed discovery experiment of vacuum birefringence at an x-ray free electron laser/optical high-intensity laser facility. Describing both pump and probe laser pulses realistically in terms of their macroscopic electromagnetic fields, we go beyond previous analyses by accounting for various effects not considered before in this context. Our study facilitates stringent quantitative predictions and optimizations of the signal in an actual experiment.

  11. Probing many-body interactions in an optical lattice clock

    SciTech Connect

    Rey, A.M.; Gorshkov, A.V.; Kraus, C.V.; Martin, M.J.; Bishof, M.; Swallows, M.D.; Zhang, X.; Benko, C.; Ye, J.; Lemke, N.D.; Ludlow, A.D.

    2014-01-15

    We present a unifying theoretical framework that describes recently observed many-body effects during the interrogation of an optical lattice clock operated with thousands of fermionic alkaline earth atoms. The framework is based on a many-body master equation that accounts for the interplay between elastic and inelastic p-wave and s-wave interactions, finite temperature effects and excitation inhomogeneity during the quantum dynamics of the interrogated atoms. Solutions of the master equation in different parameter regimes are presented and compared. It is shown that a general solution can be obtained by using the so called Truncated Wigner Approximation which is applied in our case in the context of an open quantum system. We use the developed framework to model the density shift and decay of the fringes observed during Ramsey spectroscopy in the JILA {sup 87}Sr and NIST {sup 171}Yb optical lattice clocks. The developed framework opens a suitable path for dealing with a variety of strongly-correlated and driven open-quantum spin systems. -- Highlights: •Derived a theoretical framework that describes many-body effects in a lattice clock. •Validated the analysis with recent experimental measurements. •Demonstrated the importance of beyond mean field corrections in the dynamics.

  12. The Conformation of Thermoresponsive Polymer Brushes Probed by Optical Reflectivity.

    PubMed

    Varma, Siddhartha; Bureau, Lionel; Débarre, Delphine

    2016-04-01

    We describe a microscope-based optical setup that allows us to perform space- and time-resolved measurements of the spectral reflectance of transparent substrates coated with ultrathin films. This technique is applied to investigate the behavior in water of thermosensitive polymer brushes made of poly(N-isopropylacrylamide) grafted on glass. We show that spectral reflectance measurements yield quantitative information about the conformation and axial structure of the brushes as a function of temperature. We study how parameters such as grafting density and chain length affect the hydration state of a brush, and provide one of the few experimental evidences for the occurrence of vertical phase separation in the vicinity of the lower critical solution temperature of the polymer. The origin of the hysteretic behavior of poly(N-isopropylacrylamide) brushes upon cycling the temperature is also clarified. We thus demonstrate that our optical technique allows for in-depth characterization of stimuli-responsive polymer layers, which is crucial for the rational design of smart polymer coatings in actuation, gating, or sensing applications. PMID:26986181

  13. All-optical pulse-echo ultrasound probe for intravascular imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Colchester, Richard J.; Noimark, Sacha; Mosse, Charles A.; Zhang, Edward Z.; Beard, Paul C.; Parkin, Ivan P.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2016-02-01

    High frequency ultrasound probes such as intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) catheters can be invaluable for guiding minimally invasive medical procedures in cardiology such as coronary stent placement and ablation. With current-generation ultrasound probes, ultrasound is generated and received electrically. The complexities involved with fabricating these electrical probes can result in high costs that limit their clinical applicability. Additionally, it can be challenging to achieve wide transmission bandwidths and adequate wideband reception sensitivity with small piezoelectric elements. Optical methods for transmitting and receiving ultrasound are emerging as alternatives to their electrical counterparts. They offer several distinguishing advantages, including the potential to generate and detect the broadband ultrasound fields (tens of MHz) required for high resolution imaging. In this study, we developed a miniature, side-looking, pulse-echo ultrasound probe for intravascular imaging, with fibre-optic transmission and reception. The axial resolution was better than 70 microns, and the imaging depth in tissue was greater than 1 cm. Ultrasound transmission was performed by photoacoustic excitation of a carbon nanotube/polydimethylsiloxane composite material; ultrasound reception, with a fibre-optic Fabry-Perot cavity. Ex vivo tissue studies, which included healthy swine tissue and diseased human tissue, demonstrated the strong potential of this technique. To our knowledge, this is the first study to achieve an all-optical pulse-echo ultrasound probe for intravascular imaging. The potential for performing all-optical B-mode imaging (2D and 3D) with virtual arrays of transmit/receive elements, and hybrid imaging with pulse-echo ultrasound and photoacoustic sensing are discussed.

  14. Handheld scanning probes for optical coherence tomography: developments, applications, and perspectives

    NASA Astrophysics Data System (ADS)

    Duma, V.-F.; Demian, D.; Sinescu, C.; Cernat, R.; Dobre, G.; Negrutiu, M. L.; Topala, F. I.; Hutiu, Gh.; Bradu, A.; Podoleanu, A. G.

    2016-03-01

    We present the handheld scanning probes that we have recently developed in our current project for biomedical imaging in general and for Optical Coherence Tomography (OCT) in particular. OCT is an established, but dynamic imagistic technique based on laser interferometry, which offers micrometer resolutions and millimeters penetration depths. With regard to existing devices, the newly developed handheld probes are simple, light and relatively low cost. Their design is described in detail to allow for the reproduction in any lab, including for educational purposes. Two probes are constructed almost entirely from off-the-shelf components, while a third, final variant is constructed with dedicated components, in an ergonomic design. The handheld probes have uni-dimensional (1D) galvanometer scanners therefore they achieve transversal sections through the biological sample investigated - in contrast to handheld probes equipped with bi-dimensional (2D) scanners that can also achieve volumetric (3D) reconstructions of the samples. These latter handheld probes are therefore also discussed, as well as the possibility to equip them with galvanometer 2D scanners or with Risley prisms. For galvanometer scanners the optimal scanning functions studied in a series of previous works are pointed out; these functions offer a higher temporal efficiency/duty cycle of the scanning process, as well as artifact-free OCT images. The testing of the handheld scanning probes in dental applications is presented, for metal ceramic prosthesis and for teeth.

  15. Through-wafer optical probe characterization for microelectromechanical systems positional state monitoring and feedback control

    NASA Astrophysics Data System (ADS)

    Dawson, Jeremy M.; Chen, Jingdong; Brown, Kolin S.; Famouri, Parviz F.; Hornak, Lawrence A.

    2000-12-01

    Implementation of closed-loop microelectromechanical system (MEMS) control enables mechanical microsystems to adapt to the demands of the environment that they are actuating, opening a broad range of new opportunities for future MEMS applications. Integrated optical microsystems have the potential to enable continuous in situ optical interrogation of MEMS microstructure position fully decoupled from the means of mechanical actuation that is necessary for realization of feedback control. We present the results of initial research evaluating through-wafer optical microprobes for surface micromachined MEMS integrated optical position monitoring. Results from the through-wafer free-space optical probe of a lateral comb resonator fabricated using the multiuser MEMS process service (MUMPS) indicate significant positional information content with an achievable return probe signal dynamic range of up to 80% arising from film transmission contrast. Static and dynamic deflection analysis and experimental results indicate a through-wafer probe positional signal sensitivity of 40 mV/micrometers for the present setup or 10% signal change per micrometer. A simulation of the application of nonlinear sliding control is presented illustrating position control of the lateral comb resonator structure given the availability of positional state information.

  16. Femtosecond-precision synchronization of the pump-probe optical laser for user experiments at FLASH

    NASA Astrophysics Data System (ADS)

    Schulz, S.; Czwalinna, M. K.; Felber, M.; Predki, P.; Schefer, S.; Schlarb, H.; Wegner, U.

    2013-05-01

    In this paper, we present the long-term stable synchronization of the FLASH pump-probe Ti:sapphire oscillator to an optical reference with sub-10 fs (rms) timing jitter employing a balanced optical cross-correlator. The reference pulse train, transmitted over an actively transit time-stabilized 500m long fiber link, is generated by the FLASH master laser oscillator. This laser also provides the reference for several electron bunch arrival time monitors with sub-10 fs resolution, which in turn enables a longitudinal feedback reducing the electron bunch arrival time jitter to below 25 fs (rms). Combining the precise synchronization of the laser and the longitudinal accelerator feedback enabled a proof-of-principle pump-probe experiment at FLASH, ultimately showing a significant reduction of the timing jitter between the optical laser and the XUV pulses generated by the FEL, compared to the present standard operation.

  17. Recent Advances in the Design of Electro-Optic Sensors for Minimally Destructive Microwave Field Probing

    PubMed Central

    Lee, Dong-Joon; Kang, No-Weon; Choi, Jun-Ho; Kim, Junyeon; Whitaker, John F.

    2011-01-01

    In this paper we review recent design methodologies for fully dielectric electro-optic sensors that have applications in non-destructive evaluation (NDE) of devices and materials that radiate, guide, or otherwise may be impacted by microwave fields. In many practical NDE situations, fiber-coupled-sensor configurations are preferred due to their advantages over free-space bulk sensors in terms of optical alignment, spatial resolution, and especially, a low degree of field invasiveness. We propose and review five distinct types of fiber-coupled electro-optic sensor probes. The design guidelines for each probe type and their performances in absolute electric-field measurements are compared and summarized. PMID:22346604

  18. Feasibility study on the development of a fiber-optic gamma imaging probe

    NASA Astrophysics Data System (ADS)

    Hong, Seunghan; Yoo, Wook Jae; Shin, Sang Hun; Jeon, Hyesu; Jang, Jae Seok; Kwon, Guwon; Lee, Dong Eun; Jang, Kyoung Won; Lee, Bongsoo

    2015-07-01

    In this research, we fabricated a fiber-optic gamma imaging probe that could measure the scintillation image induced by gamma-rays. For evaluating the spatial resolution of the optical and the scintillation images measured by using the proposed gamma imaging probe, first, we obtained the light intensity distributions across the sharp edge from the optical and the scintillation images by using a USAF 1951 resolution target and an X-ray beam and then analyzed each modulation transfer function (MTF) curve. Next, we measured the scintillation images with information regarding the distribution by the gamma-rays emitted from Cs-137 sources with four different radioactivities. Finally, we evaluated the intensity variation of the scintillating light from the region of interest (ROI) in the scintillation image according to the radioactivity of Cs-137.

  19. Optical pump-probe microscopy for biomedicine and art conservation

    NASA Astrophysics Data System (ADS)

    Fischer, Martin

    2013-03-01

    Nonlinear optical microscopy can provide contrast in highly heterogeneous media and a wide range of applications has emerged, primarily in biology, medicine, and materials science. Compared to linear microscopy methods, the localized nature of nonlinear interactions leads to high spatial resolution, optical sectioning, and larger possible imaging depth in scattering media. However, nonlinear contrast (other than fluorescence, harmonic generation or CARS) is generally difficult to measure because it is overwhelmed by the large background of detected illumination light. This background can be suppressed by using femtosecond pulse or pulse train shaping to encode nonlinear interactions in background-free regions of the frequency spectrum. We have developed this shaping technology to study novel intrinsic structural and molecular contrast in biological tissue, generally using less power than a laser pointer. For example we have recently been able to sensitively measure detailed transient absorption dynamics of melanin sub-types in a variety of skin lesions, showing clinically relevant differences of melanin type and distribution between cancerous and benign tissue.[1] Recently we have also applied this technology to paint samples and to historic artwork in order to provide detailed, depth-resolved pigment identification. Initial studies in different inorganic and organic pigments have shown a rich and pigment-specific nonlinear absorption signature.[2] Some pigments, for example lapis lazuli (natural ultramarine), even show marked differences in signal depending on its geographic origin and on age, demonstrating the potential of this technique to determine authenticity, provenance, technology of manufacture, or state of preservation of historic works of art.

  20. External electro-optic sampling utilizing a poled polymer asymmetric Fabry Perot cavity as an electro-optical probe tip

    NASA Astrophysics Data System (ADS)

    Chen, Kaixin; Zhang, Hongbo; Zhang, Daming; Yang, Han; Yi, Maobin

    2002-09-01

    External electro-optic sampling utilizing a poled polymer asymmetry Fabry-Perot cavity as electro-optic probe tip has been demonstrated. Electro-optical polymer spin coated on the high-reflectivity mirror (HRM) was corona poled. Thus, an asymmetric F-P cavity was formed based on the different reflectivity of the polymer and HRM and it converted the phase modulation that originates from electro-optic effect of the poled polymer to amplitude modulation, so only one laser beam is needed in this system. The principle of the sampling was analyzed by multiple reflection and index ellipsoid methods. A 1.2 GHz microwave signal propagating on coplanar waveguide transmission line was sampled, and the voltage sensitivity about 0.5 mV/ Hz was obtained.

  1. Transurethral optical-laser knife and probe director for lateral firing laser probes

    NASA Astrophysics Data System (ADS)

    Malek, Reza S.

    1994-02-01

    Laser energy has been used by many for transurethral incision of small, obstructive prostates, vesical neck contractures, and urethral strictures. The customary techniques of moving the tip of the laser fiber through a cystoscope with a conventional laser guide, almost tangentially to the tissue to be incised, or drilling radially arranged holes in the scar, or both, have been cumbersome and imprecise. To provide exact control of the laser fiber and precise delivery of laser energy, a new guide was devised. It conducts the quartz fiber through the sheath and along the lens of an optical urethrotome. The tip of the quartz fiber contacts the tissue at an angle of 20 degree(s). KTP/532 laser energy is used to perform internal urethrotomy for urethral stricture, transurethral incision of postoperative contracture of the vesical neck, and transurethral incision of the small prostate under constant visual control.

  2. Optical Riblet Sensor: Beam Parameter Requirements for the Probing Laser Source

    PubMed Central

    Tschentscher, Juliane; Hochheim, Sven; Brüning, Hauke; Brune, Kai; Voit, Kay-Michael; Imlau, Mirco

    2016-01-01

    Beam parameters of a probing laser source in an optical riblet sensor are studied by considering the high demands on a sensors’ precision and reliability for the determination of deviations of the geometrical shape of a riblet. Mandatory requirements, such as minimum intensity and light polarization, are obtained by means of detailed inspection of the optical response of the riblet using ray and wave optics; the impact of wavelength is studied. Novel measures for analyzing the riblet shape without the necessity of a measurement with a reference sample are derived; reference values for an ideal riblet structure obtained with the optical riblet sensor are given. The application of a low-cost, frequency-doubled Nd:YVO4 laser pointer sufficient to serve as a reliable laser source in an appropriate optical riblet sensor is discussed. PMID:27043567

  3. Optical Riblet Sensor: Beam Parameter Requirements for the Probing Laser Source.

    PubMed

    Tschentscher, Juliane; Hochheim, Sven; Brüning, Hauke; Brune, Kai; Voit, Kay-Michael; Imlau, Mirco

    2016-01-01

    Beam parameters of a probing laser source in an optical riblet sensor are studied by considering the high demands on a sensors' precision and reliability for the determination of deviations of the geometrical shape of a riblet. Mandatory requirements, such as minimum intensity and light polarization, are obtained by means of detailed inspection of the optical response of the riblet using ray and wave optics; the impact of wavelength is studied. Novel measures for analyzing the riblet shape without the necessity of a measurement with a reference sample are derived; reference values for an ideal riblet structure obtained with the optical riblet sensor are given. The application of a low-cost, frequency-doubled Nd:YVO₄ laser pointer sufficient to serve as a reliable laser source in an appropriate optical riblet sensor is discussed. PMID:27043567

  4. Updates on Optical Emission Spectroscopy & Langmuir Probe Investigations on the Helicon Plasma Experiment (HPX)

    NASA Astrophysics Data System (ADS)

    Karama, Jackson; Frank, John; Azzari, Phillip; Hopson, Jordan; James, Royce; Duke-Tinson, Omar; Paolino, Richard; Sandri, Eva; Sherman, Justin; Wright, Eva; Turk, Jeremy

    2015-11-01

    HPX is developing a to shorter lifetime (20 - 30 ns) more reproducible plasma at the Coast Guard Academy Plasma Laboratory (CGAPL). Once achieved, spectral and particle probes will help to verify plasma mode transitions to the W-mode. These optical probes utilize movable filters, and ccd cameras to gather data at selected spectral frequency bands. Once corrections for the RF field are in place for the Langmuir probe, raw data will be collected and used to measure the plasma's density, temperature, and potentially the structure and behavior during experiments. Direct measurements of plasma properties can be determined with modeling and by comparison with the state transition tables, both using Optical Emission Spectroscopy (OES). The spectral will add to HPX's data collection capabilities and be used in conjunction with the particle probes, and Thomson Scattering device to create a robust picture of the internal and external plasma parameters on HPX. Progress on the implementation of the OES and Langmuir probes will be reported. Supported by U.S. DEPS Grant [HEL-JTO] PRWJFY15.

  5. Probing the bulk viscosity of particles using aerosol optical tweezers

    NASA Astrophysics Data System (ADS)

    Power, Rory; Bones, David L.; Reid, Jonathan P.

    2012-10-01

    Holographic aerosol optical tweezers can be used to trap arrays of aerosol particles allowing detailed studies of particle properties and processes at the single particle level. Recent observations have suggested that secondary organic aerosol may exist as ultra-viscous liquids or glassy states at low relative humidity, potentially a significant factor in influencing their role in the atmosphere and their activation to form cloud droplets. A decrease in relative humidity surrounding a particle leads to an increased concentration of solute in the droplet as the droplet returns to equilibrium and, thus, an increase in the bulk viscosity. We demonstrate that the timescales for condensation and evaporation processes correlate with particle viscosity, showing significant inhibition in mass transfer kinetics using ternary sucrose/sodium chloride/water droplets as a proxy to atmospheric multi-component aerosol. We go on to study the fundamental process of aerosol coagulation in aerosol particle arrays, observing the relaxation of non-spherical composite particles formed on coalescence. We demonstrate the use of bright-field imaging and elastic light scattering to make measurements of the timescale for the process of binary coalescence contrasting the rheological properties of aqueous sucrose and sodium chloride aerosol over a range of relative humidities.

  6. Use of optical tweezers to probe epithelial mechanosensation

    NASA Astrophysics Data System (ADS)

    Resnick, Andrew

    2010-01-01

    Cellular mechanosensation mechanisms have been implicated in a variety of disease states. Specifically in renal tubules, the primary cilium and associated mechanosensitive ion channels are hypothesized to play a role in water and salt homeostasis, with relevant disease states including polycystic kidney disease and hypertension. Previous experiments investigating ciliary-mediated cellular mechanosensation have used either fluid flow chambers or micropipetting to elicit a biological response. The interpretation of these experiments in terms of the ``ciliary hypothesis'' has been difficult due the spatially distributed nature of the mechanical disturbance-several competing hypotheses regarding possible roles of primary cilium, glycocalyx, microvilli, cell junctions, and actin cytoskeleton exist. I report initial data using optical tweezers to manipulate individual primary cilia in an attempt to elicit a mechanotransduction response-specifically, the release of intracellular calcium. The advantage of using laser tweezers over previous work is that the applied disturbance is highly localized. I find that stimulation of a primary cilium elicits a response, while stimulation of the apical surface membrane does not. These results lend support to the hypothesis that the primary cilium mediates transduction of mechanical strain into a biochemical response in renal epithelia.

  7. Small size probe for inner profile measurement of pipes using optical fiber ring beam device

    NASA Astrophysics Data System (ADS)

    Wakayama, Toshitaka; Machi, Kizuku; Yoshizawa, Toru

    2012-11-01

    The requirements of inner profile measurement of pipes and holes become recently larger and larger, and applications of inner profile measurement have rapidly expanded to medical field as well as industrial fields such as mechanical, automobile and heavy industries. We have proposed measurement method by incorporating a ring beam device that produces a disk beam and have developed various probes for different inner profile measurement. To meet request for applying to smaller diameter pipes, we tried to improve the ring beam light source using a conical mirror, optical fiber collimator and a laser diode. At this moment a probe with the size of 5 mm in diameter has been realized.

  8. Spin-noise spectroscopy under resonant optical probing conditions: Coherent and nonlinear effects

    SciTech Connect

    Horn, H.; Mueller, G. M.; Huebner, J.; Oestreich, M.; Rasel, E. M.; Santos, L.

    2011-10-15

    Highly sensitive Faraday rotation spectroscopy is used to measure the fluctuating magnetization noise of noninteracting rubidium atoms under resonant and nonresonant optical probing conditions. The spin-noise frequency spectra, in conjunction with the probe light detuning with respect to the D{sub 2} transition, reveal clear signatures of coherent coupling of the participating electronic levels. The results are explained by extended Bloch equations, including homogeneous and inhomogeneous broadening mechanisms. Our measurements further indicate that spin noise originating from excited states is governed at high intensities by collective effects.

  9. External electro-optic probing of millimeter-wave integrated circuits

    NASA Technical Reports Server (NTRS)

    Whitaker, J. F.; Valdmanis, J. A.; Jackson, T. A.; Bhasin, K. B.; Romanofsky, Robert R.; Mourou, G. A.

    1989-01-01

    An external, noncontact electro-optic measurement system, designed to operate at the wafer level with conventional wafer probing equipment and without any special circuit preparation, has been developed. Measurements have demonstrated the system's ability to probe continuous and pulsed signals on microwave integrated circuits on arbitrary substrates with excellent spatial resolution. Experimental measurements on a variety of digital and analog circuits, including a GaAs selectively-doped heterostructure transistor prescaler, an NMOS silicon multiplexer, and a GaAs power amplifier MMIC are reported.

  10. Characterization of laser-driven shock waves in solids using a fiber optic pressure probe

    SciTech Connect

    Cranch, Geoffrey A.; Lunsford, Robert; Grun, Jacob; Weaver, James; Compton, Steve; May, Mark; Kostinski, Natalie

    2013-11-08

    Measurement of laser-driven shock wave pressure in solid blocks of polymethyl methacrylate is demonstrated using fiber optic pressure probes. Three probes based on a fiber Fabry–Perot, fiber Bragg grating, and interferometric fiber tip sensor are tested and compared. Shock waves are generated using a high-power laser focused onto a thin foil target placed in close proximity to the test blocks. The fiber Fabry–Perot sensor appears capable of resolving the shock front with a rise time of 91 ns. As a result, the peak pressure is estimated, using a separate shadowgraphy measurement, to be 3.4 GPa.

  11. Probing other solar systems with current and future adaptive optics

    SciTech Connect

    Macintosh, B; Marois, C; Phillion, D; Poyneer, L; Graham, J; Zuckerman, B; Gavel, D; Veran, J; Wilhelmsen-Evans, J; Mellis, C

    2008-09-08

    Over the past decade, the study of extrasolar planets through indirect techniques--primarily Doppler measurements--has revolutionized our understanding of other solar systems. The next major step in this field will be the direct detection and characterization, via imaging and spectroscopy, of the planets themselves. To achieve this, we must separate the light from the faint planet from the extensive glare of its parent star. We pursued this goal using the current generation of adaptive optics (AO) systems on large ground-based telescopes, using infrared imaging to search for the thermal emission from young planets and developing image processing techniques to distinguish planets from telescope-induced artifacts. Our new Angular Differential Imaging (ADI) technique, which uses the sidereal rotation of the Earth and telescope, is now standard for ground-based high-contrast imaging. Although no young planets were found in our surveys, we placed the strongest limits yet on giant planets in wide orbits (>30 AU) around young stars and characterized planetary companion candidates. The imaging of planetary companions on solar-system-like scales (5-30 AU) will require a new generation of advanced AO systems that are an order of magnitude more powerful than the LLNL-built Keck AO system. We worked to develop and test the key technologies needed for these systems, including a spatially-filtered wavefront sensor, efficient and accurate wavefront reconstruction algorithms, and precision AO wavefront control at the sub-nm level. LLNL has now been selected by the Gemini Observatory to lead the construction of the Gemini Planet Imager, a $24M instrument that will be the most advanced AO system in the world.

  12. Green synthesis of multifunctional carbon dots from coriander leaves and their potential application as antioxidants, sensors and bioimaging agents.

    PubMed

    Sachdev, Abhay; Gopinath, P

    2015-06-21

    In the present study, a facile one-step hydrothermal treatment of coriander leaves for preparing carbon dots (CDs) has been reported. Optical and structural properties of the CDs have been extensively studied by UV-visible and fluorescence spectroscopic, microscopic (transmission electron microscopy, scanning electron microscopy) and X-ray diffraction techniques. Surface functionality and composition of the CDs have been illustrated by elemental analysis and Fourier transform infrared spectroscopy (FTIR). Quenching of the fluorescence of the CDs in the presence of metal ions is of prime significance, hence CDs have been used as a fluorescence probe for sensitive and selective detection of Fe(3+) ions. Eventually, biocompatibility and bioimaging aspects of CDs have been evaluated on lung normal (L-132) and cancer (A549) cell lines. Qualitative analysis of cellular uptake of CDs has been pursued through fluorescence microscopy, while quantitative analysis using a flow cytometer provided an insight into the concentration and cell-type dependent uptake of CDs. The article further investigates the antioxidant activity of CDs. Therefore, we have validated the practicality of CDs obtained from a herbal carbon source for versatile applications. PMID:25927267

  13. Optical probes of atomic and molecular decay processes.

    SciTech Connect

    Pratt, S. T.

    2008-01-01

    characterize both the photoexcitation and subsequent decay processes. These techniques include mass spectrometry, dispersive and threshold photoelectron spectroscopy, laser-induced fluorescence, fluorescence-dip spectroscopy, and laser-induced grating spectroscopy. While the instrumentation is currently available for each of these techniques, two instruments deserve special mention. First, a high-resolution magnetic-bottle electron spectrometer has been developed that is equipped with a pulsed, skimmed molecular beam source. This instrument is capable of {approx}3-4 meV resolution in the electron kinetic energy while providing a collection efficiency of {approx}50%. Second, a time-of-flight mass spectrometer has been constructed with a similar molecular beam source. This instrument is currently being adapted to allow both ion- and electron-imaging studies. A typical experimental study is performed in three steps. First, resonant one-color multiphoton ionization is used to map out the transition between the ground state of the molecule of interest and the low-lying excited state to be used as an intermediate in the double-resonance process. The lasers used in these studies are Nd:YAG-pumped dye lasers with {approx}5 ns pulse durations. In general, this pump transition corresponds to a one- or two-photon process, and the laser output is frequency doubled, tripled, or mixed to generate light in the region of interest. In molecules such as ammonia and aniline, the pump transitions of interest are well characterized, allowing the unambiguous choice of pump transitions that access levels with the rovibronic character of interest. In other cases, the spectroscopy of the pump transition must be analyzed before it can be useful for the double-resonance experiments. In the second step, the pump laser is fixed on the pump transition of interest and a second laser is used to probe transitions from the upper state of the pump transition to the autoionizing or predissociating resonances in

  14. Probing nonlinear magnetization dynamics in Fe/MgO(001) film by all optical pump-probe technique

    SciTech Connect

    He, Wei; Hu, Bo; Zhang, Xiang-Qun; Cheng, Zhao-Hua; Zhan, Qing-Feng

    2014-04-07

    An all-optical pump-probe technique has been employed to investigate the nonlinear magnetization dynamics of a 10 nm Fe/MgO(001) thin film in time domain. The magnetization precession was excited by pump-laser pulses and modulated by laser fluence variations. With increasing the laser fluence up to 7.1 mJ/cm{sup 2}, in addition to the uniform precession mode, a second harmonic signal was detected. The time evolution of the second harmonic signal was obtained in time-frequency domain. Based on the Landau-Lifshitz-Gilbert equation, the numerical simulation was performed to reproduce the observed the frequency doubling behaviors in Fe/MgO(001) film.

  15. Design and testing of prototype handheld scanning probes for optical coherence tomography.

    PubMed

    Demian, Dorin; Duma, Virgil-Florin; Sinescu, Cosmin; Negrutiu, Meda Lavinia; Cernat, Ramona; Topala, Florin Ionel; Hutiu, Gheorghe; Bradu, Adrian; Podoleanu, Adrian Gh

    2014-08-01

    Three simple and low-cost configurations of handheld scanning probes for optical coherence tomography have been developed. Their design and testing for dentistry applications are presented. The first two configurations were built exclusively from available off-the-shelf optomechanical components, which, to the best of our knowledge, are the first designs of this type. The third configuration includes these components in an optimized and ergonomic probe. All the designs are presented in detail to allow for their duplication in any laboratory with a minimum effort, for applications that range from educational to high-end clinical investigations. Requirements that have to be fulfilled to achieve configurations which are reliable, ergonomic-for clinical environments, and easy to build are presented. While a range of applications is possible for the prototypes developed, in this study the handheld probes are tested ex vivo with a spectral domain optical coherence tomography system built in-house, for dental constructs. A previous testing with a swept source optical coherence tomography system has also been performed both in vivo and ex vivo for ear, nose, and throat-in a medical environment. The applications use the capability of optical coherence tomography to achieve real-time, high-resolution, non-contact, and non-destructive interferometric investigations with micrometer resolutions and millimeter penetration depth inside the sample. In this study, testing the quality of the material of one of the most used types of dental prosthesis, metalo-ceramic is thus demonstrated. PMID:25107512

  16. Design and testing of prototype handheld scanning probes for optical coherence tomography

    PubMed Central

    Demian, Dorin; Sinescu, Cosmin; Negrutiu, Meda Lavinia; Cernat, Ramona; Topala, Florin Ionel; Hutiu, Gheorghe; Bradu, Adrian; Podoleanu, Adrian Gh

    2014-01-01

    Three simple and low-cost configurations of handheld scanning probes for optical coherence tomography have been developed. Their design and testing for dentistry applications are presented. The first two configurations were built exclusively from available off-the-shelf optomechanical components, which, to the best of our knowledge, are the first designs of this type. The third configuration includes these components in an optimized and ergonomic probe. All the designs are presented in detail to allow for their duplication in any laboratory with a minimum effort, for applications that range from educational to high-end clinical investigations. Requirements that have to be fulfilled to achieve configurations which are reliable, ergonomic—for clinical environments, and easy to build are presented. While a range of applications is possible for the prototypes developed, in this study the handheld probes are tested ex vivo with a spectral domain optical coherence tomography system built in-house, for dental constructs. A previous testing with a swept source optical coherence tomography system has also been performed both in vivo and ex vivo for ear, nose, and throat—in a medical environment. The applications use the capability of optical coherence tomography to achieve real-time, high-resolution, non-contact, and non-destructive interferometric investigations with micrometer resolutions and millimeter penetration depth inside the sample. In this study, testing the quality of the material of one of the most used types of dental prosthesis, metalo-ceramic is thus demonstrated. PMID:25107512

  17. The Intersection of CMOS Microsystems and Upconversion Nanoparticles for Luminescence Bioimaging and Bioassays

    PubMed Central

    Wei, Liping.; Doughan, Samer.; Han, Yi.; DaCosta, Matthew V.; Krull, Ulrich J.; Ho, Derek.

