Multiphoton Laser Microscopy and Fluorescence Lifetime Imaging for the Evaluation of the Skin

Directory of Open Access Journals (Sweden)

Stefania Seidenari

2012-01-01

Full Text Available Multiphoton laser microscopy is a new, non-invasive technique providing access to the skin at a cellular and subcellular level, which is based both on autofluorescence and fluorescence lifetime imaging. Whereas the former considers fluorescence intensity emitted by epidermal and dermal fluorophores and by the extra-cellular matrix, fluorescence lifetime imaging (FLIM, is generated by the fluorescence decay rate. This innovative technique can be applied to the study of living skin, cell cultures and ex vivo samples. Although still limited to the clinical research field, the development of multiphoton laser microscopy is thought to become suitable for a practical application in the next few years: in this paper, we performed an accurate review of the studies published so far, considering the possible fields of application of this imaging method and providing high quality images acquired in the Department of Dermatology of the University of Modena.

Microstructure imaging of human rectal mucosa using multiphoton microscopy

Science.gov (United States)

Liu, N. R.; Chen, G.; Chen, J. X.; Yan, J.; Zhuo, S. M.; Zheng, L. Q.; Jiang, X. S.

2011-01-01

Multiphoton microscopy (MPM) has high resolution and sensitivity. In this study, MPM was used to image microstructure of human rectal mucosa. The morphology and distribution of the main components in mucosa layer, absorptive cells and goblet cells in the epithelium, abundant intestinal glands in the lamina propria and smooth muscle fibers in the muscularis mucosa were clearly monitored. The variations of these components were tightly relevant to the pathology in gastrointestine system, especially early rectal cancer. The obtained images will be helpful for the diagnosis of early colorectal cancer.

Use of multiphoton tomography and fluorescence lifetime imaging to investigate skin pigmentation in vivo

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Dancik, Yuri; Favre, Amandine; Loy, Chong Jin; Zvyagin, Andrei V.; Roberts, Michael S.

2013-02-01

There is a growing body of literature showing the usefulness of multiphoton tomography (MPT) and fluorescence lifetime imaging for in situ characterization of skin constituents and the ensuing development of noninvasive diagnostic tools against skin diseases. Melanin and pigmentation-associated skin cancers constitute some of the major applications. We show that MPT and fluorescence lifetime imaging can be used to measure changes in cutaneous melanin concentration and that these can be related to the visible skin color. Melanin in the skin of African, Indian, Caucasian, and Asian volunteers is detected on the basis of its emission wavelength and fluorescence lifetimes in solution and in a melanocyte-keratinocyte cell culture. Fluorescence intensity is used to characterize the melanin content and distribution as a function of skin type and depth into the skin (stratum granulosum and stratum basale). The measured fluorescence intensities in given skin types agree with melanin amounts reported by others using biopsies. Our results suggest that spatial distribution of melanin in skin can be studied using MPT and fluorescence lifetime imaging, but further studies are needed to ascertain that the method can resolve melanin amount in smaller depth intervals.

New developments in multimodal clinical multiphoton tomography

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König, Karsten

2011-03-01

80 years ago, the PhD student Maria Goeppert predicted in her thesis in Goettingen, Germany, two-photon effects. It took 30 years to prove her theory, and another three decades to realize the first two-photon microscope. With the beginning of this millennium, first clinical multiphoton tomographs started operation in research institutions, hospitals, and in the cosmetic industry. The multiphoton tomograph MPTflexTM with its miniaturized flexible scan head became the Prism-Award 2010 winner in the category Life Sciences. Multiphoton tomographs with its superior submicron spatial resolution can be upgraded to 5D imaging tools by adding spectral time-correlated single photon counting units. Furthermore, multimodal hybrid tomographs provide chemical fingerprinting and fast wide-field imaging. The world's first clinical CARS studies have been performed with a hybrid multimodal multiphoton tomograph in spring 2010. In particular, nonfluorescent lipids and water as well as mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen have been imaged in patients with dermatological disorders. Further multimodal approaches include the combination of multiphoton tomographs with low-resolution imaging tools such as ultrasound, optoacoustic, OCT, and dermoscopy systems. Multiphoton tomographs are currently employed in Australia, Japan, the US, and in several European countries for early diagnosis of skin cancer (malignant melanoma), optimization of treatment strategies (wound healing, dermatitis), and cosmetic research including long-term biosafety tests of ZnO sunscreen nanoparticles and the measurement of the stimulated biosynthesis of collagen by anti-ageing products.

High-resolution multimodal clinical multiphoton tomography of skin

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König, Karsten

2011-03-01

This review focuses on multimodal multiphoton tomography based on near infrared femtosecond lasers. Clinical multiphoton tomographs for 3D high-resolution in vivo imaging have been placed into the market several years ago. The second generation of this Prism-Award winning High-Tech skin imaging tool (MPTflex) was introduced in 2010. The same year, the world's first clinical CARS studies have been performed with a hybrid multimodal multiphoton tomograph. In particular, non-fluorescent lipids and water as well as mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen has been imaged with submicron resolution in patients suffering from psoriasis. Further multimodal approaches include the combination of multiphoton tomographs with low-resolution wide-field systems such as ultrasound, optoacoustical, OCT, and dermoscopy systems. Multiphoton tomographs are currently employed in Australia, Japan, the US, and in several European countries for early diagnosis of skin cancer, optimization of treatment strategies, and cosmetic research including long-term testing of sunscreen nanoparticles as well as anti-aging products.

Clinical multiphoton FLIM tomography

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König, Karsten

2012-03-01

This paper gives an overview on current clinical high resolution multiphoton fluorescence lifetime imaging in volunteers and patients. Fluorescence lifetime imaging (FLIM) in Life Sciences was introduced in Jena/Germany in 1988/89 based on a ZEISS confocal picosecond dye laser scanning microscope equipped with a single photon counting unit. The porphyrin distribution in living cells and living tumor-bearing mice was studied with high spatial, temporal, and spectral resolution. Ten years later, time-gated cameras were employed to detect dental caries in volunteers based on one-photon excitation of autofluorescent bacteria with long fluorescence lifetimes. Nowadays, one-photon FLIM based on picosecond VIS laser diodes are used to study ocular diseases in humans. Already one decade ago, first clinical twophoton FLIM images in humans were taken with the certified clinical multiphoton femtosecond laser tomograph DermaInspectTM. Multiphoton tomographs with FLIM modules are now operating in hospitals at Brisbane, Tokyo, Berlin, Paris, London, Modena and other European cities. Multiple FLIM detectors allow spectral FLIM with a temporal resolution down to 20 ps (MCP) / 250 ps (PMT) and a spectral resolution of 10 nm. Major FLIM applications include the detection of intradermal sunscreen and tattoo nanoparticles, the detection of different melanin types, the early diagnosis of dermatitis and malignant melanoma, as well as the measurement of therapeutic effects in pateints suffering from dermatitis. So far, more than 1,000 patients and volunteers have been investigated with the clinical multiphoton FLIM tomographs DermaInspectTM and MPTflexTM.

Current developments in clinical multiphoton tomography

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König, Karsten; Weinigel, Martin; Breunig, Hans Georg; Gregory, Axel; Fischer, Peter; Kellner-Höfer, Marcel; Bückle, Rainer

2010-02-01

Two-photon microscopy has been introduced in 1990 [1]. 13 years later, CE-marked clinical multiphoton systems for 3D imaging of human skin with subcellular resolution have been launched by the JenLab company with the tomograph DermaInspectTM. In 2010, the second generation of clinical multiphoton tomographs was introduced. The novel mobile multiphoton tomograph MPTflexTM, equipped with a flexible articulated optical arm, provides an increased flexibility and accessibility especially for clinical and cosmetical examinations. The multiphoton excitation of fluorescent biomolecules like NAD(P)H, flavins, porphyrins, elastin, and melanin as well as the second harmonic generation of collagen is induced by picojoule femtosecond laser pulses from an tunable turn-key near infrared laser system. The ability for rapid highquality image acquisition, the user-friendly operation of the system, and the compact and flexible design qualifies this system to be used for melanoma detection, diagnostics of dermatological disorders, cosmetic research, and skin aging measurements as well as in situ drug monitoring and animal research. So far, more than 1,000 patients and volunteers have been investigated with the multiphoton tomographs in Europe, Asia, and Australia.

Multiphoton microscopy based cryo-imaging of inflated frozen human lung sections at -60°C in healthy and COPD lungs

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Abraham, Thomas; Kayra, Damian; Zhang, Angela; Suzuki, Masaru; McDonough, John; Elliott, W. M.; Cooper, Joel D.; Hogg, James C.

2013-02-01

Lung is a complex gas exchanger with interfacial area (where the gas exchange takes place) is about the size of a tennis court. Respiratory function is linked to the biomechanical stability of the gas exchange or alveolar regions which directly depends on the spatial distributions of the extracellular matrix fibers such fibrillar collagens and elastin fibers. It is very important to visualize and quantify these fibers at their native and inflated conditions to have correct morphometric information on differences between control and diseased states. This can be only achieved in the ex vivo states by imaging directly frozen lung specimens inflated to total lung capacity. Multiphoton microscopy, which uses ultra-short infrared laser pulses as the excitation source, produces multiphoton excitation fluorescence (MPEF) signals from endogenously fluorescent proteins (e.g. elastin) and induces specific second harmonic generation (SHG) signals from non-centrosymmetric proteins such as fibrillar collagens in fresh human lung tissues [J. Struct. Biol. (2010)171,189-196]. Here we report for the first time 3D image data obtained directly from thick frozen inflated lung specimens (~0.7- 1.0 millimeter thick) visualized at -60°C without prior fixation or staining in healthy and diseased states. Lung specimens donated for transplantation and released for research when no appropriate recipient was identified served as controls, and diseased lung specimens donated for research by patients receiving lung transplantation for very severe COPD (n=4) were prepared as previously described [N. Engl. J. Med. (2011) 201, 1567]. Lung slices evenly spaced between apex and base were examined using multiphoton microscopy while maintained at -60°C using a temperature controlled cold stage with a temperature resolution of 0.1°C. Infrared femto-second laser pulses tuned to 880nm, dry microscopic objectives, and non-de-scanned detectors/spectrophotometer located in the reflection geometry were

In vivo multiphoton imaging of human skin: assessment of topical corticosteroid-induced epidermis atrophy and depigmentation

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Ait El Madani, Hassan; Tancrède-Bohin, Emmanuelle; Bensussan, Armand; Colonna, Anne; Dupuy, Alain; Bagot, Martine; Pena, Ana-Maria

2012-02-01

Multiphoton microscopy has emerged in the past decade as a promising tool for noninvasive skin imaging. Our aim was to evaluate the potential of multiphoton microscopy to detect topical corticosteroids side effects within the epidermis and to provide new insights into their dynamics. Healthy volunteers were topically treated with clobetasol propionate on a small region of their forearms under overnight occlusion for three weeks. The treated region of each patient was investigated at D0, D7, D15, D22 (end of the treatment), and D60. Our study shows that multiphoton microscopy allows for the detection of corticoid-induced epidermis modifications: thinning of stratum corneum compactum and epidermis, decrease of keratinocytes size, and changes in their morphology from D7 to D22. We also show that multiphoton microscopy enables in vivo three-dimensional (3-D) quantitative assessment of melanin content. We observe that melanin density decreases during treatment and almost completely disappears at D22. Moreover, these alterations are reversible as they are no longer present at D60. Our study demonstrates that multiphoton microscopy is a convenient and powerful tool for noninvasive 3-D dynamical studies of skin integrity and pigmentation.

Human bladder cancer diagnosis using multiphoton microscopy

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Mukherjee, Sushmita; Wysock, James S.; Ng, Casey K.; Akhtar, Mohammed; Perner, Sven; Lee, Ming-Ming; Rubin, Mark A.; Maxfield, Frederick R.; Webb, Watt W.; Scherr, Douglas S.

2009-02-01

At the time of diagnosis, approximately 75% of bladder cancers are non-muscle invasive. Appropriate diagnosis and surgical resection at this stage improves prognosis dramatically. However, these lesions, being small and/or flat, are often missed by conventional white-light cystoscopes. Furthermore, it is difficult to assess the surgical margin for negativity using conventional cystoscopes. Resultantly, the recurrence rates in patients with early bladder cancer are very high. This is currently addressed by repeat cystoscopies and biopsies, which can last throughout the life of a patient, increasing cost and patient morbidity. Multiphoton endoscopes offer a potential solution, allowing real time, noninvasive biopsies of the human bladder, as well as an up-close assessment of the resection margin. While miniaturization of the Multiphoton microscope into an endoscopic format is currently in progress, we present results here indicating that Multiphoton imaging (using a bench-top Multiphoton microscope) can indeed identify cancers in fresh, unfixed human bladder biopsies. Multiphoton images are acquired in two channels: (1) broadband autofluorescence from cells, and (2) second harmonic generation (SHG), mostly by tissue collagen. These images are then compared with gold standard hematoxylin/eosin (H&E) stained histopathology slides from the same specimen. Based on a "training set" and a very small "blinded set" of samples, we have found excellent correlation between the Multiphoton and histopathological diagnoses. A larger blinded analysis by two independent uropathologists is currently in progress. We expect that the conclusion of this phase will provide us with diagnostic accuracy estimates, as well as the degree of inter-observer heterogeneity.

Multiphoton autofluorescence lifetime imaging of induced pluripotent stem cells

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Uchugonova, Aisada

2017-06-01

The multiphoton fluorescence lifetime imaging tomograph MPTflex with its flexible 360-deg scan head, articulated arm, and tunable femtosecond laser source was employed to study induced pluripotent stem cell (iPS) cultures. Autofluorescence (AF) lifetime imaging was performed with 250-ps temporal resolution and submicron spatial resolution using time-correlated single-photon counting. The two-photon excited AF was based on the metabolic coenzymes NAD(P)H and flavin adenine dinucleotide/flavoproteins. iPS cells generated from mouse embryonic fibroblasts (MEFs) and cocultured with growth-arrested MEFs as feeder cells have been studied. Significant differences on AF lifetime signatures were identified between iPS and feeder cells as well as between their differentiating counterparts.

Structural and dynamical aspects of skin studied by multiphoton excitation fluorescence microscopy-based methods

DEFF Research Database (Denmark)

Bloksgaard, Maria; Brewer, Jonathan R.; Bagatolli, Luis

2013-01-01

' parameters. Specifically, by applying these methods, spatially resolved maps of water dipolar relaxation (generalized polarization function using the 6-lauroyl-2-(N,N-dimethylamino)naphthale probe), activity of protons (fluorescence lifetime imaging using a proton sensitive fluorescence probe--2,7-bis-(2......-carboxyethyl)-5-(and-6)-carboxyfluorescein) and diffusion coefficients of distinct fluorescence probes (raster imaging correlation spectroscopy) can be obtained from different regions of the tissue. Comparative studies of different tissue strata, but also between equivalent regions of normal and abnormal......This mini-review reports on applications of particular multiphoton excitation microscopy-based methodologies employed in our laboratory to study skin. These approaches allow in-depth optical sectioning of the tissue, providing spatially resolved information on specific fluorescence probes...