    2014-01-01

    Organic fluorophores and quantum dots are ubiquitous as contrast agents for bio-imaging and as labels in bioassays to enable the detection of biological targets and processes. Upconversion nanoparticles (UCNPs) offer a different set of opportunities as labels in bioassays and for bioimaging. UCNPs are excited at near-infrared (NIR) wavelengths where biological molecules are optically transparent, and their luminesce in the visible and ultraviolet (UV) wavelength range is suitable for detection using complementary metal-oxide-semiconductor (CMOS) technology. These nanoparticles provide multiple sharp emission bands, long lifetimes, tunable emission, high photostability, and low cytotoxicity, which render them particularly useful for bio-imaging applications and multiplexed bioassays. This paper surveys several key concepts surrounding upconversion nanoparticles and the systems that detect and process the corresponding luminescence signals. The principle of photon upconversion, tuning of emission wavelengths, UCNP bioassays, and UCNP time-resolved techniques are described. Electronic readout systems for signal detection and processing suitable for UCNP luminescence using CMOS technology are discussed. This includes recent progress in miniaturized detectors, integrated spectral sensing, and high-precision time-domain circuits. Emphasis is placed on the physical attributes of UCNPs that map strongly to the technical features that CMOS devices excel in delivering, exploring the interoperability between the two technologies. PMID:25211198

  18. Dendrimers Application Related to Bioimaging

    PubMed Central

    Barrett, Tristan; Ravizzini, Gregory; Choyke, Peter L.; Kobayashi, Hisataka

    2009-01-01

    Dendrimers are a class of synthetically produced highly branched, spherical nanostructures that can be used as carrier molecules for imaging agents. A variety of dendrimers exist and each has biological properties that will alter its biodistribution. Dendrimers are composed of combinations of core types such as ethylene diamine (EDA), diaminobutyl (DAB), polyamidoamine (PAMAM) and polypropylimine (PPI) and different surface residues such as amine, carboxyl, and alcoholic groups. Increasing the number of primary amine groups attached to the core will increase the size of the dendrimer, which is known by the term ‘generation’ of the dendrimer. Because dendrimers are highly structured in size and shape and have a low poly-dispersity index, each dendrimer generation has distinct pharmacokinetic and pharmacodynamic properties which may prove advantageous for particular medical applications. Research has centered on developing these macromolecules as imaging agents for numerous modalities including magnetic resonance imaging, X-ray computed tomography, optical imaging and nuclear medicine. Another prospective function of dendrimers is as drug delivery vectors, whereby therapeutic payloads are encapsulated within the shell, or incorporated onto their multivalent surface, and targeted to tumor cells using ligands that specifically bind to cancer cells or in normal cells altered by nearby cancer cells. Furthermore, the larger size of high generation dendrimers offers potential to develop dual purpose agents that can act both as imaging agents and as delivery vectors, or can be imaged with more than one modality. Herein, we discuss the current and future applications of dendrimers in medicine and the central role they play in the emerging field of nanotechnology. PMID:19150767

  19. Design of a rectal probe for diffuse optical spectroscopy imaging for chemotherapy and radiotherapy monitoring

    NASA Astrophysics Data System (ADS)

    van de Giessen, Martijn; Santoro, Ylenia; Mirzaei Zarandi, Soroush; Pigazzi, Alessio; Cerussi, Albert E.; Tromberg, Bruce J.

    2014-03-01

    Diffuse optical spectroscopy imaging (DOSI) has shown great potential for the early detection of non-responding tumors during neoadjuvant chemotherapy in breast cancer, already one day after therapy starts. Patients with rectal cancer receive similar chemotherapy treatment. The rectum geometry and tissue properties of healthy and tumor tissue in the rectum and the requirement of surface contact impose constraints on the probe design. In this work we present the design of a DOSI probe with the aim of early chemotherapy/radiotherapy effectiveness detection in rectal tumors. We show using Monte Carlo simulations and phantom measurements that the colon tissue can be characterized reliably using a source-detector separation in the order of 10 mm. We present a design and rapid prototype of a probe for DOSI measurements that can be mounted on a standard laparoscope and that fits through a standard rectoscope. Using predominantly clinically approved components we aim at fast clinical translation.

  20. Metal-based optical probes for live cell imaging of nitroxyl (HNO).

    PubMed

    Rivera-Fuentes, Pablo; Lippard, Stephen J

    2015-11-17

    Nitroxyl (HNO) is a biological signaling agent that displays distinctive reactivity compared to nitric oxide (NO). As a consequence, these two reactive nitrogen species trigger different physiological responses. Selective detection of HNO over NO has been a challenge for chemists, and several fluorogenic molecular probes have been recently developed with that goal in mind. Common constructs take advantage of the HNO-induced reduction of Cu(II) to Cu(I). The sensing mechanism of such probes relies on the ability of the unpaired electron in a d orbital of the Cu(II) center to quench the fluorescence of a photoemissive ligand by either an electron or energy transfer mechanism. Experimental and theoretical mechanistic studies suggest that proton-coupled electron transfer mediates this process, and careful tuning of the copper coordination environment has led to sensors with optimized selectivity and kinetics. The current optical probes cover the visible and near-infrared regions of the spectrum. This palette of sensors comprises structurally and functionally diverse fluorophores such as coumarin (blue/green emission), boron dipyrromethane (BODIPY, green emission), benzoresorufin (red emission), and dihydroxanthenes (near-infrared emission). Many of these sensors have been successfully applied to detect HNO production in live cells. For example, copper-based optical probes have been used to detect HNO production in live mammalian cells that have been treated with H2S and various nitrosating agents. These studies have established a link between HSNO, the smallest S-nitrosothiol, and HNO. In addition, a near-infrared HNO sensor has been used to perform multicolor/multianalyte microscopy, revealing that exogenously applied HNO elevates the concentration of intracellular mobile zinc. This mobilization of zinc ions is presumably a consequence of nitrosation of cysteine residues in zinc-chelating proteins such as metallothionein. Future challenges for the optical imaging of

  1. Fiber optic photoacoustic probe with ultrasonic tracking for guiding minimally invasive procedures

    NASA Astrophysics Data System (ADS)

    Xia, Wenfeng; Mosse, Charles A.; Colchester, Richard J.; Mari, Jean Martial; Nikitichev, Daniil I.; West, Simeon J.; Ourselin, Sebastien; Beard, Paul C.; Desjardins, Adrien E.

    2015-07-01

    In a wide range of clinical procedures, accurate placement of medical devices such as needles and catheters is critical to optimize patient outcomes. Ultrasound imaging is often used to guide minimally invasive procedures, as it can provide real-time visualization of patient anatomy and medical devices. However, this modality can provide low image contrast for soft tissues, and poor visualization of medical devices that are steeply angled with respect to the incoming ultrasound beams. Photoacoustic sensors can provide information about the spatial distributions of tissue chromophores that could be valuable for guiding minimally invasive procedures. In this study, a system for guiding minimally invasive procedures using photoacoustic sensing was developed. This system included a miniature photoacoustic probe with three optical fibers: one with a bare end for photoacoustic excitation of tissue, a second for photoacoustic excitation of an optically absorbing coating at the distal end to transmit ultrasound, and a third with a Fabry-Perot cavity at the distal end for receiving ultrasound. The position of the photoacoustic probe was determined with ultrasonic tracking, which involved transmitting pulses from a linear-array ultrasound imaging probe at the tissue surface, and receiving them with the fiber-optic ultrasound receiver in the photoacoustic probe. The axial resolution of photoacoustic sensing was better than 70 μm, and the tracking accuracy was better than 1 mm in both axial and lateral dimensions. By translating the photoacoustic probe, depth scans were obtained from different spatial positions, and two-dimensional images were reconstructed using a frequency-domain algorithm.

  2. Probe-controlled soliton frequency shift in the regime of optical event horizon.

    PubMed

    Gu, Jie; Guo, Hairun; Wang, Shaofei; Zeng, Xianglong

    2015-08-24

    In optical analogy of the event horizon, temporal pulse collision and mutual interactions are mainly between an intense solitary wave (soliton) and a dispersive probe wave. In such a regime, here we numerically investigate the probe-controlled soliton frequency shift as well as the soliton self-compression. In particular, in the dispersion landscape with multiple zero dispersion wavelengths, bi-directional soliton spectral tunneling effects is possible. Moreover, we propose a mid-infrared soliton self-compression to the generation of few-cycle ultrashort pulses, in a bulk of quadratic nonlinear crystals in contrast to optical fibers or cubic nonlinear media, which could contribute to the community with a simple and flexible method to experimental implementations. PMID:26368200

  3. A simple and non-contact optical imaging probe for evaluation of corneal diseases

    NASA Astrophysics Data System (ADS)

    Hong, Xun Jie Jeesmond; Shinoj, V. K.; Murukeshan, V. M.; Baskaran, M.; Aung, T.

    2015-09-01

    Non-contact imaging techniques are preferred in ophthalmology. Corneal disease is one of the leading causes of blindness worldwide, and a possible way of detection is by analyzing the shape and optical quality of the cornea. Here, a simple and cost-effective, non-contact optical probe system is proposed and illustrated. The probe possesses high spatial resolutions and is non-dependent on coupling medium, which are significant for a clinician and patient friendly investigation. These parameters are crucial, when considering an imaging system for the objective diagnosis and management of corneal diseases. The imaging of the cornea is performed on ex vivo porcine samples and subsequently on small laboratory animals, in vivo. The clinical significance of the proposed study is validated by performing imaging of the New Zealand white rabbit's cornea infected with Pseudomonas.

  4. Imaging individual proteins and nanodomains on intact cell membranes with a probe-based optical antenna.

    PubMed

    van Zanten, Thomas S; Lopez-Bosque, Maria J; Garcia-Parajo, Maria F

    2010-01-01

    Optical antennas that confine and enhance electromagnetic fields in a nanometric region hold great potential for nanobioimaging and biosensing. Probe-based monopole optical antennas are fabricated to enhance fields localized to <30 nm near the antenna apex in aqueous conditions. These probes are used under appropriate excitation antenna conditions to image individual antibodies with an unprecedented resolution of 26 +/- 4 nm and virtually no surrounding background. On intact cell membranes in physiological conditions, the obtained resolution is 30 +/- 6 nm. Importantly, the method allows individual proteins to be distinguished from nanodomains and the degree of clustering to be quantified by directly measuring physical size and intensity of individual fluorescent spots. Improved antenna geometries should lead to true live cell imaging below 10-nm resolution with position accuracy in the subnanometric range. PMID:19943247

  5. Lambda/4 resonance of an optical monopole antenna probed by single molecule fluorescence.

    PubMed

    Taminiau, Tim H; Moerland, Robert J; Segerink, Frans B; Kuipers, Laurens; van Hulst, Niek F

    2007-01-01

    We present a resonant optical nanoantenna positioned at the end of a metal-coated glass fiber near-field probe. Antenna resonances, excitation conditions, and field localization are directly probed in the near field by single fluorescent molecules and compared to finite integration technique simulations. It is shown that the antenna is equivalent to its radio frequency analogue, the monopole antenna. For the right antenna length and local excitation conditions, antenna resonances occur that lead to an enhanced localized field near the antenna apex. Direct mapping of this field with single fluorescent molecules reveals a spatial localization of 25 nm, demonstrating the importance of such antennas for nanometer resolution optical microscopy. PMID:17212435

  6. Design, fabrication, and characterization of thermoplastic microlenses for fiber-optic probe imaging.

    PubMed

    Shinoj, V K; Murukeshan, V M; Tor, S B; Loh, N H; Lye, S W

    2014-02-20

    Microlens-ended fibers could find great usefulness in future biomedical applications, particularly in endoscopic imaging applications. In this context, this paper focuses on microlens-attached specialty optical fibers such as imaging fiber that can be used for probe imaging applications. Stand-alone self-aligned polymer microlenses have been fabricated by microcompression molding. The fabrication parameters have been optimized for different materials, such as poly(methyl methacrylate) (PMMA), polycarbonate (PC Lexan 123R), Zeonor 1060R (ZNR), and Topas COC. A comparison study of the focusing and spatial resolution of the fabricated lenses is performed prior to employing them for fiber-optic fluorescence imaging applications. PMID:24663305

  7. Design and Evaluation of a Fiber Optic Probe as a means of Subsurface Planetary Exploration

    NASA Astrophysics Data System (ADS)

    Pilgrim, Robert Paul

    The Optical Probe for Regolith Analysis (OPRA) is an instrumentation concept designed to provide spectroscopic analysis of the near subsurface of unconsolidated regolith on bodies such as moons, asteroids and planets. Below a chemically altered surface may lay the geological history in the form of stratigraphy that is shielded from degradation due to harsh external environments. Most of what we know about our solar system comes from remote platforms, such as satellites that are deployed into orbit around the target body. In the case of Mars, we have had several successful landers and rovers however, with the exception of the Mars Science Laboratory that just drilled its first hole, the complexity of subsurface excavation has limited the extent of subsurface exploration to simple scoops deployed on the ends of robotic arms which, by their very nature, will erase any stratigraphy that it may be digging into. The OPRA instrumentation concept allows for an integrated, lightweight and simple apparatus for subsurface exploration via a small, spike like structure which contains integrated optical fibers coupled to small windows running down the length of the probe. Each window is connected to a spectrometer housed onboard the deploying spacecraft. Each window is separately interrogated via the spectrometer over the wavelength range 1-2.5 nm to produce a spectroscopic profile as a function of depth. This project takes the Technology Readiness Level (TRL) of the OPRA instrumentation concept to level 3, which is defined by NASA to be the demonstration either analytically or experimentally of the proof of concept for critical functions of the proposed instrument. Firstly, to demonstrate that optical fibers are feasible for this type of application, we report on the techniques used by NASA to space qualify optical fibers. We investigate the optical performance of several fiber optic bundle configurations, both experimentally and numerically, to help optimize bundle performance

  8. Reciprocity theory of apertureless scanning near-field optical microscopy with point-dipole probes.

    PubMed

    Esslinger, Moritz; Vogelgesang, Ralf

    2012-09-25

    Near-field microscopy offers the opportunity to reveal optical contrast at deep subwavelength scales. In scanning near-field optical microscopy (SNOM), the diffraction limit is overcome by a nanoscopic probe in close proximity to the sample. The interaction of the probe with the sample fields necessarily perturbs the bare sample response, and a critical issue is the interpretation of recorded signals. For a few specific SNOM configurations, individual descriptions have been modeled, but a general and intuitive framework is still lacking. Here, we give an exact formulation of the measurable signals in SNOM which is easily applicable to experimental configurations. Our results are in close analogy with the description Tersoff and Hamann have derived for the tunneling currents in scanning tunneling microscopy. For point-like scattering probe tips, such as used in apertureless SNOM, the theory simplifies dramatically to a single scalar relation. We find that the measured signal is directly proportional to the field of the coupled tip-sample system at the position of the tip. For weakly interacting probes, the model thus verifies the empirical findings that the recorded signal is proportional to the unperturbed field of the bare sample. In the more general case, it provides guidance to an intuitive and faithful interpretation of recorded images, facilitating the characterization of tip-related distortions and the evaluation of novel SNOM configurations, both for aperture-based and apertureless SNOM. PMID:22897563

  9. Using superlattice potentials to probe long-range magnetic correlations in optical lattices

    NASA Astrophysics Data System (ADS)

    Pedersen, Kim G. L.; Andersen, Brian M.; Bruun, Georg M.; Sørensen, Anders S.

    2015-12-01

    We previously proposed [K. G. L. Pedersen, B. M. Andersen, G. M. Bruun, O. F. Syljuåsen, and A. S. Sørensen, Phys. Rev. A 84, 041603 (2011), 10.1103/PhysRevA.84.041603] a method to utilize a temporally dependent superlattice potential to mediate spin-selective transport and thereby probe long- and short-range magnetic correlations in optical lattices. Specifically, this can be used for detecting antiferromagnetic ordering in repulsive fermionic optical lattice systems, but more generally it can serve as a means of directly probing correlations among the atoms by measuring the mean value of an observable, the number of double occupied sites. Here we provide a detailed investigation of the physical processes that limit the effectiveness of this "conveyer belt method." Furthermore, we propose a simple way to improve the procedure, resulting in an essentially perfect (error-free) probing of the magnetic correlations. These results shows that suitably constructed superlattices constitute a promising way of manipulating atoms of different spin species as well as probing their interactions.

  10. Ophthalmic diagnostics using a new dynamic light scattering fiber optic probe

    NASA Astrophysics Data System (ADS)

    Ansari, Rafat R.; Suh, Kwang I.; Dellavecchia, Michael A.; Dubin, Stephen

    1995-11-01

    A new fiber optic probe is developed to study different parts of the eye. The probe positioned in front of an eye, delivers a low power light from a laser diode into the eye and guides the light which is back scattered by different components (aqueous humor, lens, and vitreous humor) of the eye through a receiving optical fiber to a photo detector. The probe provides rapid determination of macromolecular diffusivities and their respective size distributions in the eye lens and the gel-like material in the vitreous humor. We report alpha-crystalline size distributions, as a function of penetration depth, inside the lens and hyaluronic acid molecular size distribution in the vitreous body. In a clinical setting, the probe can be mounted on a slit-lamp apparatus simply by using a H-ruby lens holder. The capability of detecting cataracts, both nuclear and peripheral, in their early stages of formation, in a non invasive and quantitative fashion, has the potential in patient monitoring and in developing and testing new drugs or diet therapies to 'dissolve' or slow down the cataract formation before surgery is necessary. The ability to detect biochemical and macromolecular changes in the vitreous structure can be very useful in identifying certain diseases of the posterior chamber, e.g., posterior vitreous detachment.

  11. Ophthalmic diagnostics using a new dynamic light scattering fiber optic probe

    NASA Astrophysics Data System (ADS)

    Ansari, Rafat R.; Suh, Kwang I.; DellaVecchia, Michael A.; Dubin, Stephen

    1996-01-01

    A new fiber optic probe is developed to study different parts of the eye. The probe positioned in front of an eye, delivers a low power light from a laser diode into the eye and guides the light which is back scattered by different components (aqueous humor, lens, and vitreous humor) of the eye through a receiving optical fiber to a photo detector. The probe provides rapid determination of macromolecular diffusivities and their respective size distributions in the eye lens and the gel-like material in the vitreous humor. We report alpha-crystalline size distributions, as a function of penetration depth, inside the lens and hyaluronic acid molecular size distribution in the vitreous body. In a clinical setting, the probe can be mounted on a slit- lamp apparatus simply by using a H-ruby lens holder. The capability of detecting cataracts, both nuclear and peripheral, in their early stages of formation, in a non invasive and quantitative fashion, has the potential in patient monitoring and in developing and testing new drugs or diet therapies to 'dissolve' or slow down the cataract formation before surgery is necessary. The ability to detect biochemical and macromolecular changes in the vitreous structure can be very useful in identifying certain diseases of the posterior chamber, e.g., posterior vitreous detachment.

  12. Ophthalmic Diagnostics Using a New Dynamic Light Scattering Fiber Optic Probe

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Suh, Kwang I.; Dellavecchia, Michael A.; Dubin, Stephen

    1995-01-01

    A new fiber optic probe is developed to study different parts of the eye. The probe positioned in front of an eye, delivers a low power light from a laser diode into the eye and guides the light which is back scattered by different components (aqueous humor, lens, and vitreous humor) of the eye through a receiving optical fiber to a photo detector. The probe provides rapid determination of macromolecular diffusivities and their respective size distributions in the eye lens and the gel-like material in the vitreous humor. We report alpha-crystalline size distributions, as a function of penetration depth, inside the lens and hyaluronic acid molecular size distribution in the vitreous body. In a clinical setting, the probe can be mounted on a slit-lamp apparatus simply by using a H-ruby lens holder. The capability of detecting cataracts, both nuclear and peripheral, in their early stages of formation, in a non invasive and quantitative fashion, has the potential in patient monitoring and in developing and testing new drugs or diet therapies to 'dissolve' or slow down the cataract formation before surgery is necessary. The ability to detect biochemical and macromolecular changes in the vitreous structure can be very useful in identifying certain diseases of the posterior chamber, e.g., posterior vitreous detachment.

  13. Nanospot soldering polystyrene nanoparticles with an optical fiber probe laser irradiating a metallic AFM probe based on the near-field enhancement effect.

    PubMed

    Cui, Jianlei; Yang, Lijun; Wang, Yang; Mei, Xuesong; Wang, Wenjun; Hou, Chaojian

    2015-02-01

    With the development of nanoscience and nanotechnology for the bottom-up nanofabrication of nanostructures formed from polystyrene nanoparticles, joining technology is an essential step in the manufacturing and assembly of nanodevices and nanostructures in order to provide mechanical integration and connection. To study the nanospot welding of polystyrene nanoparticles, we propose a new nanospot-soldering method using the near-field enhancement effect of a metallic atomic force microscope (AFM) probe tip that is irradiated by an optical fiber probe laser. On the basis of our theoretical analysis of the near-field enhancement effect, we set up an experimental system for nanospot soldering; this approach is carried out by using an optical fiber probe laser to irradiate the AFM probe tip to sinter the nanoparticles, providing a promising technical approach for the application of nanosoldering in nanoscience and nanotechnology. PMID:25582678

  14. Diffuse reflectance spectroscopy of epithelial tissue with a smart fiber-optic probe

    PubMed Central

    Yu, Bing; Shah, Amy; Nagarajan, Vivek K.; Ferris, Daron G.

    2014-01-01

    Diffuse reflectance spectroscopy (DRS) with a fiber-optic probe can noninvasively quantify the optical properties of epithelial tissues and has shown the potential as a cost-effective, fast and sensitive tool for diagnosis of early precancerous changes in the cervix and oral cavity. However, current DRS systems are susceptible to several sources of systematic and random errors, such as uncontrolled probe-to-tissue pressure and lack of a real-time calibration that can significantly impair the measurement accuracy, reliability and validity of this technology as well as its clinical utility. In addition, such systems use bulky, high power and expensive optical components which impede their widespread use in low- and middle-income countries (LMICs) where epithelial cancer related death is disproportionately high. In this paper we report a portable, easy-to-use and low cost, yet accurate and reliable DRS device that can aid in the screening and diagnosis of oral and cervical cancer. The device uses an innovative smart fiber-optic probe to eliminate operator bias, state-of-the-art photonics components to reduce size and power consumption, and automated software to reduce the need of operator training. The device showed a mean error of 1.4 ± 0.5% and 6.8 ± 1.7% for extraction of phantom absorption and reduced scattering coefficients, respectively. A clinical study on healthy volunteers indicated that a pressure below 1.0 psi is desired for oral mucosal tissues to minimize the probe effects on tissue physiology and morphology. PMID:24688805

  15. Bragg scattering as a probe of atomic wave functions and quantum phase transitions in optical lattices.

    PubMed

    Miyake, Hirokazu; Siviloglou, Georgios A; Puentes, Graciana; Pritchard, David E; Ketterle, Wolfgang; Weld, David M

    2011-10-21

    We have observed Bragg scattering of photons from quantum degenerate ^{87}Rb atoms in a three-dimensional optical lattice. Bragg scattered light directly probes the microscopic crystal structure and atomic wave function whose position and momentum width is Heisenberg limited. The spatial coherence of the wave function leads to revivals in the Bragg scattered light due to the atomic Talbot effect. The decay of revivals across the superfluid to Mott insulator transition indicates the loss of superfluid coherence. PMID:22107532

  16. Fiber-optic Raman sensing of cell proliferation probes and molecular vibrations: Brain-imaging perspective

    NASA Astrophysics Data System (ADS)

    Doronina-Amitonova, Lyubov V.; Fedotov, Il'ya V.; Ivashkina, Olga I.; Zots, Marina A.; Fedotov, Andrei B.; Anokhin, Konstantin V.; Zheltikov, Aleksei M.

    2012-09-01

    Optical fibers are employed to sense fingerprint molecular vibrations in ex vivo experiments on the whole brain and detect cell proliferation probes in a model study on a quantitatively controlled solution. A specifically adapted spectral filtering procedure is shown to allow the Raman signal from molecular vibrations of interest to be discriminated against the background from the fiber, allowing a highly sensitive Raman detection of the recently demonstrated EdU (5-ethynyl-2'-deoxyuridine) labels of DNA synthesis in cells.

  17. Optical analysis of the star-tracker telescope for Gravity Probe

    NASA Technical Reports Server (NTRS)

    Zissa, D. E.

    1984-01-01

    A ray tracing modeling of the star tracker telescope for Gravity Probe was used to predict the character of the output signal and its sensitivity to fabrication errors. In particular, the impact of the optical subsystem on the requirement of 1 milliarc second signal linearity over a + or - 50 milliarc second range was examined. Photomultiplier and solid state detector options were considered. Recommendations are made.

  18. Association dynamics and linear and nonlinear optical properties of an N-acetylaladanamide probe in a POPC membrane.

    PubMed

    Murugan, N Arul; Apostolov, Rossen; Rinkevicius, Zilvinas; Kongsted, Jacob; Lindahl, Erik; Ågren, Hans

    2013-09-11

    Along with the growing evidence that relates membrane abnormalities to various diseases, biological membranes have been acknowledged as targets for therapy. Any such abnormality in the membrane structure alters the membrane potential which in principle can be captured by measuring properties of specific optical probes. There exists by now many molecular probes with absorption and fluorescence properties that are sensitive to local membrane structure and to the membrane potential. To suggest new high-performance optical probes for membrane-potential imaging it is important to understand in detail the membrane-induced structural changes in the probe, the membrane association dynamics of the probe, and its membrane-specific optical properties. To contribute to this effort, we here study an optical probe, N-acetylaladanamide (NAAA), in the presence of a POPC lipid bilayer using a multiscale integrated approach to assess the probe structure, dynamics, and optical properties in its membrane-bound status and in water solvent. We find that the probe eventually assimilates into the membrane with a specific orientation where the hydrophobic part of the probe is buried inside the lipid bilayer, while the hydrophilic part is exposed to the water solvent. The computed absorption maximum is red-shifted when compared to the gas phase. The computations of the two-photon absorption and second harmonic generation cross sections of the NAAA probe in its membrane-bound state which is of its first kind in the literature suggest that this probe can be used for imaging the membrane potential using nonlinear optical microscopy. PMID:23951997

  19. Handheld photoacoustic tomography probe built using optical-fiber parallel acoustic delay lines

    NASA Astrophysics Data System (ADS)

    Cho, Young; Chang, Cheng-Chung; Yu, Jaesok; Jeon, Mansik; Kim, Chulhong; Wang, Lihong V.; Zou, Jun

    2014-08-01

    The development of the first miniaturized parallel acoustic delay line (PADL) probe for handheld photoacoustic tomography (PAT) is reported. Using fused-silica optical fibers with low acoustic attenuation, we constructed two arrays of eight PADLs. Precision laser micromachining was conducted to produce robust and accurate mechanical support and alignment structures for the PADLs, with minimal acoustic distortion and interchannel coupling. The 16 optical-fiber PADLs, each with a different time delay, were arranged to form one input port and two output ports. A handheld PADL probe was constructed using two single-element transducers and two data acquisition channels (equal to a channel reduction ratio of 8∶1). Photoacoustic (PA) images of a black-ink target embedded in an optically scattering phantom were successfully acquired. After traveling through the PADLs, the eight channels of differently time-delayed PA signals reached each single-element ultrasonic transducer in a designated nonoverlapping time series, allowing clear signal separation for PA image reconstruction. Our results show that the PADL technique and the handheld probe can potentially enable real-time PAT, while significantly reducing the complexity and cost of the ultrasound receiver system.

  20. Handheld photoacoustic tomography probe built using optical-fiber parallel acoustic delay lines.

    PubMed

    Cho, Young; Chang, Cheng-Chung; Yu, Jaesok; Jeon, Mansik; Kim, Chulhong; Wang, Lihong V; Zou, Jun

    2014-08-01

    The development of the first miniaturized parallel acoustic delay line (PADL) probe for handheld photoacoustic tomography (PAT) is reported. Using fused-silica optical fibers with low acoustic attenuation, we constructed two arrays of eight PADLs. Precision laser micromachining was conducted to produce robust and accurate mechanical support and alignment structures for the PADLs, with minimal acoustic distortion and interchannel coupling. The 16 optical-fiber PADLs, each with a different time delay, were arranged to form one input port and two output ports. A handheld PADL probe was constructed using two single-element transducers and two data acquisition channels (equal to a channel reduction ratio of 8∶1). Photoacoustic (PA) images of a black-ink target embedded in an optically scattering phantom were successfully acquired. After traveling through the PADLs, the eight channels of differently time-delayed PA signals reached each single-element ultrasonic transducer in a designated nonoverlapping time series, allowing clear signal separation for PA image reconstruction. Our results show that the PADL technique and the handheld probe can potentially enable real-time PAT, while significantly reducing the complexity and cost of the ultrasound receiver system. PMID:25104413

  1. Noninvasive probing of the ocean surface using laser-based nonlinear optical methods

    SciTech Connect

    Korenowski, G.M.; Frysinger, G.S.; Asher, W.E. . Dept. of Chemistry)

    1992-06-01

    The laser-based nonlinear optical methods of second-harmonic generation and sum-frequency generation have been developed to study the chemical composition and concentration of natural surfactant materials present as slicks on the ocean surface. These noninvasive second-harmonic and sum-frequency generation methods produce signals which originate from only the top few molecular layers of the ocean surface, thereby producing an accurate picture of the ocean surface condition without interference from the bulk ocean chemistry. Chemical specificity of the methods is achieved by tuning the incident laser frequency to coincide with optical absorptions in the surface absorbed materials. We show that laser-based second-order nonlinear optical processes of SHG and SFG provide highly surface selective, noninvasive, in situ probes of the ocean surface. Although only preliminary experiments are reported in this paper, the probes provide important information about the nature of surfactants at the ocean surface and their behavior in response to dynamic forces at the sea/air interface. The future of the probes lies in their further development and use as in situ interfacial spectroscopic techniques.

  2. Electric field measurement in microwave discharge ion thruster with electro-optic probe.

    PubMed

    Ise, Toshiyuki; Tsukizaki, Ryudo; Togo, Hiroyoshi; Koizumi, Hiroyuki; Kuninaka, Hitoshi

    2012-12-01

    In order to understand the internal phenomena in a microwave discharge ion thruster, it is important to measure the distribution of the microwave electric field inside the discharge chamber, which is directly related to the plasma production. In this study, we proposed a novel method of measuring a microwave electric field with an electro-optic (EO) probe based on the Pockels effect. The probe, including a cooling system, contains no metal and can be accessed in the discharge chamber with less disruption to the microwave distribution. This method enables measurement of the electric field profile under ion beam acceleration. We first verified the measurement with the EO probe by a comparison with a finite-difference time domain numerical simulation of the microwave electric field in atmosphere. Second, we showed that the deviations of the reflected microwave power and the beam current were less than 8% due to inserting the EO probe into the ion thruster under ion beam acceleration. Finally, we successfully demonstrated the measurement of the electric-field profile in the ion thruster under ion beam acceleration. These measurements show that the electric field distribution in the thruster dramatically changes in the ion thruster under ion beam acceleration as the propellant mass flow rate increases. These results indicate that this new method using an EO probe can provide a useful guide for improving the propulsion of microwave discharge ion thrusters. PMID:23278009

  3. An optical backscatter probe for time resolved droplet measurements in turbomachines

    NASA Astrophysics Data System (ADS)

    Bosdas, Ilias; Mansour, Michel; Kalfas, Anestis I.; Abhari, Reza S.

    2016-01-01

    The presence of particles in the flow path of turbomachines can result in undesirable engine operation. In order to improve the efficiency of turbomachines and guarantee their safe operation, the flow mechanisms that govern the particles’ need to be studied and associated with the main aerodynamic flow field. This paper describes a newly developed optical backscatter probe for droplet diameter and speed measurements in turbomachines. The miniature probe has a tip diameter of 5 mm and is capable of resolving droplets from 40 to 110 μm in diameter that travel up to 200 m s-1. The calibration of the novel probe is performed with a droplet generator capable of producing monodispersed water droplets. In addition, the probe is calibrated for droplet speed measurements in the same calibration facility. The paper conducts a detailed uncertainty analysis and describes the post processing code. In the final part of this paper the probe is used in an axial turbine with an installed spray generator to perform droplet measurements under two different operating conditions. Measurements have shown that the part load condition results in larger droplet diameters and higher relative droplet speeds. As a consequence higher erosion rates at the rotor leading edge suction side will occur when operating at part load condition.

  4. Electric field measurement in microwave discharge ion thruster with electro-optic probe

    SciTech Connect

    Ise, Toshiyuki; Tsukizaki, Ryudo; Koizumi, Hiroyuki; Togo, Hiroyoshi; Kuninaka, Hitoshi

    2012-12-15

    In order to understand the internal phenomena in a microwave discharge ion thruster, it is important to measure the distribution of the microwave electric field inside the discharge chamber, which is directly related to the plasma production. In this study, we proposed a novel method of measuring a microwave electric field with an electro-optic (EO) probe based on the Pockels effect. The probe, including a cooling system, contains no metal and can be accessed in the discharge chamber with less disruption to the microwave distribution. This method enables measurement of the electric field profile under ion beam acceleration. We first verified the measurement with the EO probe by a comparison with a finite-difference time domain numerical simulation of the microwave electric field in atmosphere. Second, we showed that the deviations of the reflected microwave power and the beam current were less than 8% due to inserting the EO probe into the ion thruster under ion beam acceleration. Finally, we successfully demonstrated the measurement of the electric-field profile in the ion thruster under ion beam acceleration. These measurements show that the electric field distribution in the thruster dramatically changes in the ion thruster under ion beam acceleration as the propellant mass flow rate increases. These results indicate that this new method using an EO probe can provide a useful guide for improving the propulsion of microwave discharge ion thrusters.

  5. Dual-radiolabeled nanoparticle SPECT probes for bioimaging

    NASA Astrophysics Data System (ADS)

    Black, Kvar C. L.; Akers, Walter J.; Sudlow, Gail; Xu, Baogang; Laforest, Richard; Achilefu, Samuel

    2014-12-01

    A gold nanoparticle was radiolabeled with 125I and 111In and functionalized with an MMP9-cleavable peptide to form a multispectral SPECT imaging contrast agent. Peptide cleavage from the nanoprobe by MMP9 was observed in vitro, and distinct pharmacokinetic properties of the contrast agent were observed between tumors with high or low MMP9 expression.A gold nanoparticle was radiolabeled with 125I and 111In and functionalized with an MMP9-cleavable peptide to form a multispectral SPECT imaging contrast agent. Peptide cleavage from the nanoprobe by MMP9 was observed in vitro, and distinct pharmacokinetic properties of the contrast agent were observed between tumors with high or low MMP9 expression. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05269b

  6. Single potassium niobate nano/microsized particles as local mechano-optical Brownian probes.

    PubMed

    Mor, Flavio M; Sienkiewicz, Andrzej; Magrez, Arnaud; Forró, László; Jeney, Sylvia

    2016-03-28

    Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal fluctuations and optical forces of singly-trapped KNbO3 particles within the optical trapping volume of a PFM microscope. We also show that, under near-infrared (NIR) excitation of the highly focused laser beam of the PFM microscope, a single optically-trapped KNbO3 particle reveals a strong SHG signal manifested by a narrow peak (λ(em) = 532 nm) at half the excitation wavelength (λ(ex) = 1064 nm). Moreover, we demonstrate that the thus induced SHG emission can be used as a local light source that is capable of optically exciting molecules of an organic dye, Rose Bengal (RB), which adhere to the particle surface, through the mechanism of luminescence energy transfer (LET). PMID:26956197

  7. Optical nanofiber integrated into an optical tweezers for particle manipulation and in-situ fiber probing

    NASA Astrophysics Data System (ADS)

    Gusachenko, Ivan; Frawley, Mary C.; Truong, Viet. G.; Nic Chormaic, Síle

    2014-09-01

    Precise control of particle positioning is desirable in many optical propulsion and sorting applications. Here, we develop an integrated platform for particle manipulation consisting of a combined optical nanofiber and optical tweezers system. Individual silica microspheres were introduced to the nanofiber at arbitrary points using the optical tweezers, thereby producing pronounced dips in the fiber transmission. We show that such consistent and reversible transmission modulations depend on both particle and fiber diameter, and may be used as a reference point for in-situ nanofiber or particle size measurement. Therefore we combine SEM size measurements with nanofiber transmission data to provide calibration for particle-based fiber assessment. We also demonstrate how the optical tweezers can be used to create a `particle jet' to feed a supply of microspheres to the nanofiber surface, forming a particle conveyor belt. This integrated optical platform provides a method for selective evanescent field manipulation of micron-sized particles and facilitates studies of optical binding and light-particle interaction dynamics.

  8. Investigation on Dynamic Calibration for an Optical-Fiber Solids Concentration Probe in Gas-Solid Two-Phase Flows

    PubMed Central

    Xu, Guiling; Liang, Cai; Chen, Xiaoping; Liu, Daoyin; Xu, Pan; Shen, Liu; Zhao, Changsui

    2013-01-01

    This paper presents a review and analysis of the research that has been carried out on dynamic calibration for optical-fiber solids concentration probes. An introduction to the optical-fiber solids concentration probe was given. Different calibration methods of optical-fiber solids concentration probes reported in the literature were reviewed. In addition, a reflection-type optical-fiber solids concentration probe was uniquely calibrated at nearly full range of the solids concentration from 0 to packed bed concentration. The effects of particle properties (particle size, sphericity and color) on the calibration results were comprehensively investigated. The results show that the output voltage has a tendency to increase with the decreasing particle size, and the effect of particle color on calibration result is more predominant than that of sphericity. PMID:23867745

  9. A Fiber-Optic Probe Design for Combustion Chamber Flame Detection Applications-Design Criteria, Performance Specifications, and Fabrication Technique

    NASA Technical Reports Server (NTRS)

    Borg, Stephen E.; Harper, Samuel E.

    2001-01-01

    This paper documents the design and development of the fiber-optic probes utilized in the flame detection systems used in NASA Langley Research Center's 8-Foot High Temperature Tunnel (8-ft HTT). Two independent flame detection systems are utilized to monitor the presence and stability of the main-burner and pilot-level flames during facility operation. Due to the harsh environment within the combustor, the successful development of a rugged and efficient fiber-optic probe was a critical milestone in the development of these flame detection systems. The final optical probe design for the two flame detection systems resulted from research that was conducted in Langley's 7-in High Temperature Pilot Tunnel (7-in HTT). A detailed description of the manufacturing process behind the optical probes used in the 8-ft HTT is provided in Appendix A of this report.

  10. Nanomaterials for bio-imaging and therapeutics

    NASA Astrophysics Data System (ADS)

    Liu, Yu-San

    2007-12-01

    In this thesis we studied the applications of colloidal nanocrystal quantum dots (QD) in bio-medical studies. We investigate the synthesis of QD and report a relatively simple method for synthesizing QD. To produce QDs that are more stable and have higher fluorescent quantum efficiency than those produced by other methods (typically CdSe/ZnS core/shell structures), we developed a CdSe/ZnSe/ZnS (core/shell/shell) nanocrystal complex, capped with the small molecule mercaptoacetic acid (MAA) for aqueous solubilization and low toxicity. These MAA-capped QDs can be used as the visualization aid for a multi-functional probe combining the functions of viruses and carbon nanotubes (CNT). A mild method of tagging virus through a polycationic solution, Polybrene, at 4°C is developed. This method can preserve most viral infectivity. The probes can be used to induce higher death rate in cells under near-infrared laser irradiation than in the cells without them, and thus, after additional improvements, may find applications in the study of cancer therapy. The optical properties of MAA-capped QDs are pH dependent. In particular, the fluorescence intensity increases with pH (pH between 4 and 10) of the environment. The results lead to a new venue to exploit QD as nano-scale sensors for localized physical and chemical properties in cells.

  11. Optical probe of spin-orbit fields in metallic magnetic structures

    NASA Astrophysics Data System (ADS)

    Montazeri, Mohammad; Upadhyaya, Pramey; Yu, Guoqiang; Wong, Kin L.; Lang, Murong; Fan, Yabin; Khalili Amiri, Pedram; Schwartz, Robert N.; Wang, Kang L.

    2015-03-01

    We report a novel self-consistent optical approach based on magneto-optical Kerr effect to directly and quantitatively probe the spin-orbit fields of magnetic devices with 1um diffraction limited spatial resolution. The optical probe is exemplified by investigating the spin-orbit fields in a magnetic stack of Ta(5 nm)/CoFeB(1.1 nm)/MgO(2.0 nm)/TaOx with enhanced perpendicular anisotropy. Both field-like and damping-like contributions were measured independently and their coefficients are quantified at 3 . 3 ×10-6 and - 2 . 0 ×10-6 Oe / A . cm-2 respectively. A detailed comparison with standard transport technique is presented in which a very good agreement were found. Our results establish the relevance of the optical methods for studying spin-orbit torque related physics. We acknowledge the support from the National Science Foundation (DMR-1411085) and the FAME Center, one of the six centers of STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA.

  12. Design and validation of a fiber optic point probe instrument for therapy guidance and monitoring

    NASA Astrophysics Data System (ADS)

    Xie, Haiyan; Xie, Zhiyuan; Mousavi, Monirehalsadat; Bendsoe, Niels; Brydegaard, Mikkel; Axelsson, Johan; Andersson-Engels, Stefan

    2014-07-01

    Optical techniques for tissue diagnostics currently are experiencing tremendous growth in biomedical applications, mainly due to their noninvasive, inexpensive, and real-time functionality. Here, we demonstrate a hand-held fiber optic probe instrument based on fluorescence/reflectance spectroscopy for precise tumor delineation. It is mainly aimed for brain tumor resection guidance with clinical adaptation to minimize the disruption of the standard surgical workflow and is meant as a complement to the state-of-the-art fluorescence surgical microscopy technique. Multiple light sources with fast pulse modulation and detection enable precise quantification of protoporphyrin IX (PpIX), tissue optical properties, and ambient light suppression. Laboratory measurements show the system is insensitive to strong ambient light. Validation measurements of tissue phantoms using nonlinear least squares support vector machines (LS-SVM) regression analysis demonstrate an error of <5% for PpIX concentration ranging from 400 to 1000 nM, even in the presence of large variations in phantom optical properties. The mean error is 3% for reduced scattering coefficient and 5% for blood concentration. Diagnostic precision of 100% was obtained by LS-SVM classification for in vivo skin tumors with topically applied 5-aminolevulinic acid during photodynamic therapy. The probe could easily be generalized to other tissue types and fluorophores for therapy guidance and monitoring.

  13. Design and validation of a fiber optic point probe instrument for therapy guidance and monitoring.

    PubMed

    Xie, Haiyan; Xie, Zhiyuan; Mousavi, Monirehalsadat; Bendsoe, Niels; Brydegaard, Mikkel; Axelsson, Johan; Andersson-Engels, Stefan

    2014-07-01

    Optical techniques for tissue diagnostics currently are experiencing tremendous growth in biomedical applications, mainly due to their noninvasive, inexpensive, and real-time functionality. Here, we demonstrate a hand-held fiber optic probe instrument based on fluorescence/reflectance spectroscopy for precise tumor delineation. It is mainly aimed for brain tumor resection guidance with clinical adaptation to minimize the disruption of the standard surgical workflow and is meant as a complement to the state-of-the-art fluorescence surgical microscopy technique. Multiple light sources with fast pulse modulation and detection enable precise quantification of protoporphyrin IX (PpIX), tissue optical properties, and ambient light suppression. Laboratory measurements show the system is insensitive to strong ambient light. Validation measurements of tissue phantoms using nonlinear least squares support vector machines (LS-SVM) regression analysis demonstrate an error of <5% for PpIX concentration ranging from 400 to 1000 nM, even in the presence of large variations in phantom optical properties. The mean error is 3% for reduced scattering coefficient and 5% for blood concentration. Diagnostic precision of 100% was obtained by LS-SVM classification for in vivo skin tumors with topically applied 5-aminolevulinic acid during photodynamic therapy. The probe could easily be generalized to other tissue types and fluorophores for therapy guidance and monitoring. PMID:24623193

  14. Lensed fiber-optic probe design for efficient photon collection in scattering media

    PubMed Central

    Ryu, Youngjae; Shin, Younghoon; Lee, Dasol; Altarejos, Judith Y.; Chung, Euiheon; Kwon, Hyuk-Sang

    2014-01-01

    Abstract: Measurement of bioluminescent or fluorescent optical reporters with an implanted fiber-optic probe is a promising approach to allow real-time monitoring of molecular and cellular processes in conscious behaving animals. Technically, this approach relies on sensitive light detection due to the relatively limited light signal and inherent light attenuation in scattering tissue. In this paper, we show that specific geometries of lensed fiber probes improve photon collection in turbid tissue such as brain. By employing Monte Carlo simulation and experimental measurement, we demonstrate that hemispherical- and axicon-shaped lensed fibers increase collection efficiency by up to 2-fold when compared with conventional bare fiber. Additionally we provide theoretical evidence that axicon lenses with specific angles improve photon collection over a wider axial range while conserving lateral collection when compared to hemispherical lensed fiber. These findings could guide the development of a minimally-invasive highly sensitive fiber optic-based light signal monitoring technique and may have broad implications such as fiber-based detection used in diffuse optical spectroscopy. PMID:25657886

  15. Use of fiber-optic-based flow cells and probes in the chemical and petroleum industries

    NASA Astrophysics Data System (ADS)

    Ponstingl, Mike; Vetter, Hans

    1992-08-01

    Fiber-optic-based, on-line photometric/spectrophotometric analytic methods are becoming increasingly more important in the process control industries because of unique benefits such as: safety, real-time data capture, immunity to EMI/RFI, and simplicity of installation. End- users employing fiber-optic methods are experiencing increased production yields, less waster, and greater product consistency all because the process can be controlled more efficiently. Extractive and in-situ flow cells have proven to be valuable means of 'looking' at the process stream. These techniques are currently being offered by several manufacturers of on-line fiber-optic photometric/spectrophotometric instruments. Custom Sensors & Technology has developed practical techniques for optical energy transmission in the 250 - 2000 nm wavelength range. In addition to discussing extractive and in-situ methods of sampling, various design considerations are addressed which relate to the efficiency of coupling light energy into and out of extractive flow cells and in-situ probes. In-situ probes can be of the transmission, turbidity, attenuated total reflection, or diffuse reflection types; and can be installed in a sanitary or threaded pipe fitting.

  16. Novel failure analysis techniques using photon probing with a scanning optical microscope

    SciTech Connect

    Cole, E.I. Jr.; Soden, J.M.; Rife, J.L.; Barton, D.L.; Henderson, C.L.

    1993-12-31

    Three new failure analysis techniques for integrated circuits (ICs) have been developed using localized photon probing with a scanning optical microscope (SOM). The first two are light-induced voltage alteration (LIVA) imaging techniques that (1) localize open-circuited and damaged junctions and (2) image transistor logic states. The third technique uses the SOM to control logic states optically from the IC backside. LIVA images are produced by monitoring the voltage fluctuations of a constant current power supply as a laser beam is scanned over the IC. High selectivity for localizing defects has been demonstrated using the LIVA approach. Logic state mapping results, similar to previous work using biased optical beam induced current (OBIC) and laser probing approaches have also been produced using LIVA. Application of the two LIVA based techniques to backside failure analysis has been demonstrated using an infrared laser source. Optical logic state control is based upon earlier work examining transistor response to photon injection. The physics of each method and their applications for failure analysis are described.

  17. X-ray pump optical probe cross-correlation study of GaAs

    SciTech Connect

    Durbin, S.M.; Clevenger, T.; Graber, T.; Henning, R.

    2012-09-10

    Ultrafast dynamics in atomic, molecular and condensed-matter systems are increasingly being studied using optical-pump, X-ray probe techniques where subpicosecond laser pulses excite the system and X-rays detect changes in absorption spectra and local atomic structure. New opportunities are appearing as a result of improved synchrotron capabilities and the advent of X-ray free-electron lasers. These source improvements also allow for the reverse measurement: X-ray pump followed by optical probe. We describe here how an X-ray pump beam transforms a thin GaAs specimen from a strong absorber into a nearly transparent window in less than 100 ps, for laser photon energies just above the bandgap. We find the opposite effect - X-ray induced optical opacity - for photon energies just below the bandgap. This raises interesting questions about the ultrafast many-body response of semiconductors to X-ray absorption, and provides a new approach for an X-ray/optical cross-correlator for synchrotron and X-ray free-electron laser applications.

  18. A handheld optical fiber parallel acoustic delay line (PADL) probe for photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Cho, Young; Chang, Cheung-Chung; Jeon, Mansik; Kim, Chulhong; Wang, Lihong V.; Zou, Jun

    2014-03-01

    In current photoacoustic tomography (PAT), l-D or 2-D ultrasound arrays and multi-channel data acquisition (DAQ) electronics are used to detect the photoacoustic signals simultaneously for "real-time" image construction. However, as the number of transducer elements and DAQ channels increase, the construction and operation of the ultrasound receiving system will become complex and costly. This situation can be addressed by using parallel acoustic delay lines (PADLs) to create true time delays in multiple PA signal channels. The time-delayed PA signals will reach the ultrasound transducer at different times and therefore can be received by one single-element transducer without mixing with each other. In this paper, we report the development of the first miniaturized PADL probe suitable for handheld operations. Fusedsilica optical fibers with low acoustic attenuation were used to construct the 16 PADLs with specific time delays. The handheld probe structure was fabricated using precision laser-micromachining process to provide robust mechanical support and accurate alignment of the PADLs with minimal acoustic distortion and inter-channel coupling. The 16 optical-fiber PADLs were arranged to form one input port and two output ports. Photoacoustic imaging of a black-ink target embedded in an optically-scattering phantom was successfully conducted using the handheld PADL probe with two single-element transducers and two DAQ channels (equal to a channel reduction ratio of 8:1). Our results show that the PADL technique and the handheld probe could provide a promising solution for real-time PAT with significantly reduced complexity and cost of the ultrasound receiver system.

  19. Influence of the Spot Size of the Probe Beam on the Detected THz Power Using Electro-Optic Detection Method

    NASA Astrophysics Data System (ADS)

    Metbulut, Mukaddes Meliz; Güllü, Hasan Hüseyin; Altan, Hakan

    We compared the detected THz power through electro-optic detection for different spot sizes of a probe beam on the < 110 > ZnTe crystal. We find that there is a proportional relationship between the detected THz power and spot size of the probe beam by theoretically analyzing its effect on the intensity profile of the terahertz beam.

  20. Fabrication of a Near-Field Optical Fiber Probe Based on Electroless Nickel Plating under Ultrasonic Irradiation

    NASA Astrophysics Data System (ADS)

    Mononobe, Shuji; Saito, Yuichi; Ohtsu, Motoichi; Honma, Hideo

    2004-05-01

    We present a method of fabricating a near-field optical probe with a nickel film whose thickness gradually decreases to a few tens of nanometers toward the apex. This method involves etching an optical fiber and electroless nickel plating with ultrasonic agitation. Using 1 MHz ceramic transducers, we have reproducibly fabricated the probe with a tip diameter of less than 40 nm. This reproducibility is high compared to those for Langevin-type transducers.

  1. An optical biopsy system with miniaturized Raman and spectral imaging probes; in vivo animal and ex vivo clinical application studies

    NASA Astrophysics Data System (ADS)

    Sato, Hidetoshi; Suzuki, Toshiaki; Andriana, Bibin B.; Morita, Shin'ichi; Maruyama, Atsushi; Shinzawa, Hideyuki; Komachi, Yuichi; Kanai, Gen'ichi; Ura, Nobuo; Masutani, Koji; Matsuura, Yuji; Toi, Masakazu; Shimosegawa, Toru; Ozaki, Yukihiro

    2009-02-01

    An optical biopsy system which equips miniaturized Raman probes, a miniaturized endoscope and a fluorescent image probe has been developed for in vivo studies of live experimental animals. The present report describes basic optical properties of the system and its application studies for in vivo cancer model animals and ex vivo human cancer tissues. It was developed two types of miniaturized Raman probes, micro Raman probe (MRP) made of optical fibers and ball lens hollow optical fiber Raman probe (BHRP) made of single hollow optical fiber (HOF) with a ball lens. The former has rather large working distance (WD), up to one millimeter. The latter has small WD (~300μm) which depends on the focal length of the ball lens. Use of multiple probes with different WD allows one to obtain detailed information of subsurface tissues in the totally noninvasive manner. The probe is enough narrow to be inserted into a biopsy needle (~19G), for observations of the lesion at deeper inside bodies. The miniaturized endoscope has been applied to observe progression of a stomach cancer in the same rat lesion. It was succeeded to visualize structure of non-stained cancer tissue in live model animals by the fluorescent image technique. The system was also applied to ex vivo studies of human breast and stomach cancers.

  2. The optical properties of a weak probe field in a graphene ensemble under Raman excitation

    NASA Astrophysics Data System (ADS)

    Raheli, Ali; Hamedi, H. R.; Sahrai, M.

    2016-06-01

    We investigate the coherent manipulation of certain optical properties in graphene under Raman excitation by using a density-matrix approach. It is shown that the absorption and dispersion, the group velocity, and the transmission coefficient of the probe field can be efficiently controlled through proper adjustment of the intensity and frequency detuning of the control field. In addition, the optical bistability (OB) behavior is explored for the proposed system. It is found that the bistable threshold intensity and related hysteresis loop of OB can be controlled by the parameters of the system. The results obtained may be used in real experiments for the development of new types of nanoelectronic devices used for the realization of all-optical switching processes.

  3. Writing 40 nm marks by using a beaked metallic plate near-field optical probe.

    PubMed

    Matsumoto, T; Anzai, Y; Shintani, T; Nakamura, K; Nishida, T

    2006-01-15

    We have developed a near-field optical probe that uses a triangular metallic plate with a three-dimensionally tapered apex as a light source for thermally assisted magnetic recording. Numerical analysis using a finite-element method shows that the size of the optical spot generated at the apex is 15 nm x 20 nm, and the efficiency (defined as the ratio between the power of the optical near field at the surface of the recording medium and that of the incident light) is 15% when the incident light is focused by a lens with a numerical aperture of 0.8. The metallic plate was fabricated on the surface of a quartz slider and used for writing marks on a phase change recording medium. The marks were observed with a scanning electron microscope, and we confirmed that marks with a diameter of 40 nm were successfully written on the medium. PMID:16441049

  4. Evaluation of improvement of diffuse optical imaging of brain function by high-density probe arrangements and imaging algorithms

    NASA Astrophysics Data System (ADS)

    Sakakibara, Yusuke; Kurihara, Kazuki; Okada, Eiji

    2016-04-01

    Diffuse optical imaging has been applied to measure the localized hemodynamic responses to brain activation. One of the serious problems with diffuse optical imaging is the limitation of the spatial resolution caused by the sparse probe arrangement and broadened spatial sensitivity profile for each probe pair. High-density probe arrangements and an image reconstruction algorithm considering the broadening of the spatial sensitivity can improve the spatial resolution of the image. In this study, the diffuse optical imaging of the absorption change in the brain is simulated to evaluate the effect of the high-density probe arrangements and imaging methods. The localization error, equivalent full-width half maximum and circularity of the absorption change in the image obtained by the mapping and reconstruction methods from the data measured by five probe arrangements are compared to quantitatively evaluate the imaging methods and probe arrangements. The simple mapping method is sufficient for the density of the measurement points up to the double-density probe arrangement. The image reconstruction method considering the broadening of the spatial sensitivity of the probe pairs can effectively improve the spatial resolution of the image obtained from the probe arrangements higher than the quadruple density, in which the distance between the neighboring measurement points is 10.6 mm.

  5. A Fiber Optic Probe for Monitoring Protein Aggregation, Nucleation, and Crystallization

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Suh, Kwang I.; Arabshahi, Alireza; Wilson, William W.; Bray, Terry L.; DeLucas, Lawrence J.

    1996-01-01

    Protein crystals are experimentally grown in hanging drops in microgravity experiments on-board the Space Shuttle orbiter. The technique of dynamic light scattering (DLS) can be used to monitor crystal growth process in hanging droplets (approx. 30 (L)) in microgravity experiments, but elaborate instrumentation and optical alignment problems have made in-situ applications difficult. In this paper we demonstrate that such experiments are now feasible. We apply a newly developed fiber optic probe to various earth and space (micro- gravity) bound protein crystallization system configurations to test its capability. These include conventional batch (cuvette or capillary) systems, hanging drop method in a six-pack hanging drop vapor diffusion apparatus (HDVDA), a modified HDVDA for temperature- induced nucleation and aggregation studies, and a newly envisioned dynamically controlled vapor diffusion system (DCVDS) configuration. Our compact system exploits the principles of DLS and offers a fast (within a few seconds) means of quantitatively and non-invasively monitoring the various growth stages of protein crystallization. In addition to DLS capability, the probe can also be used for performing single-angle static light scattering measurements. It utilizes extremely low levels of laser power (approx. few (W)) without a need of having any optical alignment and vibration isolation. The compact probe is also equipped with a miniaturized microscope for visualization of macroscopic protein crystals. This new optical diagnostic system opens up enormous opportunity for exploring new ways to grow good quality crystals suitable for x-ray crystallographic analysis and may help develop a concrete scientific basis for understanding the process of crystallization.

  6. All-optical optoacoustic microscopy system based on probe beam deflection technique

    NASA Astrophysics Data System (ADS)

    Maswadi, Saher M.; Tsyboulskic, Dmitri; Roth, Caleb C.; Glickman, Randolph D.; Beier, Hope T.; Oraevsky, Alexander A.; Ibey, Bennett L.

    2016-03-01

    It is difficult to achieve sub-micron resolution in backward mode OA microscopy using conventional piezoelectric detectors, because of wavefront distortions caused by components placed in the optical path, between the sample and the objective lens, that are required to separate the acoustic wave from the optical beam. As an alternate approach, an optoacoustic microscope (OAM) was constructed using the probe beam deflection technique (PBDT) to detect laserinduced acoustic signals. The all-optical OAM detects laser-generated pressure waves using a probe beam passing through a coupling medium, such as water, filling the space between the microscope objective lens and sample. The acoustic waves generated in the sample propagate through the coupling medium, causing transient changes in the refractive index that deflect the probe beam. These deflections are measured with a high-speed, balanced photodiode position detector. The deflection amplitude is directly proportional to the magnitude of the acoustic pressure wave, and provides the data required for image reconstruction. The sensitivity of the PBDT detector expressed as noise equivalent pressure was 12 Pa, comparable to that of existing high-performance ultrasound detectors. Because of the unimpeded working distance, a high numerical aperture objective lens, i.e. NA = 1, was employed in the OAM to achieve near diffraction-limited lateral resolution of 0.5 μm at 532nm. The all-optical OAM provides several benefits over current piezoelectric detector-based systems, such as increased lateral and axial resolution, higher sensitivity, robustness, and potentially more compatibility with multimodal instruments.

  7. Protein rotational dynamics investigated with a dual EPR/optical molecular probe. Spin-labeled eosin.

    PubMed Central

    Cobb, C E; Hustedt, E J; Beechem, J M; Beth, A H

    1993-01-01

    An acyl spin-label derivative of 5-aminoeosin (5-SLE) was chemically synthesized and employed in studies of rotational dynamics of the free probe and of the probe when bound noncovalently to bovine serum albumin using the spectroscopic techniques of fluorescence anisotropy decay and electron paramagnetic resonance (EPR) and their long-lifetime counterparts phosphorescence anisotropy decay and saturation transfer EPR. Previous work (Beth, A. H., Cobb, C. E., and J. M. Beechem, 1992. Synthesis and characterization of a combined fluorescence, phosphorescence, and electron paramagnetic resonance probe. Society of Photo-Optical Instrumentation Engineers. Time-Resolved Laser Spectroscopy III. 504-512) has shown that the spin-label moiety only slightly altered the fluorescence and phosphorescence lifetimes and quantum yields of 5-SLE when compared with 5-SLE whose nitroxide had been reduced with ascorbate and with the diamagnetic homolog 5-acetyleosin. In the present work, we have utilized time-resolved fluorescence anisotropy decay and linear EPR spectroscopies to observe and quantitate the psec motions of 5-SLE in solution and the nsec motions of the 5-SLE-bovine serum albumin complex. Time-resolved phosphorescence anisotropy decay and saturation transfer EPR studies have been carried out to observe and quantitate the microseconds motions of the 5-SLE-albumin complex in glycerol/buffer solutions of varying viscosity. These latter studies have enabled a rigorous comparison of rotational correlation times obtained from these complementary techniques to be made with a single probe. The studies described demonstrate that it is possible to employ a single molecular probe to carry out the full range of fluorescence, phosphorescence, EPR, and saturation transfer EPR studies. It is anticipated that "dual" molecular probes of this general type will significantly enhance capabilities for extracting dynamics and structural information from macromolecules and their functional

  8. Probing vacuum-induced coherence via magneto-optical rotation in molecular systems

    NASA Astrophysics Data System (ADS)

    Kumar, Pardeep; Deb, Bimalendu; Dasgupta, Shubhrangshu

    2016-05-01

    Vacuum-induced coherence (VIC) arises due to the quantum interference between the spontaneous emission pathways from the degenerate excited states to a common ground state. The stringent requirement for the VIC to occur is the nonorthogonality of the transition dipole matrix elements. Unlike atoms, molecules are the promising systems for exploration of VIC, as it is possible to identify the non-orthogonal transitions due to the coupling of the rotation of molecular axis with molecular electronic angular momentum. Usually, the possible signatures of VIC are obtained by manipulating the absorption of the probe field. In this paper, we show how the dispersion of the probe field can be manipulated to obtain a measurable signature of VIC. Precisely speaking, we explore a way to probe VIC in molecules by observing its influence on magneto-optical rotation (MOR). We show that VIC in the presence of a control laser and a magnetic field can lead to large enhancement in the rotation of the plane of polarization of a linearly polarized weak laser with vanishing circular dichroism. This effect can be realized in cold molecular gases. Such a large MOR angle may be used as a tool for optical magnetometry to detect weak magnetic field with large measurement sensitivity.

  9. Design of “smart” probes for optical imaging of apoptosis

    PubMed Central

    Huang, Xinglu; Lee, Seulki; Chen, Xiaoyuan

    2011-01-01

    Apoptosis is a mode of programmed cell death in multicellular organisms and plays a central role in controlling embryonic development, growth and differentiation and monitoring the induction of tumor cell death through anticancer therapy. Since the most effective chemotherapeutics rely on apoptosis, imaging apoptotic processes can be an invaluable tool to monitor therapeutic intervention and discover new drugs modulating apoptosis. The most attractive target for developing specific apoptosis imaging probes is caspases, crucial mediators of apoptosis. Up to now, various optical imaging strategies for apoptosis have been developed as an easy and economical modality. However, current optical applications are limited by poor sensitivity and specificity. A subset of molecular imaging contrast agents known as “activatable” or “smart” molecular probes allow for very high signal-to-background ratios compared to conventional targeted contrast agents and open up the possibility of imaging intracellular targets. In this review, we will discuss the unique design strategies and applications of activatable probes recently developed for fluorescence and bioluminescence imaging of caspase activity. PMID:22514789

  10. Fiber-Optic Imaging Probe Developed for Space Used to Detect Diabetes Through the Eye

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Chenault, Michelle V.; Datiles, Manuel B., III; Sebag, J.; Suh, Kwang I.

    2000-01-01

    Approximately 16 million Americans have diabetes mellitus, which can severely impair eyesight by causing cataracts, diabetic retinopathy, and glaucoma. Cataracts are 1.6 times more common in people with diabetes than in those without diabetes, and cataract extraction is the only surgical treatment. In many cases, diabetes-related ocular pathologies go undiagnosed until visual function is compromised. This ongoing pilot project seeks to study the progression of diabetes in a unique animal model by monitoring changes in the lens with a safe, sensitive, dynamic light-scattering probe. Dynamic light scattering (DLS), has the potential to diagnose cataracts at the molecular level. Recently, a new DLS fiber-optic probe was developed at the NASA Glenn Research Center at Lewis Field for noncontact, accurate, and extremely sensitive particle-sizing measurements in fluid dispersions and suspensions (ref. 1). This compact, portable, and rugged probe is free of optical alignment, offers point-and-shoot operation for various online field applications and challenging environments, and yet is extremely flexible in regards to sample container sizes, materials, and shapes. No external vibration isolation and no index matching are required. It can measure particles as small as 1 nm and as large as few micrometers in a wide concentration range from very dilute (waterlike) dispersions to very turbid (milklike) suspensions. It is safe and fast to use, since it only requires very low laser power (10 nW to 3 mW) with very short data acquisition times (2 to 10 sec).

  11. Fiber optic probes for laser light scattering: Ground based evaluation for micgrogravity flight experimentation. Integrated coherent imaging fiber optic systems for laser light scattering and other applications

    NASA Technical Reports Server (NTRS)

    Dhadwal, Harbans Singh

    1994-01-01

    The research work presented in this report has established a new class of backscatter fiber optics probes for remote dynamic light scattering capability over a range of scattering angles from 94 degrees to 175 degrees. The fiber optic probes provide remote access to scattering systems, and can be utilized in either a noninvasive or invasive configuration. The fiber optics create an interference free data channel to inaccessible and harsh environments. Results from several studies of concentrated suspension, microemulsions, and protein systems are presented. The second part of the report describes the development of a new technology of wavefront processing within the optical fiber, that is, integrated fiber optics. Results have been very encouraging and the technology promises to have significant impact on the development of fiber optic sensors in a variety of fields ranging from environmental monitoring to optical recording, from biomedical sensing to photolithography.

  12. Fiber optic probe having fibers with endfaces formed for improved coupling efficiency and method using same

    DOEpatents

    O'Rourke, Patrick E.; Livingston, Ronald R.