Athermal electron distribution probed by femtosecond multiphoton photoemission from image potential states

International Nuclear Information System (INIS)

Ferrini, Gabriele; Giannetti, Claudio; Pagliara, Stefania; Banfi, Francesco; Galimberti, Gianluca; Parmigiani, Fulvio

2005-01-01

Image potential states are populated through indirect, scattering-mediated multiphoton absorption induced by femtosecond laser pulses and revealed by single-photon photoemission. The measured effective mass is significantly different from that obtained with direct, resonant population. These features reveal a strong coupling of the electrons residing in the image potential state, outside the solid, with the underlying hot electron population created by the laser pulse. The coupling is mediated by a many-body scattering interaction between the image potential state electrons and bulk electrons in highly excited states

Advanced multiphoton methods for in vitro and in vivo functional imaging of mouse retinal neurons (Conference Presentation)

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Cohen, Noam; Schejter, Adi; Farah, Nairouz; Shoham, Shy

2016-03-01

Studying the responses of retinal ganglion cell (RGC) populations has major significance in vision research. Multiphoton imaging of optogenetic probes has recently become the leading approach for visualizing neural populations and has specific advantages for imaging retinal activity during visual stimulation, because it leads to reduced direct photoreceptor excitation. However, multiphoton retinal activity imaging is not straightforward: point-by-point scanning leads to repeated neural excitation while optical access through the rodent eye in vivo has proven highly challenging. Here, we present two enabling optical designs for multiphoton imaging of responses to visual stimuli in mouse retinas expressing calcium indicators. First, we present an imaging solution based on Scanning Line Temporal Focusing (SLITE) for rapidly imaging neuronal activity in vitro. In this design, we scan a temporally focused line rather than a point, increasing the scan speed and reducing the impact of repeated excitation, while maintaining high optical sectioning. Second, we present the first in vivo demonstration of two-photon imaging of RGC activity in the mouse retina. To obtain these cellular resolution recordings we integrated an illumination path into a correction-free imaging system designed using an optical model of the mouse eye. This system can image at multiple depths using an electronically tunable lens integrated into its optical path. The new optical designs presented here overcome a number of outstanding obstacles, allowing the study of rapid calcium- and potentially even voltage-indicator signals both in vitro and in vivo, thereby bringing us a step closer toward distributed monitoring of action potentials.

Imaging photoelectron circular dichroism of chiral molecules by femtosecond multiphoton coincidence detection

Energy Technology Data Exchange (ETDEWEB)

Lehmann, C. Stefan; Ram, N. Bhargava; Janssen, Maurice H. M., E-mail: m.h.m.janssen@vu.nl [LaserLaB Amsterdam, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); Powis, Ivan [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2013-12-21

Here, we provide a detailed account of novel experiments employing electron-ion coincidence imaging to discriminate chiral molecules. The full three-dimensional angular scattering distribution of electrons is measured after photoexcitation with either left or right circular polarized light. The experiment is performed using a simplified photoelectron-photoion coincidence imaging setup employing only a single particle imaging detector. Results are reported applying this technique to enantiomers of the chiral molecule camphor after three-photon ionization by circularly polarized femtosecond laser pulses at 400 nm and 380 nm. The electron-ion coincidence imaging provides the photoelectron spectrum of mass-selected ions that are observed in the time-of-flight mass spectra. The coincident photoelectron spectra of the parent camphor ion and the various fragment ions are the same, so it can be concluded that fragmentation of camphor happens after ionization. We discuss the forward-backward asymmetry in the photoelectron angular distribution which is expressed in Legendre polynomials with moments up to order six. Furthermore, we present a method, similar to one-photon electron circular dichroism, to quantify the strength of the chiral electron asymmetry in a single parameter. The circular dichroism in the photoelectron angular distribution of camphor is measured to be 8% at 400 nm. The electron circular dichroism using femtosecond multiphoton excitation is of opposite sign and about 60% larger than the electron dichroism observed before in near-threshold one-photon ionization with synchrotron excitation. We interpret our multiphoton ionization as being resonant at the two-photon level with the 3s and 3p Rydberg states of camphor. Theoretical calculations are presented that model the photoelectron angular distribution from a prealigned camphor molecule using density functional theory and continuum multiple scattering X alpha photoelectron scattering calculations

A pragmatic guide to multiphoton microscope design

Science.gov (United States)

Young, Michael D.; Field, Jeffrey J.; Sheetz, Kraig E.; Bartels, Randy A.; Squier, Jeff

2016-01-01

Multiphoton microscopy has emerged as a ubiquitous tool for studying microscopic structure and function across a broad range of disciplines. As such, the intent of this paper is to present a comprehensive resource for the construction and performance evaluation of a multiphoton microscope that will be understandable to the broad range of scientific fields that presently exploit, or wish to begin exploiting, this powerful technology. With this in mind, we have developed a guide to aid in the design of a multiphoton microscope. We discuss source selection, optical management of dispersion, image-relay systems with scan optics, objective-lens selection, single-element light-collection theory, photon-counting detection, image rendering, and finally, an illustrated guide for building an example microscope. PMID:27182429

Video-rate resonant scanning multiphoton microscopy: An emerging technique for intravital imaging of the tumor microenvironment.

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Kirkpatrick, Nathaniel D; Chung, Euiheon; Cook, Daniel C; Han, Xiaoxing; Gruionu, Gabriel; Liao, Shan; Munn, Lance L; Padera, Timothy P; Fukumura, Dai; Jain, Rakesh K

2012-01-01

The abnormal tumor microenvironment fuels tumor progression, metastasis, immune suppression, and treatment resistance. Over last several decades, developments in and applications of intravital microscopy have provided unprecedented insights into the dynamics of the tumor microenvironment. In particular, intravital multiphoton microscopy has revealed the abnormal structure and function of tumor-associated blood and lymphatic vessels, the role of aberrant tumor matrix in drug delivery, invasion and metastasis of tumor cells, the dynamics of immune cell trafficking to and within tumors, and gene expression in tumors. However, traditional multiphoton microscopy suffers from inherently slow imaging rates-only a few frames per second, thus unable to capture more rapid events such as blood flow, lymphatic flow, and cell movement within vessels. Here, we report the development and implementation of a video-rate multiphoton microscope (VR-MPLSM) based on resonant galvanometer mirror scanning that is capable of recording at 30 frames per second and acquiring intravital multispectral images. We show that the design of the system can be readily implemented and is adaptable to various experimental models. As examples, we demonstrate the utility of the system to directly measure flow within tumors, capture metastatic cancer cells moving within the brain vasculature and cells in lymphatic vessels, and image acute responses to changes in a vascular network. VR-MPLSM thus has the potential to further advance intravital imaging and provide new insight into the biology of the tumor microenvironment.

In vivo stepwise multi-photon activation fluorescence imaging of melanin in human skin

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Lai, Zhenhua; Gu, Zetong; Abbas, Saleh; Lowe, Jared; Sierra, Heidy; Rajadhyaksha, Milind; DiMarzio, Charles

2014-03-01

The stepwise multi-photon activated fluorescence (SMPAF) of melanin is a low cost and reliable method of detecting melanin because the activation and excitation can be a continuous-wave (CW) mode near infrared (NIR) laser. Our previous work has demonstrated the melanin SMPAF images in sepia melanin, mouse hair, and mouse skin. In this study, we show the feasibility of using SMPAF to detect melanin in vivo. in vivo melanin SMPAF images of normal skin and benign nevus are demonstrated. SMPAF images add specificity for melanin detection than MPFM images and CRM images. Melanin SMPAF is a promising technology to enable early detection of melanoma for dermatologists.

Design and development of compact multiphoton microscopes

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Mehravar, SeyedSoroush

A compact multi-photon microscope (MPM) was designed and developed with the use of low-cost mode-locked fiber lasers operating at 1040nm and 1560nm. The MPM was assembled in-house and the system aberration was investigated using the optical design software: Zemax. A novel characterization methodology based on 'nonlinear knife-edge' technique was also introduced to measure the axial, lateral resolution, and the field curvature of the multi-photon microscope's image plane. The field curvature was then post-corrected using data processing in MATLAB. A customized laser scanning software based on LabVIEW was developed for data acquisition, image display and controlling peripheral electronics. Finally, different modalities of multi-photon excitation such as second- and third harmonic generation, two- and three-photon fluorescence were utilized to study a wide variety of samples from cancerous cells to 2D-layered materials.

Multiphoton tomography of the human eye

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König, Karsten; Batista, Ana; Hager, Tobias; Seitz, Berthold

2017-02-01

Multiphoton tomography (MPT) is a novel label-free clinical imaging method for non-invasive tissue imaging with high spatial (300 nm) and temporal (100 ps) resolutions. In vivo optical histology can be realized due to the nonlinear excitation of endogenous fluorophores and second-harmonic generation (SHG) of collagen. Furthermore, optical metabolic imaging (OMI) is performed by two-photon autofluorescence lifetime imaging (FLIM). So far, applications of the multiphoton tomographs DermaInspect and MPTflex were limited to dermatology. Novel applications include intraoperative brain tumor imaging as well as cornea imaging. In this work we describe two-photon imaging of ex vivo human corneas unsuitable for transplantation. Furthermore, the cross-linking (CXL) process of corneal collagen based on UVA exposure and 0.1 % riboflavin was studied. The pharmacokinetics of the photosensitizer could be detected with high spatial resolution. Interestingly, an increase in the stromal autofluorescence intensity and modifications of the autofluorescence lifetimes were observed in the human corneal samples within a few days following CXL.

Using multiphoton fluorescence lifetime imaging to characterize liver damage and fluorescein disposition in liver in vivo

Science.gov (United States)

Thorling, Camilla A.; Studier, Hauke; Crawford, Darrell; Roberts, Michael S.

2016-03-01

Liver disease is the fifth most common cause of death and unlike many other major causes of mortality, liver disease rates are increasing rather than decreasing. There is no ideal measurement of liver disease and although biopsies are the gold standard, this only allows for a spot examination and cannot follow dynamic processes of the liver. Intravital imaging has the potential to extract detailed information over a larger sampling area continuously. The aim of this project was to investigate whether multiphoton and fluorescence lifetime imaging microscopy could detect early liver damage and to assess whether it could detect changes in metabolism of fluorescein in normal and diseased livers. Four experimental groups were used in this study: 1) control; 2) ischemia reperfusion injury; 3) steatosis and 4) steatosis with ischemia reperfusion injury. Results showed that multiphoton microscopy could visualize morphological changes such as decreased fluorescence of endogenous fluorophores and the presence of lipid droplets, characteristic of steatosis. Fluorescence lifetime imaging microscopy showed increase in NADPH in steatosis with and without ischemia reperfusion injury and could detect changes in metabolism of fluorescein to fluorescein monoglurcuronide, which was impaired in steatosis with ischemia reperfusion injury. These results concluded that the combination of multiphoton microscopy and fluorescence lifetime imaging is a promising method of assessing early stage liver damage and that it can be used to study changes in drug metabolism in the liver as an indication of liver disease and has the potential to replace the traditional static liver biopsy currently used.

Improving spatial resolution in quantum imaging beyond the Rayleigh diffraction limit using multiphoton W entangled states

Energy Technology Data Exchange (ETDEWEB)

Wen Jianming, E-mail: jianming.wen@gmail.co [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Department of Physics, University of Arkansas, Fayetteville, AR 72701 (United States); Du, Shengwang [Department of Physics, Hong Kong University of Science and Technology, Clear Bay (Hong Kong); Xiao Min [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Department of Physics, University of Arkansas, Fayetteville, AR 72701 (United States); School of Modern Engineering and Applied Science, Nanjing University, Nanjing 210093 (China)

2010-08-23

Using multiphoton entangled states, we demonstrate improving spatial imaging resolution beyond the Rayleigh diffraction limit in the quantum imaging process. In particular, we examine resolution enhancement using triphoton W state and a factor of 2 is achievable as with the use of the Greenberger-Horne-Zeilinger state, compared to using a classical-light source.

Multi-photon vertical cross-sectional imaging with a dynamically-balanced thin-film PZT z-axis microactuator.

Science.gov (United States)

Choi, Jongsoo; Duan, Xiyu; Li, Haijun; Wang, Thomas D; Oldham, Kenn R

2017-10-01

Use of a thin-film piezoelectric microactuator for axial scanning during multi-photon vertical cross-sectional imaging is described. The actuator uses thin-film lead-zirconate-titanate (PZT) to generate upward displacement of a central mirror platform, micro-machined from a silicon-on-insulator (SOI) wafer to dimensions compatible with endoscopic imaging instruments. Device modeling in this paper focuses on existence of frequencies near device resonance producing vertical motion with minimal off-axis tilt even in the presence of multiple vibration modes and non-uniformity in fabrication outcomes. Operation near rear resonance permits large stroke lengths at low voltages relative to other vertical microactuators. Highly uniform vertical motion of the mirror platform is a key requirement for vertical cross-sectional imaging in the remote scan architecture being used for multi-photon instrument prototyping. The stage is installed in a benchtop testbed in combination with an electrostatic mirror that performs in-plane scanning. Vertical sectional images are acquired from 15 μm diameter beads and excised mouse colon tissue.

Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

Energy Technology Data Exchange (ETDEWEB)

Idrish Miah, M., E-mail: m.miah@griffith.edu.a [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

2011-01-17

Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

International Nuclear Information System (INIS)

Idrish Miah, M.

2011-01-01

Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

Potential of ultraviolet widefield imaging and multiphoton microscopy for analysis of dehydroergosterol in cellular membranes

DEFF Research Database (Denmark)

Wüstner, Daniel; Brewer, Jonathan R.; Bagatolli, Luis

2011-01-01

Dehydroergosterol (DHE) is an intrinsically fluorescent sterol with absorption/emission in the ultraviolet (UV) region and biophysical properties similar to those of cholesterol. We compared the potential of UV-sensitive low-light-level wide-field (UV-WF) imaging with that of multiphoton (MP) exc...

Direct trabecular meshwork imaging in porcine eyes through multiphoton gonioscopy

Science.gov (United States)

Masihzadeh, Omid; Ammar, David A.; Kahook, Malik Y.; Gibson, Emily A.; Lei, Tim C.

2013-03-01

The development of technologies to characterize the ocular aqueous outflow system (AOS) is important for the understanding of the pathophysiology of glaucoma. Multiphoton microscopy (MPM) offers the advantage of high-resolution, label-free imaging with intrinsic image contrast because the emitted signals result from the specific biomolecular content of the tissue. Previous attempts to use MPM to image the murine irido-corneal region directly through the sclera have suffered from degradation in image resolution due to scattering of the focused laser light. As a result, transscleral MPM has limited ability to observe fine structures in the AOS. In this work, the porcine irido-corneal angle was successfully imaged through the transparent cornea using a gonioscopic lens to circumvent the highly scattering scleral tissue. The resulting high-resolution images allowed the detailed structures in the trabecular meshwork (TM) to be observed. Multimodal imaging by two-photon autofluorescence and second harmonic generation allowed visualization of different features in the TM without labels and without disruption of the TM or surrounding tissues. MPM gonioscopy is a promising noninvasive imaging tool for high-resolution studies of the AOS, and research continues to explore the potential for future clinical applications in humans.

Multiphoton gonioscopy to image the trabecular meshwork of porcine eyes

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Masihzadeh, Omid; Ammar, David A.; Kahook, Malik Y.; Gibson, Emily A.; Lei, Tim C.

2013-03-01

The aqueous outflow system (AOS), including the trabecular meshwork (TM), the collector channels (CC) and the Schlemm's canal (SC), regulates intraocular pressure (IOP) through the drainage of the aqueous humor (AH). Abnormal IOP elevation leads to increased pressure stress to retinal ganglion cells, resulting in cell loss that can ultimately lead to complete loss of eyesight. Therefore, development of imaging tools to detect abnormal structural and functional changes of the AOS is important in early diagnosis and prevention of glaucoma. Multiphoton microscopy (MPM), including twophoton autofluorescence (TPAF) and second harmonic generation (SHG), is a label-free microscopic technique that allows molecular specific imaging of biological tissues like the TM. Since the TM and other AOS structures are located behind the highly scattering scleral tissue, transscleral imaging of the TM does not provide enough optical resolution. In this work, a gonioscopic lens is used to allow direct optical access of the TM through the cornea for MPM imaging. Compared to transscleral imaging, the acquired MPM images show improved resolution as individual collagen fiber bundles of the TM can be observed. MPM gonioscopy may have the potential to be developed as a future clinical imaging tool for glaucoma diagnostics.

Distinguishing human normal or cancerous esophagus tissue ex vivo using multiphoton microscopy

International Nuclear Information System (INIS)

Liu, N R; Chen, G N; Wu, S S; Chen, R

2014-01-01

Application of multiphoton microscopy (MPM) to clinical cancer research has greatly developed over the last few years. In this paper, we mainly focus on two-photon excitation fluorescence (TPEF) and second harmonic generation (SHG) for investigating esophageal cancer. We chiefly discuss the SHG/TPEF image and spectral characteristics of normal and cancerous esophagus submucosa with the combined multi-channel imaging mode and Lambda mode of a multiphoton microscope (LSM 510 META). Great differences can be detected, such as collagen content and morphology, glandular-shaped cancer cells, TPEF/SHG intensity ratio, and so on, which demonstrate that the multiphoton imaging technique has the potential ability for minimally-invasive early cancer diagnosis. (paper)

Distinguishing human normal or cancerous esophagus tissue ex vivo using multiphoton microscopy

Science.gov (United States)

Liu, N. R.; Chen, G. N.; Wu, S. S.; Chen, R.

2014-02-01

Application of multiphoton microscopy (MPM) to clinical cancer research has greatly developed over the last few years. In this paper, we mainly focus on two-photon excitation fluorescence (TPEF) and second harmonic generation (SHG) for investigating esophageal cancer. We chiefly discuss the SHG/TPEF image and spectral characteristics of normal and cancerous esophagus submucosa with the combined multi-channel imaging mode and Lambda mode of a multiphoton microscope (LSM 510 META). Great differences can be detected, such as collagen content and morphology, glandular-shaped cancer cells, TPEF/SHG intensity ratio, and so on, which demonstrate that the multiphoton imaging technique has the potential ability for minimally-invasive early cancer diagnosis.

Transverse correlations in multiphoton entanglement

International Nuclear Information System (INIS)

Wen Jianming; Rubin, Morton H.; Shih Yanhua

2007-01-01

We have analyzed the transverse correlation in multiphoton entanglement. The generalization of quantum ghost imaging is extended to the N-photon state. The Klyshko's two-photon advanced-wave picture is generalized to the N-photon case

Video-rate resonant scanning multiphoton microscopy

Science.gov (United States)

Kirkpatrick, Nathaniel D.; Chung, Euiheon; Cook, Daniel C.; Han, Xiaoxing; Gruionu, Gabriel; Liao, Shan; Munn, Lance L.; Padera, Timothy P.; Fukumura, Dai; Jain, Rakesh K.

2013-01-01

The abnormal tumor microenvironment fuels tumor progression, metastasis, immune suppression, and treatment resistance. Over last several decades, developments in and applications of intravital microscopy have provided unprecedented insights into the dynamics of the tumor microenvironment. In particular, intravital multiphoton microscopy has revealed the abnormal structure and function of tumor-associated blood and lymphatic vessels, the role of aberrant tumor matrix in drug delivery, invasion and metastasis of tumor cells, the dynamics of immune cell trafficking to and within tumors, and gene expression in tumors. However, traditional multiphoton microscopy suffers from inherently slow imaging rates—only a few frames per second, thus unable to capture more rapid events such as blood flow, lymphatic flow, and cell movement within vessels. Here, we report the development and implementation of a video-rate multiphoton microscope (VR-MPLSM) based on resonant galvanometer mirror scanning that is capable of recording at 30 frames per second and acquiring intravital multispectral images. We show that the design of the system can be readily implemented and is adaptable to various experimental models. As examples, we demonstrate the utility of the system to directly measure flow within tumors, capture metastatic cancer cells moving within the brain vasculature and cells in lymphatic vessels, and image acute responses to changes in a vascular network. VR-MPLSM thus has the potential to further advance intravital imaging and provide new insight into the biology of the tumor microenvironment. PMID:24353926

Multiphoton processes

International Nuclear Information System (INIS)

Manus, C.; Mainfray, G.

1980-01-01

The main features of multiphoton processes are described on a somewhat elementary basis. The emphasis is put on multiphoton ionization of atoms where the influence of resonance effects is given through typical examples. The important role played by the coherence of light is shown to produce a very dramatic influence on multiphoton absorption. Different observations concerning molecules, electrons, as well as solid surfaces illustrate the generality of these very non linear interaction between light and matter

Characterizing lamina propria of human gastric mucosa by multiphoton microscopy

Energy Technology Data Exchange (ETDEWEB)

Liu, Y C; Yang, H Q; Zhuo, S M [Institute of Laser and Optoelectronics Technology, Fujian Provincial Key Laboratory for Photonics Technology, Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou 350007 (China); Chen, G; Chen, J X [Department of Pathology, Fujian Provincial Tumor Hospital, Fuzhou, 350014 (China); Yan, J, E-mail: chenjianxin@fjnu.edu.cn, E-mail: ynjun@yahoo.com [Department of Surgery, Fujian Provincial Tumor Hospital, Fuzhou, 350014 (China)

2011-01-01

Lamina propria (LP) of gastric mucosa plays an important role in progression of gastric cancer because of the site at where inflammatory reactions occur. Multiphoton imaging has been recently employed for microscopic examination of intact tissue. In this paper, using multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG), high resolution multiphoton microscopic images of lamina propria (LP) are obtained in normal human gastric mucosa at excitation wavelength {lambda}{sub ex} = 800 nm. The main source of tissue TPEF originated from the cells of gastric glands, and loose connective tissue, collagen, produced SHG signals. Our results demonstrated that MPM can be effective for characterizing the microstructure of LP in human gastric mucosa. The findings will be helpful for diagnosing and staging early gastric cancer in the clinics.

Characterizing lamina propria of human gastric mucosa by multiphoton microscopy

Science.gov (United States)

Liu, Y. C.; Yang, H. Q.; Chen, G.; Zhuo, S. M.; Chen, J. X.; Yan, J.

2011-01-01

Lamina propria (LP) of gastric mucosa plays an important role in progression of gastric cancer because of the site at where inflammatory reactions occur. Multiphoton imaging has been recently employed for microscopic examination of intact tissue. In this paper, using multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG), high resolution multiphoton microscopic images of lamina propria (LP) are obtained in normal human gastric mucosa at excitation wavelength λex = 800 nm. The main source of tissue TPEF originated from the cells of gastric glands, and loose connective tissue, collagen, produced SHG signals. Our results demonstrated that MPM can be effective for characterizing the microstructure of LP in human gastric mucosa. The findings will be helpful for diagnosing and staging early gastric cancer in the clinics.

In vivo multiphoton and fluorescence lifetime imaging microscopy of the healthy and cholestatic liver

Science.gov (United States)

Kuznetsova, Daria S.; Dudenkova, Varvara V.; Rodimova, Svetlana A.; Bobrov, Nikolai V.; Zagainov, Vladimir E.; Zagaynova, Elena V.

2018-02-01

A cholestatic liver disease presents one of the most common liver diseases and can potentially progress to cirrhosis or even cholangiocarcinoma. Conventional techniques are insufficient to precisely describe the complex internal structure, heterogeneous cell populations and the dynamics of biological processes of the liver. Currently, the methods of multiphoton and fluorescence lifetime imaging microscopy are actively introducing to biomedical research. Those methods are extremely informative and non-destructive that allows studying of a large number of processes occurring inside cells and tissues, analyzing molecular cellular composition, as well as evaluating the state of connective tissue fibers due to their ability to generate a second optical harmonic. Multiphoton and FLIM microscopy do not need additional staining of samples or the incorporation of any markers to study metabolism, lipid composition, microstructure analysis, evaluation of fibrous structures. These parameters have pronounced changes in hepatocytes of liver with common pathological diseases. Thereby in this study we investigated metabolic changes in the healthy and cholestatic liver based on the fluorescence of the metabolic co-factors NAD(P)H and FAD by multiphoton microscopy combined with FLIM. To estimate the contribution of energy metabolism and lipogenesis in the observed changes of the metabolic profile, a separate analysis of NADH and NADPH was presented. The data can be used to develop new criteria for the identification of hepatic pathology at the level of hepatocyte changes directed to personalized medicine in the future.

Imaging the morphological change of tissue structure during the early phase of esophageal tumor progression using multiphoton microscopy

Science.gov (United States)

Xu, Jian; Kang, Deyong; Xu, Meifang; Zhu, Xiaoqin; Zhuo, Shuangmu; Chen, Jianxin

2012-12-01

Esophageal cancer is a common malignancy with a very poor prognosis. Successful strategies for primary prevention and early detection are critically needed to control this disease. Multiphoton microscopy (MPM) is becoming a novel optical tool of choice for imaging tissue architecture and cellular morphology by two-photon excited fluorescence. In this study, we used MPM to image microstructure of human normal esophagus, carcinoma in situ (CIS), and early invasive carcinoma in order to establish the morphological features to differentiate these tissues. The diagnostic features such as the appearance of cancerous cells, the significant loss of stroma, the absence of the basement membrane were extracted to distinguish between normal and cancerous esophagus tissue. These results correlated well with the paired histological findings. With the advancement of clinically miniaturized MPM and the multi-photon probe, combining MPM with standard endoscopy will therefore allow us to make a real-time in vivo diagnosis of early esophageal cancer at the cellular level.

Differentiating the two main histologic categories of fibroadenoma tissue from normal breast tissue by using multiphoton microscopy.

Science.gov (United States)

Nie, Y T; Wu, Y; Fu, F M; Lian, Y E; Zhuo, S M; Wang, C; Chen, J X

2015-04-01

Multiphoton microscopy has become a novel biological imaging technique that allows cellular and subcellular microstructure imaging based on two-photon excited fluorescence and second harmonic generation. In this work, we used multiphoton microscopy to obtain the high-contrast images of human normal breast tissue and two main histologic types of fibroadenoma (intracanalicular, pericanalicular). Moreover, quantitative image analysis was performed to characterize the changes of collagen morphology (collagen content, collagen orientation). The results show that multiphoton microscopy combined with quantitative method has the ability to identify the characteristics of fibroadenoma including changes of the duct architecture and collagen morphology in stroma. With the advancement of multiphoton microscopy, we believe that the technique has great potential to be a real-time histopathological diagnostic tool for intraoperative detection of fibroadenoma in the future. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Rapid in vivo vertical tissue sectioning by multiphoton tomography

Science.gov (United States)

Batista, Ana; Breunig, Hans Georg; König, Karsten

2018-02-01

A conventional tool in the pathological field is histology which involves the analysis of thin sections of tissue in which specific cellular structures are stained with different dyes. The process to obtain these stained tissue sections is time consuming and invasive as it requires tissue removal, fixation, sectioning, and staining. Moreover, imaging of live tissue is not possible. We demonstrate that multiphoton tomography can provide within seconds, non-invasive, label-free, vertical images of live tissue which are in quality similar to conventional light micrographs of histologic stained specimen. In contrast to conventional setups based on laser scanning which image horizontally sections, the vertical in vivo images are directly recorded by combined line scanning and timed adjustments of the height of the focusing optics. In addition, multiphoton tomography provides autofluorescence lifetimes which can be used to determine the metabolic states of cells.

Multiphoton microscopy for the in-situ investigation of cellular processes and integrity in cryopreservation.

Science.gov (United States)

Doerr, Daniel; Stark, Martin; Ehrhart, Friederike; Zimmermann, Heiko; Stracke, Frank

2009-08-01

In this study we demonstrate a new noninvasive imaging method to monitor freezing processes in biological samples and to investigate life in the frozen state. It combines a laser scanning microscope with a computer-controlled cryostage. Nearinfrared (NIR) femtosecond laser pulses evoke the fluorescence of endogenous fluorophores and fluorescent labels due to multiphoton absorption.The inherent optical nonlinearity of multiphoton absorption allows 3D fluorescence imaging for optical tomography of frozen biological material in-situ. As an example for functional imaging we use fluorescence lifetime imaging (FLIM) to create images with chemical and physical contrast.

Knowledge Extraction from Atomically Resolved Images.

Science.gov (United States)

Vlcek, Lukas; Maksov, Artem; Pan, Minghu; Vasudevan, Rama K; Kalinin, Sergei V

2017-10-24

Tremendous strides in experimental capabilities of scanning transmission electron microscopy and scanning tunneling microscopy (STM) over the past 30 years made atomically resolved imaging routine. However, consistent integration and use of atomically resolved data with generative models is unavailable, so information on local thermodynamics and other microscopic driving forces encoded in the observed atomic configurations remains hidden. Here, we present a framework based on statistical distance minimization to consistently utilize the information available from atomic configurations obtained from an atomically resolved image and extract meaningful physical interaction parameters. We illustrate the applicability of the framework on an STM image of a FeSe x Te 1-x superconductor, with the segregation of the chalcogen atoms investigated using a nonideal interacting solid solution model. This universal method makes full use of the microscopic degrees of freedom sampled in an atomically resolved image and can be extended via Bayesian inference toward unbiased model selection with uncertainty quantification.

Multiphoton processes: conference proceedings

International Nuclear Information System (INIS)

Lambropoulos, P.; Smith, S.J.

1984-01-01

The chapters of this volume represent the invited papers delivered at the conference. They are arranged according to thermatic proximity beginning with atoms and continuing with molecules and surfaces. Section headings include multiphoton processes in atoms, field fluctuations and collisions in multiphoton process, and multiphoton processes in molecules and surfaces. Abstracts of individual items from the conference were prepared separately for the data base

Multiphoton processes: conference proceedings

Energy Technology Data Exchange (ETDEWEB)

Lambropoulos, P.; Smith, S.J. (eds.)

1984-01-01

The chapters of this volume represent the invited papers delivered at the conference. They are arranged according to thermatic proximity beginning with atoms and continuing with molecules and surfaces. Section headings include multiphoton processes in atoms, field fluctuations and collisions in multiphoton process, and multiphoton processes in molecules and surfaces. Abstracts of individual items from the conference were prepared separately for the data base. (GHT)

Dynamic multiphoton imaging of acellular dermal matrix scaffolds seeded with mesenchymal stem cells in diabetic wound healing.

Science.gov (United States)

Chu, Jing; Shi, Panpan; Deng, Xiaoyuan; Jin, Ying; Liu, Hao; Chen, Maosheng; Han, Xue; Liu, Hanping

2018-03-25

Significantly effective therapies need to be developed for chronic nonhealing diabetic wounds. In this work, the topical transplantation of mesenchymal stem cell (MSC) seeded on an acellular dermal matrix (ADM) scaffold is proposed as a novel therapeutic strategy for diabetic cutaneous wound healing. GFP-labeled MSCs were cocultured with an ADM scaffold that was decellularized from normal mouse skin. These cultures were subsequently transplanted as a whole into the full-thickness cutaneous wound site in streptozotocin-induced diabetic mice. Wounds treated with MSC-ADM demonstrated an increased percentage of wound closure. The treatment of MSC-ADM also greatly increased angiogenesis and rapidly completed the reepithelialization of newly formed skin on diabetic mice. More importantly, multiphoton microscopy was used for the intravital and dynamic monitoring of collagen type I (Col-I) fibers synthesis via second harmonic generation imaging. The synthesis of Col-I fibers during diabetic wound healing is of great significance for revealing wound repair mechanisms. In addition, the activity of GFP-labeled MSCs during wound healing was simultaneously traced via two-photon excitation fluorescence imaging. Our research offers a novel advanced nonlinear optical imaging method for monitoring the diabetic wound healing process while the ADM and MSCs interact in situ. Schematic of dynamic imaging of ADM scaffolds seeded with mesenchymal stem cells in diabetic wound healing using multiphoton microscopy. PMT, photo-multiplier tube. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

From morphology to biochemical state - intravital multiphoton fluorescence lifetime imaging of inflamed human skin

Science.gov (United States)

Huck, Volker; Gorzelanny, Christian; Thomas, Kai; Getova, Valentina; Niemeyer, Verena; Zens, Katharina; Unnerstall, Tim R.; Feger, Julia S.; Fallah, Mohammad A.; Metze, Dieter; Ständer, Sonja; Luger, Thomas A.; Koenig, Karsten; Mess, Christian; Schneider, Stefan W.