    1995-01-01

    A fiber optic probe for detecting scattered light, with transmitting and receiving fibers having slanted ends and bundled together to form a bevel within the tip of the probe. The probe comprises a housing with a transparent window across its tip for protecting the transmitting and receiving fibers held therein. The endfaces of the fibers are slanted, by cutting, polishing and the like, so that they lie in a plane that is not perpendicular to the longitudinal axis of the respective fiber. The fibers are held in the tip of the probe using an epoxy and oriented so that lines normal to the slanted endfaces are divergent with respect to one another. The epoxy, which is positioned substantially between the transmitting and receiving fibers, is tapered so that the transmitting fiber, the epoxy and the receiving fiber form a bevel of not more than 20 degrees. The angled fiber endfaces cause directing of the light cones toward each other, resulting in improved light coupling efficiency. A light absorber, such as carbon black, is contained in the epoxy to reduce crosstalk between the transmitting and receiving fibers.

  13. Fiber optic probe having fibers with endfaces formed for improved coupling efficiency and method using same

    DOEpatents

    O`Rourke, P.E.; Livingston, R.R.

    1995-03-28

    A fiber optic probe is disclosed for detecting scattered light, with transmitting and receiving fibers having slanted ends and bundled together to form a bevel within the tip of the probe. The probe comprises a housing with a transparent window across its tip for protecting the transmitting and receiving fibers held therein. The endfaces of the fibers are slanted, by cutting, polishing and the like, so that they lie in a plane that is not perpendicular to the longitudinal axis of the respective fiber. The fibers are held in the tip of the probe using an epoxy and oriented so that lines normal to the slanted endfaces are divergent with respect to one another. The epoxy, which is positioned substantially between the transmitting and receiving fibers, is tapered so that the transmitting fiber, the epoxy and the receiving fiber form a bevel of not more than 20 degrees. The angled fiber endfaces cause directing of the light cones toward each other, resulting in improved light coupling efficiency. A light absorber, such as carbon black, is contained in the epoxy to reduce crosstalk between the transmitting and receiving fibers. 3 figures.

  14. Nanocluster: photothermal bubble as optical probes for cytometric and microscopic applications

    NASA Astrophysics Data System (ADS)

    Lapotko, Dmitri O.; Lukianova-Hleb, Ekaterina Y.; Hafner, Jason H.

    2007-06-01

    The ability to detect optical signals form a cellular target depends upon the amount of optical energy that can be generated by this target as the signal. Given that the sensitivity of optical detectors has some finite limit, further increase of the sensitivity of optical diagnostic methods requires increasing the energy of target-generated signal. Usually this energy is converted by the cellular target upon its optical excitation and is limited by many factors such as: cell and target damage thresholds, efficiency of excitation energy conversion, size of the target etc. All these put principal limitation on sensing small targets (like molecules) in living cells with any optical method because the energy that can be safely converted by the target into a signal is limited. To overcome this limitation and to improve the sensitivity of optical microscopy of living cells (and cytometry in general) we propose the concept of intracellular amplification of the optical signal. This concept includes two major steps. First, primary (pump) optical radiation interacts with the target (a probe molecule) to generate a transient target. Second, the transient target is sensed with additional optical radiation that does not interact strongly with primary target or the cell, and, hence, may have high enough energy to increase the signal from transient target even above the energy of pump radiation, which is limited by cell and target damage thresholds. We propose to use optical scattering from clusters of gold nanoparticles (the target) that are selectively formed in specific cells through antibody-receptor interaction and through endocytosis. To amplify this optical signal we propose to generate photothermal bubbles (the transient target) around those clusters. In experiments with water suspensions and with individual tumor K562 cells we have achieved optical signal amplification in individual cells (relatively to the scattering signal from intact cells): with gold nanorod

  15. Probing and Modeling of Carrier Motion in Organic Field Effect Transistors by Optical Second Harmonic Generation

    SciTech Connect

    Iwamoto, Mitsumasa

    2009-07-10

    We here report a novel optical second harmonic generation (SHG) measurement that allows an electric field formed in organic solid to be probed. We examined the SHG intensity profile that changes depending on space charge field caused by carrier injection. Experiments making use of time resolved SHG technique has revealed dynamic changes of SHG intensity profiles arising from pentacene, and that carrier transport in OFET was diffusion-like. Calculations using drift-diffusion equation well accounted for the visualized carrier motion probed by time-resolved SHG. Finally, we conclude that experiments and analysis based on dielectrics physics is a very effective way for analyzing carrier behaviors in organic materials as well as in organic thin film devices.

  16. Fiber optic displacement sensor for medal detection using fiber bundled probe

    NASA Astrophysics Data System (ADS)

    Yasin, M.; Samian, Supadi, Pujiyanto, Yhuwana, Y. G. Yhun

    2016-03-01

    A simple fiber optic displacement sensor (FODS) based on intensity modulation technique is investigated using a bundle multimode plastic fiber as a probe for various medals detection. The sensor consists of a light source, a probe, and photodiode detector. The sensor is capable of measuring displacements of flat medals ranging from 0.05 to 4.2 mm using a red light source of wavelength 630 nm. The highest sensitivity of the sensor is found to be 0.0048 mV/μm over 50-650 µm for the gold medal. The sensor is highly sensitive at the front slope and very useful for close distance target. The simplicity of the design, high sensitivity, long dynamic range and the low cost of the fabrication make it suitable for wider applications in industries as position control and micro displacement measurement in the hazardous region.

  17. Dicke superradiance as nondestructive probe for the state of atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    ten Brinke, Nicolai; Schützhold, Ralf

    2016-04-01

    We present a proposal for a probing scheme utilizing Dicke superradiance to obtain information about ultracold atoms in optical lattices. A probe photon is absorbed collectively by an ensemble of lattice atoms generating a Dicke state. The lattice dynamics (e.g., tunneling) affects the coherence properties of that Dicke state and thus alters the superradiant emission characteristics - which in turn provides insight into the lattice (dynamics). Comparing the Bose-Hubbard and the Fermi-Hubbard model, we find similar superradiance in the strongly interacting Mott insulator regime, but crucial differences in the weakly interacting (superfluid or metallic) phase. Furthermore, we study the possibility to detect whether a quantum phase transition between the two regimes can be considered adiabatic or a quantum quench.

  18. Dicke superradiance as nondestructive probe for the state of atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    Brinke, Nicolai ten; Schützhold, Ralf

    2016-05-01

    We present a proposal for a probing scheme utilizing Dicke superradiance to obtain information about ultracold atoms in optical lattices. A probe photon is absorbed collectively by an ensemble of lattice atoms generating a Dicke state. The lattice dynamics (e.g., tunneling) affects the coherence properties of that Dicke state and thus alters the superradiant emission characteristics - which in turn provides insight into the lattice (dynamics). Comparing the Bose-Hubbard and the Fermi-Hubbard model, we find similar superradiance in the strongly interacting Mott insulator regime, but crucial differences in the weakly interacting (superfluid or metallic) phase. Furthermore, we study the possibility to detect whether a quantum phase transition between the two regimes can be considered adiabatic or a quantum quench.

  19. In vivo pump-probe optical coherence tomography imaging in Xenopus laevis.

    PubMed

    Carrasco-Zevallos, Oscar; Shelton, Ryan L; Kim, Wihan; Pearson, Jeremy; Applegate, Brian E

    2015-01-01

    Currently, optical coherence tomography (OCT), is not capable of obtaining molecular information often crucial for identification of disease. To enable molecular imaging with OCT, we have further developed a technique that harnesses transient changes in light absorption in the sample to garner molecular information. A Fourier-domain Pump-Probe OCT (PPOCT) system utilizing a 532 nm pump and 830 nm probe has been developed for imaging hemoglobin. Methylene blue, a biological dye with well-know photophysics, was used to characterize the system before investigating the origin of the hemoglobin PPOCT signal. The first in vivo PPOCT images were recorded of the vasculature in Xenopus laevis. The technique was shown to work equally well in flowing and nonflowing vessels. Furthermore, PPOCT was compared with other OCT extensions which require flow, such as Doppler OCT and phase-variance OCT. PPOCT was shown to better delineate tortuous vessels, where nodes often restrict Doppler and phase-variance reconstruction. PMID:24282110

  20. Characterization of dilute optical lattices using pump-probe spectroscopy and photon correlation measurements

    NASA Astrophysics Data System (ADS)

    Clements, Ethan; Ross, Preston; Rapp, Anthony; Cai, Hong; Reigle, Alex; Schlonsky, Eli; Lee, Hoseong; Clemens, James; Bali, Samir

    2016-05-01

    We experimentally investigate optical lattices using three different methods: pump-probe spectroscopy of vibrational energy levels, photon correlation of light scattered by cold atoms, and fluorescence imaging. Photon correlations of the scattered light can be used to measure lattice dwell times and crossover times between lattice sites. From this information we can derive the diffusion constant which can then be compared to direct measurement via fluorescence imaging. Furthermore, by Fourier transforming the time delayed photon correlations we can obtain the intensity spectrum which can be compared directly to pump-probe spectroscopy of the vibrational energy levels. We plan to carefully study situations in which the atomic transport properties deviate from Boltzman Gibbs statistics.

  1. Molecular Imaging Probes for Positron Emission Tomography and Optical Imaging of Sentinel Lymph Node and Tumor

    NASA Astrophysics Data System (ADS)

    Qin, Zhengtao

    Molecular imaging is visualizations and measurements of in vivo biological processes at the molecular or cellular level using specific imaging probes. As an emerging technology, biocompatible macromolecular or nanoparticle based targeted imaging probes have gained increasing popularities. Those complexes consist of a carrier, an imaging reporter, and a targeting ligand. The active targeting ability dramatically increases the specificity. And the multivalency effect may further reduce the dose while providing a decent signal. In this thesis, sentinel lymph node (SLN) mapping and cancer imaging are two research topics. The focus is to develop molecular imaging probes with high specificity and sensitivity, for Positron Emission Tomography (PET) and optical imaging. The objective of this thesis is to explore dextran radiopharmaceuticals and porous silicon nanoparticles based molecular imaging agents. Dextran polymers are excellent carriers to deliver imaging reporters or therapeutic agents due to its well established safety profile and oligosaccharide conjugation chemistry. There is also a wide selection of dextran polymers with different lengths. On the other hand, Silicon nanoparticles represent another class of biodegradable materials for imaging and drug delivery. The success in fluorescence lifetime imaging and enhancements of the immune activation potency was briefly discussed. Chapter 1 begins with an overview on current molecular imaging techniques and imaging probes. Chapter 2 presents a near-IR dye conjugated probe, IRDye 800CW-tilmanocept. Fluorophore density was optimized to generate the maximum brightness. It was labeled with 68Ga and 99mTc and in vivo SLN mapping was successfully performed in different animals, such as mice, rabbits, dogs and pigs. With 99mTc labeled IRDye 800CW-tilmanocept, chapter 3 introduces a two-day imaging protocol with a hand-held imager. Chapter 4 proposed a method to dual radiolabel the IRDye 800CW-tilmanocept with both 68Ga and

  2. Single potassium niobate nano/microsized particles as local mechano-optical Brownian probes

    NASA Astrophysics Data System (ADS)

    Mor, Flavio M.; Sienkiewicz, Andrzej; Magrez, Arnaud; Forró, László; Jeney, Sylvia

    2016-03-01

    Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal fluctuations and optical forces of singly-trapped KNbO3 particles within the optical trapping volume of a PFM microscope. We also show that, under near-infrared (NIR) excitation of the highly focused laser beam of the PFM microscope, a single optically-trapped KNbO3 particle reveals a strong SHG signal manifested by a narrow peak (λem = 532 nm) at half the excitation wavelength (λex = 1064 nm). Moreover, we demonstrate that the thus induced SHG emission can be used as a local light source that is capable of optically exciting molecules of an organic dye, Rose Bengal (RB), which adhere to the particle surface, through the mechanism of luminescence energy transfer (LET).Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal

  3. Probing the micro-rheological properties of aerosol particles using optical tweezers

    NASA Astrophysics Data System (ADS)

    Power, Rory M.; Reid, Jonathan P.

    2014-07-01

    The use of optical trapping techniques to manipulate probe particles for performing micro-rheological measurements on a surrounding fluid is well-established. Here, we review recent advances made in the use of optical trapping to probe the rheological properties of trapped particles themselves. In particular, we review observations of the continuous transition from liquid to solid-like viscosity of sub-picolitre supersaturated solution aerosol droplets using optical trapping techniques. Direct measurements of the viscosity of the particle bulk are derived from the damped oscillations in shape following coalescence of two particles, a consequence of the interplay between viscous and surface forces and the capillary driven relaxation of the approximately spheroidal composite particle. Holographic optical tweezers provide a facile method for the manipulation of arrays of particles allowing coalescence to be controllably induced between two micron-sized aerosol particles. The optical forces, while sufficiently strong to confine the composite particle, are several orders of magnitude weaker than the capillary forces driving relaxation. Light, elastically back-scattered by the particle, is recorded with sub-100 ns resolution allowing measurements of fast relaxation (low viscosity) dynamics, while the brightfield image can be used to monitor the shape relaxation extending to times in excess of 1000 s. For the slowest relaxation dynamics studied (particles with the highest viscosity) the presence and line shape of whispering gallery modes in the cavity enhanced Raman spectrum can be used to infer the relaxation time while serving the dual purpose of allowing the droplet size and refractive index to be measured with accuracies of ±0.025% and ±0.1%, respectively. The time constant for the damped relaxation can be used to infer the bulk viscosity, spanning from the dilute solution limit to a value approaching that of a glass, typically considered to be >1012 Pa s, whilst

  4. Nano-scale optical and electrical probes of materials and processes.

    SciTech Connect

    Bogart, Katherine Huderle Andersen

    2007-03-01

    This report describes the investigations and milestones of the Nano-Scale Optical and Electrical Probes of Materials and Processes Junior/Senior LDRD. The goal of this LDRD was to improve our understanding of radiative and non-radiative mechanisms at the nanometer scale with the aim of increasing LED and solar cell efficiencies. These non-radiative mechanisms were investigated using a unique combination of optical and scanning-probe microscopy methods for surface, materials, and device evaluation. For this research we utilized our new near-field scanning optical microscope (NSOM) system to aid in understanding of defect-related emission issues for GaN-based materials. We observed micrometer-scale variations in photoluminescence (PL) intensity for GaN films grown on Cantilever Epitaxy pattern substrates, with lower PL intensity observed in regions with higher dislocation densities. By adding electrical probes to the NSOM system, the photocurrent and surface morphology could be measured concurrently. Using this capability we observed reduced emission in InGaN MQW LEDs near hillock-shaped material defects. In spatially- and spectrally-resolved PL studies, the emission intensity and measured wavelength varied across the wafer, suggesting the possibility of indium segregation within the InGaN quantum wells. Blue-shifting of the InGaN MQW wavelength due to thinning of quantum wells was also observed on top of large-scale ({micro}m) defect structures in GaN. As a direct result of this program, we have expanded the awareness of our new NSOM/multifunctional SPM capability at Sandia and formed several collaborations within Sandia and with NINE Universities. Possible future investigations with these new collaborators might include GaN-based compound semiconductors for green LEDs, nanoscale materials science, and nanostructures, novel application of polymers for OLEDs, and phase imprint lithography for large area 3D nanostructures.

  5. Pulse pressure waveform estimation using distension profiling with contactless optical probe.

    PubMed

    Pereira, Tânia; Santos, Inês; Oliveira, Tatiana; Vaz, Pedro; Pereira, Telmo; Santos, Helder; Pereira, Helena; Correia, Carlos; Cardoso, João

    2014-11-01

    The pulse pressure waveform has, for long, been known as a fundamental biomedical signal and its analysis is recognized as a non-invasive, simple, and resourceful technique for the assessment of arterial vessels condition observed in several diseases. In the current paper, waveforms from non-invasive optical probe that measures carotid artery distension profiles are compared with the waveforms of the pulse pressure acquired by intra-arterial catheter invasive measurement in the ascending aorta. Measurements were performed in a study population of 16 patients who had undergone cardiac catheterization. The hemodynamic parameters: area under the curve (AUC), the area during systole (AS) and the area during diastole (AD), their ratio (AD/AS) and the ejection time index (ETI), from invasive and non-invasive measurements were compared. The results show that the pressure waveforms obtained by the two methods are similar, with 13% of mean value of the root mean square error (RMSE). Moreover, the correlation coefficient demonstrates the strong correlation. The comparison between the AUCs allows the assessment of the differences between the phases of the cardiac cycle. In the systolic period the waveforms are almost equal, evidencing greatest clinical relevance during this period. Slight differences are found in diastole, probably due to the structural arterial differences. The optical probe has lower variability than the invasive system (13% vs 16%). This study validates the capability of acquiring the arterial pulse waveform with a non-invasive method, using a non-contact optical probe at the carotid site with residual differences from the aortic invasive measurements. PMID:25169470

  6. Effect of reference spectra in spectral fitting to discriminate enzyme-activatable photoacoustic probe from intrinsic optical absorbers

    NASA Astrophysics Data System (ADS)

    Hirasawa, Takeshi; Okawa, Shinpei; Iwatate, Ryu J.; Kamiya, Mako; Urano, Yasuteru; Ishihara, Miya

    2016-03-01

    Multispectral photoacoustic (MS-PA) imaging has been researched to image molecular probes in the presence of strong background signals produced from intrinsic optical absorbers. Spectral fitting method (SFM) discriminates probe signals from background signals by fitting the PA spectra that are calculated from MS-PA images to reference spectra of the probe and background, respectively. Because hemoglobin is a dominant optical absorber in visible to near-infrared wavelength range, absorption spectra of hemoglobin have been widely used as reference background spectra. However, the spectra of background signals produced from heterogeneous biological tissue differ from the reference background spectra due to presence of other intrinsic optical absorbers and effect of optical scattering. Due to the difference, the background signals partly remain in the probe images. To image the probe injected in subcutaneous tumors of mice clearly, we added the melanosome absorption spectrum to the reference background spectra because skin contains nonnegligible concentration of melanosome and the spectrum is very similar to the scattering spectrum of biological tissue. The probe injected in the subcutaneous tumor of mice was an enzyme-activatable probe which show their original colors only in the presence of γ-glutamyltranspeptidase, an enzyme associated with cancer. The probes have been successfully used for rapid fluorescence imaging of cancer. As a result of MS-PA imaging, by considering the melanosome absorption spectrum, the background signals were successfully suppressed and then clearer probe image was obtained. Our MS-PA imaging method afforded successful imaging of tumors in mice injected with activatable PA probes.

  7. A wireless handheld probe with spectrally constrained evolution strategies for diffuse optical imaging of tissue

    PubMed Central

    Flexman, M. L.; Kim, H. K.; Stoll, R.; Khalil, M. A.; Fong, C. J.; Hielscher, A. H.

    2012-01-01

    We present a low-cost, portable, wireless diffuse optical imaging device. The handheld device is fast, portable, and can be applied to a wide range of both static and dynamic imaging applications including breast cancer, functional brain imaging, and peripheral artery disease. The continuous-wave probe has four near-infrared wavelengths and uses digital detection techniques to perform measurements at 2.3 Hz. Using a multispectral evolution algorithm for chromophore reconstruction, we can measure absolute oxygenated and deoxygenated hemoglobin concentration as well as scattering in tissue. Performance of the device is demonstrated using a series of liquid phantoms comprised of Intralipid®, ink, and dye. PMID:22462907

  8. Cavity-Enhanced Light Scattering in Optical Lattices to Probe Atomic Quantum Statistics

    SciTech Connect

    Mekhov, Igor B.; Maschler, Christoph; Ritsch, Helmut

    2007-03-09

    Different quantum states of atoms in optical lattices can be nondestructively monitored by off-resonant collective light scattering into a cavity. Angle resolved measurements of photon number and variance give information about atom-number fluctuations and pair correlations without single-site access. Observation at angles of diffraction minima provides information on quantum fluctuations insensitive to classical noise. For transverse probing, no photon is scattered into a cavity from a Mott insulator phase, while the photon number is proportional to the atom number for a superfluid.

  9. Probing vacuum-induced coherence via magneto-optical rotation in molecular systems

    NASA Astrophysics Data System (ADS)

    Kumar, Pardeep; Deb, Bimalendu; Dasgupta, Shubhrangshu

    2016-06-01

    We investigate theoretically the effects of vacuum-induced coherence (VIC) on magneto-optical rotation (MOR). We carry out a model study to show that VIC in the presence of a control laser and a magnetic field can lead to large enhancement in the rotation of the plane of polarization of a linearly polarized weak laser with vanishing circular dichroism. This effect can be realized in cold molecular gases and may be used as a sensitive probe for VIC. Such a large MOR angle can also be used to detect weak magnetic field with large measurement sensitivity.

  10. Optical pump-probe measurements of local nuclear spin coherence in semiconductor quantum wells.

    PubMed

    Sanada, H; Kondo, Y; Matsuzaka, S; Morita, K; Hu, C Y; Ohno, Y; Ohno, H

    2006-02-17

    We demonstrate local manipulation and detection of nuclear spin coherence in semiconductor quantum wells by an optical pump-probe technique combined with pulse rf NMR. The Larmor precession of photoexcited electron spins is monitored by time-resolved Kerr rotation (TRKR) as a measure of nuclear magnetic field. Under the irradiation of resonant pulsed rf magnetic fields, Rabi oscillations of nuclear spins are traced by TRKR signals. The intrinsic coherence time evaluated by a spin-echo technique reveals the dependence on the orientation of the magnetic field with respect to the crystalline axis as expected by the nearest neighbor dipole-dipole interaction. PMID:16606048

  11. Light scattering from ultracold atoms in optical lattices as an optical probe of quantum statistics

    SciTech Connect

    Mekhov, Igor B.; Maschler, Christoph; Ritsch, Helmut

    2007-11-15

    We study off-resonant collective light scattering from ultracold atoms trapped in an optical lattice. Scattering from different atomic quantum states creates different quantum states of the scattered light, which can be distinguished by measurements of the spatial intensity distribution, quadrature variances, photon statistics, or spectral measurements. In particular, angle-resolved intensity measurements reflect global statistics of atoms (total number of radiating atoms) as well as local statistical quantities (single-site statistics even without optical access to a single site) and pair correlations between different sites. As a striking example we consider scattering from transversally illuminated atoms into an optical cavity mode. For the Mott-insulator state, similar to classical diffraction, the number of photons scattered into a cavity is zero due to destructive interference, while for the superfluid state it is nonzero and proportional to the number of atoms. Moreover, we demonstrate that light scattering into a standing-wave cavity has a nontrivial angle dependence, including the appearance of narrow features at angles, where classical diffraction predicts zero. The measurement procedure corresponds to the quantum nondemolition measurement of various atomic variables by observing light.

  12. Nonlinear optical characterization of cluster dynamic in water in oil microemulsion by a pump probe laser beam technique

    NASA Astrophysics Data System (ADS)

    Vicari, L.

    2002-11-01

    We present a new pump probe laser beams configuration for the nonlinear optical characterization of microemulsions. We detect the variation of the on-axis optical intensity of the probe beam as generated by the concentration profile induced in an optically thin film of microemulsion by the pump beam. A mathematical model has been introduced to describe the phenomenon. The technique allows the determination of both Kerr-like optical nonlinearity and time constants and, therefore, it gives information both on cluster dimension and their shape. We discuss its application to WAD (water/AOT/decane, where AOT denotes sodium-bis-di-ethyl-sulfosuccinate) with the application of a strong electric field of optical source. Comparison between theoretical predictions and experimental results confirms the presence of giant optical nonlinearity in the absence of turbidity divergence. Chainlike shape of clusters, of the kind already reported with the application of strong electric field, could justify this result.

  13. Nonlinear optical characterization of cluster dynamic in water in oil microemulsion by a pump probe laser beam technique.

    PubMed

    Vicari, L

    2002-11-01

    We present a new pump probe laser beams configuration for the nonlinear optical characterization of microemulsions. We detect the variation of the on-axis optical intensity of the probe beam as generated by the concentration profile induced in an optically thin film of microemulsion by the pump beam. A mathematical model has been introduced to describe the phenomenon. The technique allows the determination of both Kerr-like optical nonlinearity and time constants and, therefore, it gives information both on cluster dimension and their shape. We discuss its application to WAD (water/AOT/decane, where AOT denotes sodium-bis-di-ethyl-sulfosuccinate) with the application of a strong electric field of optical source. Comparison between theoretical predictions and experimental results confirms the presence of giant optical nonlinearity in the absence of turbidity divergence. Chainlike shape of clusters, of the kind already reported with the application of strong electric field, could justify this result. PMID:15010903

  14. Fourier domain Pump-Probe Optical Coherence Tomography imaging of melanin.

    PubMed

    Jacob, Desmond; Shelton, Ryan L; Applegate, Brian E

    2010-06-01

    We report the development of a two-color Fourier domain Pump-Probe Optical Coherence Tomography (PPOCT) system. Tissue phantom experiments to characterize the system performance demonstrated imaging depths in excess of 725 microm, nearly comparable to the base Optical Coherence Tomography system. PPOCT A-line rates were also demonstrated in excess of 1 kHz. The physical origin of the PPOCT signal was investigated with a series of experiments which revealed that the signal is a mixture of short and long lifetime component signals. The short lifetime component was attributed to transient absorption while the long lifetime component may be due to a mixture of transient absorption and thermal effects. Ex vivo images of porcine iris demonstrated the potential for imaging melanin in the eye, where cancer of the melanocytes is the most common form of eye cancer in adults. PMID:20588366

  15. Optical probe investigation of laser ablated carbon plasma plume in nitrogen ambient

    SciTech Connect

    Singh, Ravi Pratap; Gupta, Shyam L.; Thareja, Raj K.

    2013-12-15

    We report the study of carbon plasma produced using 1064 nm laser in nitrogen ambient at atmospheric pressure using 2-dimensional fast imaging of ablated plume, optical emission spectroscopy, and optical probe at 532 nm for interferometry and shadowgraphy. The dominance of C{sub 2} and CN molecules over ionic species at later stages of expanding carbon plasma plume is reported. The observed ring structure in shadowgrams and change in the direction of fringe shift from positive to negative in recorded interferograms are correlated with the relative abundance of different species in the plasma plume as function of time delay with respect to ablating pulse. An agreement in observed onset time of formation of clusters/atomic species or low ionic species using different diagnostic techniques has been reported.

  16. Custom-Built Optical Tweezers for Locally Probing the Viscoelastic Properties of Cancer Cells

    NASA Astrophysics Data System (ADS)

    Tavano, Federica; Bonin, Serena; Pinato, Giulietta; Stanta, Giorgio; Cojoc, Dan

    2011-07-01

    We report a home built optical tweezers setup to investigate the mechanism of the membrane tether formation from single cells in vitro. Using an optically trapped microbead as probe, we have determined the force-elongation curve during tether formation and extracted several parameters characterizing the viscoelastic behavior of the cell membrane: tether stiffness, force, and viscosity. Breast cancer MDA-MB-231 cells have been studied in two different conditions, at room and physiological temperatures, showing a strong temperature dependence of the visoelastic properties of the cell membrane. To get detailed inside information about the tether formation mechanism we have extended the analysis of the force-elongation curves fitting them with a Kelvin model. These preliminary results are part of a larger project of whose goal is to compare the viscoelastic properties of several types of cancer cell lines, characterized by different aggressiveness and metastatic potential.

  17. Intrinsic carrier multiplication efficiency in bulk Si crystals evaluated by optical-pump/terahertz-probe spectroscopy

    SciTech Connect

    Yamashita, G.; Nagai, M. E-mail: ashida@mp.es.osaka-u.ac.jp; Ashida, M. E-mail: ashida@mp.es.osaka-u.ac.jp; Matsubara, E.; Kanemitsu, Y.

    2014-12-08

    We estimated the carrier multiplication efficiency in the most common solar-cell material, Si, by using optical-pump/terahertz-probe spectroscopy. Through close analysis of time-resolved data, we extracted the exact number of photoexcited carriers from the sheet carrier density 10 ps after photoexcitation, excluding the influences of spatial diffusion and surface recombination in the time domain. For incident photon energies greater than 4.0 eV, we observed enhanced internal quantum efficiency due to carrier multiplication. The evaluated value of internal quantum efficiency agrees well with the results of photocurrent measurements. This optical method allows us to estimate the carrier multiplication and surface recombination of carriers quantitatively, which are crucial for the design of the solar cells.

  18. Development of dual-probe atomic force microscopy system using optical beam deflection sensors with obliquely incident laser beams

    NASA Astrophysics Data System (ADS)

    Tsunemi, Eika; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

    2011-03-01

    We developed a dual-probe (DP) atomic force microscopy (AFM) system that has two independently controlled probes. The deflection of each cantilever is measured by the optical beam deflection (OBD) method. In order to keep a large space over the two probes for an objective lens with a large numerical aperture, we employed the OBD sensors with obliquely incident laser beams. In this paper, we describe the details of our developed DP-AFM system, including analysis of the sensitivity of the OBD sensor for detection of the cantilever deflection. We also describe a method to eliminate the crosstalk caused by the vertical translation of the cantilever. In addition, we demonstrate simultaneous topographic imaging of a test sample by the two probes and surface potential measurement on an α-sexithiophene (α-6T) thin film by one probe while electrical charges were injected by the other probe.

  19. Development of dual-probe atomic force microscopy system using optical beam deflection sensors with obliquely incident laser beams.

    PubMed

    Tsunemi, Eika; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

    2011-03-01

    We developed a dual-probe (DP) atomic force microscopy (AFM) system that has two independently controlled probes. The deflection of each cantilever is measured by the optical beam deflection (OBD) method. In order to keep a large space over the two probes for an objective lens with a large numerical aperture, we employed the OBD sensors with obliquely incident laser beams. In this paper, we describe the details of our developed DP-AFM system, including analysis of the sensitivity of the OBD sensor for detection of the cantilever deflection. We also describe a method to eliminate the crosstalk caused by the vertical translation of the cantilever. In addition, we demonstrate simultaneous topographic imaging of a test sample by the two probes and surface potential measurement on an α-sexithiophene (α-6T) thin film by one probe while electrical charges were injected by the other probe. PMID:21456752

  20. Validity Using Pump-Probe Pulses to Determine the Optical Response of Niobate Crystals

    NASA Technical Reports Server (NTRS)

    Liu, Huimin; Jia, Weiyi

    1997-01-01

    A variety of niobate crystals have found their places in nonlinear optical applications as well as in laser devices. In recent years much attention has been paid to study the ultrafast optical response in a variety of photorefractive crystals such as KTa(1-x)Nb(x)O3 and KNbO3 crystals, glasses, semiconductors and polymers for applications in optical switching, information processing, optical computing, and all-optical device systems. Third-order optical nonlinearity is the most important property for realization of all-optical switching. Therefore experiments have been performed on the third order susceptibility using a variety of techniques such as the third-order harmonic generation, EFISH and degenerate four-wave mixing(DFWM). The latter has been conducted with a variety of pump wavelengths and with nanosecond, picosecond and femtosecond pulses. Niobate crystals, such as potassium niobate KNbO3, potassium tantalate niobate KTN family (KTa(1-x)Nb(x)O3), strontium barium niobate SBN (Sr(x)Ba(1-x)Nb2O6) and potassium-sodium niobate SBN (KNSBN) are attractive due to their photorefractive properties for application in optical storage and processing. The pulsed probe experiments performed on theses materials have suggested two types of time responses. These responses have been associated with an coherent response due to Chi(sup 3), and a long lived component due to excited state population. Recent study of DFWM on KNbO3 and KTN family reveals that the long lived component of those crystals depends on the crystal orientation. A slowly decaying signal is observable when the grating vector K(sub g) is not perpendicular to the C-axis of those photorefractive crystals', otherwise the optical response signal would be only a narrow coherent peak with FWHM equal to the cross-correlation width of the write beam pulses. Based on this understanding, we study the photodynamical process of a variety of niobate crystals using DFWM in a Kg perpindicular to C geometry with a ps

  1. Near-field fluorescence thermometry using highly efficient triple-tapered near-field optical fiber probe

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Taguchi, Y.; Saiki, T.; Nagasaka, Y.

    2012-12-01

    A novel local temperature measurement method using fluorescence near-field optics thermal nanoscopy (Fluor-NOTN) has been developed. Fluor-NOTN enables nanoscale temperature measurement in situ by detecting the temperature-dependent fluorescence lifetime of CdSe quantum dots (QDs). In this paper, we report a novel triple-tapered near-field optical fiber probe that can increase the temperature measurement sensitivity of Fluor-NOTN. The performance of the proposed probe was numerically evaluated by the finite difference time domain method. Due to improvements in both the throughput and collection efficiency of near-field light, the sensitivity of the proposed probe was 1.9 times greater than that of typical double-tapered probe. The proposed shape of the triple-tapered core was successfully fabricated utilizing a geometrical model. The detected signal intensity of dried layers of QDs was greater by more than two orders than that of auto-fluorescence from the fiber core. In addition, the near-field fluorescence lifetime of the QDs and its temperature dependence were successfully measured by the fabricated triple-tapered near-field optical fiber probe. These measurement results verified the capability of the proposed triple-tapered near-field optical fiber probe to improve the collection efficiency of near-field fluorescence.

  2. Targeted illumination and tracking using optical fiber probe for optogenetics application

    NASA Astrophysics Data System (ADS)

    Shinde, Anant; Perinchery, Sandeep M.; Matham, Murukeshan V.

    2016-03-01

    There was a renewed interest, during the recent years, in the imaging and tracking of targeted cells or organelles for a variety of biomedical and lab-on a chip applications that include particles movement. However, nonspecific illumination during tracking can have adverse effects such as heating, reduced image contrast and photo bleaching. In fact, current available tracking and imaging systems are unable to selectively illuminate the particle being tracked. To fill this void, we have developed a fiber optics based probe system incorporating a spatial light modulator (SLM) and an imaging fiber bundle for selective illumination on the targeted particle. A GRIN lens is attached at the distal endface of the image fiber bundle for optimised illumination and collection. A tracking algorithm is developed in order to enable controlled illumination through SLM to target the illumination point or location in accordance with the particle movement and size variation. Further with this probe, particles can be illuminated with light pulses of controllable duty cycle and frequency. The proposed methodology and developed probe have good significance and expected to find potential applications areas such as optogenetics, cell signalling studies, and lab-on a chip systems.

  3. Optical probe for porosity defect detection on inner diameter surfaces of machined bores

    NASA Astrophysics Data System (ADS)

    Kulkarni, Ojas P.; Islam, Mohammed N.; Terry, Fred L.

    2010-12-01

    We demonstrate an optical probe for detection of porosity inside spool bores of a transmission valve body with diameters down to 5 mm. The probe consists of a graded-index relay rod that focuses a laser beam spot onto the inner surface of the bore. Detectors, placed in the specular and grazing directions with respect to the incident beam, measure the change in scattered intensity when a surface defect is encountered. Based on the scattering signatures in the two directions, the system can also validate the depth of the defect and distinguish porosity from bump-type defects coming out of the metal surface. The system can detect porosity down to a 50-μm lateral dimension and ~40 μm in depth with >3-dB contrast over the background intensity fluctuations. Porosity detection systems currently use manual inspection techniques on the plant floor, and the demonstrated probe provides a noncontact technique that can help automotive manufacturers meet high-quality standards during production.

  4. Probing the size dependence on the optical modes of anatase nanoplatelets using STEM-EELS.

    PubMed

    Liberti, Emanuela; Menzel, Robert; Shaffer, Milo S P; McComb, David W

    2016-05-14

    Anatase titania nanoplatelets with predominantly exposed {001} facets have been reported to have enhanced catalytic properties in comparison with bulk anatase. To understand their unusual behaviour, it is essential to fully characterize their electronic and optical properties at the nanometer scale. One way of assessing these fundamental properties is to study the dielectric function. Valence electron energy-loss spectroscopy (EELS) performed using a scanning transmission electron microscope (STEM) is the only analytical method that can probe the complex dielectric function with both high energy (<100 meV) and high spatial (<1 nm) resolution. By correlating experimental STEM-EELS data with simulations based on semi-classical dielectric theory, the dielectric response of thin (<5 nm) anatase nanoplatelets was found to be largely dominated by characteristic (optical) surface modes, which are linked to surface plasmon modes of anatase. For platelets less than 10 nm thick, the frequency of these optical modes varies according to their thickness. This unique optical behaviour prompts the enhancement of light absorption in the ultraviolet regime. Finally, the effect of finite size on the dielectric signal is gradually lost by stacking consistently two or more platelets in a specific crystal orientation, and eventually suppressed for large stacks of platelets. PMID:27113455

  5. Degradation of silver near-field optical probes and its electrochemical reversal

    NASA Astrophysics Data System (ADS)

    Opilik, Lothar; Dogan, Üzeyir; Szczerbiński, Jacek; Zenobi, Renato

    2015-08-01

    Deterioration of the outstanding optical properties of elemental silver due to atmospheric corrosion compromises its use in the field of plasmonics. Therefore, more chemically inert, but more lossy, metals (e.g., gold) are often used as a compromise. Silver tips for near-field optical microscopy are only utilized by specialized laboratories with in-house tip production facilities. This article presents a time-dependent study of the effect of atmospheric corrosion on the electromagnetic enhancement of solid silver tips. It was found that chemical degradation renders them unusable for tip-enhanced Raman spectroscopy (TERS) within the first two days after production. Furthermore, we present a simple electrochemical method for recovering the enhancing effect of corroded silver tips, as well as for storing freshly prepared probes, for example, for easy shipment. The present work greatly simplifies the experimental aspects of near-field optical microscopy, which should make near-field optical techniques, and, in particular, TERS, more accessible to the scientific community.

  6. Emission Spectroscopic Measurements with an Optical Probe in the NASA Ames IHF Arc Jet Facility

    NASA Technical Reports Server (NTRS)

    Winter, Michael; Prabhu, Dinesh K.; Raiche, George A.; Terrazas-Salinas, Imelda; Hui, Frank C. L.

    2011-01-01

    An optical probe was designed to measure radiation (from inside the arc heater) incident on a test sample immersed in the arc-heated stream. Currently, only crude estimates are available for this incident radiation. Unlike efforts of the past, where the probe line of sight was inclined to the nozzle centerline, the present development focuses on having the probe line of sight coincide with the nozzle centerline. A fiber-coupled spectrometer was used to measure the spectral distribution of incident radiation in the wavelength range of 225 to 900 nm. The radiation heat flux in this wavelength range was determined by integration of measured emission spectral intensity calibrated to incident irradiance from an integrating sphere. Two arc-heater conditions, corresponding to stream bulk enthalpy levels of 12 and 22 MJ/kg, were investigated in the 13-inch diameter nozzle of the Interaction Heating Facility at NASA Ames Research Center. With the probe placed at a distance of 10 inches from the nozzle exit plane, total radiative heat fluxes were measured to be 3.3 and 8.4 W/sq cm for the 12 and 22 MJ/kg conditions, respectively. About 17% of these radiative fluxes were due to bound-bound radiation from atoms and molecules, while the remaining 83% could be attributed to continua (bound-free and/or free-free). A comparison with spectral simulation based on CFD solutions for the arc-heater flow field and with spectroscopic measurements in the plenum region indicates that more than 95% of the measured radiation is generated in the arc region. The total radiative heat flux from the line radiation could increase by a factor of two through contributions from wavelengths outside the measured range, i.e., from the vacuum ultraviolet (wavelengths less than 225 nm) and the infrared (wavelengths greater than 900 nm). An extrapolation of the continuum radiation to these two wavelength regions was not attempted. In the tested configuration, the measured radiative heat flux accounts for

  7. Clinical translation of an ultrasmall inorganic optical-PET imaging nanoparticle probe

    PubMed Central

    Phillips, Evan; Penate-Medina, Oula; Zanzonico, Pat B.; Carvajal, Richard D.; Mohan, Pauliah; Ye, Yunpeng; Humm, John; Gönen, Mithat; Kalaigian, Hovanes; Schöder, Heiko; Strauss, H. William; Larson, Steven M.; Wiesner, Ulrich; Bradbury, Michelle S.

    2015-01-01

    A first-in-human clinical trial of ultrasmall inorganic hybrid nanoparticles, “C dots” (Cornell dots), in patients with metastatic melanoma is described for the imaging of cancer. These renally excreted silica particles were labeled with 124I for positron emission tomography (PET) imaging and modified with cRGDY peptides for molecular targeting. 124I-cRGDY–PEG–C dot particles are inherently fluorescent, containing the dye, Cy5, so they may be used as hybrid PET-optical imaging agents for lesion detection, cancer staging, and treatment management in humans. However, the clinical translation of nanoparticle probes, including quantum dots, has not kept pace with the accelerated growth in minimally invasive surgical tools that rely on optical imaging agents. The safety, pharmacokinetics, clearance properties, and radiation dosimetry of 124I-cRGDY–PEG–C dots were assessed by serial PET and computerized tomography after intravenous administration in patients. Metabolic profiles and laboratory tests of blood and urine specimens, obtained before and after particle injection, were monitored over a 2-week interval. Findings are consistent with a well-tolerated inorganic particle tracer exhibiting in vivo stability and distinct, reproducible pharmacokinetic signatures defined by renal excretion. No toxic or adverse events attributable to the particles were observed. Coupled with preferential uptake and localization of the probe at sites of disease, these first-in-human results suggest safe use of these particles in human cancer diagnostics. PMID:25355699

  8. Clinical translation of an ultrasmall inorganic optical-PET imaging nanoparticle probe.

    PubMed

    Phillips, Evan; Penate-Medina, Oula; Zanzonico, Pat B; Carvajal, Richard D; Mohan, Pauliah; Ye, Yunpeng; Humm, John; Gönen, Mithat; Kalaigian, Hovanes; Schöder, Heiko; Strauss, H William; Larson, Steven M; Wiesner, Ulrich; Bradbury, Michelle S

    2014-10-29

    A first-in-human clinical trial of ultrasmall inorganic hybrid nanoparticles, "C dots" (Cornell dots), in patients with metastatic melanoma is described for the imaging of cancer. These renally excreted silica particles were labeled with (124)I for positron emission tomography (PET) imaging and modified with cRGDY peptides for molecular targeting. (124)I-cRGDY-PEG-C dot particles are inherently fluorescent, containing the dye, Cy5, so they may be used as hybrid PET-optical imaging agents for lesion detection, cancer staging, and treatment management in humans. However, the clinical translation of nanoparticle probes, including quantum dots, has not kept pace with the accelerated growth in minimally invasive surgical tools that rely on optical imaging agents. The safety, pharmacokinetics, clearance properties, and radiation dosimetry of (124)I-cRGDY-PEG-C dots were assessed by serial PET and computerized tomography after intravenous administration in patients. Metabolic profiles and laboratory tests of blood and urine specimens, obtained before and after particle injection, were monitored over a 2-week interval. Findings are consistent with a well-tolerated inorganic particle tracer exhibiting in vivo stability and distinct, reproducible pharmacokinetic signatures defined by renal excretion. No toxic or adverse events attributable to the particles were observed. Coupled with preferential uptake and localization of the probe at sites of disease, these first-in-human results suggest safe use of these particles in human cancer diagnostics. PMID:25355699

  9. Modifications of the structure of the pericellular matrix measured via optical force probe microscopy

    NASA Astrophysics Data System (ADS)

    McLane, Louis; Kramer, Anthony; Chang, Patrick; Curtis, Jennifer

    2013-03-01

    The pericellular matrix is a large protein and polysaccharide rich polymer layer attached to the surface of many cells, and which often extends several microns out from the cell surface into the surrounding extracellular space. Here we study the intrinsic nature and modifications of the structure of the pericellular coat on rat chondrocytes with the use of optical force probe microscopy. Optical force probe studies allow us to make both dynamic force measurements as well as equilibrium force measurements throughout the coat. These force measurements are used to observe the structural change in the coat with the addition of exogenous aggrecan. Not only does addition of exogenous aggrecan dramatically swell our coat to well over twice in size, our analysis indicates that the addition of exogenous aggrecan decreases the mesh size throughout the coat. We speculate that the added aggrecan binds to available binding sites along the hyaluronan chain, both enlarging the coat's size as well as tightening up the opening within the coat. We further suggest that the available binding sites for the exogenous aggrecan are abundant in the outer edges of the coat, as both the dynamic and equilibrium forces in this region are changed. Here, both force measurements show that forces closest to the cell membrane remain relatively unchanged, while the forces in the outer region of the coat are increased. These results are consistent with those obtained with complementary measurements using quantitative particle exclusion assays.

  10. Optical fiber probe spectroscopy for laparoscopic monitoring of tissue oxygenation during esophagectomies

    NASA Astrophysics Data System (ADS)

    Gareau, Daniel S.; Truffer, Frederic; Perry, Kyle; Pham, Thai; Enestvedt, C. Kristian; Dolan, James; Hunter, John G.; Jacques, Steven L.

    2010-11-01

    Anastomotic complication is a major morbidity associated with esophagectomy. Gastric ischemia after conduit creation contributes to anastomotic complications, but a reliable method to assess oxygenation in the gastric conduit is lacking. We hypothesize that fiber optic spectroscopy can reliably assess conduit oxygenation, and that intraoperative gastric ischemia will correlate with the development of anastomotic complications. A simple optical fiber probe spectrometer is designed for nondestructive laparoscopic measurement of blood content and hemoglobin oxygen saturation in the stomach tissue microvasculature during human esophagectomies. In 22 patients, the probe measured the light transport in stomach tissue between two fibers spaced 3-mm apart (500- to 650-nm wavelength range). The stomach tissue site of measurement becomes the site of a gastroesophageal anastamosis following excision of the cancerous esophagus and surgical ligation of two of the three gastric arteries that provide blood perfusion to the anastamosis. Measurements are made at each of five steps throughout the surgery. The resting baseline saturation is 0.51+/-0.15 and decreases to 0.35+/-0.20 with ligation. Seven patients develop anastomotic complications, and a decreased saturation at either of the last two steps (completion of conduit and completion of anastamosis) is predictive of complication with a sensitivity of 0.71 when the specificity equaled 0.71.

  11. Articulated dual modality photoacoustic and optical coherence tomography probe for preclinical and clinical imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Mengyang; Zabihian, Behrooz; Weingast, Jessika; Hermann, Boris; Chen, Zhe; Zhang, Edward Z.; Beard, Paul C.; Pehamberger, Hubert; Drexler, Wolfgang

    2016-03-01

    The combination of photoacoustic tomography (PAT) with optical coherence tomography (OCT) has seen steady progress over the past few years. With the benchtop and semi-benchtop configurations, preclinical and clinical results have been demonstrated, paving the way for wider applications using dual modality PAT/OCT systems. However, as for the most updated semi-benchtop PAT/OCT system which employs a Fabry-Perot polymer film sensor, it is restricted to only human palm imaging due to the limited flexibility of the probe. The passband limit of the polymer film sensor further restricts the OCT source selection and reduces the sensitivity of the combined OCT system. To tackle these issues, we developed an articulated PAT/OCT probe for both preclinical and clinical applications. In the probe design, the sample arm of OCT sub-system and the interrogation part of the PAT sub-system are integrated into one compact unit. The polymer film sensor has a quick release function so that before each OCT scan, the sensor can be taken off to avoid the sensitivity drop and artefacts in OCT. The holding mechanism of the sensor is also more compact compared to previous designs, permitting access to uneven surfaces of the subjects. With the help of the articulated probe and a patient chair, we are able to perform co-registered imaging on human subjects on both upper and lower extremities while they are at rest positions. An increase in performance characteristics is also achieved. Patients with skin diseases are currently being recruited to test its clinical feasibility.

  12. Novel Strategy for Preparing Dual-Modality Optical/PET Imaging Probes via Photo-Click Chemistry.

    PubMed

    Sun, Lingyi; Ding, Jiule; Xing, Wei; Gai, Yongkang; Sheng, Jing; Zeng, Dexing

    2016-05-18

    Preparation of small molecule based dual-modality probes remains a challenging task due to the complicated synthetic procedure. In this study, a novel concise and generic strategy for preparing dual-modality optical/PET imaging probes via photo-click chemistry was developed, in which the diazole photo-click linker functioned not only as a bridge between the targeting-ligand and the PET imaging moiety, but also as the fluorophore for optical imaging. A dual-modality AE105 peptidic probe was successfully generated via this strategy and subsequently applied in the fluorescent staining of U87MG cells and the (68)Ga based PET imaging of mice bearing U87MG xenograft. In addition, dual-modality monoclonal antibody cetuximab has also been generated via this strategy and labeled with (64)Cu for PET imaging studies, broadening the application of this strategy to include the preparation of macromolecule based imaging probes. PMID:27098544

  13. Handheld, rapidly switchable, anterior/posterior segment swept source optical coherence tomography probe

    PubMed Central

    Nankivil, Derek; Waterman, Gar; LaRocca, Francesco; Keller, Brenton; Kuo, Anthony N.; Izatt, Joseph A.

    2015-01-01

    We describe the first handheld, swept source optical coherence tomography (SSOCT) system capable of imaging both the anterior and posterior segments of the eye in rapid succession. A single 2D microelectromechanical systems (MEMS) scanner was utilized for both imaging modes, and the optical paths for each imaging mode were optimized for their respective application using a combination of commercial and custom optics. The system has a working distance of 26.1 mm and a measured axial resolution of 8 μm (in air). In posterior segment mode, the design has a lateral resolution of 9 μm, 7.4 mm imaging depth range (in air), 4.9 mm 6dB fall-off range (in air), and peak sensitivity of 103 dB over a 22° field of view (FOV). In anterior segment mode, the design has a lateral resolution of 24 μm, imaging depth range of 7.4 mm (in air), 6dB fall-off range of 4.5 mm (in air), depth-of-focus of 3.6 mm, and a peak sensitivity of 99 dB over a 17.5 mm FOV. In addition, the probe includes a wide-field iris imaging system to simplify alignment. A fold mirror assembly actuated by a bi-stable rotary solenoid was used to switch between anterior and posterior segment imaging modes, and a miniature motorized translation stage was used to adjust the objective lens position to correct for patient refraction between −12.6 and + 9.9 D. The entire probe weighs less than 630 g with a form factor of 20.3 x 9.5 x 8.8 cm. Healthy volunteers were imaged to illustrate imaging performance. PMID:26601014

  14. Handheld, rapidly switchable, anterior/posterior segment swept source optical coherence tomography probe.

    PubMed

    Nankivil, Derek; Waterman, Gar; LaRocca, Francesco; Keller, Brenton; Kuo, Anthony N; Izatt, Joseph A

    2015-11-01

    We describe the first handheld, swept source optical coherence tomography (SSOCT) system capable of imaging both the anterior and posterior segments of the eye in rapid succession. A single 2D microelectromechanical systems (MEMS) scanner was utilized for both imaging modes, and the optical paths for each imaging mode were optimized for their respective application using a combination of commercial and custom optics. The system has a working distance of 26.1 mm and a measured axial resolution of 8 μm (in air). In posterior segment mode, the design has a lateral resolution of 9 μm, 7.4 mm imaging depth range (in air), 4.9 mm 6dB fall-off range (in air), and peak sensitivity of 103 dB over a 22° field of view (FOV). In anterior segment mode, the design has a lateral resolution of 24 μm, imaging depth range of 7.4 mm (in air), 6dB fall-off range of 4.5 mm (in air), depth-of-focus of 3.6 mm, and a peak sensitivity of 99 dB over a 17.5 mm FOV. In addition, the probe includes a wide-field iris imaging system to simplify alignment. A fold mirror assembly actuated by a bi-stable rotary solenoid was used to switch between anterior and posterior segment imaging modes, and a miniature motorized translation stage was used to adjust the objective lens position to correct for patient refraction between -12.6 and + 9.9 D. The entire probe weighs less than 630 g with a form factor of 20.3 x 9.5 x 8.8 cm. Healthy volunteers were imaged to illustrate imaging performance. PMID:26601014

  15. Ultrasensitive near-infrared fluorescence-enhanced probe for in vivo nitroreductase imaging.

    PubMed

    Li, Yuhao; Sun, Yun; Li, Jiachang; Su, Qianqian; Yuan, Wei; Dai, Yu; Han, Chunmiao; Wang, Qiuhong; Feng, Wei; Li, Fuyou

    2015-05-20

    Nitroreductase (NTR) can be overexpressed in hypoxic tumors, thus the selective and efficient detection of NTR is of great importance. To date, although a few optical methods have been reported for the detection of NTR in solution, an effective optical probe for NTR monitoring in vivo is still lacking. Therefore, it is necessary to develop a near-infrared (NIR) fluorescent detection probe for NTR. In this study, five NIR cyanine dyes with fluorescence reporting structure decorated with different nitro aromatic groups, Cy7-1-5, have been designed and explored for possible rapid detection of NTR. Our experimental results presented that only a para-nitro benzoate group modified cyanine probe (Cy7-1) could serve as a rapid NIR fluorescence-enhanced probe for monitoring and bioimaging of NTR. The structure-function relationship has been revealed by theoretical study. The linker connecting the detecting and fluorescence reporting groups and the nitro group position is a key factor for the formation of hydrogen bonds and spatial structure match, inducing the NTR catalytic ability enhancement. The in vitro response and mechanism of the enzyme-catalyzed reduction of Cy7-1 have been investigated through kinetic optical studies and other methods. The results have indicated that an electro-withdrawing group induced electron-transfer process becomes blocked when Cy7-1 is catalytically reduced to Cy7-NH2 by NTR, which is manifested in enhanced fluorescence intensity during the detection process. Confocal fluorescence imaging of hypoxic A549 cells has confirmed the NTR detection ability of Cy7-1 at the cellular level. Importantly, Cy7-1 can detect tumor hypoxia in a murine hypoxic tumor model, showing a rapid and significant enhancement of its NIR fluorescence characteristics suitable for fluorescence bioimaging. This method may potentially be used for tumor hypoxia diagnosis. PMID:25923361

  16. High Performance Photoluminescent Carbon Dots for In Vitro and In Vivo Bioimaging: Effect of Nitrogen Doping Ratios.

    PubMed

    Wang, Junqing; Zhang, Pengfei; Huang, Chao; Liu, Gang; Leung, Ken Cham-Fai; Wáng, Yì Xiáng J

    2015-07-28

    Photoluminescent carbon dots (CDs) have received ever-increasing attention in the application of optical bioimaging because of their low toxicity, tunable fluorescent properties, and ultracompact size. We report for the first time on enhanced photoluminescence (PL) performance influenced by structure effects among the various types of nitrogen doped (N-doped) PL CDs. These CDs were facilely synthesized from condensation carbonization of linear polyethylenic amine (PEA) analogues and citric acid (CA) of different ratios. Detailed structural and property studies demonstrated that either the structures or the molar ratio of PEAs altered the PL properties of the CDs. The content of conjugated π-domains with C═N in the carbon backbone was correlated with their PL Quantum Yield (QY) (up to 69%). The hybridization between the surface/molecule state and the carbon backbone synergistically affected the chemical/physical properties. Also, long-chain polyethylenic amine (PEA) molecule-doped CDs exhibit increasing photostability, but at the expense of PL efficiency, proving that the PL emission of high QY CDs arise not only from the sp(2)/sp(3) carbon core and surface passivation of CDs, but also from the molecular fluorophores integrated in the CDs. In vitro and in vivo bioimaging of these N-doped CDs showed strong photoluminescence signals. Good biocompatibility demonstrates their potential feasibility for bioimaging applications. In addition, the overall size profile of the as-prepared CDs is comparable to the average size of capillary pores in normal living tissues (∼5 nm). Our study provides valuable insights into the effects of the PEA doping ratios on photoluminescence efficiency, biocompatibility, cellular uptake, and optical bioimaging of CDs. PMID:26135003

  17. Probe assembly

    SciTech Connect

    Avera, C.J.

    1981-01-06

    A hand-held probe assembly, suitable for monitoring a radioactive fibrinogen tracer, is disclosed comprising a substantially cylindrically shaped probe handle having an open end. The probe handle is adapted to be interconnected with electrical circuitry for monitoring radioactivity that is sensed or detected by the probe assembly. Mounted within the probe handle is a probe body assembly that includes a cylindrically shaped probe body inserted through the open end of the probe handle. The probe body includes a photomultiplier tube that is electrically connected with a male connector positioned at the rearward end of the probe body. Mounted at the opposite end of the probe body is a probe head which supports an optical coupler therewithin. The probe head is interconnected with a probe cap which supports a detecting crystal. The probe body assembly, which consists of the probe body, the probe head, and the probe cap is supported within the probe handle by means of a pair of compressible o-rings which permit the probe assembly to be freely rotatable, preferably through 360*, within the probe handle and removable therefrom without requiring any disassembly.

  18. Micromachined diffraction based optical microphones and intensity probes with electrostatic force feedback

    NASA Astrophysics Data System (ADS)

    Bicen, Baris

    Measuring acoustic pressure gradients is critical in many applications such as directional microphones for hearing aids and sound intensity probes. This measurement is especially challenging with decreasing microphone size, which reduces the sensitivity due to small spacing between the pressure ports. Novel, micromachined biomimetic microphone diaphragms are shown to provide high sensitivity to pressure gradients on one side of the diaphragm with low thermal mechanical noise. These structures have a dominant mode shape with see-saw like motion in the audio band, responding to pressure gradients as well as spurious higher order modes sensitive to pressure. In this dissertation, integration of a diffraction based optical detection method with these novel diaphragm structures to implement a low noise optical pressure gradient microphone is described and experimental characterization results are presented, showing 36 dBA noise level with 1mm port spacing, nearly an order of magnitude better than the current gradient microphones. The optical detection scheme also provides electrostatic actuation capability from both sides of the diaphragm separately which can be used for active force feedback. A 4-port electromechanical equivalent circuit model of this microphone with optical readout is developed to predict the overall response of the device to different acoustic and electrostatic excitations. The model includes the damping due to complex motion of air around the microphone diaphragm, and it calculates the detected optical signal on each side of the diaphragm as a combination of two separate dominant vibration modes. This equivalent circuit model is verified by experiments and used to predict the microphone response with different force feedback schemes. Single sided force feedback is used for active damping to improve the linearity and the frequency response of the microphone. Furthermore, it is shown that using two sided force feedback one can significantly suppress

  19. In vivo optical modulation of neural signals using monolithically integrated two-dimensional neural probe arrays.

    PubMed

    Son, Yoojin; Lee, Hyunjoo Jenny; Kim, Jeongyeon; Shin, Hyogeun; Choi, Nakwon; Lee, C Justin; Yoon, Eui-Sung; Yoon, Euisik; Wise, Kensall D; Kim, Tae Geun; Cho, Il-Joo

    2015-01-01

    Integration of stimulation modalities (e.g. electrical, optical, and chemical) on a large array of neural probes can enable an investigation of important underlying mechanisms of brain disorders that is not possible through neural recordings alone. Furthermore, it is important to achieve this integration of multiple functionalities in a compact structure to utilize a large number of the mouse models. Here we present a successful optical modulation of in vivo neural signals of a transgenic mouse through our compact 2D MEMS neural array (optrodes). Using a novel fabrication method that embeds a lower cladding layer in a silicon substrate, we achieved a thin silicon 2D optrode array that is capable of delivering light to multiple sites using SU-8 as a waveguide core. Without additional modification to the microelectrodes, the measured impedance of the multiple microelectrodes was below 1 MΩ at 1 kHz. In addition, with a low background noise level (± 25 μV), neural spikes from different individual neurons were recorded on each microelectrode. Lastly, we successfully used our optrodes to modulate the neural activity of a transgenic mouse through optical stimulation. These results demonstrate the functionality of the 2D optrode array and its potential as a next-generation tool for optogenetic applications. PMID:26494437

  20. A novel optical probe for pH sensing in gastro-esophageal apparatus

    NASA Astrophysics Data System (ADS)

    Baldini, F.; Ghini, G.; Giannetti, A.; Senesi, F.; Trono, C.

    2011-03-01

    Monitoring gastric pH for long periods, usually 24 h, may be essential in analyzing the physiological pattern of acidity, in obtaining information on changes in activity during peptic ulcer disease, and in assessing the effect of antisecretory drugs. Gastro-esophageal reflux, which causes a pH decrease in the esophagus content from pH 7 even down to pH 2, can determine esophagitis with possible strictures and Barrett's esophagus. One of the difficulties of the optical measurement of pH in the gastro-esophageal apparatus lies in the required extended working range from 1 to 8 pH units. The present paper deals with a novel optical pH sensor, using methyl red as optical pH indicator. Contrary to all acidbase indicators characterized by working ranges limited to 2-3 pH units, methyl red, after its covalent immobilization on controlled pore glass (CPG), is characterized by a wide working range which fits with the clinical requirements. The novel probe design here described is suitable for gastro-esophageal applications and allows the optimization of the performances of the CPG with the immobilised indicator. This leads to a very simple configuration characterized by a very fast response time.

  1. Forward-viewing photoacoustic imaging probe with bundled ultra-thin hollow optical fibers

    NASA Astrophysics Data System (ADS)

    Seki, A.; Iwai, K.; Katagiri, T.; Matsuura, Y.

    2016-07-01

    A photoacoustic imaging system composed of a flexible bundle of thin hollow-optical fibers is proposed for endoscopic diagnosis. In this system, a bundle of 127 hollow-optical fibers with an inner diameter of 100 μm was fabricated. The total diameter of the bundle was 2.1 mm, and the minimum bending radius was around 10 mm. Owing to the small numerical aperture of hollow optical fibers, a high resolution image was obtained without using a lens array at the distal end. In the imaging system, the hollow fibers in the bundle were aligned at the input end, so the hollow fibers were sequentially excited by linearly scanning the laser beam at the input end. Photoacoustic imaging systems consisting of the bundled fibers for excitation of acoustic wave and piezoelectric probes for detection of photoacoustic signals were built. By using the systems, photoacoustic images of blood vessels in the ovarian membrane of fish were taken to test the feasibility of the system. As a result, photoacoustic images of the vessel were successfully obtained with a laser fluence of around 6.6 mJ cm‑2.

  2. In vivo optical modulation of neural signals using monolithically integrated two-dimensional neural probe arrays

    PubMed Central

    Son, Yoojin; Jenny Lee, Hyunjoo; Kim, Jeongyeon; Shin, Hyogeun; Choi, Nakwon; Justin Lee, C.; Yoon, Eui-Sung; Yoon, Euisik; Wise, Kensall D.; Geun Kim, Tae; Cho, Il-Joo

    2015-01-01

    Integration of stimulation modalities (e.g. electrical, optical, and chemical) on a large array of neural probes can enable an investigation of important underlying mechanisms of brain disorders that is not possible through neural recordings alone. Furthermore, it is important to achieve this integration of multiple functionalities in a compact structure to utilize a large number of the mouse models. Here we present a successful optical modulation of in vivo neural signals of a transgenic mouse through our compact 2D MEMS neural array (optrodes). Using a novel fabrication method that embeds a lower cladding layer in a silicon substrate, we achieved a thin silicon 2D optrode array that is capable of delivering light to multiple sites using SU-8 as a waveguide core. Without additional modification to the microelectrodes, the measured impedance of the multiple microelectrodes was below 1 MΩ at 1 kHz. In addition, with a low background noise level (±25 μV), neural spikes from different individual neurons were recorded on each microelectrode. Lastly, we successfully used our optrodes to modulate the neural activity of a transgenic mouse through optical stimulation. These results demonstrate the functionality of the 2D optrode array and its potential as a next-generation tool for optogenetic applications. PMID:26494437

  3. In vivo optical modulation of neural signals using monolithically integrated two-dimensional neural probe arrays

    NASA Astrophysics Data System (ADS)

    Son, Yoojin; Jenny Lee, Hyunjoo; Kim, Jeongyeon; Shin, Hyogeun; Choi, Nakwon; Justin Lee, C.; Yoon, Eui-Sung; Yoon, Euisik; Wise, Kensall D.; Geun Kim, Tae; Cho, Il-Joo

    2015-10-01

    Integration of stimulation modalities (e.g. electrical, optical, and chemical) on a large array of neural probes can enable an investigation of important underlying mechanisms of brain disorders that is not possible through neural recordings alone. Furthermore, it is important to achieve this integration of multiple functionalities in a compact structure to utilize a large number of the mouse models. Here we present a successful optical modulation of in vivo neural signals of a transgenic mouse through our compact 2D MEMS neural array (optrodes). Using a novel fabrication method that embeds a lower cladding layer in a silicon substrate, we achieved a thin silicon 2D optrode array that is capable of delivering light to multiple sites using SU-8 as a waveguide core. Without additional modification to the microelectrodes, the measured impedance of the multiple microelectrodes was below 1 MΩ at 1 kHz. In addition, with a low background noise level (±25 μV), neural spikes from different individual neurons were recorded on each microelectrode. Lastly, we successfully used our optrodes to modulate the neural activity of a transgenic mouse through optical stimulation. These results demonstrate the functionality of the 2D optrode array and its potential as a next-generation tool for optogenetic applications.