2016-03-01

The application of multiphoton microscopy in the field of biomedical research and advanced diagnostics promises unique insights into the pathophysiology of inflammatory skin diseases. In the present study, we combined multiphoton-based intravital tomography (MPT) and fluorescence lifetime imaging (MPT-FLIM) within the scope of a clinical trial of atopic dermatitis with the aim of providing personalised data on the aetiopathology of inflammation in a non-invasive manner at patients’ bedsides. These ‘optical biopsies’ generated via MPT were morphologically analysed and aligned with classical skin histology. Because of its subcellular resolution, MPT provided evidence of a redistribution of mitochondria in keratinocytes, indicating an altered cellular metabolism. Two independent morphometric algorithms reliably showed an even distribution in healthy skin and a perinuclear accumulation in inflamed skin. Moreover, using MPT-FLIM, detection of the onset and progression of inflammatory processes could be achieved. In conclusion, the change in the distribution of mitochondria upon inflammation and the verification of an altered cellular metabolism facilitate a better understanding of inflammatory skin diseases and may permit early diagnosis and therapy.

A multiphoton laser scanning microscope setup for transcranial in vivo brain imaging on mice

Science.gov (United States)

Nase, Gabriele; Helm, P. Johannes; Reppen, Trond; Ottersen, Ole Petter

2005-12-01

We describe a multiphoton laser scanning microscope setup for transcranial in vivo brain imaging in mice. The modular system is based on a modified industrial standard Confocal Scanning Laser Microscope (CSLM) and is assembled mainly from commercially available components. A special multifunctional stage, which is optimized for both laser scanning microscopic observation and preparative animal surgery, has been developed and built. The detection unit includes a highly efficient photomultiplier tube installed in a Peltier-cooled thermal box shielding the detector from changes in room temperature and from distortions caused by external electromagnetic fields. The images are recorded using a 12-bit analog-to-digital converter. Depending on the characteristics of the staining, individual nerve cells can be imaged down to at least 100μm below the intact cranium and down to at least 200μm below the opened cranium.

MULTI-PHOTON PHOSPHOR FEASIBILITY RESEARCH

Energy Technology Data Exchange (ETDEWEB)

R. Graham; W. Chow

2003-05-01

Development of multi-photon phosphor materials for discharge lamps represents a goal that would achieve up to a doubling of discharge (fluorescent) lamp efficacy. This report reviews the existing literature on multi-photon phosphors, identifies obstacles in developing such phosphors, and recommends directions for future research to address these obstacles. To critically examine issues involved in developing a multi-photon phosphor, the project brought together a team of experts from universities, national laboratories, and an industrial lamp manufacturer. Results and findings are organized into three categories: (1) Multi-Photon Systems and Processes, (2) Chemistry and Materials Issues, and (3) Concepts and Models. Multi-Photon Systems and Processes: This category focuses on how to use our current understanding of multi-photon phosphor systems to design new phosphor systems for application in fluorescent lamps. The quickest way to develop multi-photon lamp phosphors lies in finding sensitizer ions for Gd{sup 3+} and identifying activator ions to red shift the blue emission from Pr{sup 3+} due to the {sup 1}S{sub 0} {yields} {sup 1}I{sub 6} transition associated with the first cascading step. Success in either of these developments would lead to more efficient fluorescent lamps. Chemistry and Materials Issues: The most promising multi-photon phosphors are found in fluoride hosts. However, stability of fluorides in environments typically found in fluorescent lamps needs to be greatly improved. Experimental investigation of fluorides in actual lamp environments needs to be undertaken while working on oxide and oxyfluoride alternative systems for backup. Concepts and Models: Successful design of a multi-photon phosphor system based on cascading transitions of Gd{sup 3+} and Pr{sup 3+} depends critically on how the former can be sensitized and the latter can sensitize an activator ion. Methods to predict energy level diagrams and Judd-Ofelt parameters of multi-photon

Application of multiphoton microscopy in dermatological studies: A mini-review

Directory of Open Access Journals (Sweden)

Elijah Yew

2014-09-01

Full Text Available This review summarizes the historical and more recent developments of multiphoton microscopy, as applied to dermatology. Multiphoton microscopy offers several advantages over competing microscopy techniques: there is an inherent axial sectioning, penetration depths that compete well with confocal microscopy on account of the use of near-infrared light, and many two-photon contrast mechanisms, such as second-harmonic generation, have no analogue in one-photon microscopy. While the penetration depths of photons into tissue are typically limited on the order of hundreds of microns, this is of less concern in dermatology, as the skin is thin and readily accessible. As a result, multiphoton microscopy in dermatology has generated a great deal of interest, much of which is summarized here. The review covers the interaction of light and tissue, as well as the various considerations that must be made when designing an instrument. The state of multiphoton microscopy in imaging skin cancer and various other diseases is also discussed, along with the investigation of aging and regeneration phenomena, and finally, the use of multiphoton microscopy to analyze the transdermal transport of drugs, cosmetics and other agents is summarized. The review concludes with a look at potential future research directions, especially those that are necessary to push these techniques into widespread clinical acceptance.

A review of biomedical multiphoton microscopy and its laser sources

International Nuclear Information System (INIS)

Lefort, Claire

2017-01-01

Multiphoton microscopy (MPM) has been the subject of major development efforts for about 25 years for imaging biological specimens at micron scale and presented as an elegant alternative to classical fluorescence methods such as confocal microscopy. In this topical review, the main interests and technical requirements of MPM are addressed with a focus on the crucial role of excitation source for optimization of multiphoton processes. Then, an overview of the different sources successfully demonstrated in literature for MPM is presented, and their physical parameters are inventoried. A classification of these sources in function with their ability to optimize multiphoton processes is proposed, following a protocol found in literature. Starting from these considerations, a suggestion of a possible identikit of the ideal laser source for MPM concludes this topical review. (topical review)

A review of biomedical multiphoton microscopy and its laser sources

Science.gov (United States)

Lefort, Claire

2017-10-01

Multiphoton microscopy (MPM) has been the subject of major development efforts for about 25 years for imaging biological specimens at micron scale and presented as an elegant alternative to classical fluorescence methods such as confocal microscopy. In this topical review, the main interests and technical requirements of MPM are addressed with a focus on the crucial role of excitation source for optimization of multiphoton processes. Then, an overview of the different sources successfully demonstrated in literature for MPM is presented, and their physical parameters are inventoried. A classification of these sources in function with their ability to optimize multiphoton processes is proposed, following a protocol found in literature. Starting from these considerations, a suggestion of a possible identikit of the ideal laser source for MPM concludes this topical review. Dedicated to Martin.

PScan 1.0: flexible software framework for polygon based multiphoton microscopy

Science.gov (United States)

Li, Yongxiao; Lee, Woei Ming

2016-12-01

Multiphoton laser scanning microscopes exhibit highly localized nonlinear optical excitation and are powerful instruments for in-vivo deep tissue imaging. Customized multiphoton microscopy has a significantly superior performance for in-vivo imaging because of precise control over the scanning and detection system. To date, there have been several flexible software platforms catered to custom built microscopy systems i.e. ScanImage, HelioScan, MicroManager, that perform at imaging speeds of 30-100fps. In this paper, we describe a flexible software framework for high speed imaging systems capable of operating from 5 fps to 1600 fps. The software is based on the MATLAB image processing toolbox. It has the capability to communicate directly with a high performing imaging card (Matrox Solios eA/XA), thus retaining high speed acquisition. The program is also designed to communicate with LabVIEW and Fiji for instrument control and image processing. Pscan 1.0 can handle high imaging rates and contains sufficient flexibility for users to adapt to their high speed imaging systems.

Multifocal multiphoton microscopy with adaptive optical correction

Science.gov (United States)

Coelho, Simao; Poland, Simon; Krstajic, Nikola; Li, David; Monypenny, James; Walker, Richard; Tyndall, David; Ng, Tony; Henderson, Robert; Ameer-Beg, Simon

2013-02-01

Fluorescence lifetime imaging microscopy (FLIM) is a well established approach for measuring dynamic signalling events inside living cells, including detection of protein-protein interactions. The improvement in optical penetration of infrared light compared with linear excitation due to Rayleigh scattering and low absorption have provided imaging depths of up to 1mm in brain tissue but significant image degradation occurs as samples distort (aberrate) the infrared excitation beam. Multiphoton time-correlated single photon counting (TCSPC) FLIM is a method for obtaining functional, high resolution images of biological structures. In order to achieve good statistical accuracy TCSPC typically requires long acquisition times. We report the development of a multifocal multiphoton microscope (MMM), titled MegaFLI. Beam parallelization performed via a 3D Gerchberg-Saxton (GS) algorithm using a Spatial Light Modulator (SLM), increases TCSPC count rate proportional to the number of beamlets produced. A weighted 3D GS algorithm is employed to improve homogeneity. An added benefit is the implementation of flexible and adaptive optical correction. Adaptive optics performed by means of Zernike polynomials are used to correct for system induced aberrations. Here we present results with significant improvement in throughput obtained using a novel complementary metal-oxide-semiconductor (CMOS) 1024 pixel single-photon avalanche diode (SPAD) array, opening the way to truly high-throughput FLIM.

Adaptive optics improves multiphoton super-resolution imaging

Science.gov (United States)

Zheng, Wei; Wu, Yicong; Winter, Peter; Shroff, Hari

2018-02-01

Three dimensional (3D) fluorescence microscopy has been essential for biological studies. It allows interrogation of structure and function at spatial scales spanning the macromolecular, cellular, and tissue levels. Critical factors to consider in 3D microscopy include spatial resolution, signal-to-noise (SNR), signal-to-background (SBR), and temporal resolution. Maintaining high quality imaging becomes progressively more difficult at increasing depth (where optical aberrations, induced by inhomogeneities of refractive index in the sample, degrade resolution and SNR), and in thick or densely labeled samples (where out-of-focus background can swamp the valuable, in-focus-signal from each plane). In this report, we introduce our new instrumentation to address these problems. A multiphoton structured illumination microscope was simply modified to integrate an adpative optics system for optical aberrations correction. Firstly, the optical aberrations are determined using direct wavefront sensing with a nonlinear guide star and subsequently corrected using a deformable mirror, restoring super-resolution information. We demonstrate the flexibility of our adaptive optics approach on a variety of semi-transparent samples, including bead phantoms, cultured cells in collagen gels and biological tissues. The performance of our super-resolution microscope is improved in all of these samples, as peak intensity is increased (up to 40-fold) and resolution recovered (up to 176+/-10 nm laterally and 729+/-39 nm axially) at depths up to 250 μm from the coverslip surface.

Pancreatic cancer cell detection by targeted lipid microbubbles and multiphoton imaging

Science.gov (United States)

Cromey, Benjamin; McDaniel, Ashley; Matsunaga, Terry; Vagner, Josef; Kieu, Khanh Quoc; Banerjee, Bhaskar

2018-04-01

Surgical resection of pancreatic cancer represents the only chance of cure and long-term survival in this common disease. Unfortunately, determination of a cancer-free margin at surgery is based on one or two tiny frozen section biopsies, which is far from ideal. Not surprisingly, cancer is usually left behind and is responsible for metastatic disease. We demonstrate a method of receptor-targeted imaging using peptide ligands, lipid microbubbles, and multiphoton microscopy that could lead to a fast and accurate way of examining the entire cut surface during surgery. Using a plectin-targeted microbubble, we performed a blinded in-vitro study to demonstrate avid binding of targeted microbubbles to pancreatic cancer cells but not noncancerous cell lines. Further work should lead to a much-needed point-of-care diagnostic test for determining clean margins in oncologic surgery.

High-resolution multiphoton microscopy with a low-power continuous wave laser pump.

Science.gov (United States)

Chen, Xiang-Dong; Li, Shen; Du, Bo; Dong, Yang; Wang, Ze-Hao; Guo, Guang-Can; Sun, Fang-Wen

2018-02-15

Multiphoton microscopy (MPM) has been widely used for three-dimensional biological imaging. Here, based on the photon-induced charge state conversion process, we demonstrated a low-power high-resolution MPM with a nitrogen vacancy (NV) center in diamond. Continuous wave green and orange lasers were used to pump and detect the two-photon charge state conversion, respectively. The power of the laser for multiphoton excitation was 40 μW. Both the axial and lateral resolutions were improved approximately 1.5 times compared with confocal microscopy. The results can be used to improve the resolution of the NV center-based quantum sensing and biological imaging.

Multiphoton spectroscopy of human skin in vivo

Science.gov (United States)

Breunig, Hans G.; Weinigel, Martin; König, Karsten

2012-03-01

In vivo multiphoton-intensity images and emission spectra of human skin are reported. Optical sections from different depths of the epidermis and dermis have been measured with near-infrared laser-pulse excitation. While the intensity images reveal information on the morphology, the spectra show emission characteristics of main endogenous skin fluorophores like keratin, NAD(P)H, melanin, elastin and collagen as well as of second harmonic generation induced by the excitation-light interaction with the dermal collagen network.

From morphology to clinical pathophysiology: multiphoton fluorescence lifetime imaging at patients' bedside

Science.gov (United States)

Mess, Christian; Zens, Katharina; Gorzelanny, Christian; Metze, Dieter; Luger, Thomas A.; König, Karsten; Schneider, Stefan W.; Huck, Volker

2017-02-01

Application of multiphoton microscopy in the field of biomedical research and advanced diagnostics promises unique insights into the pathophysiology of skin diseases. By means of multiphoton excitation, endogenous biomolecules like NADH, collagen or elastin show autofluorescence or second harmonic generation. Thus, these molecules provide information about the subcellular morphology, epidermal architecture and physiological condition of the skin. To gain a deeper understanding of the linkage between cellular structure and physiological processes, non-invasive multiphotonbased intravital tomography (MPT) and fluorescence lifetime imaging (FLIM) were combined within the scopes of inflammatory skin, chronic wounds and drug delivery in clinical application. The optical biopsies generated via MPT were morphologically analyzed and aligned with classical skin histology. Because of its subcellular resolution, MPT provided evidence of a redistribution of mitochondria in keratinocytes, indicating an altered cellular metabolism. Independent morphometric algorithms reliably showed a perinuclear accumulation in lesional skin in contrast to an even distribution in healthy skin. Confirmatively, MPT-FLIM showed an obvious metabolic shift in lesions. Moreover, detection of the onset and progression of inflammatory processes could be achieved. The feasibility of primary in vivo tracking of applied therapeutic agents further broadened our scope: We examined the permeation and subsequent distribution of agents directly visualized in patientś skin in short-term repetitive measurements. Furthermore, we performed MPT-FLIM follow-up investigations in the long-term course of therapy. Therefore, clinical MPT-FLIM application offers new insights into the pathophysiology and the individual therapeutic course of skin diseases, facilitating a better understanding of the processes of inflammation and wound healing.

Multiphoton quantum optics and quantum state engineering

International Nuclear Information System (INIS)

Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

2006-01-01

We present a review of theoretical and experimental aspects of multiphoton quantum optics. Multiphoton processes occur and are important for many aspects of matter-radiation interactions that include the efficient ionization of atoms and molecules, and, more generally, atomic transition mechanisms; system-environment couplings and dissipative quantum dynamics; laser physics, optical parametric processes, and interferometry. A single review cannot account for all aspects of such an enormously vast subject. Here we choose to concentrate our attention on parametric processes in nonlinear media, with special emphasis on the engineering of nonclassical states of photons and atoms that are relevant for the conceptual investigations as well as for the practical applications of forefront aspects of modern quantum mechanics. We present a detailed analysis of the methods and techniques for the production of genuinely quantum multiphoton processes in nonlinear media, and the corresponding models of multiphoton effective interactions. We review existing proposals for the classification, engineering, and manipulation of nonclassical states, including Fock states, macroscopic superposition states, and multiphoton generalized coherent states. We introduce and discuss the structure of canonical multiphoton quantum optics and the associated one- and two-mode canonical multiphoton squeezed states. This framework provides a consistent multiphoton generalization of two-photon quantum optics and a consistent Hamiltonian description of multiphoton processes associated to higher-order nonlinearities. Finally, we discuss very recent advances that by combining linear and nonlinear optical devices allow to realize multiphoton entangled states of the electromagnetic field, either in discrete or in continuous variables, that are relevant for applications to efficient quantum computation, quantum teleportation, and related problems in quantum communication and information

Multiphoton quantum optics and quantum state engineering

Energy Technology Data Exchange (ETDEWEB)

Dell' Anno, Fabio [Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, CNISM and CNR-INFM Coherentia, and INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, I-84081 Baronissi (Saudi Arabia) (Italy)]. E-mail: dellanno@sa.infn.it; De Siena, Silvio [Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, CNISM and CNR-INFM Coherentia, and INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, I-84081 Baronissi (SA) (Italy)]. E-mail: desiena@sa.infn.it; Illuminati, Fabrizio [Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, CNISM and CNR-INFM Coherentia, and INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, I-84081 Baronissi (SA) (Italy)]. E-mail: illuminati@sa.infn.it

2006-05-15

We present a review of theoretical and experimental aspects of multiphoton quantum optics. Multiphoton processes occur and are important for many aspects of matter-radiation interactions that include the efficient ionization of atoms and molecules, and, more generally, atomic transition mechanisms; system-environment couplings and dissipative quantum dynamics; laser physics, optical parametric processes, and interferometry. A single review cannot account for all aspects of such an enormously vast subject. Here we choose to concentrate our attention on parametric processes in nonlinear media, with special emphasis on the engineering of nonclassical states of photons and atoms that are relevant for the conceptual investigations as well as for the practical applications of forefront aspects of modern quantum mechanics. We present a detailed analysis of the methods and techniques for the production of genuinely quantum multiphoton processes in nonlinear media, and the corresponding models of multiphoton effective interactions. We review existing proposals for the classification, engineering, and manipulation of nonclassical states, including Fock states, macroscopic superposition states, and multiphoton generalized coherent states. We introduce and discuss the structure of canonical multiphoton quantum optics and the associated one- and two-mode canonical multiphoton squeezed states. This framework provides a consistent multiphoton generalization of two-photon quantum optics and a consistent Hamiltonian description of multiphoton processes associated to higher-order nonlinearities. Finally, we discuss very recent advances that by combining linear and nonlinear optical devices allow to realize multiphoton entangled states of the electromagnetic field, either in discrete or in continuous variables, that are relevant for applications to efficient quantum computation, quantum teleportation, and related problems in quantum communication and information.

Clinical optical coherence tomography combined with multiphoton tomography for evaluation of several skin disorders

Science.gov (United States)

König, Karsten; Speicher, Marco; Bückle, Rainer; Reckfort, Julia; McKenzie, Gordon; Welzel, Julia; Koehler, Martin J.; Elsner, Peter; Kaatz, Martin

2010-02-01

The first clinical trial of optical coherence tomography (OCT) combined with multiphoton tomography (MPT) and dermoscopy is reported. State-of-the-art (i) OCT systems for dermatology (e.g. multibeam swept source OCT), (ii) the femtosecond laser multiphoton tomograph DermaInspectTM, and (iii) digital dermoscopes were applied to 47 patients with a diversity of skin diseases and disorders such as skin cancer, psoriasis, hemangioma, connective tissue diseases, pigmented lesions, and autoimmune bullous skin diseases. Dermoscopy, also called 'epiluminescent microscopy', provides two-dimensional color images of the skin surface. OCT imaging is based on the detection of optical reflections within the tissue measured interferometrically whereas nonlinear excitation of endogenous fluorophores and the second harmonic generation are the bases of MPT images. OCT cross sectional "wide field" image provides a typical field of view of 5 x 2 mm2 and offers fast information on the depth and the volume of the investigated lesion. In comparison, multiphoton tomography presents 0.36 x 0.36 mm2 horizontal or diagonal sections of the region of interest within seconds with submicron resolution and down to a tissue depth of 200 μm. The combination of OCT and MPT provides a synergistic optical imaging modality for early detection of skin cancer and other skin diseases.

Visualizing radiofrequency-skin interaction using multiphoton microscopy in vivo.

Science.gov (United States)

Tsai, Tsung-Hua; Lin, Sung-Jan; Lee, Woan-Ruoh; Wang, Chun-Chin; Hsu, Chih-Ting; Chu, Thomas; Dong, Chen-Yuan

2012-02-01

Redundant skin laxity is a major feature of aging. Recently, radiofrequency has been introduced for nonablative tissue tightening by volumetric heating of the deep dermis. Despite the wide range of application based on this therapy, the effect of this technique on tissue and the subsequent tissue remodeling have not been investigated in detail. Our objective is to evaluate the potential of non-linear optics, including multiphoton autofluorescence and second harmonic generation (SHG) microscopy, as a non-invasive imaging modality for the real-time study of radiofrequency-tissue interaction. Electro-optical synergy device (ELOS) was used as the radiofrequency source in this study. The back skin of nude mouse was irradiated with radiofrequency at different passes. We evaluated the effect on skin immediately and 1 month after treatment with multiphoton microscopy. Corresponding histology was performed for comparison. We found that SHG is negatively correlated to radiofrequency passes, which means that collagen structural disruption happens immediately after thermal damage. After 1 month of collagen remodeling, SHG signals increased above baseline, indicating that collagen regeneration has occurred. Our findings may explain mechanism of nonablative skin tightening and were supported by histological examinations. Our work showed that monitoring the dermal heating status of RF and following up the detailed process of tissue reaction can be imaged and quantified with multiphoton microscopy non-invasively in vivo. Copyright © 2011. Published by Elsevier Ireland Ltd.

Multiphoton imaging of low grade, high grade intraepithelial neoplasia and intramucosal invasive cancer of esophagus

Science.gov (United States)

Xu, Jian; Jiang, Liwei; Kang, Deyong; Wu, Xuejing; Xu, Meifang; Zhuo, Shuangmu; Zhu, Xiaoqin; Lin, Jiangbo; Chen, Jianxin

2017-04-01

Esophageal squamous cell carcinoma (ESCC) is devastating because of its aggressive lymphatic spread and clinical course. It is believed to occur through low-grade intraepithelial neoplasia (LGIN), high-grade intraepithelial neoplasia (HGIN), and intramucosal invasive cancer (IMC) before transforming to submucosal cancer. In particular, these early lesions (LGIN, HGIN and IMC), which involve no lymph node nor distant metastasis, can be cured by endoscopic treatment. Therefore, early identification of these lesions is important so as to offer a curative endoscopic resection, thus slowing down the development of ESCC. In this work, spectral information and morphological features of the normal esophageal mucosa are first studied. Then, the morphological changes of LGIN, HGIN and IMC are described. Lastly, quantitative parameters are also extracted by calculating the nuclear-to-cytoplasmic ratio of epithelial cells and the pixel density of collagen in the lamina propria. These results show that multiphoton microscopy (MPM) has the ability to identify normal esophageal mucosa, LGIN, HGIN and IMC. With the development of multiphoton endoscope systems for in vivo imaging, combined with a laser ablation system, MPM has the potential to provide immediate pathologic diagnosis and curative treatment of ESCC before the transformation to submucosal cancer in the future.

Characteristics of subgingival calculus detection by multiphoton fluorescence microscopy

Science.gov (United States)

Tung, Oi-Hong; Lee, Shyh-Yuan; Lai, Yu-Lin; Chen, How-Foo

2011-06-01

Subgingival calculus has been recognized as a major cause of periodontitis, which is one of the main chronic infectious diseases of oral cavities and a principal cause of tooth loss in humans. Bacteria deposited in subgingival calculus or plaque cause gingival inflammation, function deterioration, and then periodontitis. However, subgingival calculus within the periodontal pocket is a complicated and potentially delicate structure to be detected with current dental armamentaria, namely dental x-rays and dental probes. Consequently, complete removal of subgingival calculus remains a challenge to periodontal therapies. In this study, the detection of subgingival calculus employing a multiphoton autofluorescence imaging method was characterized in comparison with a one-photon confocal fluorescence imaging technique. Feasibility of such a system was studied based on fluorescence response of gingiva, healthy teeth, and calculus with and without gingiva covered. The multiphoton fluorescence technology perceived the tissue-covered subgingival calculus that cannot be observed by the one-photon confocal fluorescence method.

Metabolic Mapping of Breast Cancer with Multiphoton Spectral and Lifetime Imaging

Science.gov (United States)

2007-03-01

2002. Spectrally resolved fluorescence lifetime imaging microscopy. Appl. Spec- trosc. 56 :155-166. 38. Becker, W., A. Bergmann, E. Haustein , Z...photon fluores- cence lifetime imaging microscopy of macrophage-mediated antigen processing. J. Microsc. 185 :339-353. 45. Lin, H.J., P. Herman , and

Time-resolved PHERMEX image restorations constrained with an additional multiply-exposed image

International Nuclear Information System (INIS)

Kruger, R.P.; Breedlove, J.R. Jr.; Trussell, H.J.

1978-06-01

There are a number of possible industrial and scientific applications of nanosecond cineradiographs. Although the technology exists to produce closely spaced pulses of x rays for this application, the quality of the time-resolved radiographs is severely limited. The limitations arise from the necessity of using a fluorescent screen to convert the transmitted x rays to light and then using electro-optical imaging systems to gate and to record the images with conventional high-speed cameras. It has been proposed that, in addition to the time-resolved images, a conventional multiply exposed radiograph be obtained. This report uses both PHERMEX and conventional photographic simulations to demonstrate that the additional information supplied by the multiply exposed radiograph can be used to improve the quality of digital image restorations of the time-resolved pictures over what could be achieved with the degraded images alone

Multi-Photon Entanglement and Quantum Teleportation

National Research Council Canada - National Science Library

Shih, Yanhua

1999-01-01

The project 'Multi-Photon Entanglement and Quantum Teleportation' concerns a series of experimental and theoretical investigations on multi-photon entangled states and the applications, for example...

Flexible digital signal processing architecture for narrowband and spread-spectrum lock-in detection in multiphoton microscopy and time-resolved spectroscopy.

Science.gov (United States)

Wilson, Jesse W; Park, Jong Kang; Warren, Warren S; Fischer, Martin C

2015-03-01

The lock-in amplifier is a critical component in many different types of experiments, because of its ability to reduce spurious or environmental noise components by restricting detection to a single frequency and phase. One example application is pump-probe microscopy, a multiphoton technique that leverages excited-state dynamics for imaging contrast. With this application in mind, we present here the design and implementation of a high-speed lock-in amplifier on the field-programmable gate array (FPGA) coprocessor of a data acquisition board. The most important advantage is the inherent ability to filter signals based on more complex modulation patterns. As an example, we use the flexibility of the FPGA approach to enable a novel pump-probe detection scheme based on spread-spectrum communications techniques.

In vivo 3D measurement of moxifloxacin and gatifloxacin distributions in the mouse cornea using multiphoton microscopy

Science.gov (United States)

Lee, Seunghun; Lee, Jun Ho; Park, Jin Hyoung; Yoon, Yeoreum; Chung, Wan Kyun; Tchah, Hungwon; Kim, Myoung Joon; Kim, Ki Hean

2016-05-01

Moxifloxacin and gatifloxacin are fourth-generation fluoroquinolone antibiotics used in the clinic to prevent or treat ocular infections. Their pharmacokinetics in the cornea is usually measured from extracted ocular fluids or tissues, and in vivo direct measurement is difficult. In this study multiphoton microscopy (MPM), which is a 3D optical microscopic technique based on multiphoton fluorescence, was applied to the measurement of moxifloxacin and gatifloxacin distribution in the cornea. Intrinsic multiphoton fluorescence properties of moxifloxacin and gatifloxacin were characterized, and their distributions in mouse cornea in vivo were measured by 3D MPM imaging. Both moxifloxacin and gatifloxacin had similar multiphoton spectra, while moxifloxacin had stronger fluorescence than gatifloxacin. MPM imaging of mouse cornea in vivo showed (1) moxifloxacin had good penetration through the superficial corneal epithelium, while gatifloxacin had relatively poor penetration, (2) both ophthalmic solutions had high intracellular distribution. In vivo MPM results were consistent with previous studies. This study demonstrates the feasibility of MPM as a method for in vivo direct measurement of moxifloxacin and gatifloxacin in the cornea.

Temporal focusing-based widefield multiphoton microscopy with spatially modulated illumination for biotissue imaging.

Science.gov (United States)

Chang, Chia-Yuan; Lin, Cheng-Han; Lin, Chun-Yu; Sie, Yong-Da; Hu, Yvonne Yuling; Tsai, Sheng-Feng; Chen, Shean-Jen

2018-01-01

A developed temporal focusing-based multiphoton excitation microscope (TFMPEM) has a digital micromirror device (DMD) which is adopted not only as a blazed grating for light spatial dispersion but also for patterned illumination simultaneously. Herein, the TFMPEM has been extended to implement spatially modulated illumination at structured frequency and orientation to increase the beam coverage at the back-focal aperture of the objective lens. The axial excitation confinement (AEC) of TFMPEM can be condensed from 3.0 μm to 1.5 μm for a 50 % improvement. By using the TFMPEM with HiLo technique as two structured illuminations at the same spatial frequency but different orientation, reconstructed biotissue images according to the condensed AEC structured illumination are shown obviously superior in contrast and better scattering suppression. Picture: TPEF images of the eosin-stained mouse cerebellar cortex by conventional TFMPEM (left), and the TFMPEM with HiLo technique as 1.09 μm -1 spatially modulated illumination at 90° (center) and 0° (right) orientations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A time-resolved image sensor for tubeless streak cameras

Science.gov (United States)

Yasutomi, Keita; Han, SangMan; Seo, Min-Woong; Takasawa, Taishi; Kagawa, Keiichiro; Kawahito, Shoji

2014-03-01

This paper presents a time-resolved CMOS image sensor with draining-only modulation (DOM) pixels for tube-less streak cameras. Although the conventional streak camera has high time resolution, the device requires high voltage and bulky system due to the structure with a vacuum tube. The proposed time-resolved imager with a simple optics realize a streak camera without any vacuum tubes. The proposed image sensor has DOM pixels, a delay-based pulse generator, and a readout circuitry. The delay-based pulse generator in combination with an in-pixel logic allows us to create and to provide a short gating clock to the pixel array. A prototype time-resolved CMOS image sensor with the proposed pixel is designed and implemented using 0.11um CMOS image sensor technology. The image array has 30(Vertical) x 128(Memory length) pixels with the pixel pitch of 22.4um. .

Multiphoton microscopy in every lab: the promise of ultrafast semiconductor disk lasers

Science.gov (United States)

Emaury, Florian; Voigt, Fabian F.; Bethge, Philipp; Waldburger, Dominik; Link, Sandro M.; Carta, Stefano; van der Bourg, Alexander; Helmchen, Fritjof; Keller, Ursula

2017-07-01

We use an ultrafast diode-pumped semiconductor disk laser (SDL) to demonstrate several applications in multiphoton microscopy. The ultrafast SDL is based on an optically pumped Vertical External Cavity Surface Emitting Laser (VECSEL) passively mode-locked with a semiconductor saturable absorber mirror (SESAM) and generates 170-fs pulses at a center wavelength of 1027 nm with a repetition rate of 1.63 GHz. We demonstrate the suitability of this laser for structural and functional multiphoton in vivo imaging in both Drosophila larvae and mice for a variety of fluorophores (including mKate2, tdTomato, Texas Red, OGB-1, and R-CaMP1.07) and for endogenous second-harmonic generation in muscle cell sarcomeres. We can demonstrate equivalent signal levels compared to a standard 80-MHz Ti:Sapphire laser when we increase the average power by a factor of 4.5 as predicted by theory. In addition, we compare the bleaching properties of both laser systems in fixed Drosophila larvae and find similar bleaching kinetics despite the large difference in pulse repetition rates. Our results highlight the great potential of ultrafast diode-pumped SDLs for creating a cost-efficient and compact alternative light source compared to standard Ti:Sapphire lasers for multiphoton imaging.