  4. Evaluating a hybrid three-dimensional metrology system: merging data from optical and touch probe devices

    NASA Astrophysics Data System (ADS)

    Gerde, Janice R.; Christens-Barry, William A.

    2011-08-01

    In a project to meet requirements for CBP Laboratory analysis of footwear under the Harmonized Tariff Schedule of the United States (HTSUS), a hybrid metrology system comprising both optical and touch probe devices has been assembled. A unique requirement must be met: To identify the interface-typically obscured in samples of concern-of the "external surface area upper" (ESAU) and the sole without physically destroying the sample. The sample outer surface is determined by discrete point cloud coordinates obtained using laser scanner optical measurements. Measurements from the optically inaccessible insole region are obtained using a coordinate measuring machine (CMM). That surface similarly is defined by point cloud data. Mathematically, the individual CMM and scanner data sets are transformed into a single, common reference frame. Custom software then fits a polynomial surface to the insole data and extends it to intersect the mesh fitted to the outer surface point cloud. This line of intersection defines the required ESAU boundary, thus permitting further fractional area calculations to determine the percentage of materials present. With a draft method in place, and first-level method validation underway, we examine the transformation of the two dissimilar data sets into the single, common reference frame. We also will consider the six previously-identified potential error factors versus the method process. This paper reports our on-going work and discusses our findings to date.

  5. Optical sectioning using a fiber probe with an angled illumination-collection geometry: evaluation in engineered tissue phantoms

    NASA Astrophysics Data System (ADS)

    Nieman, Linda; Myakov, Alexey; Aaron, Jesse; Sokolov, Konstantin

    2004-02-01

    We present a fiber optic probe that combines polarized illumination and detection with an angled distal probe geometry to detect the size-dependent scattering at a specific depth within epithelium. Analysis of the scattering signal by use of Mie theory allows the extraction of scatterer size and size distribution-key parameters for precancer detection. The probe was evaluated in two tissue phantoms: polystyrene beads atop collagen gel and multiple layers of cancer cells atop collagen. We also present in vivo measurements in the oral cavity of normal volunteers. The sizes of scatterers extracted from the scattering spectra corresponded to independently measured values.

  6. Optical sectioning using a fiber probe with an angled illumination-collection geometry: evaluation in engineered tissue phantoms.

    PubMed

    Nieman, Linda; Myakov, Alexey; Aaron, Jesse; Sokolov, Konstantin

    2004-02-20

    We present a fiber optic probe that combines polarized illumination and detection with an angled distal probe geometry to detect the size-dependent scattering at a specific depth within epithelium. Analysis of the scattering signal by use of Mie theory allows the extraction of scatterer size and size distribution-key parameters for precancer detection. The probe was evaluated in two tissue phantoms: polystyrene beads atop collagen gel and multiple layers of cancer cells atop collagen. We also present in vivo measurements in the oral cavity of normal volunteers. The sizes of scatterers extracted from the scattering spectra corresponded to independently measured values. PMID:15008534

  7. Quantitative optical coherence elastography based on fiber-optic probe with integrated Fabry-Perot force sensor

    NASA Astrophysics Data System (ADS)

    Qiu, Yi; Wang, Yahui; Xu, Yiqing; Chandra, Namas; Haorah, James; Hubbi, Basil; Pfister, Bryan J.; Liu, Xuan

    2016-03-01

    Optical coherence tomography (OCT) is a versatile imaging technique and has great potential in tissue characterization for breast cancer diagnosis and surgical guidance. In addition to structural difference, cancerous breast tissue is usually stiffer compared to normal adipose breast tissue. However, previous studies on compression optical coherence elastography (OCE) are qualitative rather than quantitative. It is challenging to identify the cancerous status of tissue based on qualitative OCE results obtained from different measurement sessions or from different patients. Therefore, it is critical to develop technique that integrates structural imaging and force sensing, for quantitative elasticity characterization of breast tissue. In this work, we demonstrate a quantitative OCE (qOCE) microsurgery device which simultaneously quantifies force exerted to tissue and measures the resultant tissue deformation. The qOCE system is based on a spectral domain OCT engine operated at 1300 nm and a probe with an integrated Febry-Perot (FP) interferometric cavity at its distal end. The FP cavity is formed by the cleaved end of the lead-in fiber and the end surface of a GRIN lens which allows light to incident into tissue for structural imaging. The force exerted to tissue is quantified by the change of FP cavity length which is interrogated by a fiber-optic common-paths phase resolved OCT system with sub-nanometer sensitivity. Simultaneously, image of the tissue structure is acquired from photons returned from tissue through the GRIN lens. Tissue deformation is obtained through Doppler analysis. Tissue elasticity can be quantified by comparing the force exerted and tissue deformation.

  8. Graphene-based Materials for Biosensing and Bioimaging

    SciTech Connect

    Du, Dan; Yang, Yuqi; Lin, Yuehe

    2012-12-01

    Graphene, a free-standing two-dimensional crystal with one-atom thickness, exhibits distinct properties that are highly attractive for biosensing and bioimaging, such as a high electrical conductivity, a large planar area, and an excellent ability to quench fluorescence. This article selectively reviews recent advances in the field of graphene-based materials for biosensing and bioimaging. In particular, graphene-based enzyme biosensors, DNA biosensors, and immunosensors are summarized in detail. Graphene-based biotechnology for cell imaging is also described. Future perspectives and possible challenges in this rapidly developing area are also discussed.

  9. Highly Efficient Far Red/Near-Infrared Solid Fluorophores: Aggregation-Induced Emission, Intramolecular Charge Transfer, Twisted Molecular Conformation, and Bioimaging Applications.

    PubMed

    Lu, Hongguang; Zheng, Yadan; Zhao, Xiaowei; Wang, Lijuan; Ma, Suqian; Han, Xiongqi; Xu, Bin; Tian, Wenjing; Gao, Hui

    2016-01-01

    The development of organic fluorophores with efficient solid-state emissions or aggregated-state emissions in the red to near-infrared region is still challenging. Reported herein are fluorophores having aggregation-induced emission ranging from the orange to far red/near-infrared (FR/NIR) region. The bioimaging performance of the designed fluorophore is shown to have potential as FR/NIR fluorescent probes for biological applications. PMID:26576818

  10. Facile Synthesis and Potential Bioimaging Applications of Hybrid Upconverting and Plasmonic NaGdF4: Yb3+, Er3+/Silica/Gold Nanoparticles

    PubMed Central

    Liu, Sha; Chen, Guanying; Ohulchanskyy, Tymish Y.; Swihart, Mark T.; Prasad, Paras N.

    2013-01-01

    We present a simple method for preparing water dispersible NaGdF4: Yb3+, Er3+/silica/gold nanoparticles. The emission intensity and color of the upconverting cores are modulated by the plasmonic absorbance and field enhancement from the gold nanoparticles. The applicability of hybrid NPs for multi-modal bioimaging probes is illustrated by in vitro confocal microscopy of living cancer cells. PMID:23606914

  11. Probing the size dependence on the optical modes of anatase nanoplatelets using STEM-EELS

    NASA Astrophysics Data System (ADS)

    Liberti, Emanuela; Menzel, Robert; Shaffer, Milo S. P.; McComb, David W.

    2016-05-01

    Anatase titania nanoplatelets with predominantly exposed {001} facets have been reported to have enhanced catalytic properties in comparison with bulk anatase. To understand their unusual behaviour, it is essential to fully characterize their electronic and optical properties at the nanometer scale. One way of assessing these fundamental properties is to study the dielectric function. Valence electron energy-loss spectroscopy (EELS) performed using a scanning transmission electron microscope (STEM) is the only analytical method that can probe the complex dielectric function with both high energy (<100 meV) and high spatial (<1 nm) resolution. By correlating experimental STEM-EELS data with simulations based on semi-classical dielectric theory, the dielectric response of thin (<5 nm) anatase nanoplatelets was found to be largely dominated by characteristic (optical) surface modes, which are linked to surface plasmon modes of anatase. For platelets less than 10 nm thick, the frequency of these optical modes varies according to their thickness. This unique optical behaviour prompts the enhancement of light absorption in the ultraviolet regime. Finally, the effect of finite size on the dielectric signal is gradually lost by stacking consistently two or more platelets in a specific crystal orientation, and eventually suppressed for large stacks of platelets.Anatase titania nanoplatelets with predominantly exposed {001} facets have been reported to have enhanced catalytic properties in comparison with bulk anatase. To understand their unusual behaviour, it is essential to fully characterize their electronic and optical properties at the nanometer scale. One way of assessing these fundamental properties is to study the dielectric function. Valence electron energy-loss spectroscopy (EELS) performed using a scanning transmission electron microscope (STEM) is the only analytical method that can probe the complex dielectric function with both high energy (<100 meV) and high

  12. Enabling freehand lateral scanning of optical coherence tomography needle probes with a magnetic tracking system

    PubMed Central

    Yeo, Boon Y.; McLaughlin, Robert A.; Kirk, Rodney W.; Sampson, David D.

    2012-01-01

    We present a high-resolution three-dimensional position tracking method that allows an optical coherence tomography (OCT) needle probe to be scanned laterally by hand, providing the high degree of flexibility and freedom required in clinical usage. The method is based on a magnetic tracking system, which is augmented by cross-correlation-based resampling and a two-stage moving window average algorithm to improve upon the tracker's limited intrinsic spatial resolution, achieving 18 µm RMS position accuracy. A proof-of-principle system was developed, with successful image reconstruction demonstrated on phantoms and on ex vivo human breast tissue validated against histology. This freehand scanning method could contribute toward clinical implementation of OCT needle imaging. PMID:22808429

  13. Experimental strategies for optical pump - soft x-ray probe experiments at the LCLS

    NASA Astrophysics Data System (ADS)

    McFarland, B. K.; Berrah, N.; Bostedt, C.; Bozek, J.; Bucksbaum, P. H.; Castagna, J. C.; Coffee, R. N.; Cryan, J. P.; Fang, L.; Farrell, J. P.; Feifel, R.; Gaffney, K. J.; Glownia, J. M.; Martinez, T. J.; Miyabe, S.; Mucke, M.; Murphy, B.; Natan, A.; Osipov, T.; Petrovic, V. S.; Schorb, S.; Schultz, Th; Spector, L. S.; Swiggers, M.; Tarantelli, F.; Tenney, I.; Wang, S.; White, J. L.; White, W.; Gühr, M.

    2014-04-01

    Free electron laser (FEL) based x-ray sources show great promise for use in ultrafast molecular studies due to the short pulse durations and site/element sensitivity in this spectral range. However, the self amplified spontaneous emission (SASE) process mostly used in FELs is intrinsically noisy resulting in highly fluctuating beam parameters. Additionally timing synchronization of optical and FEL sources adds delay jitter in pump-probe experiments. We show how we mitigate the effects of source noise for the case of ultrafast molecular spectroscopy of the nucleobase thymine. Using binning and resorting techniques allows us to increase time and spectral resolution. In addition, choosing observables independent of noisy beam parameters enhances the signal fidelity.

  14. System of laser pump and synchrotron radiation probe microdiffraction to investigate optical recording process.

    PubMed

    Yasuda, Nobuhiro; Fukuyama, Yoshimitsu; Kimura, Shigeru; Ito, Kiminori; Tanaka, Yoshihito; Osawa, Hitoshi; Matsunaga, Toshiyuki; Kojima, Rie; Hisada, Kazuya; Tsuchino, Akio; Birukawa, Masahiro; Yamada, Noboru; Sekiguchi, Koji; Fujiie, Kazuhiko; Kawakubo, Osamu; Takata, Masaki

    2013-06-01

    We have developed a system of laser-pump and synchrotron radiation probe microdiffraction to investigate the phase-change process on a nanosecond time scale of Ge2Sb2Te5 film embedded in multi-layer structures, which corresponds to real optical recording media. The measurements were achieved by combining (i) the pump-laser system with a pulse width of 300 ps, (ii) a highly brilliant focused microbeam with wide peak-energy width (ΔE∕E ~ 2%) made by focusing helical undulator radiation without monochromatization, and (iii) a precise sample rotation stage to make repetitive measurements. We successfully detected a very weak time-resolved diffraction signal by using this system from 100-nm-thick Ge2Sb2Te5 phase-change layers. This enabled us to find the dependence of the crystal-amorphous phase change process of the Ge2Sb2Te5 layers on laser power. PMID:23822352

  15. Comparison of Light Spot Hydrophone (LSHD) and Fiber Optic Probe Hydrophone (FOPH) for Lithotripter Field Characterization

    NASA Astrophysics Data System (ADS)

    Leitao, Victor A.; Simmons, W. Neal; Zhou, Yufeng; Qin, Jun; Sankin, Georgii; Cocks, Franklin H.; Fehre, Jens; Granz, Bernd; Nanke, Ralf; Preminger, Glenn M.; Zhong, Pei

    2007-04-01

    Characterization of the acoustic field of a shock wave lithotripter is important for determining the performance of the device. In this study, we compare the performance of a newly developed Light Spot Hydrophone (LSHD) with the current standard, i.e., the Fiber Optic Probe Hydrophone (FOPH). An electromagnetic (EM) shock wave lithotripter was selected and each hydrophone was used to map the acoustic field of the lithotripter. The peak positive pressure P+, peak negative pressure P-, pulse duration, and effective acoustic energy were calculated using the collected data. Both the LSHD and the FOPH have similar measurement characteristics. They both provide excellent P+ measurement accuracy and response. Although the LSHD was found to provide more repeatable P- pressure measurements, both devices provide excellent pressure measurement of lithotripter shock fields.

  16. Molecular imaging of hemoglobin using ground state recovery pump-probe optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Applegate, Brian E.; Izatt, Joseph A.

    2007-02-01

    We have undertaken an effort to further develop ground state recovery Pump-Probe Optical Coherence Tomograpy (gsrPPOCT) to specifically target and measure 3-D images of hemoglobin concentration with the goals of mapping tissue vasculature, total hemoglobin, and hemoglobin oxygen saturation. As a first step toward those goals we have measured the gsrPPOCT signal from the hemoglobin in the filament arteries of a zebra danio fish. We have further processed the resulting signal to extract a qualitative map of the hemoglobin concentration. We have also demonstrated the potential to use ground state recovery times to differentiate between two chromophores which may prove to be an effective tool for differentiating between oxy and deoxy hemoglobin.

  17. Investigation of implosion dynamics and magnetic fields in 1-MA wire arrays by optical probing diagnostics

    NASA Astrophysics Data System (ADS)

    Laca, P. J.; Sarkisov, G. S.

    2005-10-01

    Multiframe optical probing diagnostics were applied for the investigation of implosion dynamics and magnetic fields in z-pinch plasma of wire arrays and x-pinches at the Nevada Terawatt Facility (NTF). Five shadow frames per shot, with a long 34-ns or short 9-ns pulse train, presents fine details of plasma evolution in the wire array. A Faraday rotation diagnostic consists of identical shadow and Faraday channels, shearing air-wedge interferometer, and schlieren channel. Evolution of the wire array z-pinch in different regimes of implosion was investigated. Fast dynamics of bubbles in plasma streams were studied in detail. A current in the plasma column of Al wire arrays and magnetic bubbles were found by the Faraday rotation diagnostic.

  18. Probing dark energy with an atom interferometer in an optical cavity

    NASA Astrophysics Data System (ADS)

    Jaffe, Matthew; Haslinger, Philipp; Hamilton, Paul; Mueller, Holger; Khoury, Justin; Elder, Benjamin

    2016-05-01

    If dark energy -- which drives the accelerated expansion of the universe -- consists of a light scalar field, it might be detectable as a ``fifth force'' between normal-matter objects, in potential conflict with precision tests of gravity. Chameleon fields and other theories with screening mechanisms can evade such tests by suppressing this force in regions of high density, such as the laboratory. Our experiments constrain these dark energy models using atoms in an ultrahigh-vacuum chamber as probes to expose the screened fields. Using a cesium matter wave interferometer in an optical cavity, we set stringent bounds on coupling screened theories to matter. A further 4 to 5 orders of magnitude would completely rule out chameleon and f(R) theories. I will describe this first tabletop dark energy search, and present the hundredfold boost in sensitivity we have since achieved.

  19. Biomedical Probes Based on Inorganic Nanoparticles for Electrochemical and Optical Spectroscopy Applications

    PubMed Central

    Yakoh, Abdulhadee; Pinyorospathum, Chanika; Siangproh, Weena; Chailapakul, Orawon

    2015-01-01

    Inorganic nanoparticles usually provide novel and unique physical properties as their size approaches nanometer scale dimensions. The unique physical and optical properties of nanoparticles may lead to applications in a variety of areas, including biomedical detection. Therefore, current research is now increasingly focused on the use of the high surface-to-volume ratios of nanoparticles to fabricate superb chemical- or biosensors for various detection applications. This article highlights various kinds of inorganic nanoparticles, including metal nanoparticles, magnetic nanoparticles, nanocomposites, and semiconductor nanoparticles that can be perceived as useful materials for biomedical probes and points to the outstanding results arising from their use in such probes. The progress in the use of inorganic nanoparticle-based electrochemical, colorimetric and spectrophotometric detection in recent applications, especially bioanalysis, and the main functions of inorganic nanoparticles in detection are reviewed. The article begins with a conceptual discussion of nanoparticles according to types, followed by numerous applications to analytes including biomolecules, disease markers, and pharmaceutical substances. Most of the references cited herein, dating from 2010 to 2015, generally mention one or more of the following characteristics: a low detection limit, good signal amplification and simultaneous detection capabilities. PMID:26343676

  20. HER2- and EGFR-specific affiprobes: novel recombinant optical probes for cell imaging.

    PubMed

    Lyakhov, Ilya; Zielinski, Rafal; Kuban, Monika; Kramer-Marek, Gabriela; Fisher, Robert; Chertov, Oleg; Bindu, Lakshman; Capala, Jacek

    2010-02-15

    The human epidermal growth factor receptors, EGFR and HER2, are members of the EGFR family of cell-surface receptors/tyrosine kinases. EGFR- and HER2-positive cancers represent a more aggressive disease with greater likelihood of recurrence, poorer prognosis, and decreased survival rate, compared to EGFR- or HER2-negative cancers. The details of HER2 proto-oncogenic functions are not deeply understood, partially because of a restricted availability of tools for EGFR and HER2 detection (A. Sorkin and L. K. Goh, Exp. Cell Res. 2009, 315, 683-696). We have created photostable and relatively simple-to-produce imaging probes for in vitro staining of EGFR and HER2. These new reagents, called affiprobes, consist of a targeting moiety, a HER2- or EGFR-specific Affibody molecule, and a fluorescent moiety, mCherry (red) or EGFP (green). Our flow cytometry and confocal microscopy experiments demonstrated high specificity and signal/background ratio of affiprobes. Affiprobes are able to stain both live cells and frozen tumor xenograph sections. This type of optical probe can easily be extended for targeting other cell-surface antigens/ receptors. PMID:20052708

  1. 2D optical array probe analysis of precipitating cumulonimbus clouds during EPIC 2001

    NASA Astrophysics Data System (ADS)

    Baumgardner, D.; Raga, G. B.

    2007-05-01

    During the 2001 East Pacific Investigation of Climate (EPIC) experiment, numerous measurements were made of the size distributions of raindrops in convective clouds that were developing over a region of the Mexican inter- tropical convergence zone (ITCZ). These measurements were made with optical array probes (PMS 2D-C and 2D-P) mounted on the National Science Foundation Hercules C-130, operated by the National Center for Atmospheric Research. In addition to capturing shadow images of individual drops between 25 μm and 6400 μm, these instruments also record the distance between each drop via a measurement of arrival times in the spectrometers lasers. The separation distance, along with the drop size, provides detailed information about the microstructure of precipitation. The 2D probe measurements have been analyzed as a function of altitude above cloud base, horizontal distance from cloud edges, cloud droplet size distributions (2-50 μm) and vertical wind velocities. The objective of the analysis is to evaluate the spatial distribution of precipitation events with respect to the microphysical and dynamical processes that are related to the development and evolution of rain in tropical convective clouds. In addition, the reflectivity is calculated from the size distributions and evaluated to assess how inhomogeneities in the precipitation might be observed by meteorological radars.

  2. Ultrafast probing of transient electric fields from optical field ionized plasmas using picosecond electron deflectometry

    NASA Astrophysics Data System (ADS)

    He, Zhaohan; Nees, John; Hou, Bixue; Krushelnick, Karl; Thomas, Alec

    2015-11-01

    Femtosecond bunches of electrons with relativistic to ultra-relativistic energies can be robustly produced in laser plasma wakefield accelerators (LWFA). Scaling the electron energy down to sub-relativistic and MeV level using a millijoule laser system will make such electron source a promising candidate for ultrafast electron diffraction (UED) the applications due to the intrinsic short bunch duration and perfect synchronization with optical pump. Electrons with sub-relativistic (~100 keV) energies can be used to probe transient electric field generated in laser plasmas with very high sensitivity. In a proof-of-principle experiment, we measured field evolution from plasma produced by focusing femtosecond laser pulses into a gas jet at intensities up to 1017 W/cm2. Due to the energy spread in laser plasma generated electrons, dipole magnets are used to record a streaked electron image such that the temporal evolution can be mapped in a single shot. This technique allows for probing irreversible processes such as melting of crystalline samples.

  3. A fiber optic probe for measurement of an autonomic dysreflexia event on SCI patients

    NASA Astrophysics Data System (ADS)

    Ramella-Roman, J. C.; Hidler, J. M.

    2008-02-01

    Autonomic Dysreflexia (AD) is an inappropriate response of the sympathetic nervous system that often occurs in individuals with spinal cord injury (SCI ) at or above the sixth thoracic vertebrae (T6) level when a noxius stimulus is applied below the level of injury. An AD event can be put into motion by something as simple as an ingrown toenail or a full bladder, with symptoms such as headache, elevated blood pressure, reduced heart rate, decreases in blood flow below the level of injury, and in extreme cases, stroke. We have developed a quantitative method of measuring skin oxygen levels during AD using a fiber optics based probe. Two such probes were located above and below the injury level (on the patient forearm and thigh respectively) and were connected to a dual channel spectrophotometer. Oxygen saturation was calculated using the reflectance spectra and an algorithm based on melanin and hemoglobin absorption. We found that during an AD event, the amount of oxygen in the skin below the injury level drops by as much as 40%, while above the injury level skin oxygenation remains constant. Additionally, we observed elevated persperation levels below the injury level. We hypothesize that the combination of AD-related ischemia with pressure related ischemia and increased perspiration places individuals with injury level at T6 or above at significant risk for developing a pressure sore below the injury site.

  4. Biomedical Probes Based on Inorganic Nanoparticles for Electrochemical and Optical Spectroscopy Applications.

    PubMed

    Yakoh, Abdulhadee; Pinyorospathum, Chanika; Siangproh, Weena; Chailapakul, Orawon

    2015-01-01

    Inorganic nanoparticles usually provide novel and unique physical properties as their size approaches nanometer scale dimensions. The unique physical and optical properties of nanoparticles may lead to applications in a variety of areas, including biomedical detection. Therefore, current research is now increasingly focused on the use of the high surface-to-volume ratios of nanoparticles to fabricate superb chemical- or biosensors for various detection applications. This article highlights various kinds of inorganic nanoparticles, including metal nanoparticles, magnetic nanoparticles, nanocomposites, and semiconductor nanoparticles that can be perceived as useful materials for biomedical probes and points to the outstanding results arising from their use in such probes. The progress in the use of inorganic nanoparticle-based electrochemical, colorimetric and spectrophotometric detection in recent applications, especially bioanalysis, and the main functions of inorganic nanoparticles in detection are reviewed. The article begins with a conceptual discussion of nanoparticles according to types, followed by numerous applications to analytes including biomolecules, disease markers, and pharmaceutical substances. Most of the references cited herein, dating from 2010 to 2015, generally mention one or more of the following characteristics: a low detection limit, good signal amplification and simultaneous detection capabilities. PMID:26343676

  5. Laser Paint Interactions Studied by Optical Emission Spectroscopy and Pump and Probe Analysis of the Ablation Plume

    NASA Astrophysics Data System (ADS)

    Rebollar, E.; Oujja, M.; Martín, M.; Castillejo, M.

    The ablation plumes resulting from the laser irradiation of pigments in the form of pellets and as tempera paints were studied by optical spectroscopic methods including optical emission spectroscopy (OES) and laser induced fluorescence (LIF), using a probe laser, delayed with respect to the ablation laser. The differences observed between emissions from pellets and from tempera paints of a given pigment, and between organic and inorganic pigments, serve to discuss the mechanisms operating in the laser irradiation of the paint systems.

  6. Probing quantum confinement at the atomic scale with optically detected nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Kempf, James G.

    2001-09-01

    Near-band-gap circularly polarized excitation in III-V semiconductors provides spin-polarized electrons that transfer spin order to lattice nuclei via fluctuations in the contact hyperfine interaction. This process of optical nuclear polarization and the complementary technique of optical detection of nuclear magnetic resonance (NMR) provide extreme sensitivity enhancement and spatial selectivity in structured samples, enabling collection of NMR spectra from samples such as single quantum wells or dots containing as few as ˜105 nuclei. Combining these advances with novel techniques for high spectral resolution, we have probed quantum-confined electronic states near the interface of a single epitaxially grown Al1-x As/GaAs (x = 0.36) heterojunction. Using a novel strategy that we refer to as POWER (p&barbelow;erturbations o&barbelow;bserved w&barbelow;ith e&barbelow;nhanced ṟesolution) NMR, multiple-pulse time suspension is synchronized with bandgap optical irradiation to reveal spectra of effective spin Hamiltonians that are differences between those of the occupied and unoccupied photoexcited electronic state. The underlying NMR linewidth is reduced by three orders of magnitude in these experiments, enabling resolution of an asymmetric line shape due to light-induced hyperfine interactions. The results are successfully fit with the coherent nuclear spin evolution and relaxation theoretically expected for sites distributed over the volume of an electronic excitation weakly localized at a point defect. This analysis establishes a one-to-one relationship, which can be used to follow nuclear spin diffusion, between optical Knight shift and the radial position of lattice nuclei. We have also introduced POWER NMR techniques to characterize the change in electric field associated with cycling from light-on to light-off states via a linear quadrupole Stark effect (LQSE) of the nuclear spins. Simulations of these NMR spectra in terms of the radial electric fields of

  7. Modeling the Optical Response to a Near-Field Probe Tip from a Generalized Multilayer Thin Film

    NASA Astrophysics Data System (ADS)

    Lawrence, A. J.

    The contrast mechanism in Kerr imaging is the apparent angle through which the plane of polarization is rotated upon reflection from a magnetic surface. This can be calculated for a well characterized surface given the polarization state of the incident light. As in traditional optical microscopy, the spatial resolution is limited by diffraction to roughly half the wavelength of the illumination light. The diffraction limit can be circumvented through the use of near-field scanning optical microscopy, in which the illumination source is an evanescent field at the tip of a tapered optical fiber. A novel probe design for near-field optical imaging in reflection mode will be proposed, and experimental work on the development of a near-field Kerr microscope performed up to this point will be presented. The complication in merging these two techniques arises from the complex polarization profile of the evanescent field. This profile can be characterized for a given probe geometry with the use of electromagnetic field modeling software, allowing for subsequent modeling of the polarization profile of the optical response. An algorithm for predicting the optical response to a near-field probe tip from a generalized multilayer thin-film is presented.

  8. Multihydroxy dendritic upconversion nanoparticles with enhanced water dispersibility and surface functionality for bioimaging.

    PubMed

    Zhou, Li; He, Benzhao; Huang, Jiachang; Cheng, Zehong; Xu, Xu; Wei, Chun

    2014-05-28

    Upconversion nanoparticle (UCNP) as a new class of imaging agent is gaining prominence because of its unique optical properties. An ideal UCNP for bioimaging should simultaneously possess fine water dispersibility and favorable functional groups. In this paper, we present a simple but effective method to the synthesis of a UCNP-based nanohybrid bearing a multihydroxy hyperbranched polyglycerol (HPG) shell by the combination of a "grafting from" strategy with a ring-opening polymerization technique. The structure and morphology of the resulting UCNP-g-HPG nanohybrid were characterized in detail by Fourier transform infrared, (1)H NMR, thermogravimetric analysis, and transmission electron microscopy measurements. The results reveal that the amount of grafted HPG associated with the thickness of the HPG shell can be well tuned. UCNP-g-HPG shows high water dispersibility and strong and stable upconversion luminescence. On the basis of its numerous surface hydroxyl groups, UCNP-g-HPG can be tailored by a representative fluorescent dye rhodamine B to afford a UCNP-g-HPG-RB nanohybrid that simultaneously presents upconversion and downconversion luminescence. Preliminary biological studies demonstrate that UCNP-g-HPG shows low cytotoxicity, high luminescent contrast, and deep light penetration depth, posing promising potential for bioimaging applications. PMID:24749852

  9. Recent conjugation strategies of small organic fluorophores and ligands for cancer-specific bioimaging.

    PubMed

    Ha, Yonghwang; Choi, Hyun-Kyung

    2016-03-25

    Conjugation between various small fluorophores and specific ligands has become one of the main strategies for bioimaging in disease diagnosis, medicinal chemistry, immunology, and fluorescence-guided surgery, etc. Herein, we present our review of recent studies relating to molecular fluorescent imaging techniques for various cancers in cell-based and animal-based models. Various organic fluorophores, especially near-infrared (NIR) probes, have been employed with specific ligands. Types of ligands used were small molecules, peptides, antibodies, and aptamers; each has specific affinities for cellular receptor proteins, cancer-specific antigens, enzymes, and nucleic acids. This review can aid in the selection of cancer-specific ligands and fluorophores, and may inspire the further development of new conjugation strategies in various cellular and animal models. PMID:26892219

  10. The viscoelastic properties of the vitreous humor measured using an optically trapped local probe

    NASA Astrophysics Data System (ADS)

    Watts, Fiona; Tan, Lay Ean; Tassieri, Manlio; McAlinden, Niall; Wilson, Clive G.; Girkin, John M.; Wright, Amanda J.

    2011-10-01

    We present results demonstrating for the first time that an optically trapped bead can be used as a local probe to measure the variation in the viscoelastic properties of the vitreous humor of a rabbit eye. The Brownian motion of the optically trapped bead was monitored on a fast CCD camera on the millisecond timescale. Analysis of the bead trajectory provides local information about the viscoelastic properties of the medium surrounding the particle. Previous, bulk, methods for measuring the viscoelastic properties of the vitreous destroy the sample and allow only a single averaged measurement to be taken per eye. Whereas, with our approach, we were able to observe local behaviour typical of non-Newtonian and gel-like materials, along with the homogenous and in-homogeneous nature of different regions of the dissected vitreous humor. The motivation behind these measurements is to gain a better understanding of the structure of the vitreous humor in order to design effective drug delivery techniques. In particular, we are interested in methods for delivering drug to the retina of the eye in order to treat sight threatening diseases such as age related macular degeneration.

  11. Field programmable gate array based reconfigurable scanning probe/optical microscope.

    PubMed

    Nowak, Derek B; Lawrence, A J; Dzegede, Zechariah K; Hiester, Justin C; Kim, Cliff; Sánchez, Erik J

    2011-10-01

    The increasing popularity of nanometrology and nanospectroscopy has pushed researchers to develop complex new analytical systems. This paper describes the development of a platform on which to build a microscopy tool that will allow for flexibility of customization to suit research needs. The novelty of the described system lies in its versatility of capabilities. So far, one version of this microscope has allowed for successful near-field and far-field fluorescence imaging with single molecule detection sensitivity. This system is easily adapted for reflection, polarization (Kerr magneto-optical (MO)), Raman, super-resolution techniques, and other novel scanning probe imaging and spectroscopic designs. While collecting a variety of forms of optical images, the system can simultaneously monitor topographic information of a sample with an integrated tuning fork based shear force system. The instrument has the ability to image at room temperature and atmospheric pressure or under liquid. The core of the design is a field programmable gate array (FPGA) data acquisition card and a single, low cost computer to control the microscope with analog control circuitry using off-the-shelf available components. A detailed description of electronics, mechanical requirements, and software algorithms as well as examples of some different forms of the microscope developed so far are discussed. PMID:22047297

  12. Field programmable gate array based reconfigurable scanning probe/optical microscope

    NASA Astrophysics Data System (ADS)

    Nowak, Derek B.; Lawrence, A. J.; Dzegede, Zechariah K.; Hiester, Justin C.; Kim, Cliff; Sánchez, Erik J.