Depth-resolved ballistic imaging in a low-depth-of-field optical Kerr gated imaging system

Energy Technology Data Exchange (ETDEWEB)

Zheng, Yipeng; Tan, Wenjiang, E-mail: tanwenjiang@mail.xjtu.edu.cn; Si, Jinhai; Ren, YuHu; Xu, Shichao; Hou, Xun [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xianning-xilu 28, Xi' an 710049 (China); Tong, Junyi [Departments of Applied Physics, Xi' an University of Technology, Xi' an 710048 (China)

2016-09-07

We demonstrate depth-resolved imaging in a ballistic imaging system, in which a heterodyned femtosecond optical Kerr gate is introduced to extract useful imaging photons for detecting an object hidden in turbid media and a compound lens is proposed to ensure both the depth-resolved imaging capability and the long working distance. Two objects of about 15-μm widths hidden in a polystyrene-sphere suspension have been successfully imaged with approximately 600-μm depth resolution. Modulation-transfer-function curves with the object in and away from the object plane have also been measured to confirm the depth-resolved imaging capability of the low-depth-of-field (low-DOF) ballistic imaging system. This imaging approach shows potential for application in research of the internal structure of highly scattering fuel spray.

Laser-induced multiphoton transitions

International Nuclear Information System (INIS)

Stenholm, S.

1978-06-01

Laser induced multiphoton processes are reviewed. The effects of strong fields on atoms are discussed. The perturbation treatment is presented and also its generalization to treat intermediate resonances. The influence of atomic coherence is discussed heuristically and the relation between quantal and classical descriptions of the field is elucidated by reference to the dressed atom description. Atomic ionization experiments are reviewed and the present understanding of multiphoton dissociation of molecules is explained. Finally some prospects for the future are discussed. (author)

A novel flexible clinical multiphoton tomograph for early melanoma detection, skin analysis, testing of anti-age products, and in situ nanoparticle tracking

Science.gov (United States)

Weinigel, Martin; Breunig, Hans Georg; Gregory, Axel; Fischer, Peter; Kellner-Höfer, Marcel; Bückle, Rainer; König, Karsten

2010-02-01

High-resolution 3D microscopy based on multiphoton induced autofluorescence and second harmonic generation have been introduced in 1990. 13 years later, CE-marked clinical multiphoton systems for 3D imaging of human skin with subcellular resolution have first been launched by JenLab company with the tomography DermaInspect®. This year, the second generation of clinical multiphoton tomographs was introduced. The novel multiphoton tomograph MPTflex, equipped with a flexible articulated optical arm, provides an increased flexibility and accessibility especially for clinical and cosmetical examinations. Improved image quality and signal to noise ratio (SNR) are achieved by a very short source-drain spacing, by larger active areas of the detectors and by single photon counting (SPC) technology. Shorter image acquisition time due to improved image quality reduces artifacts and simplifies the operation of the system. The compact folded optical design and the light-weight structure of the optical head eases the handling. Dual channel detectors enable to distinguish between intratissue elastic fibers and collagenous structures simultaneously. Through the use of piezo-driven optics a stack of optical cross-sections (optical sectioning) can be acquired and 3D imaging can be performed. The multiphoton excitation of biomolecules like NAD(P)H, flavins, porphyrins, elastin, and melanin is done by picojoule femtosecond laser pulses from an tunable turn-key femtosescond near infrared laser system. The ability for rapid high-quality image acquisition, the user-friendly operation of the system and the compact and flexible design qualifies this system to be used for melanoma detection, diagnostics of dermatological disorders, cosmetic research and skin aging measurements as well as in situ drug monitoring and animal research.

Multiphoton states and amplitude k-th power squeezing

International Nuclear Information System (INIS)

Buzek, V.; Jex, I.

1991-01-01

On the basis of the work of d'Ariano and coworkers a new type of multiphoton states is introduced. Amplitude k-th power squeezing of the multiphoton states are analysed. In particular, it is shown that even if the multiphoton states do not exhibit ordinary squeezing they can be amplitude k-th power squeezed

Multi-photon excited luminescence of magnetic FePt core-shell nanoparticles.

Science.gov (United States)

Seemann, K M; Kuhn, B

2014-07-01

We present magnetic FePt nanoparticles with a hydrophilic, inert, and biocompatible silico-tungsten oxide shell. The particles can be functionalized, optically detected, and optically manipulated. To show the functionalization the fluorescent dye NOPS was bound to the FePt core-shell nanoparticles with propyl-triethoxy-silane linkers and fluorescence of the labeled particles were observed in ethanol (EtOH). In aqueous dispersion the NOPS fluorescence is quenched making them invisible using 1-photon excitation. However, we observe bright luminescence of labeled and even unlabeled magnetic core-shell nanoparticles with multi-photon excitation. Luminescence can be detected in the near ultraviolet and the full visible spectral range by near infrared multi-photon excitation. For optical manipulation, we were able to drag clusters of particles, and maybe also single particles, by a focused laser beam that acts as optical tweezers by inducing an electric dipole in the insulated metal nanoparticles. In a first application, we show that the luminescence of the core-shell nanoparticles is bright enough for in vivo multi-photon imaging in the mouse neocortex down to cortical layer 5.

Imaging-guided two-photon excitation-emission-matrix measurements of human skin tissues

Science.gov (United States)

Yu, Yingqiu; Lee, Anthony M. D.; Wang, Hequn; Tang, Shuo; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan

2012-07-01

There are increased interests on using multiphoton imaging and spectroscopy for skin tissue characterization and diagnosis. However, most studies have been done with just a few excitation wavelengths. Our objective is to perform a systematic study of the two-photon fluorescence (TPF) properties of skin fluorophores, normal skin, and diseased skin tissues. A nonlinear excitation-emission-matrix (EEM) spectroscopy system with multiphoton imaging guidance was constructed. A tunable femtosecond laser was used to vary excitation wavelengths from 730 to 920 nm for EEM data acquisition. EEM measurements were performed on excised fresh normal skin tissues, seborrheic keratosis tissue samples, and skin fluorophores including: NADH, FAD, keratin, melanin, collagen, and elastin. We found that in the stratum corneum and upper epidermis of normal skin, the cells have large sizes and the TPF originates from keratin. In the lower epidermis, cells are smaller and TPF is dominated by NADH contributions. In the dermis, TPF is dominated by elastin components. The depth resolved EEM measurements also demonstrated that keratin structure has intruded into the middle sublayers of the epidermal part of the seborrheic keratosis lesion. These results suggest that the imaging guided TPF EEM spectroscopy provides useful information for the development of multiphoton clinical devices for skin disease diagnosis.

Monitoring wound healing by multiphoton tomography/endoscopy

Science.gov (United States)

König, Karsten; Weinigel, Martin; Bückle, Rainer; Kaatz, Martin; Hipler, Christina; Zens, Katharina; Schneider, Stefan W.; Huck, Volker

2015-02-01

Certified clinical multiphoton tomographs are employed to perform rapid label-free high-resolution in vivo histology. Novel tomographs include a flexible 360° scan head attached to a mechano-optical arm for autofluorescence and SHG imaging as well as rigid two-photon GRIN microendoscope. Mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen can be imaged with submicron resolution in human skin. The system was employed to study the healing of chronic wounds (venous leg ulcer) and acute wounds (curettage of actinic or seborrheic keratosis) on a subcellular level. Furthermore, a flexible sterile foil as interface between wound and focusing optic was tested.

Coherent beam control through inhomogeneous media in multi-photon microscopy

Science.gov (United States)

Paudel, Hari Prasad

Multi-photon fluorescence microscopy has become a primary tool for high-resolution deep tissue imaging because of its sensitivity to ballistic excitation photons in comparison to scattered excitation photons. The imaging depth of multi-photon microscopes in tissue imaging is limited primarily by background fluorescence that is generated by scattered light due to the random fluctuations in refractive index inside the media, and by reduced intensity in the ballistic focal volume due to aberrations within the tissue and at its interface. We built two multi-photon adaptive optics (AO) correction systems, one for combating scattering and aberration problems, and another for compensating interface aberrations. For scattering correction a MEMS segmented deformable mirror (SDM) was inserted at a plane conjugate to the objective back-pupil plane. The SDM can pre-compensate for light scattering by coherent combination of the scattered light to make an apparent focus even at a depths where negligible ballistic light remains (i.e. ballistic limit). This problem was approached by investigating the spatial and temporal focusing characteristics of a broad-band light source through strongly scattering media. A new model was developed for coherent focus enhancement through or inside the strongly media based on the initial speckle contrast. A layer of fluorescent beads under a mouse skull was imaged using an iterative coherent beam control method in the prototype two-photon microscope to demonstrate the technique. We also adapted an AO correction system to an existing in three-photon microscope in a collaborator lab at Cornell University. In the second AO correction approach a continuous deformable mirror (CDM) is placed at a plane conjugate to the plane of an interface aberration. We demonstrated that this "Conjugate AO" technique yields a large field-of-view (FOV) advantage in comparison to Pupil AO. Further, we showed that the extended FOV in conjugate AO is maintained over a

Multiphoton Processes and Attosecond Physics

CERN Document Server

Midorikawa, Katsumi; 12th International Conference on Multiphoton Processes; 3rd International Conference on Attosecond Physics

2012-01-01

Recent advances in ultrashort pulsed laser technology have opened new frontiers in atomic, molecular and optical sciences. The 12th International Conference on Multiphoton Processes (ICOMP12) and the 3rd International Conference on Attosecond Physics (ATTO3), held jointly in Sapporo, Japan, during July 3-8, showcased studies at the forefront of research on multiphoton processes and attosecond physics. This book summarizes presentations and discussions from these two conferences.

Label-free identification of intestinal metaplasia in the stomach using multiphoton microscopy

International Nuclear Information System (INIS)

Wu, G; Wei, J; Zheng, Z; Ye, J; Zeng, S

2014-01-01

The early diagnosis of intestinal metaplasia (IM) in the stomach together with effective therapeutic interventions is crucial to reducing the mortality-rates of the patients associated with gastric cancer. However, it is challenging during conventional white-light endoscopy, and histological analysis remains the ‘gold standard’ for the final diagnosis. Here, we describe a label-free imaging method, multiphoton microscopy (MPM), for the identification of IM in the stomach. It was found that multiphoton imaging provides cellular and subcellular details to the identification of IM from normal gastric tissues. In particular, there is significant difference in the population density of goblet cells between normal and IM gastric tissues, providing substantial potential to become a quantitative intrinsic marker for in vivo clinical diagnosis of early gastric lesions. To our knowledge, this is the first demonstration of the potential of MPM for the identification of IM. (letters)

Photon-number-resolving SSPDs with system detection efficiency over 50% at telecom range

Science.gov (United States)

Zolotov, P.; Divochiy, A.; Vakhtomin, Yu.; Moshkova, M.; Morozov, P.; Seleznev, V.; Smirnov, K.

2018-02-01

We used technology of making high-efficiency superconducting single-photon detectors as a basis for improvement of photon-number-resolving devices. By adding optical cavity and using an improved NbN superconducting film, we enhanced previously reported system detection efficiency at telecom range for such detectors. Our results show that implementation of optical cavity helps to develop four-section device with quantum efficiency over 50% at 1.55 µm. Performed experimental studies of detecting multi-photon optical pulses showed irregularities over defining multi-photon through single-photon quantum efficiency.

Multiphoton microscopy as a diagnostic imaging modality for pancreatic neoplasms without hematoxylin and eosin stains

Science.gov (United States)

Chen, Youting; Chen, Jing; Chen, Hong; Hong, Zhipeng; Zhu, Xiaoqin; Zhuo, Shuangmu; Chen, Yanling; Chen, Jianxin

2014-09-01

Hematoxylin and eosin (H&E) staining of tissue samples is the standard approach in histopathology for imaging and diagnosing cancer. Recent reports have shown that multiphoton microscopy (MPM) provides better sample interface with single-cell resolution, which enhances traditional H&E staining and offers a powerful diagnostic tool with potential applications in oncology. The purpose of this study was to further expand the versatility of MPM by establishing the optical parameters required for imaging unstained histological sections of pancreatic neoplasms, thereby providing an efficient and environmentally sustainable alternative to H&E staining while improving the accuracy of pancreatic cancer diagnoses. We found that the high-resolution MPM images clearly distinguish between the structure of normal pancreatic tissues compared with pancreatic neoplasms in unstained histological sections, and discernable differences in tissue architecture and cell morphology between normal versus tumorigenic cells led to enhanced optical diagnosis of cancerous tissue. Moreover, quantitative assessment of the cytomorphological features visualized from MPM images showed significant differences in the nuclear-cytoplasmic ratios of pancreatic neoplasms compared with normal pancreas, as well as further distinguished pancreatic malignant tumors from benign tumors. These results indicate that the MPM could potentially serve as an optical tool for the diagnosis of pancreatic neoplasms in unstained histological sections.

A least squares approach to estimating the probability distribution of unobserved data in multiphoton microscopy

Science.gov (United States)

Salama, Paul

2008-02-01

Multi-photon microscopy has provided biologists with unprecedented opportunities for high resolution imaging deep into tissues. Unfortunately deep tissue multi-photon microscopy images are in general noisy since they are acquired at low photon counts. To aid in the analysis and segmentation of such images it is sometimes necessary to initially enhance the acquired images. One way to enhance an image is to find the maximum a posteriori (MAP) estimate of each pixel comprising an image, which is achieved by finding a constrained least squares estimate of the unknown distribution. In arriving at the distribution it is assumed that the noise is Poisson distributed, the true but unknown pixel values assume a probability mass function over a finite set of non-negative values, and since the observed data also assumes finite values because of low photon counts, the sum of the probabilities of the observed pixel values (obtained from the histogram of the acquired pixel values) is less than one. Experimental results demonstrate that it is possible to closely estimate the unknown probability mass function with these assumptions.

The Usefulness of Readout-Segmented Echo-Planar Imaging (RESOLVE) for Bio-phantom Imaging Using 3-Tesla Clinical MRI.

Science.gov (United States)

Yoshimura, Yuuki; Kuroda, Masahiro; Sugiantoc, Irfan; Bamgbosec, Babatunde O; Miyahara, Kanae; Ohmura, Yuichi; Kurozumi, Akira; Matsushita, Toshi; Ohno, Seiichiro; Kanazawa, Susumu; Asaumi, Junichi

2018-02-01

Readout-segmented echo-planar imaging (RESOLVE) is a multi-shot echo-planar imaging (EPI) modality with k-space segmented in the readout direction. We investigated whether RESOLVE decreases the distortion and artifact in the phase direction and increases the signal-to-noise ratio (SNR) in phantoms image taken with 3-tesla (3T) MRI versus conventional EPI. We used a physiological saline phantom and subtraction mapping and observed that RESOLVE's SNR was higher than EPI's. Using RESOLVE, the combination of a special-purpose coil and a large-loop coil had a higher SNR compared to using only a head/neck coil. RESOLVE's image distortioas less than EPI's. We used a 120 mM polyethylene glycol phantom to examine the phase direction artifact.vThe range where the artifact appeared in the apparent diffusion coefficient (ADC) image was shorter with RESOLVE compared to EPI. We used RESOLVE to take images of a Jurkat cell bio-phantom: the cell-region ADC was 856×10-6mm2/sec and the surrounding physiological saline-region ADC was 2,951×10-6mm2/sec. The combination of RESOLVE and the 3T clinical MRI device reduced image distortion and improved SNR and the identification of accurate ADC values due to the phase direction artifact reduction. This combination is useful for obtaining accurate ADC values of bio-phantoms.

Multiphoton bibliography

International Nuclear Information System (INIS)

Eberly, J.H.; Gallagher, J.W.

1981-12-01

A bibliography is presented of approximately 275 references from literature published since 1980 on multiphoton research. A subject list is provided which divides the references into four subdivisions, i.e., ionization, bound-bound transitions, dissociation, and free-free transitions. An author index is included

Depth-resolved incoherent and coherent wide-field high-content imaging (Conference Presentation)

Science.gov (United States)

So, Peter T.

2016-03-01

Recent advances in depth-resolved wide-field imaging technique has enabled many high throughput applications in biology and medicine. Depth resolved imaging of incoherent signals can be readily accomplished with structured light illumination or nonlinear temporal focusing. The integration of these high throughput systems with novel spectroscopic resolving elements further enable high-content information extraction. We will introduce a novel near common-path interferometer and demonstrate its uses in toxicology and cancer biology applications. The extension of incoherent depth-resolved wide-field imaging to coherent modality is non-trivial. Here, we will cover recent advances in wide-field 3D resolved mapping of refractive index, absorbance, and vibronic components in biological specimens.

Multiphoton microscopic imaging of histological sections without hematoxylin and eosin staining differentiates carcinoma in situ lesion from normal oesophagus

Science.gov (United States)

Chen, Jianxin; Xu, Jian; Kang, Deyong; Xu, Meifang; Zhuo, Shuangmu; Zhu, Xiaoqin; Jiang, Xingshan

2013-10-01

Multiphoton microscopy (MPM) has become a powerful, important tool for tissues imaging at the molecular level. In this paper, this technique was extended to histological investigations, differentiating carcinoma in situ (CIS) lesion from normal oesophagus by imaging histological sections without hematoxylin and eosin (H&E) staining. The results show that the histology procedures of dehydration, paraffin embedding, and de-paraffinizing highlighted two photon excited fluorescence of cytoplasm and nucleolus of epithelial cell and collagen in stroma. MPM has the ability to identify the characteristics of CIS lesion including changes of squamous cells and full epithelium, identification of basement membrane, especially prominent nucleolus. The studies described here show that MPM has the potential for future retrospective studies of tumor staging by employing on histological section specimens without H&E staining.

In vivo, label-free, three-dimensional quantitative imaging of liver surface using multi-photon microscopy

Energy Technology Data Exchange (ETDEWEB)

Zhuo, Shuangmu, E-mail: shuangmuzhuo@gmail.com, E-mail: hanry-yu@nuhs.edu.sg [Biosystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, #04-13/14 Enterprise Wing, 138602 Singapore (Singapore); Institute of Laser and Optoelectronics Technology, Fujian Normal University, Fuzhou 350007 (China); Yan, Jie [Biosystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, #04-13/14 Enterprise Wing, 138602 Singapore (Singapore); Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, #04-01, 138669 Singapore (Singapore); Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive, MD 11 #04-01A, 117599 Singapore (Singapore); Kang, Yuzhan [Biosystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, #04-13/14 Enterprise Wing, 138602 Singapore (Singapore); Xu, Shuoyu [Biosystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, #04-13/14 Enterprise Wing, 138602 Singapore (Singapore); Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, #04-01, 138669 Singapore (Singapore); Computation and System Biology Program, Singapore-MIT Alliance, 4 Engineering Drive 3, E4-04-10, 117576 Singapore (Singapore); Peng, Qiwen [Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, #04-01, 138669 Singapore (Singapore); Computation and System Biology Program, Singapore-MIT Alliance, 4 Engineering Drive 3, E4-04-10, 117576 Singapore (Singapore); Mechanobiology Institute, 5A Engineering Drive 1, T-Lab #05-01, 117411 Singapore (Singapore); and others

2014-07-14

Various structural features on the liver surface reflect functional changes in the liver. The visualization of these surface features with molecular specificity is of particular relevance to understanding the physiology and diseases of the liver. Using multi-photon microscopy (MPM), we have developed a label-free, three-dimensional quantitative and sensitive method to visualize various structural features of liver surface in living rat. MPM could quantitatively image the microstructural features of liver surface with respect to the sinuosity of collagen fiber, the elastic fiber structure, the ratio between elastin and collagen, collagen content, and the metabolic state of the hepatocytes that are correlative with the pathophysiologically induced changes in the regions of interest. This study highlights the potential of this technique as a useful tool for pathophysiological studies and possible diagnosis of the liver diseases with further development.

Amplitudes for multiphoton quantum processes in linear optics

International Nuclear Information System (INIS)

UrIas, Jesus

2011-01-01

The prominent role that linear optical networks have acquired in the engineering of photon states calls for physically intuitive and automatic methods to compute the probability amplitudes for the multiphoton quantum processes occurring in linear optics. A version of Wick's theorem for the expectation value, on any vector state, of products of linear operators, in general, is proved. We use it to extract the combinatorics of any multiphoton quantum processes in linear optics. The result is presented as a concise rule to write down directly explicit formulae for the probability amplitude of any multiphoton process in linear optics. The rule achieves a considerable simplification and provides an intuitive physical insight about quantum multiphoton processes. The methodology is applied to the generation of high-photon-number entangled states by interferometrically mixing coherent light with spontaneously down-converted light.

Amplitudes for multiphoton quantum processes in linear optics

Science.gov (United States)

Urías, Jesús

2011-07-01

The prominent role that linear optical networks have acquired in the engineering of photon states calls for physically intuitive and automatic methods to compute the probability amplitudes for the multiphoton quantum processes occurring in linear optics. A version of Wick's theorem for the expectation value, on any vector state, of products of linear operators, in general, is proved. We use it to extract the combinatorics of any multiphoton quantum processes in linear optics. The result is presented as a concise rule to write down directly explicit formulae for the probability amplitude of any multiphoton process in linear optics. The rule achieves a considerable simplification and provides an intuitive physical insight about quantum multiphoton processes. The methodology is applied to the generation of high-photon-number entangled states by interferometrically mixing coherent light with spontaneously down-converted light.

High-resolution imaging of basal cell carcinoma: a comparison between multiphoton microscopy with fluorescence lifetime imaging and reflectance confocal microscopy.

Science.gov (United States)

Manfredini, Marco; Arginelli, Federica; Dunsby, Christopher; French, Paul; Talbot, Clifford; König, Karsten; Pellacani, Giovanni; Ponti, Giovanni; Seidenari, Stefania

2013-02-01

The aim of this study was to compare morphological aspects of basal cell carcinoma (BCC) as assessed by two different imaging methods: in vivo reflectance confocal microscopy (RCM) and multiphoton tomography with fluorescence lifetime imaging implementation (MPT-FLIM). The study comprised 16 BCCs for which a complete set of RCM and MPT-FLIM images were available. The presence of seven MPT-FLIM descriptors was evaluated. The presence of seven RCM equivalent parameters was scored in accordance to their extension. Chi-squared test with Fisher's exact test and Spearman's rank correlation coefficient were determined between MPT-FLIM scores and adjusted-RCM scores. MPT-FLIM and RCM descriptors of BCC were coupled to match the descriptors that define the same pathological structures. The comparison included: Streaming and Aligned elongated cells, Streaming with multiple directions and Double alignment, Palisading (RCM) and Palisading (MPT-FLIM), Typical tumor islands, and Cell islands surrounded by fibers, Dark silhouettes and Phantom islands, Plump bright cells and Melanophages, Vessels (RCM), and Vessels (MPT-FLIM). The parameters that were significantly correlated were Melanophages/Plump Bright Cells, Aligned elongated cells/Streaming, Double alignment/Streaming with multiple directions, and Palisading (MPT-FLIM)/Palisading (RCM). According to our data, both methods are suitable to image BCC's features. The concordance between MPT-FLIM and RCM is high, with some limitations due to the technical differences between the two devices. The hardest difficulty when comparing the images generated by the two imaging modalities is represented by their different field of view. © 2012 John Wiley & Sons A/S.

Atom-resolved AFM imaging of calcite nanoparticles in water

Energy Technology Data Exchange (ETDEWEB)

Imada, Hirotake; Kimura, Kenjiro [Department of Chemistry, School of Science, Kobe University, Rokko-dai, Nada, Kobe 657-8501 (Japan); Onishi, Hiroshi, E-mail: oni@kobe-u.ac.jp [Department of Chemistry, School of Science, Kobe University, Rokko-dai, Nada, Kobe 657-8501 (Japan)

2013-06-20

Highlights: ► An advanced frequency-modulation AFM (FM-AFM) was applied for imaging particles. ► Atom-resolved topography of nano-sized particles of calcite was observed in water. ► Locally ordered structures were found and assigned to a (104) facet of calcite. ► A promising ability of FM-AFM was demonstrated in imaging nano-sized particles. - Abstract: The atom-resolved topography of calcite nanoparticles was observed in water using a frequency-modulation atomic force microscope. Locally ordered structures were found and assigned to a (104) facet of crystalline calcite.

Atom-resolved AFM imaging of calcite nanoparticles in water

International Nuclear Information System (INIS)

Imada, Hirotake; Kimura, Kenjiro; Onishi, Hiroshi

2013-01-01

Highlights: ► An advanced frequency-modulation AFM (FM-AFM) was applied for imaging particles. ► Atom-resolved topography of nano-sized particles of calcite was observed in water. ► Locally ordered structures were found and assigned to a (104) facet of calcite. ► A promising ability of FM-AFM was demonstrated in imaging nano-sized particles. - Abstract: The atom-resolved topography of calcite nanoparticles was observed in water using a frequency-modulation atomic force microscope. Locally ordered structures were found and assigned to a (104) facet of crystalline calcite

Miniature fiber-optic multiphoton microscopy system using frequency-doubled femtosecond Er-doped fiber laser.

Science.gov (United States)

Huang, Lin; Mills, Arthur K; Zhao, Yuan; Jones, David J; Tang, Shuo

2016-05-01

We report on a miniature fiber-optic multiphoton microscopy (MPM) system based on a frequency-doubled femtosecond Er-doped fiber laser. The femtosecond pulses from the laser source are delivered to the miniature fiber-optic probe at 1.58 µm wavelength, where a standard single mode fiber is used for delivery without the need of free-space dispersion compensation components. The beam is frequency-doubled inside the probe by a periodically poled MgO:LiNbO3 crystal. Frequency-doubled pulses at 786 nm with a maximum power of 80 mW and a pulsewidth of 150 fs are obtained and applied to excite intrinsic signals from tissues. A MEMS scanner, a miniature objective, and a multimode collection fiber are further used to make the probe compact. The miniature fiber-optic MPM system is highly portable and robust. Ex vivo multiphoton imaging of mammalian skins demonstrates the capability of the system in imaging biological tissues. The results show that the miniature fiber-optic MPM system using frequency-doubled femtosecond fiber laser can potentially bring the MPM imaging for clinical applications.

Label-free in vivo in situ diagnostic imaging by cellular metabolism quantification with a flexible multiphoton endomicroscope (Conference Presentation)

Science.gov (United States)

Leclerc, Pierre; Hage, Charles-Henri; Fabert, Marc; Brevier, Julien; O'Connor, Rodney P.; Bardet-Coste, Sylvia M.; Habert, Rémi; Braud, Flavie; Kudlinski, Alexandre; Louradour, Frederic

2017-02-01

Multiphoton microscopy is a cutting edge imaging modality leading to increasing advances in biology and also in the clinical field. To use it at its full potential and at the very heart of clinical practice, there have been several developments of fiber-based multiphoton microendoscopes. The application for those probes is now limited by few major restrictions, such as the difficulty to collect autofluorescence signals from tissues and cells theses being inherently weak (e.g. the ones from intracellular NADH or FAD metabolites). This limitation reduces the usefulness of microendoscopy in general, effectively restraining it to morphological imaging modality requiring staining of the tissues. Our aim is to go beyond this limitation, showing for the first time label-free cellular metabolism monitoring, in vivo in situ in real time. The experimental setup is an upgrade of a recently published one (Ducourthial et.al, Scientific Reports, 2016) where femtosecond pulse fiber delivery is further optimized thank's to a new transmissive-GRISM-based pulse stretcher permitting high energy throughput and wide bandwidth. This device allows fast sequential operation with two different excitation wavelengths for efficient two-photon excited NADH and FAD autofluorescence endoscopic detection (i.e. 860 nm for FAD and 760 nm for NADH), enabling cellular optical redox ratio quantification at 8 frames/s. The obtained results on cell models in vitro and also on animal models in vivo (e.g. neurons of a living mouse) prove that we accurately assess the level of NADH and FAD at subcellular resolution through a 3-meters-long fiber with our miniaturized probe (O.D. =2.2 mm).

Multi-photon microscope driven by novel green laser pump

Science.gov (United States)

Marti, Dominik; Djurhuus, Martin; Jensen, Ole Bjarlin; Andersen, Peter E.

2016-03-01

Multi-photon microscopy is extensively used in research due to its superior possibilities when compared to other microscopy modalities. The technique also has the possibility to advance diagnostics in clinical applications, due to its capabilities complementing existing technology in a multimodal system. However, translation is hindered due to the high cost, high training demand and large footprint of a standard setup. We show in this article that minification of the setup, while also reducing cost and complexity, is indeed possible without compromising on image quality, by using a novel diode laser replacing the commonly used conventional solid state laser as the pump for the femtosecond system driving the imaging.

Visualizing a protein quake with time-resolved X-ray scattering at a free-electron laser

DEFF Research Database (Denmark)

Arnlund, David; Johansson, Linda C.; Wickstrand, Cecilia

2014-01-01

We describe a method to measure ultrafast protein structural changes using time-resolved wide-angle X-ray scattering at an X-ray free-electron laser. We demonstrated this approach using multiphoton excitation of the Blastochloris viridis photosynthetic reaction center, observing an ultrafast glob...

Evaluation of multiphoton effects in down-conversion

International Nuclear Information System (INIS)

Yoshimi, Kazuyoshi; Koshino, Kazuki

2010-01-01

Multiphoton effects in down-conversion are investigated based on the full-quantum multimode formalism by considering a three-level system as a prototype nonlinear system. We analytically derive the three-photon output wave function for two input photons, where one of the two input photons is down-converted and the other one is not. Using this output wave function, we calculate the down-conversion probability, the purity, and the fidelity to evaluate the entanglement between a down-converted photon pair and a non-down-converted photon. It is shown that the saturation effect occurs by multiphoton input and that it affects both the down-conversion probability and the quantum correlation between the down-converted photon pair and the non-down-converted photon. We also reveal the necessary conditions for multiphoton effects to be strong.

Multiphoton resonances

International Nuclear Information System (INIS)

Shore, B.W.

1977-01-01

The long-time average of level populations in a coherently-excited anharmonic sequence of energy levels (e.g., an anharmonic oscillator) exhibits sharp resonances as a function of laser frequency. For simple linearly-increasing anharmonicity, each resonance is a superposition of various multiphoton resonances (e.g., a superposition of 3, 5, 7, . . . photon resonances), each having its own characteristic width predictable from perturbation theory

QED theory of multiphoton transitions in atoms and ions

Science.gov (United States)

Zalialiutdinov, Timur A.; Solovyev, Dmitry A.; Labzowsky, Leonti N.; Plunien, Günter

2018-03-01

This review surveys the quantum theory of electromagnetic radiation for atomic systems. In particular, a review of current theoretical studies of multiphoton processes in one and two-electron atoms and highly charged ions is provided. Grounded on the quantum electrodynamics description the multiphoton transitions in presence of cascades, spin-statistic behaviour of equivalent photons and influence of external electric fields on multiphoton in atoms and anti-atoms are discussed. Finally, the nonresonant corrections which define the validity of the concept of the excited state energy levels are introduced.