    2011-10-01

    The increasing popularity of nanometrology and nanospectroscopy has pushed researchers to develop complex new analytical systems. This paper describes the development of a platform on which to build a microscopy tool that will allow for flexibility of customization to suit research needs. The novelty of the described system lies in its versatility of capabilities. So far, one version of this microscope has allowed for successful near-field and far-field fluorescence imaging with single molecule detection sensitivity. This system is easily adapted for reflection, polarization (Kerr magneto-optical (MO)), Raman, super-resolution techniques, and other novel scanning probe imaging and spectroscopic designs. While collecting a variety of forms of optical images, the system can simultaneously monitor topographic information of a sample with an integrated tuning fork based shear force system. The instrument has the ability to image at room temperature and atmospheric pressure or under liquid. The core of the design is a field programmable gate array (FPGA) data acquisition card and a single, low cost computer to control the microscope with analog control circuitry using off-the-shelf available components. A detailed description of electronics, mechanical requirements, and software algorithms as well as examples of some different forms of the microscope developed so far are discussed.

  13. Atomic force microscopy deep trench and sidewall imaging with an optical fiber probe

    SciTech Connect

    Xie, Hui Hussain, Danish; Yang, Feng; Sun, Lining

    2014-12-15

    We report a method to measure critical dimensions of micro- and nanostructures using the atomic force microscope (AFM) with an optical fiber probe (OFP). This method is capable of scanning narrow and deep trenches due to the long and thin OFP tip, as well as imaging of steep sidewalls with unique profiling possibilities by laterally tilting the OFP without any modifications of the optical lever. A switch control scheme is developed to measure the sidewall angle by flexibly transferring feedback control between the Z- and Y-axis, for a serial scan of the horizontal surface (raster scan on XY-plane) and sidewall (raster scan on the YZ-plane), respectively. In experiments, a deep trench with tapered walls (243.5 μm deep) and a microhole (about 14.9 μm deep) have been imaged with the orthogonally aligned OFP, as well as a silicon sidewall (fabricated by deep reactive ion etching) has been characterized with the tilted OFP. Moreover, the sidewall angle of TGZ3 (AFM calibration grating) was accurately measured using the switchable scan method.

  14. Photoacoustic endoscopy probe using a coherent fibre-optic bundle and Fabry-Pérot ultrasound sensor (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ansari, Rehman; Beard, Paul C.; Zhang, Edward Z.; Desjardins, Adrien E.

    2016-03-01

    There is considerable interest in the development of photoacoustic endoscopy (PAE) probes for the clinical assessment of pathologies in the gastrointestinal (GI) tract, guiding minimally invasive laparoscopic surgeries and applications in foetal medicine. However, most previous PAE probes integrate mechanical scanners and piezoelectric transducers at the distal end which can be technically complex, expensive and pose challenges in achieving the necessary level of miniaturisation. We present two novel all-optical forward-viewing endoscopic probes operating in widefield tomography mode that have the potential to overcome these limitations. In one configuration, the probe comprises a transparent 40 MHz Fabry-Pérot ultrasound sensor deposited at the tip of a rigid, 3 mm diameter coherent fibre-optic bundle. In this way, the distal end of coherent fibre bundle acts as a 2D array of wideband ultrasound detectors. In another configuration, an optical relay is used between the distal end face of flexible fibre bundle and the Fabry-Pérot sensor to enlarge the lateral field of view to 6 mm x 6 mm. In both configurations, the pulsed excitation laser beam is full-field coupled into the fibre bundle at the proximal end for uniform backward-mode illumination of the tissue at the probe tip. In order to record the photoacoustic waves arriving at the probe tip, the proximal end of the fibre bundle is optically scanned in 2D with a CW wavelength-tunable interrogation laser beam thereby interrogating different spatial points on the sensor. A time-reversal image reconstruction algorithm was used to reconstruct a 3D image from the detected signals. The 3D field of view of the flexible PAE probe is 6 mm x 6 mm x 6 mm and the axial and lateral spatial resolution is 30 µm and 90 µm, respectively. 3D imaging capability is demonstrated using tissue phantoms, ex vivo tissues and in vivo. To the best of our knowledge, this is the first forward-viewing implementation of a photoacoustic

  15. Bioimage informatics: a new area of engineering biology

    PubMed Central

    Peng, Hanchuan

    2008-01-01

    In recent years, the deluge of complicated molecular and cellular microscopic images creates compelling challenges for the image computing community. There has been an increasing focus on developing novel image processing, data mining, database and visualization techniques to extract, compare, search and manage the biological knowledge in these data-intensive problems. This emerging new area of bioinformatics can be called ‘bioimage informatics’. This article reviews the advances of this field from several aspects, including applications, key techniques, available tools and resources. Application examples such as high-throughput/high-content phenotyping and atlas building for model organisms demonstrate the importance of bioimage informatics. The essential techniques to the success of these applications, such as bioimage feature identification, segmentation and tracking, registration, annotation, mining, image data management and visualization, are further summarized, along with a brief overview of the available bioimage databases, analysis tools and other resources. Contact: pengh@janelia.hhmi.org Supplementary information: Supplementary data are available at Bioinformatics online. PMID:18603566

  16. A novel minimally invasive dual-modality fiber optic probe for prostate cancer detection

    NASA Astrophysics Data System (ADS)

    Sharma, Vikrant

    Prostate cancer is the most common form of cancer in males, and is the second leading cause of cancer related deaths in United States. In prostate cancer diagnostics and therapy, there is a critical need for a minimally invasive tool for in vivo evaluation of prostate tissue. Such a tool finds its niche in improving TRUS (trans-rectal ultrasound) guided biopsy procedure, surgical margin assessment during radical prostatectomy, and active surveillance of patients with a certain risk levels. This work is focused on development of a fiber-based dual-modality optical device (dMOD), to differentiate prostate cancer from benign tissue, in vivo. dMOD utilizes two independent optical techniques, LRS (light reflectance spectroscopy) and AFLS (auto-fluorescence lifetime spectroscopy). LRS quantifies scattering coefficient of the tissue, as well as concentrations of major tissue chromophores like hemoglobin derivatives, β-carotene and melanin. AFLS was designed to target lifetime signatures of multiple endogenous fluorophores like flavins, porphyrins and lipo-pigments. Each of these methods was independently developed, and the two modalities were integrated using a thin (1-mm outer diameter) fiber-optic probe. Resulting dMOD probe was implemented and evaluated on animal models of prostate cancer, as well as on human prostate tissue. Application of dMOD to human breast cancer (invasive ductal carcinoma) identification was also evaluated. The results obtained reveal that both LRS and AFLS are excellent techniques to discriminate prostate cancer tissue from surrounding benign tissue in animal models. Each technique independently is capable of providing near absolute (100%) accuracy for cancer detection, indicating that either of them could be used independently without the need of implementing them together. Also, in case of human breast cancer, LRS and AFLS provided comparable accuracies to dMOD, LRS accuracy (96%) being the highest for the studied population. However, the

  17. Comparison of the simplified laterally uniform and geometrically realistic optical fiber probe-tissue interface in terms of Monte Carlo simulated diffuse reflectance

    NASA Astrophysics Data System (ADS)

    Naglič, Peter; Pernuš, Franjo; Likar, Boštjan; Bürmen, Miran

    2015-07-01

    Diffuse reflectance spectroscopy utilizing optical fiber probes is a useful and simple method for non-invasive determination of biological tissue optical properties. In order to extract the optical properties from the acquired diffuse reflectance spectra, an accurate light propagation model, such as Monte Carlo, is required. The results obtained by the model can significantly depend on the description of the tissue and optical fiber probe geometry. Optical fiber probes commonly comprise fibers arranged into a desired source-detector layout enclosed in a stainless steel ferrule. By using Monte Carlo simulations, we investigate the impact of the stainless steel optical fiber probe-tissue interface on the diffuse reflectance spectra. For this purpose, a commonly used simple laterally uniform optical probe-tissue interface with mismatched refractive indices was compared to the improved optical probe-tissue interface taking into account the fiber layout and the specular reflections from the stainless steel probe tip. The results show that the error introduced into the simulated diffuse reflectance by the simplified probe-tissue interface can easily exceed 5%.

  18. A novel electro-optical pump-probe system for bioelectromagnetic investigations

    NASA Astrophysics Data System (ADS)

    De Angelis, Annalisa; Couderc, Vincent; Leproux, Philippe; Labruyère, Alexis; Tonello, Alessandro; El Amari, Saad; Arnaud-Cormos, Delia; Leveque, Philippe

    2012-10-01

    In the area of bioelectromagnetic studies there is a growing interest to understand the mechanisms leading to nanosecond electric fields induced electroporation. Real-time imaging techniques at molecular level could probably bring further advances on how electric fields interact with living cells. However the investigations are limited by the present-day lack of these kinds of advanced instrumentations. In this context, we present an innovative electro-optical pump-probe system. The aim of our project is to provide a performing and compact device for electrical stimulation and multiplex Coherent anti-Stokes Raman Scattering (M-CARS) imaging of biological cells at once. The system consists of a 1064 nm sub-nanosecond laser source providing both a monochromatic pump and a polychromatic Stokes optical beam used in a CARS process, as well as the trigger beam for the optoelectronic switching-based electrical pulse generator. The polychromatic Stokes beam (from 600 to 1700 nm) results from a supercontinuum generation in a photonic crystal fiber (PCF). A detailed spectro-temporal characterization of such a broadband spectrum shows the impact of the nonlinear propagation in the fiber on the Stokes wave. Despite the temporal distortions observable on Stokes pulse profiles, their spectral synchronization with the pump pulse remains possible and efficient in the interesting region between 1100 nm and 1700 nm. The electrical stimulation device consists of a customized generator combining microstrip-line technology and laser-triggered photoconductive semiconductor switches. Our experimental characterization highlights the capability for such a generator to control the main pulse parameters (profile, amplitude and duration) and to be easily synchronized with the imaging system. We finally test and calibrate the system by means of a KDP crystal. The preliminary results suggest that this electro-optical system provides a suitable tool for real-time investigation of

  19. Investigation on probing quadratic electro-optic coefficient of tantalum potassium niobate crystal based on Fourier transform

    NASA Astrophysics Data System (ADS)

    Gao, Ch. Y.; Yu, H. T.; Wen, J.; Zhao, M.; Shang, J. J.; Li, X. L.

    2016-02-01

    A method for probing quadratic electro-optic(QEO) coefficient of tantalum potassium niobate crystal based on Fourier transform was proposed. We acquired all the independent component of QEO coefficient tensor of crystal, they are h11 = 1.56 ×10-14m2 /V2 , h12 = 1.24 ×10-14m2 /V2 and h44 = 0.160 ×10-14m2 /V2 respectively. With the help of the computer digital image processing technology, this method should have further application prospect in the areas of optical properties parameters measuring to the optical functional materials.

  20. Multiscale 3D bioimaging: from cell, tissue to whole organism

    NASA Astrophysics Data System (ADS)

    Lau, S. H.; Wang, Ge; Chandrasekeran, Margam; Fan, Victor; Nazrul, Mohd; Chang, Hauyee; Fong, Tiffany; Gelb, Jeff; Feser, Michael; Yun, Wenbing

    2009-05-01

    While electron microscopes and AFMs are capable of high resolution imaging to molecular levels, there is an ongoing problem in integrating these results into the larger scale structure and functions of tissue and organs within a complex organism. Imaging biological samples with optical microscopy is predominantly done with histology and immunohistochemistry, which can take up to a several weeks to prepare, are artifact prone and only available as individual 2D images. At the nano resolution scale, the higher resolution electron microscopy and AFM are used, but again these require destructive sample preparation and data are in 2D. To bridge this gap, we describe a rapid non invasive hierarchical bioimaging technique using a novel lab based x-ray computed tomography to characterize complex biological organism in multiscale- from whole organ (mesoscale) to calcified and soft tissue (microscale), to subcellular structures, nanomaterials and cellular-scaffold interaction (nanoscale). While MicroCT (micro x-ray computed tomography) is gaining in popularity for non invasive bones and tissue imaging, contrast and resolution are still vastly inadequate compared to histology. In this study we will present multiscale results from a novel microCT and nanoCT (nano x-ray tomography system). The novel MicroCT can image large specimen and tissue sample at histology resolution of submicron voxel resolution, often without contrast agents, while the nanoCT using x-ray optics similar to those used in synchrotron radiation facilities, has 20nm voxel resolution, suitable for studying cellular, subcellular morphology and nanomaterials. Multiscale examples involving both calcified and soft tissue will be illustrated, which include imaging a rat tibia to the individual channels of osteocyte canaliculli and lacunae and an unstained whole murine lung to its alveoli. The role of the novel CT will also be discussed as a possible means for rapid virtual histology using a biopsy of a human

  1. An analogue contact probe using a compact 3D optical sensor for micro/nano coordinate measuring machines

    NASA Astrophysics Data System (ADS)

    Li, Rui-Jun; Fan, Kuang-Chao; Miao, Jin-Wei; Huang, Qiang-Xian; Tao, Sheng; Gong, Er-min

    2014-09-01

    This paper presents a new analogue contact probe based on a compact 3D optical sensor with high precision. The sensor comprises an autocollimator and a polarizing Michelson interferometer, which can detect two angles and one displacement of the plane mirror at the same time. In this probe system, a tungsten stylus with a ruby tip-ball is attached to a floating plate, which is supported by four V-shape leaf springs fixed to the outer case. When a contact force is applied to the tip, the leaf springs will experience elastic deformation and the plane mirror mounted on the floating plate will be displaced. The force-motion characteristics of this probe were investigated and optimum parameters were obtained with the constraint of allowable physical size of the probe. Simulation results show that the probe is uniform in 3D and its contacting force gradient is within 1 mN µm - 1. Experimental results indicate that the probe has 1 nm resolution,  ± 10 µm measuring range in X - Y plane, 10 µm measuring range in Z direction and within 30 nm measuring standard deviation. The feasibility of the probe has been preliminarily verified by testing the flatness and step height of high precision gauge blocks.

  2. Metal and complementary molecular bioimaging in Alzheimer's disease.

    PubMed

    Braidy, Nady; Poljak, Anne; Marjo, Christopher; Rutlidge, Helen; Rich, Anne; Jayasena, Tharusha; Inestrosa, Nibaldo C; Sachdev, Perminder

    2014-01-01

    spectrometry (MALDI-IMS), and Fourier transform infrared spectroscopy (FTIR) can be used to correlate changes in elemental distribution with the underlying pathology in AD brain specimens. Taken together, these techniques provide new techniques to probe the pathobiology of AD and pave the way for identifying new therapeutic targets. The current review aims to discuss the advantages and challenges of using these emerging elemental and molecular imaging techniques, and highlight clinical achievements in AD research using bioimaging techniques. PMID:25076902

  3. Metal and complementary molecular bioimaging in Alzheimer's disease

    PubMed Central

    Braidy, Nady; Poljak, Anne; Marjo, Christopher; Rutlidge, Helen; Rich, Anne; Jayasena, Tharusha; Inestrosa, Nibaldo C.; Sachdev, Perminder

    2014-01-01

    spectrometry (MALDI-IMS), and Fourier transform infrared spectroscopy (FTIR) can be used to correlate changes in elemental distribution with the underlying pathology in AD brain specimens. Taken together, these techniques provide new techniques to probe the pathobiology of AD and pave the way for identifying new therapeutic targets. The current review aims to discuss the advantages and challenges of using these emerging elemental and molecular imaging techniques, and highlight clinical achievements in AD research using bioimaging techniques. PMID:25076902

  4. Fiber optic probe enabled by surface-enhanced Raman scattering for early diagnosis of potential acute rejection of kidney transplant

    NASA Astrophysics Data System (ADS)

    Chi, Jingmao; Chen, Hui; Tolias, Peter; Du, Henry

    2014-06-01

    We have explored the use of a fiber-optic probe with surface-enhanced Raman scattering (SERS) sensing modality for early, noninvasive and, rapid diagnosis of potential renal acute rejection (AR) and other renal graft dysfunction of kidney transplant patients. Multimode silica optical fiber immobilized with colloidal Ag nanoparticles at the distal end was used for SERS measurements of as-collected urine samples at 632.8 nm excitation wavelength. All patients with abnormal renal graft function (3 AR episodes and 2 graft failure episodes) who were clinically diagnosed independently show common unique SERS spectral features in the urines collected just one day after transplant. SERS-based fiber-optic probe has excellent potential to be a bedside tool for early diagnosis of kidney transplant patients for timely medical intervention of patients at high risk of transplant dysfunction.

  5. Method of detecting tissue contact for fiber-optic probes to automate data acquisition without hardware modification

    PubMed Central

    Ruderman, Sarah; Mueller, Scott; Gomes, Andrew; Rogers, Jeremy; Backman, Vadim

    2013-01-01

    We present a novel algorithm to detect contact with tissue and automate data acquisition. Contact fiber-optic probe systems are useful in noninvasive applications and real-time analysis of tissue properties. However, applications of these technologies are limited to procedures with visualization to ensure probe-tissue contact and individual user techniques can introduce variability. The software design exploits the system previously designed by our group as an optical method to automatically detect tissue contact and trigger acquisition. This method detected tissue contact with 91% accuracy, detected removal from tissue with 83% accuracy and reduced user variability by > 8%. Without the need for additional hardware, this software algorithm can easily integrate into any fiber-optic system and expands applications where visualization is difficult. PMID:24010002

  6. Magnetization precession of magnetic thin films studied by all optical pump-probe technique

    NASA Astrophysics Data System (ADS)

    Michalski, Steven A.

    The study of magnetization dynamics such as magnetization precession and precessional damping provides insights into the behavior of complex magnetic systems, and indeed may lead to a better understanding of the fundamental limits of magnetic reversal process. In this work, a time-resolved magneto-optic Kerr effect system (TRMOKE) was developed to study magnetization dynamics: Precession and damping. The system uses a femtosecond laser in a pump-probe experiment with direct optical excitation, very similar to the method introduced by Ganping Ju and coworkers. Also, a model based on the Landau-Lifshitz-Gilbert equation (LLG) was developed and used to interpret and analyze the experimental magnetization precession data of a single magnetic layer. The model can be used to predict the precession frequencies with and without damping, the eigenvectors of the magnetization and allows the Gilbert damping parameter (alpha) to be determined. The model is extended to a system of two magnetic layers coupled through a nonmagnetic spacer layer. The capabilities of the TRMOKE system and the LLG models, were demonstrated by studying the magnetization dynamics of Ni/Pt bilayers. Static and dynamic magnetic properties of exchange-coupled magnetic layers have been investigated by magneto-optical measurements. The samples are [Pt/Co] multilayers with perpendicular magnetic anisotropy (PMA) exchange-coupled to a Co layer with in-plane magnetic anisotropy. The exchange is indirect, realized and tuned by an intervening Pt layer of varying thickness. Both the strength and the angle of an external applied magnetic field were varied and for many samples, two modes with two distinct precession frequencies were observed in the precession measurements. The frequencies of both modes depend on the strength and the angle of the applied magnetic field. The LLG model predicts two precessional modes ("acoustic" and "optic") whose behaviors depend on the strength and sign of the exchange coupling

  7. Spectrophotometric probe

    DOEpatents

    Prather, W.S.; O'Rourke, P.E.

    1994-08-02

    A support structure is described bearing at least one probe for making spectrophotometric measurements of a fluid using a source of light and a spectrophotometer. The probe includes a housing with two optical fibers and a planoconvex lens. A sleeve bearing a mirror surrounds the housing. The lens is separated from the mirror by a fixed distance, defining an interior space for receiving a volume of the fluid sample. A plurality of throughholes extending through the sleeve communicate between the sample volume and the exterior of the probe, all but one hole bearing a screen. A protective jacket surrounds the probe. A hollow conduit bearing a tube is formed in the wall of the probe for venting any air in the interior space when fluid enters. The probe is held at an acute angle so the optic fibers carrying the light to and from the probe are not bent severely on emergence from the probe. 3 figs.

  8. Spectrophotometric probe

    DOEpatents

    Prather, William S.; O'Rourke, Patrick E.

    1994-01-01

    A support structure bearing at least one probe for making spectrophotometric measurements of a fluid using a source of light and a spectrophotometer. The probe includes a housing with two optical fibers and a planoconvex lens. A sleeve bearing a mirror surrounds the housing. The lens is separated from the mirror by a fixed distance, defining an interior space for receiving a volume of the fluid sample. A plurality of throughholes extending through the sleeve communicate between the sample volume and the exterior of the probe, all but one hole bearing a screen. A protective jacket surrounds the probe. A hollow conduit bearing a tube is formed in the wall of the probe for venting any air in the interior space when fluid enters. The probe is held at an acute angle so the optic fibers carrying the light to and from the probe are not bent severely on emergence from the probe.

  9. The Backscatter Cloud Probe - a compact low-profile autonomous optical spectrometer

    NASA Astrophysics Data System (ADS)

    Beswick, K.; Baumgardner, D.; Gallagher, M.; Newton, R.

    2013-08-01

    A compact (500 cm3), lightweight (500 g), near-field, single particle backscattering optical spectrometer is described that mounts flush with the skin of an aircraft and measures the concentration and optical equivalent diameter of particles from 5 to 75 μm. The Backscatter Cloud Probe (BCP) was designed as a real-time qualitative cloud detector primarily for data quality control of trace gas instruments developed for the climate monitoring instrument packages that are being installed on commercial passenger aircraft as part of the European Union In-Service Aircraft for a Global Observing System (IAGOS) program (http://www.iagos.org/). Subsequent evaluations of the BCP measurements on a number of research aircraft, however, have revealed it capable of delivering quantitative particle data products including size distributions, liquid water content and other information on cloud properties. We demonstrate the instrument's capability for delivering useful long-term climatological information, across a wide range of environmental conditions. The BCP has been evaluated by comparing its measurements with those from other cloud particle spectrometers on research aircraft and several BCPs are currently flying on commercial A340/A330 Airbus passenger airliners. The design and calibration of the BCP is described in this presentation, along with an evaluation of measurements made on the research and commercial aircraft. Comparisons of the BCP with two other cloud spectrometers, the Cloud Droplet Probe (CDP) and the Cloud and Aerosol Spectrometer (CAS), show that the BCP size distributions agree well with those from the other two, given the intrinsic limitations and uncertainties related to the three instruments. Preliminary results from more than 7000 h of airborne measurements by the BCP on two Airbus A-340s operating on routine global traffic routes (one Lufthansa, the other China Airlines) show that more than 340 h of

  10. Ultrahigh resolution endoscopic spectral domain optical coherence tomography with a tiny rotary probe driven by a hollow ultrasonic motor

    NASA Astrophysics Data System (ADS)

    Zhang, Ning; Chen, Tianyuan; Huo, Tiancheng; Wang, Chengming; Zheng, Jing-gao; Zhou, Tieying; Xue, Ping

    2013-03-01

    This paper proposes a novel rotary endoscopic probe for spectral-domain optical coherence tomography (SD-OCT). The probe with a large N.A. objective lens is driven by an ultra-small hollow rectangular ultrasonic motor for circular scanning. Compared to the conventional driven techniques, the hollow ultrasonic motor enables the fiber to pass through its inside. Therefore the fiber, the objective lens and the motor are all at the same side. This enables 360 degree unobstructed imaging without any shadow resulted from power wire as in the conventional motor-driven endoscopic OCT. Moreover, it shortens the length of the rigid tip and enhances the flexibility of the probe. Meanwhile, the ultrasonic motor is robust, simple, quiet and of high torque, very suitable for OCT endoscopic probe. The side length of the motor is 0.7 mm with 5mm in length. The outer diameter of the probe is 1.5mm. A significant improvement in the lateral resolution is demonstrated due to the novel design of the objective lens. A right-angle lens is utilized instead of the traditional right-angle prism as the last optics close to the sample, leading to a reduction of the working distance and an enlargement of the N.A. of the objective lens. It is demonstrated that the endoscopic SD-OCT system achieves an axial resolution of ~7μm, a lateral resolution of ~6μm and a SNR of ~96dB.

  11. Dual Femtosecond TITANIUM:SAPPHIRE Laser for Ultrafast Optical Sampling Two-Color Pump/probe Studies.

    NASA Astrophysics Data System (ADS)

    Luo, Ningyi Daniel

    A pair of self-synchronous Ti:Sapphire lasers have been setup for two-color pump/probe detection in the sub-picosecond time regime. The two 75 femtosecond self -mode-locked Ti:Sapphire lasers are operated asynchronously at slightly different repetition rates to provide continuously varying dynamic delay times. They are tunable at 700-890 nm. The shorter wavelength pulses from one laser are used as a pump source, while the longer wavelength pulses are used as a probe. The sum-frequency pulses generated by the cross-correlation of the two laser pulses are used to define the "time-zero" position and trigger the pump/probe process. The experiment is triggered at the difference frequency, and the signal can be averaged many times allowing a weak signal to build up. Dual-time scale is involved with the interpretation of the signal, which allows the experiment to be carried on the real time scale and the signal to be recorded on a much reduced equivalent time scale. Excited state lifetime measurement of laser HITCI has proven that this technology is practically feasible. Several advantages have been seen: (1) independent wavelength tunability of the pump and probe lasers; (2) variable femto- to nano -second pump/probe time delay; (3) fast (mu s-ms) data collection time; (4) compact optical layout, without the need for optical delay lines and modulators, and thus, simple optical alignment. This study sheds light on the development of a novel compact high speed optical instrument.

  12. Probing iron spin state by optical absorption in laser-heated diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Lobanov, S.; Goncharov, A. F.; Holtgrewe, N.; Lin, J. F.

    2015-12-01

    Pressure-induced spin-pairing transitions in iron-bearing minerals have been in the focus of geophysical studies1. Modern consensus is that iron spin state in the lower mantle is a complex function of crystal structure, composition, pressure, and temperature. Discontinuities in physical properties of lower mantle minerals have been revealed over the spin transition pressure range, but at room temperature. In this work, we have used a supercontinuum laser source and an intensified CCD camera to probe optical properties of siderite, FeCO3, and post-perovskite, Mg0.9Fe0.1SiO3, across the spin transition in laser-heated diamond anvil cell. Synchronously gating the CCD with the supercontinuum pulses (Fig. 1A) allowed diminishing thermal background to ~8.3*10-4. Utilizing the experimental setup we infer the spin state of ferrous iron in siderite at high pressure and temperature conditions (Fig. 1B). Similar behavior is observed for low spin ferric iron in post-perovskite at 130 GPa indicating that all iron in post-perovskite is high spin at lower mantle conditions. Also, our experimental setup holds promise for measuring radiative thermal conductivity of mantle minerals at relevant mantle conditions. Figure 1. (A) Timing of the optical absorption measurements at high temperature. (B) High temperature siderite absorption spectra at 45 GPa. Before heating and quenched after 1300 K spectra are shown in light and dark blue, respectively. Green and red curves are absorption spectra at 1200 K and 1300 K, respectively. Spectra shown in black represent room temperature absorption data on HS (43 GPa) and LS (45.5 GPa) siderite after Lobanov et al., 2015, shown for comparison.

  13. Reduced-density-matrix description for pump-probe optical phenomena in moving atomic systems

    NASA Astrophysics Data System (ADS)

    Jacobs, V. L.

    2014-09-01

    Linear and nonlinear (especially coherent) electromagnetic interactions of moving many-electron atoms are investigated using a reduced-density-matrix description, which is applied to electromagnetically induced transparency and related resonant pump-probe optical phenomena. External magnetic fields are included on an equal footing with the electromagnetic fields and spin-Zeeman interactions are taken into account. Complimentary time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations of the reduced-density-matrix description are self-consistently developed. The general nonperturbative and non-Markovian formulations provide a fundamental framework for systematic evaluations of corrections to the standard Born (lowest-order-perturbation) and Markov (short-memory-time) approximations. The macroscopic electromagnetic response is described semiclassically, employing a perturbation expansion of the reduced-density operator in powers of the classical electromagnetic field. Our primary results are compact Liouville-space operator expressions for the linear and general (nth-order) nonlinear macroscopic electromagnetic-response tensors, which can be evaluated for nonlocal and nonstationary optical media described by multilevel atomic-system representations. Interactions among atoms and with environmental photons are treated as line-broadening effects by means of a general Liouville-space self-energy operator, for which the tetradic-matrix elements are explicitly evaluated in the diagonal, lowest-order, and Markov approximations. The compact Liouville-space operator expressions that are derived for the macroscopic electromagnetic-response tensors are introduced into the dynamical description of the electromagnetic-field propagation. It is pointed out that a quantized-electromagnetic-field approach will be required for a fully self-consistent quantum-mechanical treatment of local-field effects and radiative corrections.

  14. Probing Transition Metal Dichalcogenide Monolayers and Heterostructures by Optical Spectroscopy and Scanning Tunneling Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hill, Heather M.

    Atomically thin two-dimensional materials, such as graphene and semiconductor transition metal dichalcogenides (TMDCs), exhibit remarkable and desirable optical and electronic properties. This dissertation focuses on the excitonic properties of monolayer TMDCs taken first in isolation and then in contact with another material. We begin with a study of the exciton binding energy in two monolayer TMDCs, WS2 and MoS2. We observe excited states of the exciton by two dierent optical spectroscopy techniques: reflectance contrast and photoluminescence excitation (PLE) spectroscopy. We fit a hydrogenic model to the energies associated with the excited states and infer a binding energy, which is an order of magnitude higher than the bulk material. In the second half of this work, we study two types of two-dimensional vertical heterostructures. First, we investigate heterostructures composed of monolayer WS2 partially capped with graphene one to four layers thick. Using reflectance contrast to measure the spectral broadening of the excitonic features, we measure the decrease in the coherence lifetime of the exciton in WS2 due to charge and energy transfer when in contact with graphene. We then compare our results with the exciton lifetime in MoS 2/WS2 and MoSe2/WSe2 heterostructures. In TMDC/TMDC heterostructures, the decrease in exciton lifetime is twice that in WS2/graphene heterostructures and due predominantly to charge transfer between the layers. Finally, we probe the band alignment in MoS2/WS2 heterostructures using scanning tunneling microscopy (STM) and spectroscopy (STS). We confirm the monolayer band gaps and the predicted type II band alignment in the heterostructure. Drawing from all the research presented, we arrive at a favorable conclusion about the viability of TMDC based devices.

  15. Near-infrared fluorescence imaging of lymph nodes using a new enzyme sensing activatable macromolecular optical probe.

    PubMed

    Wunderbaldinger, Patrick; Turetschek, Karl; Bremer, Christoph

    2003-09-01

    The aim of this study was to validate the use of near infrared fluorescence imaging (NIRF) using enzyme-sensitive optical probes for lymph node detection. An optical contrast probe that is activated by cystein proteases, such as cathepsin B, was used to visualize lymph nodes by NIRF reflectance imaging. In order to quantitate the uptake of the optical probe in lymphatic tissue, the biodistribution was assessed using the Indium-111 labeled optical probe. Sixteen Balb-c mice were injected either intravenously (i.v.) or subcutaneously (s.c.) with the NIRF-probe (2 micromol cyanine (Cy)/animal; i.v., n=10; s.c., n=6) and imaged 24 h after injection. Signal intensities and target-to-background ratios of various lymph nodes were measured by manual regions of interest (ROIs). Additional signal intensity measurements were performed of excised lymph nodes (n=21) from i.v. injected mice (24 h after injection) and compared with excised lymph nodes (n=8) of non-injected mice. The probe employed in this study was lymphotropic with approximately 3-4% accumulation in lymph nodes (3.4+/-0.8% ID/g). Measurements of the excised lymph nodes (after i.v. injection) confirmed a significant increase in lymph node fluorescence signal from baseline 26+/-7.6 arbitary units (AU) to 146+/-10.9 AU (p<0.0001). A significant increase in lymph node fluorescence signal was also seen in vivo throughout the body after i.v. injection (96+/-7.8 AU) and/or regionally after s.c. injection (141+/-11.5 AU) in comparison with baseline autofluorescence (26+/-7.6 AU). Target-to-background ratio was significantly higher after s.c. injection (6.6%+/-0.81) compared with i.v. injection (4.8+/-0.67%). Detection and visualization of lymph nodes is feasible by NIRF imaging using a cystein-protease sensitive optical probe. PMID:12802615

  16. Photoplastic near-field optical probe with sub-100 nm aperture made by replication from a nanomould.

    PubMed

    Kim, G M; Kim, B J; Ten Have, E S; Segerink, F; Van Hulst, N F; Brugger, J

    2003-03-01

    Polymers have the ability to conform to surface contours down to a few nanometres. We studied the filling of transparent epoxy-type EPON SU-8 into nanoscale apertures made in a thin metal film as a new method for polymer/metal near-field optical structures. Mould replica processes combining silicon micromachining with the photo-curable SU-8 offer great potential for low-cost nanostructure fabrication. In addition to offering a route for mass production, the transparent pyramidal probes are expected to improve light transmission thanks to a wider geometry near the aperture. By combining silicon MEMS, mould geometry tuning by oxidation, anti-adhesion coating by self-assembled monolayer and mechanical release steps, we propose an advanced method for near-field optical probe fabrication. The major improvement is the possibility to fabricate nanoscale apertures directly on wafer scale during the microfabrication process and not on free-standing tips. Optical measurements were performed with the fabricated probes. The full width half maximum after a Gaussian fit of the intensity profile indicates a lateral optical resolution of approximately 60 nm. PMID:12641773

  17. GRIN lens rod based probe for endoscopic spectral domain optical coherence tomography with fast dynamic focus tracking

    NASA Astrophysics Data System (ADS)

    Xie, Tuqiang; Guo, Shuguang; Chen, Zhongping; Mukai, David; Brenner, Matthew

    2006-04-01

    In this manuscript, a GRIN (gradient index) lens rod based probe for endoscopic spectral domain optical coherence tomography (OCT) with dynamic focus tracking is presented. Current endoscopic OCT systems have a fixed focal plane or working distance. In contrast, the focus of this endoscopic OCT probe can dynamically be adjusted at a high speed (500 mm/s) without changing reference arm length to obtain high quality OCT images for contact or non-contact tissue applications, or for areas of difficult access for probes. The dynamic focusing range of the probe can be from 0 to 7.5 mm without moving the probe itself. The imaging depth is 2.8 mm and the lateral scanning range is up to 2.7 mm or 4.5 mm (determined by the diameter of different GRIN lens rods). Three dimensional imaging can be performed using this system over an area of tissue corresponding to the GRIN lens surface. The experimental results demonstrate that this GRIN lens rod based OCT system can perform a high quality non-contact in vivo imaging. This rigid OCT probe is solid and can be adapted to safely access internal organs, to perform front or side view imaging with an imaging speed of 8 frames per second, with all moving parts proximal to the GRIN lens, and has great potential for use in extremely compact OCT endoscopes for in vivo imaging in both biological research and clinical applications.

  18. Next generation of optical diagnostics for bladder cancer using probe-based confocal laser endomicroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Jen-Jane; Chang, Timothy C.; Pan, Ying; Hsiao, Shelly T.; Mach, Kathleen E.; Jensen, Kristin C.; Liao, Joseph C.

    2012-02-01

    Real-time imaging with confocal laser endomicroscopy (CLE) probes that fit in standard endoscopes has emerged as a clinically feasible technology for optical biopsy of bladder cancer. Confocal images of normal, inflammatory, and neoplastic urothelium obtained with intravesical fluorescein can be differentiated by morphologic characteristics. We compiled a confocal atlas of the urinary tract using these diagnostic criteria to be used in a prospective diagnostic accuracy study. Patients scheduled to undergo transurethral resection of bladder tumor underwent white light cystoscopy (WLC), followed by CLE, and histologic confirmation of resected tissue. Areas that appeared normal by WLC were imaged and biopsied as controls. We imaged and prospectively analyzed 135 areas in 57 patients. We show that CLE improves the diagnostic accuracy of WLC for diagnosing benign tissue, low and high grade cancer. Interobserver studies showed a moderate level of agreement by urologists and nonclinical researchers. Despite morphologic differences between inflammation and cancer, real-time differentiation can still be challenging. Identification of bladder cancer-specific contrast agents could provide molecular specificity to CLE. By using fluorescently-labeled antibodies or peptides that bind to proteins expressed in bladder cancer, we have identified putative molecular contrast agents for targeted imaging with CLE. We describe one candidate agent - anti-CD47 - that was instilled into bladder specimens. The tumor and normal urothelium were imaged with CLE, with increased fluorescent signal demonstrated in areas of tumor compared to normal areas. Thus, cancer-specificity can be achieved using molecular contrast agents ex vivo in conjunction with CLE.

  19. Embedded Fiber Optic Probes to Measure Detonation Velocities Using the Photonic Doppler Velocimeter

    SciTech Connect

    Hare, D E; Holtkamp, D B; Strand, O T

    2010-03-02

    Detonation velocities for high explosives can be in the 7 to 8 km/s range. Previous work has shown that these velocities may be measured by inserting an optical fiber probe into the explosive assembly and recording the velocity time history using a Fabry-Perot velocimeter. The measured velocity using this method, however, is the actual velocity multiplied times the refractive index of the fiber core, which is on the order of 1.5. This means that the velocimeter diagnostic must be capable of measuring velocities as high as 12 km/s. Until recently, a velocity of 12 km/s was beyond the maximum velocity limit of a homodyne-based velocimeter. The limiting component in a homodyne system is usually the digitizer. Recently, however, digitizers have come on the market with 20 GHz bandwidth and 50 GS/s sample rate. Such a digitizer coupled with high bandwidth detectors now have the total bandwidth required to make velocity measurements in the 12 km/s range. This paper describes measurements made of detonation velocities using a high bandwidth homodyne system.

  20. Ultrafast pump-probe ellipsometry setup for the measurement of transient optical properties during laser ablation.

    PubMed

    Rapp, Stephan; Kaiser, Michael; Schmidt, Michael; Huber, Heinz P

    2016-08-01

    Ultrashort pulsed lasers offer a high potential in precise and efficient material processing and deep understanding of the fundamental laser-material interaction aspects is of great importance. The transient pulse reflectivity in conjunction with the transient absorption influences decisively the laser-material interaction. Direct measurements of the absorption properties by ultrafast time-resolved ellipsometry are missing to date. In this work, a unique pump-probe ellipsometry microscope is presented allowing the determination of the transient complex refractive index with a sub-ps temporal resolution. Measurements on molybdenum show ultrafast optical penetration depth changes of -6% to + 77% already within the first 10 ps after the laser pulse impact. This indicates a significant absorption variation of the pump pulse or subsequent pulses irradiating the sample on this timescale and paves the road towards a better understanding of pulse duration dependent laser ablation efficiency, double or burst mode laser ablation and lattice modifications in the first ps after the laser pulse impact. PMID:27505728

  1. A comparison of light spot hydrophone and fiber optic probe hydrophone for lithotripter field characterization

    NASA Astrophysics Data System (ADS)

    Smith, N.; Sankin, G. N.; Simmons, W. N.; Nanke, R.; Fehre, J.; Zhong, P.

    2012-01-01

    The performance of a newly developed light spot hydrophone (LSHD) in lithotripter field characterization was compared to that of the fiber optic probe hydrophone (FOPH). Pressure waveforms produced by a stable electromagnetic shock wave source were measured by the LSHD and FOPH under identical experimental conditions. In the low energy regime, focus and field acoustic parameters matched well between the two hydrophones. At clinically relevant high energy settings for shock wave lithotripsy, the measured leading compressive pressure waveforms matched closely with each other. However, the LSHD recorded slightly larger |P-| (p < 0.05) and secondary peak compressive pressures (p < 0.01) than the FOPH, leading to about 20% increase in total acoustic pulse energy calculated in a 6 mm radius around the focus (p = 0.06). Tensile pulse durations deviated ˜5% (p < 0.01) due to tensile wave shortening from cavitation activity using the LSHD. Intermittent compression spikes and laser light reflection artifacts have been correlated to bubble activity based on simultaneous high-speed imaging analysis. Altogether, both hydrophones are adequate for lithotripter field characterization as specified by the international standard IEC 61846.

  2. A comparison of light spot hydrophone and fiber optic probe hydrophone for lithotripter field characterization.

    PubMed

    Smith, N; Sankin, G N; Simmons, W N; Nanke, R; Fehre, J; Zhong, P

    2012-01-01

    The performance of a newly developed light spot hydrophone (LSHD) in lithotripter field characterization was compared to that of the fiber optic probe hydrophone (FOPH). Pressure waveforms produced by a stable electromagnetic shock wave source were measured by the LSHD and FOPH under identical experimental conditions. In the low energy regime, focus and field acoustic parameters matched well between the two hydrophones. At clinically relevant high energy settings for shock wave lithotripsy, the measured leading compressive pressure waveforms matched closely with each other. However, the LSHD recorded slightly larger |P_| (p < 0.05) and secondary peak compressive pressures (p < 0.01) than the FOPH, leading to about 20% increase in total acoustic pulse energy calculated in a 6 mm radius around the focus (p = 0.06). Tensile pulse durations deviated ~5% (p < 0.01) due to tensile wave shortening from cavitation activity using the LSHD. Intermittent compression spikes and laser light reflection artifacts have been correlated to bubble activity based on simultaneous high-speed imaging analysis. Altogether, both hydrophones are adequate for lithotripter field characterization as specified by the international standard IEC 61846. PMID:22299970

  3. Pixelation effect removal from fiber bundle probe based optical coherence tomography imaging

    PubMed Central

    Han, Jae-Ho; Lee, Junghoon; Kang, Jin U.

    2010-01-01

    A method of eliminating pixelization effect from en face optical coherence tomography (OCT) image when a fiber bundle is used as an OCT imaging probe is presented. We have demonstrated that applying a histogram equalization process before performing a weighted-averaged Gaussian smoothing filter to the original lower gray level intensity based image not only removes the structural artifact of the bundle but also enhances the image quality with minimum blurring of object’s image features. The measured contrast-to-noise ratio (CNR) for an image of the US Air Force test target was 14.7dB (4.9dB), after (before) image processing. In addition, by performing the spatial frequency analysis based on two-dimensional discrete Fourier transform (2-D DFT), we were able to observe that the periodic intensity peaks induced by the regularly arrayed structure of the fiber bundle can be efficiently suppressed by 41.0dB for the first nearby side lobe as well as to obtain the precise physical spacing information of the fiber grid. The proposed combined method can also be used as a straight forward image processing tool for any imaging system utilizing fiber bundle as a high-resolution imager. PMID:20389766

  4. Probing matrix and tumor mechanics with in situ calibrated optical trap based active microrheology

    NASA Astrophysics Data System (ADS)

    Staunton, Jack Rory; Vieira, Wilfred; Tanner, Kandice; Tissue Morphodynamics Unit Team

    Aberrant extracellular matrix deposition and vascularization, concomitant with proliferation and phenotypic changes undergone by cancer cells, alter mechanical properties in the tumor microenvironment during cancer progression. Tumor mechanics conversely influence progression, and the identification of physical biomarkers promise improved diagnostic and prognostic power. Optical trap based active microrheology enables measurement of forces up to 0.5 mm within a sample, allowing interrogation of in vitro biomaterials, ex vivo tissue sections, and small organisms in vivo. We fabricated collagen I hydrogels exhibiting distinct structural properties by tuning polymerization temperature Tp, and measured their shear storage and loss moduli at frequencies 1-15k Hz at multiple amplitudes. Lower Tp gels, with larger pore size but thicker, longer fibers, were stiffer than higher Tp gels; decreasing strain increased loss moduli and decreased storage moduli at low frequencies. We subcutanously injected probes with metastatic murine melanoma cells into mice. The excised tumors displayed storage and loss moduli 40 Pa and 10 Pa at 1 Hz, increasing to 500 Pa and 1 kPa at 15 kHz, respectively.

  5. Embedded optical probes for simultaneous pressure and temperature measurement of materials in extreme conditions

    NASA Astrophysics Data System (ADS)

    Sandberg, R. L.; Rodriguez, G.; Gibson, L. L.; Dattelbaum, D. M.; Stevens, G. D.; Grover, M.; Lalone, B. M.; Udd, E.

    2014-05-01

    We present recent efforts at Los Alamos National Laboratory (LANL) to develop sensors for simultaneous, in situ pressure and temperature measurements under dynamic conditions by using an all-optical fiber-based approach. While similar tests have been done previously in deflagration-to-detonation tests (DDT), where pressure and temperature were measured to 82 kbar and 400°C simultaneously, here we demonstrate the use of embedded fiber grating sensors to obtain high temporal resolution, in situ pressure measurements in inert materials. We present two experimental demonstrations of pressure measurements: (1) under precise shock loading from a gas-gun driven plate impact and (2) under high explosive driven shock in a water filled vessel. The system capitalizes on existing telecom components and fast transient digitizing recording technology. It operates as a relatively inexpensive embedded probe (single-mode 1550 nm fiber-based Bragg grating) that provides a continuous fast pressure record during shock and/or detonation. By applying well-controlled shock wave pressure profiles to these inert materials, we study the dynamic pressure response of embedded fiber Bragg gratings to extract pressure amplitude of the shock wave and compare our results with particle velocity wave profiles measured simultaneously.

  6. Embedded optical probes for simultaneous pressure and temperature measurement of materials in extreme conditions

    NASA Astrophysics Data System (ADS)

    Sandberg, Richard; Rodriguez, George; Gibson, Lee; Dattelbaum, Dana; Udd, Eric

    2013-06-01

    We present a new technique for simultaneous, in situ pressure and temperature measurements under dynamic conditions by using an all-optical fiber-based approach. While similar tests have been done previously in deflagration-to-detonation tests (DDT), where pressure and temperature were measured to 82 kbar and 400 °C simultaneously, here we demonstrate the use of embedded fiber grating sensors to obtain high temporal resolution in situ pressure measurements in inert materials under precise shock loading from a gas-gun driven plate impact. The system capitalizes on existing telecom components and fast transient digitizing recording technology. It operates as a relatively inexpensive embedded probe (single-mode 1550 nm fiber-based Bragg grating - FBG) that provides a continuous fast pressure record during shock and/or detonation. Fiber Bragg grating sensors have predictable thermal and mechanical response properties with pressure spectrally shifting the reflectance peak at λ = 1550 nm to the blue and temperature shifting the peak to the red. By applying well-controlled steady shock wave pressure profiles to soft materials such as PMMA, we study the dynamic pressure response of embedded fiber Bragg gratings to extract pressure amplitude of the shock wave and compare our results with in situ particle velocity wave profiles measured simultaneously.

  7. System of laser pump and synchrotron radiation probe microdiffraction to investigate optical recording process

    SciTech Connect

    Yasuda, Nobuhiro; Fukuyama, Yoshimitsu; Osawa, Hitoshi; Kimura, Shigeru; Ito, Kiminori; Tanaka, Yoshihito; Matsunaga, Toshiyuki; Kojima, Rie; Hisada, Kazuya; Tsuchino, Akio; Birukawa, Masahiro; Yamada, Noboru; Sekiguchi, Koji; Fujiie, Kazuhiko; Kawakubo, Osamu; Takata, Masaki

    2013-06-15

    We have developed a system of laser-pump and synchrotron radiation probe microdiffraction to investigate the phase-change process on a nanosecond time scale of Ge{sub 2}Sb{sub 2}Te{sub 5} film embedded in multi-layer structures, which corresponds to real optical recording media. The measurements were achieved by combining (i) the pump-laser system with a pulse width of 300 ps, (ii) a highly brilliant focused microbeam with wide peak-energy width ({Delta}E/E {approx} 2%) made by focusing helical undulator radiation without monochromatization, and (iii) a precise sample rotation stage to make repetitive measurements. We successfully detected a very weak time-resolved diffraction signal by using this system from 100-nm-thick Ge{sub 2}Sb{sub 2}Te{sub 5} phase-change layers. This enabled us to find the dependence of the crystal-amorphous phase change process of the Ge{sub 2}Sb{sub 2}Te{sub 5} layers on laser power.

  8. Biconically Tapered Fiber Optic Probes for Rapid Label-Free Immunoassays ǂ

    PubMed Central

    Miller, John; Castaneda, Angelica; Lee, Kun Ho; Sanchez, Martin; Ortiz, Adrian; Almaz, Ekrem; Turkoglu Almaz, Zuleyha; Murinda, Shelton; Lin, Wei-Jen; Salik, Ertan

    2015-01-01

    We report use of U-shaped biconically tapered optical fibers (BTOF) as probes for label-free immunoassays. The tapered regions of the sensors were functionalized by immobilization of immunoglobulin-G (Ig-G) and tested for detection of anti-IgG at concentrations of 50 ng/mL to 50 µg/mL. Antibody-antigen reaction creates a biological nanolayer modifying the waveguide structure leading to a change in the sensor signal, which allows real-time monitoring. The kinetics of the antibody (mouse Ig-G)-antigen (rabbit anti-mouse IgG) reactions was studied. Hydrofluoric acid treatment makes the sensitive region thinner to enhance sensitivity, which we confirmed by experiments and simulations. The limit of detection for the sensor was estimated to be less than 50 ng/mL. Utilization of the rate of the sensor peak shift within the first few minutes of the antibody-antigen reaction is proposed as a rapid protein detection method. PMID:25836359

  9. Pump-probe optical coherence tomography using microencapsulated methylene blue as a contrast agent (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kim, Wihan; Zebrowski, Erin; Lopez, Hazel C.; Applegate, Brian E.; Charoenphol, Phapanin; Jo, Javier A.

    2016-03-01

    Molecular contrast imaging can target specific molecules or receptors to provide detailed information on the local biochemistry and yield enhanced visualization of pathological and physiological processes. When paired with Optical Coherence Tomography (OCT) it can simultaneously supply the morphological context for the molecular information. We recently demonstrated in vivo molecular contrast imaging of methylene blue (MB) using a 663 nm diode laser as a pump in a Pump-Probe OCT (PPOCT) system. The simple addition of a dichroic mirror in the sample arm enabled PPOCT imaging with a typical 830-nm band spectral-domain OCT system. Here we report on the development of a microencapsulated MB contrast agent. The poly lactic-co-glycolic acid (PLGA) microspheres loaded with MB offer several advantages over bare MB. The microsphere encapsulation improves the PPOCT signal both by enhancing the scattering and preventing the reduction of MB to leucomethylene blue. The surface of the microsphere can readily be functionalized to enable active targeting of the contrast agent without modifying the excited state dynamics of MB that enable PPOCT imaging. Both MB and PLGA are used clinically. PLGA is FDA approved and used in drug delivery and tissue engineering applications. 2.5 μm diameter microspheres were synthesized with an inner core containing 0.01% (w/v) aqueous MB. As an initial demonstration the MB microspheres were imaged in a 100 μm diameter capillary tube submerged in a 1% intralipid emulsion.

  10. Non-contact sound speed measurement by optical probing of beam deflection due to sound wave.

    PubMed

    Jung, Sung Soo; Kim, Yong Tae; Pu, Yu Cheon; Kim, Min Gon; Kim, Ho Chul

    2006-01-01

    We report a non-contact and non-invasive method of sound speed measurement by optical probing of deflected laser beam due to normally incident degenerated shock wave. In this study the shock wave from an exploding wire was degenerated to an ordinary sound wave at the distance exceeding 0.23 m. Temporal resolution of the deflected beam signal was improved by passing through an adequate electronic high-pass filter, as a result we obtained a better temporal resolution than that of the acoustic pressure detection by PZT transducer in terms of rising time. The spatial resolution was improved by passing the refracted beam signal into the edge of focusing lens to make a larger deflection angle. Sound speed was calculated by monitoring the time of flight of transient deflected signal at the predetermined position. Sound speed has been measured in air, distilled water and acryl, agreed well with the published values. The sound speed measured in the solution of glycerin, magnesium sulfate (MgSO4), and dimethylformamide with various mole fractions also agrees within 3% of relative error with those measured in the present work by ultrasonic pulse echo method. The results suggest that the method proposed is to be reliable and reproducible. PMID:16122774

  11. One-step green synthetic approach for the preparation of multicolor emitting copper nanoclusters and their applications in chemical species sensing and bioimaging.

    PubMed

    Bhamore, Jigna R; Jha, Sanjay; Mungara, Anil Kumar; Singhal, Rakesh Kumar; Sonkeshariya, Dhanshri; Kailasa, Suresh Kumar

    2016-06-15

    One-step green microwave synthetic approach was developed for the synthesis of copper nanoclusters (Cu NCs) and used as a fluorescent probe for the sensitive detection of thiram and paraquat in water and food samples. Unexpectedly, the prepared Cu NCs exhibited strong orange fluorescence and showed emission peak at 600nm, respectively. Under optimized conditions, the quenching of Cu NCs emission peak at 600nm was linearly proportional to thiram and paraquat concentrations in the ranges from 0.5 to 1000µM, and from 0.2 to 1000µM, with detection limits of 70nM and 49nM, respectively. In addition, bioimaging studies against Bacillus subtilis through confocal fluorescence microscopy indicated that Cu NCs showed strong blue and green fluorescence signals, good permeability and minimum toxicity against the various bacteria species, which demonstrates their potential feasibility for chemical species sensing and bioimaging applications. PMID:26851582

  12. Long-wavelength analyte-sensitive luminescent probes and optical (bio)sensors

    PubMed Central

    Staudinger, Christoph; Borisov, Sergey M

    2016-01-01

    Long-wavelength luminescent probes and sensors become increasingly popular. They offer the advantage of lower levels of autofluorescence in most biological probes. Due to high penetration depth and low scattering of red and NIR light such probes potentially enable in vivo measurements in tissues and some of them have already reached a high level of reliability required for such applications. This review focuses on the recent progress in development and application of long-wavelength analyte-sensitive probes which can operate both reversibly and irreversibly. Photophysical properties, sensing mechanisms, advantages and limitations of individual probes are discussed. PMID:27134748

  13. Isoquinoline-based lanthanide complexes: bright NIR optical probes and efficient MRI agents.

    PubMed

    Caillé, Fabien; Bonnet, Célia S; Buron, Frédéric; Villette, Sandrine; Helm, Lothar; Petoud, Stéphane; Suzenet, Franck; Tóth, Eva

    2012-02-20

    In the objective of developing ligands that simultaneously satisfy the requirements for MRI contrast agents and near-infrared emitting optical probes that are suitable for imaging, three isoquinoline-based polyaminocarboxylate ligands, L1, L2 and L3, have been synthesized and the corresponding Gd(3+), Nd(3+) and Yb(3+) complexes investigated. The specific challenge of the present work was to create NIR emitting agents which (i) have excitation wavelengths compatible with biological applications and (ii) are able to emit a sufficient number of photons to ensure sensitive NIR detection for microscopic imaging. Here we report the first observation of a NIR signal arising from a Ln(3+) complex in aqueous solution in a microscopy setup. The lanthanide complexes have high thermodynamic stability (log K(LnL) =17.7-18.7) and good selectivity for lanthanide ions versus the endogenous cations Zn(2+), Cu(2+), and Ca(2+) thus preventing transmetalation. A variable temperature and pressure (17)O NMR study combined with nuclear magnetic relaxation dispersion measurements yielded the microscopic parameters characterizing water exchange and rotation. Bishydration of the lanthanide cation in the complexes, an important advantage to obtain high relaxivity for the Gd(3+) chelates, has been demonstrated by (17)O chemical shifts for the Gd(3+) complexes and by luminescence lifetime measurements for the Yb(3+) analogues. The water exchange on the three Gd(3+) complexes is considerably faster (k(ex)(298) = (13.9-15.4) × 10(6) s(-1)) than on commercial Gd(3+)-based contrast agents and proceeds via a dissociative mechanism, as evidenced by the large positive activation volumes for GdL1 and GdL2 (+10.3 ± 0.9 and +10.6 ± 0.9 cm(3) mol(-1), respectively). The relaxivity of GdL1 is doubled at 40 MHz and 298 K in fetal bovine serum (r(1) = 16.1 vs 8.5 mM(-1) s(-1) in HEPES buffer), due to hydrophobic interactions between the chelate and serum proteins. The isoquinoline core allows for the

  14. Multimodal optical biopsy probe to improve the safety and diagnostic yield of brain needle biopsies (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Desroches, Joannie; Pichette, Julien; Goyette, Andréanne; Tremblay, Marie-Andrée.; Jermyn, Michael; Petrecca, Kevin; Leblond, Frédéric

    2016-03-01

    Brain needle biopsy (BNB) is performed to collect tissue when precise neuropathological diagnosis is required to provide information about tumor type, grade, and growth patterns. The principal risks associated with this procedure are intracranial hemorrhage (due to clipping blood vessels during tissue extraction), incorrect tumor typing/grading due to non-representative or non-diagnostic samples (e.g. necrotic tissue), and missing the lesion. We present an innovative device using sub-diffuse optical tomography to detect blood vessels and Raman spectroscopy to detect molecular differences between tissue types, in order to reduce the risks of misdiagnosis, incorrect tumour grading, and non-diagnostic samples. The needle probe integrates optical fibers directly onto the external cannula of a commercial BNB needle, and can perform measurements for both optical techniques through the same fibers. This integrated optical spectroscopy system uses diffuse reflectance signals to perform a 360-degree reconstruction of the tissue adjacent to the biopsy needle, based on the optical contrast associated with hemoglobin light absorption, thereby localizing blood vessels. Raman spectra measurements are also performed interstitially for tissue characterization. A detailed sensitivity of the system is presented to demonstrate that it can detect absorbers with diameters <300 µm located up to ˜2 mm from the biopsy needle core, for bulk optical properties consistent with brain tissue. Results from animal experiments are presented to validate blood vessel detection and Raman spectrum measurement without disruption of the surgical workflow. We also present phantom measurements of Raman spectra with the needle probe and a comparison with a clinically validated Raman spectroscopy probe.

  15. A fiber optic probe design to measure depth- limited optical properties in-vivo with Low-coherence Enhanced Backscattering (LEBS) Spectroscopy

    PubMed Central

    Mutyal, Nikhil N.; Radosevich, Andrew; Gould, Bradley; Rogers, Jeremy D.; Gomes, Andrew; Turzhitsky, Vladimir; Backman, Vadim

    2012-01-01

    Low-coherence enhanced backscattering (LEBS) spectroscopy is an angular resolved backscattering technique that is sensitive to sub-diffusion light transport length scales in which information about scattering phase function is preserved. Our group has shown the ability to measure the spatial backscattering impulse response function along with depth-selective optical properties in tissue ex-vivo using LEBS. Here we report the design and implementation of a lens-free fiber optic LEBS probe capable of providing depth-limited measurements of the reduced scattering coefficient in-vivo. Experimental measurements combined with Monte Carlo simulation of scattering phantoms consisting of polystyrene microspheres in water are used to validate the performance of the probe. Additionally, depth-limited capabilities are demonstrated using Monte Carlo modeling and experimental measurements from a two-layered phantom. PMID:23037017

  16. In situ synthesis of luminescent carbon nanoparticles toward target bioimaging.

    PubMed

    Sharker, Shazid Md; Kim, Sung Min; Lee, Jung Eun; Jeong, Ji Hoon; In, Insik; Lee, Kang Dea; Lee, Haeshin; Park, Sung Young

    2015-03-12

    This paper describes the in situ synthesis of single fluorescence carbon nanoparticles (FCNs) for target bioimaging applications derived from biocompatible hyaluronic acid (HA) without using common conjugation processes. FCNs formed via the dehydration of hyaluronic acid, which were obtained by carbonizing HA, and partially carbonized HA fluorescence carbon nanoparticles (HA-FCNs), formed by a lower degree of carbonization, show good aqueous solubility, small particle size (<20 nm) and different fluorescence intensities with a red shift. After confirming the cytotoxicity of HA-FCNs and FCNs, we carried out in vitro and in vivo bioimaging studies where HA-FCNs themselves functioned as single particle triggers in target imaging. The converted nanocrystal carbon particles from HA provide outstanding features for in vitro and in vivo new targeted delivery and diagnostic tools. PMID:25732701

  17. All-optical pump-and-probe detection of two-time correlations in a Fermi gas

    SciTech Connect

    Dao, T.-L.; Kollath, C.; Carusotto, I.; Koehl, M.

    2010-04-15

    We propose an all-optical scheme to probe the dynamical correlations of a strongly interacting gas of ultracold atoms in an optical lattice potential. The proposed technique is based on a pump-and-probe scheme: a coherent light pulse is initially converted into an atomic coherence and later retrieved after a variable storage time. The efficiency of the proposed method to measure the two-time one-particle Green function of the gas is validated by numerical and analytical calculations of the expected signal for the two cases of a normal Fermi gas and a BCS superfluid state. Protocols to extract the superfluid gap and the full quasiparticle dispersions are discussed.

  18. In vivo Raman measurement of levofloxacin lactate in blood using a nanoparticle-coated optical fiber probe

    PubMed Central

    Liu, Shupeng; Rong, Ming; Zhang, Heng; Chen, Na; Pang, Fufei; Chen, Zhenyi; Wang, Tingyun; Yan, Jianshe

    2016-01-01

    Monitoring drug concentrations in vivo is very useful for adjusting a drug dosage during treatment and for drug research. Specifically, cutting-edge “on-line” drug research relies on knowing how drugs are metabolized or how they interact with the blood in real-time. Thus, this study explored performing in vivo Raman measurements of the model drug levofloxacin lactate in the blood using a nanoparticle-coated optical fiber probe (optical fiber nano-probe). The results show that we were able to measure real-time changes in the blood concentration of levofloxacin lactate, suggesting that this technique could be helpful for performing drug analyses and drug monitoring in a clinical setting without repeatedly withdrawing blood from patients. PMID:27231590

  19. In vivo Raman measurement of levofloxacin lactate in blood using a nanoparticle-coated optical fiber probe.

    PubMed

    Liu, Shupeng; Rong, Ming; Zhang, Heng; Chen, Na; Pang, Fufei; Chen, Zhenyi; Wang, Tingyun; Yan, Jianshe

    2016-03-01

    Monitoring drug concentrations in vivo is very useful for adjusting a drug dosage during treatment and for drug research. Specifically, cutting-edge "on-line" drug research relies on knowing how drugs are metabolized or how they interact with the blood in real-time. Thus, this study explored performing in vivo Raman measurements of the model drug levofloxacin lactate in the blood using a nanoparticle-coated optical fiber probe (optical fiber nano-probe). The results show that we were able to measure real-time changes in the blood concentration of levofloxacin lactate, suggesting that this technique could be helpful for performing drug analyses and drug monitoring in a clinical setting without repeatedly withdrawing blood from patients. PMID:27231590

  20. Transient Luminous Events: optical emissions from high altitudes to probe the Earth's upper atmosphere

    NASA Astrophysics Data System (ADS)

    Luque, A.; Gordillo-Vázquez, F. J.

    2012-04-01

    Transient Luminous Events are short but intense optical emissions from the upper terrestrial atmosphere, driven by the electric fields generated by a tropospheric electric storm. They were first observed in 1989 [1] but they had been predicted by C.T.R. Wilson already in 1925 [2]. Wilson argued that the electric field needed to initiate a discharge (the breakdown field) is proportional to the atmospheric density and therefore decreases exponentially with altitude; meanwhile the electric field created by a charged cloud is roughly dipolar and decays slower. Therefore there exists an altitude where the cloud field surpasses the breakdown field and an electric discharge is initiated. The combination of modeling and observations of TLEs allows us to quantify their influence in the global atmospheric chemistry and the global electric circuit that connects the surface of the Earth with the ionosphere. But, equally importantly, TLEs serve as natural probes to remotely investigate the atmosphere that surrounds them. In this talk we will survey some recent results on the modelling of TLEs. 1. Sprite beads provide an example of a possible use of TLEs to remotely probe the Earth's mesosphere. Sprites are filamentary discharges, some tens of kilometers wide, appearing at altitudes from about 50 to about 85 km. Sometimes, in the wake of a sprite, luminous spots (beads) persist much longer than the main emissions. These sprite beads reveal underlying inhomogeneities in the atmospheric conductivity [4] whose precise origin is still uncertain. 2. Another path to investigate the mesosphere through TLE observations is to compare observed spectra with kinetic models [5] combined with electrodynamic simulations [6]. For that purpose, we have modeled emissions from terrestrial TLEs: we calculated the expected emissions in the ultraviolet (Lyman-Birge-Hopfield band of molecular nitrogen), in the near UV and visible blue (second positive system of N2) and in the red and near infrared