Graphene oxide from silk cocoon: a novel magnetic fluorophore for multi-photon imaging.

Science.gov (United States)

Roy, Manas; Kusurkar, Tejas Sanjeev; Maurya, Sandeep Kumar; Meena, Sunil Kumar; Singh, Sushil Kumar; Sethy, Niroj; Bhargava, Kalpana; Sharma, Raj Kishore; Goswami, Debabrata; Sarkar, Sabyasachi; Das, Mainak

2014-02-01

In this work, we synthesized graphene oxide from silk cocoon embarking its new dimension as a magnetic fluorophore when compared with its present technical status, which at best is for extracting silk as a biomaterial for tissue engineering applications. We produced graphene oxide by pyrolysing the silk cocoon in an inert atmosphere. The collected raw carbon is oxidized by nitric acid that readily produces multilayer graphene oxide with nano carbon particulates. Structural properties of the graphene oxide were analyzed using scanning electron microscopy, transmission electron microscopy, Fourier transform infra-red spectroscopy, and Raman spectroscopy. The oxidized sample shows remarkable fluorescence, multi-photon imaging and magnetic properties. On increasing the excitation wavelength, the fluorescence emission intensity of the graphene oxide also increases and found maximum emission at 380 nm excitation wavelength. On studying the two photon absorption (TPA) property of aqueous graphene oxide using Z-scan technique, we found significant TPA activity at near infrared wavelength. In addition, the graphene oxide shows ferromagnetic behavior at room temperature. The observed fluorescence and magnetic property were attributed to the defects caused in the graphene oxide structure by introducing oxygen containing hydrophilic groups during the oxidation process. Previously silk cocoon has been used extensively in deriving silk-based tissue engineering materials and as gas filter. Here we show a novel application of silk cocoon by synthesizing graphene oxide based magnetic-fluorophore for bio-imaging applications.

Depth resolved hyperspectral imaging spectrometer based on structured light illumination and Fourier transform interferometry

Science.gov (United States)

Choi, Heejin; Wadduwage, Dushan; Matsudaira, Paul T.; So, Peter T.C.

2014-01-01

A depth resolved hyperspectral imaging spectrometer can provide depth resolved imaging both in the spatial and the spectral domain. Images acquired through a standard imaging Fourier transform spectrometer do not have the depth-resolution. By post processing the spectral cubes (x, y, λ) obtained through a Sagnac interferometer under uniform illumination and structured illumination, spectrally resolved images with depth resolution can be recovered using structured light illumination algorithms such as the HiLo method. The proposed scheme is validated with in vitro specimens including fluorescent solution and fluorescent beads with known spectra. The system is further demonstrated in quantifying spectra from 3D resolved features in biological specimens. The system has demonstrated depth resolution of 1.8 μm and spectral resolution of 7 nm respectively. PMID:25360367

Stepwise multiphoton activation fluorescence reveals a new method of melanin detection

Science.gov (United States)

Lai, Zhenhua; Kerimo, Josef; Mega, Yair; DiMarzio, Charles A.

2013-06-01

The stepwise multiphoton activated fluorescence (SMPAF) of melanin, activated by a continuous-wave mode near infrared (NIR) laser, reveals a broad spectrum extending from the visible spectra to the NIR and has potential application for a low-cost, reliable method of detecting melanin. SMPAF images of melanin in mouse hair and skin are compared with conventional multiphoton fluorescence microscopy and confocal reflectance microscopy (CRM). By combining CRM with SMPAF, we can locate melanin reliably. However, we have the added benefit of eliminating background interference from other components inside mouse hair and skin. The melanin SMPAF signal from the mouse hair is a mixture of a two-photon process and a third-order process. The melanin SMPAF emission spectrum is activated by a 1505.9-nm laser light, and the resulting spectrum has a peak at 960 nm. The discovery of the emission peak may lead to a more energy-efficient method of background-free melanin detection with less photo-bleaching.

Multiphoton excitation and high-harmonics generation in topological insulator.

Science.gov (United States)

Avetissian, H K; Avetissian, A K; Avchyan, B R; Mkrtchian, G F

2018-05-10

Multiphoton interaction of coherent electromagnetic radiation with 2D metallic carriers confined on the surface of the 3D topological insulator is considered. A microscopic theory describing the nonlinear interaction of a strong wave and metallic carriers with many-body Coulomb interaction is developed. The set of integrodifferential equations for the interband polarization and carrier occupation distribution is solved numerically. Multiphoton excitation of Fermi-Dirac sea of 2D massless carriers is considered for a THz pump wave. It is shown that in the moderately strong pump wave field along with multiphoton interband/intraband transitions the intense radiation of high harmonics takes place.

Multiphoton excitation and high-harmonics generation in topological insulator

Science.gov (United States)

Avetissian, H. K.; Avetissian, A. K.; Avchyan, B. R.; Mkrtchian, G. F.

2018-05-01

Multiphoton interaction of coherent electromagnetic radiation with 2D metallic carriers confined on the surface of the 3D topological insulator is considered. A microscopic theory describing the nonlinear interaction of a strong wave and metallic carriers with many-body Coulomb interaction is developed. The set of integrodifferential equations for the interband polarization and carrier occupation distribution is solved numerically. Multiphoton excitation of Fermi–Dirac sea of 2D massless carriers is considered for a THz pump wave. It is shown that in the moderately strong pump wave field along with multiphoton interband/intraband transitions the intense radiation of high harmonics takes place.

Spin Multiphoton Antiresonance at Finite Temperatures

Science.gov (United States)

Hicke, Christian; Dykman, Mark

2007-03-01

Weakly anisotropic S>1 spin systems display multiphoton antiresonance. It occurs when an Nth overtone of the radiation frequency coincides with the distance between the ground and the Nth excited energy level (divided by ). The coherent response of the spin displays a sharp minimum or maximum as a function of frequency, depending on which state was initially occupied. We find the spectral shape of the response dips/peaks. We also study the stationary response for zero and finite temperatures. The response changes dramatically with increasing temperature, when excited states become occupied even in the absence of radiation. The change is due primarily to the increasing role of single-photon resonances between excited states, which occur at the same frequencies as multiphoton resonances. Single-photon resonances are broad, because the single-photon Rabi frequencies largely exceed the multi-photon ones. This allows us to separate different resonances and to study their spectral shape. We also study the change of the spectrum due to relaxational broadening of the peaks, with account taken of both decay and phase modulation.

Multiphotonic resonance processes in potassium vapor

International Nuclear Information System (INIS)

Bensoussan, Paul.

1975-01-01

Despite several theoretical and experimental investigations, the phenomena of resonance multiphotonic ionization are still not completely understood. The following lines of investigation were undertaken to try and elucidate certain aspects of the resonance processes. The first line of investigation aims at finding the processes which can compete with ionization. Resonance ionization processes can be considered as taking place in two stages: absorption induced excitation of a bound state, followed by photoionization from the excited level. The problem is now to determine what are the processes which compete with the ionization processes starting from a level selectively populated by the absorption of one or two photons. The second line aims at finding the influence of the polarization of the radiation on resonance multiphotonic ionization for the second photon and to check the validity of the selection rules on the magnetic quantic number of the resonance bound linked states. The last study therefore relates to the development of a method of multiphotonic spectrometry which could determine the energy levels in the alcaline f series [fr

Comparison of higher-order multiphoton signal generation and collection at the 1700-nm window based on transmittance measurement of objective lenses.

Science.gov (United States)

Wen, Wenhui; Wang, Yuxin; Liu, Hongji; Wang, Kai; Qiu, Ping; Wang, Ke

2018-01-01

One benefit of excitation at the 1700-nm window is the more accessible modalities of multiphoton signal generation. It is demonstrated here that the transmittance performance of the objective lens is of vital importance for efficient higher-order multiphoton signal generation and collection excited at the 1700-nm window. Two commonly used objective lenses for multiphoton microscopy (MPM) are characterized and compared, one with regular coating and the other with customized coating for high transmittance at the 1700-nm window. Our results show that, fourth harmonic generation imaging of mouse tail tendon and 5-photon fluorescence of carbon quantum dots using the regular objective lens shows an order of magnitude signal higher than those using the customized objective lens. Besides, the regular objective lens also enables a 3-photon fluorescence imaging depth of >1600 μm in mouse brain in vivo. Our results will provide guidelines for objective lens selection for MPM at the 1700-nm window. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Field enhancement of multiphoton induced luminescence processes in ZnO nanorods

Science.gov (United States)

Hyyti, Janne; Perestjuk, Marko; Mahler, Felix; Grunwald, Rüdiger; Güell, Frank; Gray, Ciarán; McGlynn, Enda; Steinmeyer, Günter

2018-03-01

The near-ultraviolet photoluminescence of ZnO nanorods induced by multiphoton absorption of unamplified Ti:sapphire pulses is investigated. Power dependence measurements have been conducted with an adaptation of the ultrashort pulse characterization method of interferometric frequency-resolved optical gating. These measurements enable the separation of second harmonic and photoluminescence bands due to their distinct coherence properties. A detailed analysis yields fractional power dependence exponents in the range of 3-4, indicating the presence of multiple nonlinear processes. The range in measured exponents is attributed to differences in local field enhancement, which is supported by independent photoluminescence and structural measurements. Simulations based on Keldysh theory suggest contributions by three- and four-photon absorption as well as avalanche ionization in agreement with experimental findings.

Limiting energy loss distributions for multiphoton channeling radiation

International Nuclear Information System (INIS)

Bondarenco, M.V.

2015-01-01

Recent results in the theory of multiphoton spectra for coherent radiation sources are overviewed, with the emphasis on channeling radiation. For the latter case, the importance of the order of resummation and averaging is emphasized. Limiting shapes of multiphoton spectra at high intensity are discussed for different channeling regimes. In some spectral regions, there emerges a correspondence between the radiative energy loss and the electron integrals of motion

The importance of spectroscopy for infrared multiphoton excitation

International Nuclear Information System (INIS)

Fuss, W.; Kompa, K.L.

1980-07-01

It is substantiated by examples that the infrared spectra of molecules in high vibrational states are similar in width to those of the ground states. Therefore in order to explain collisionless infrared multiphoton excitation, the existence of resonance has to be checked, not only for the first three steps, but for all of them. That is, their (low resolution) spectra should be studied. This review summarizes the spectroscopic mechanisms contributing to multiphoton excitation, which have been suggested to date, including several kinds of rotational compensation and of vibrational level splitting, which cooperate to overcome the anharmonic shift. The spectral quasicontinuum, generated by intensity borrowing, must neither be very broad nor dense, and collisionless vibrational relaxation is only important at very high energies. Knowledge of relatively few spectroscopic detailes helps to understand many details and many differences in multiphoton excitatio. (orig.)

Optical Magnetometry Using Multiphoton Transitions

Science.gov (United States)

Degenkolb, Skyler M.

Optical magnetometry plays a critical role in low-energy precision measurements and numerous other applications. In particular, permanent electric dipole moment (EDM) searches impose strict requirements on magnetic field sensitivity of the underlying atomic or molecular species. Other magnetometer properties - such as chemical reactivity, dielectric strength, and interaction cross-sections with other species - also impose limitations on experimental conditions. Here, we explore a novel approach to optical magnetometry, using multiphoton transitions of diamagnetic atoms to detect Larmor precession of polarized nuclei. Resonant probes are possible at moderate ultraviolet wavelengths, and hyperfine structure couples spin precession to fluorescence transitions with negligible backgrounds; paramagnetic rotation due to intensity-dependent dispersion may also be detectable. Nuclear spins and nonlinear optical excitation introduce new degrees of freedom, and evade limitations arising from rapid electronic decoherence. This dissertation reports progress towards two-photon optical magnetometry using ytterbium, rubidium, and xenon. We characterize the influence of probe polarization and magnetic fields on fluorescence spectra, for one- and two-photon continuous-wave (cw) excitation of ytterbium. Resolved hyperfine and isotope structure allow us to use spin-zero isotopes for diagnostics and normalization, and we develop analysis for overlapping two-photon resonances. We also report measurements of two-photon excitation in ytterbium and rubidium using picosecond laser pulses, and in xenon using a cw laser. Although hyperfine structure is unresolved, the rubidium measurements are sensitive to probe field polarization. Fluorescence spectra from two-photon excitation of ytterbium with femtosecond pulses show modulation when the repetition rate changes. Although techniques for polarizing noble gas nuclei are mature, existing cell designs are incompatible with two

Angle-resolved imaging of single-crystal materials with MeV helium ions

Energy Technology Data Exchange (ETDEWEB)

Strathman, M D; Baumann, S [Charles Evans and Associates, Redwood City, CA (United States)

1992-02-01

The simplest form of angle-resolved mapping for single-crystal materials is the creation of a channeling angular scan. Several laboratories have expanded this simple procedure to include mapping as a function of two independent tilts. These angle-resolved images are particularly suited to the assessment of crystal parameters including disorder, lattice location of impurities, and lattice stress. This paper will describe the use of the Charles Evans and Associates RBS-400 scattering chamber for acquisition, display, and analysis of angle-resolved images obtained from backscattered helium ions. Typical data acquisition times are 20 min for a {+-}2deg X-Y tilt scan with 2500 pixels (8/100deg resolution), and 10 nC per pixel. In addition, we will present a method for automatically aligning crystals for channeling measurements based on this imaging technology. (orig.).

Angle-resolved imaging of single-crystal materials with MeV helium ions

International Nuclear Information System (INIS)

Strathman, M.D.; Baumann, S.

1992-01-01

The simplest form of angle-resolved mapping for single-crystal materials is the creation of a channeling angular scan. Several laboratories have expanded this simple procedure to include mapping as a function of two independent tilts. These angle-resolved images are particularly suited to the assessment of crystal parameters including disorder, lattice location of impurities, and lattice stress. This paper will describe the use of the Charles Evans and Associates RBS-400 scattering chamber for acquisition, display, and analysis of angle-resolved images obtained from backscattered helium ions. Typical data acquisition times are 20 min for a ±2deg X-Y tilt scan with 2500 pixels (8/100deg resolution), and 10 nC per pixel. In addition, we will present a method for automatically aligning crystals for channeling measurements based on this imaging technology. (orig.)

Multi-photon ionization of atoms in intense short-wavelength radiation fields

Science.gov (United States)

Meyer, Michael

2015-05-01

The unprecedented characteristics of XUV and X-ray Free Electron Lasers (FELs) have stimulated numerous investigations focusing on the detailed understanding of fundamental photon-matter interactions in atoms and molecules. In particular, the high intensities (up to 106 W/cm2) giving rise to non-linear phenomena in the short wavelength regime. The basic phenomenology involves the production of highly charged ions via electron emission to which both sequential and direct multi-photon absorption processes contribute. The detailed investigation of the role and relative weight of these processes under different conditions (wavelength, pulse duration, intensity) is the key element for a comprehensive understanding of the ionization dynamics. Here the results of recent investigations are presented, performed at the FELs in Hamburg (FLASH) and Trieste (FERMI) on atomic systems with electronic structures of increasing complexity (Ar, Ne and Xe). Mainly, electron spectroscopy is used to obtain quantitative information about the relevance of various multi-photon ionization processes. For the case of Ar, a variety of processes including above threshold ionization (ATI) from 3p and 3s valence shells, direct 2p two-photon ionization and resonant 2p-4p two-photon excitations were observed and their role was quantitatively determined comparing the experimental ionization yields to ab-initio calculations of the cross sections for the multi-photon processes. Using Ar as a benchmark to prove the reliability of the combined experimental and theoretical approach, the more complex and intriguing case of Xe was studied. Especially, the analysis of the two-photon ATI from the Xe 4d shell reveals new insight into the character of the 4d giant resonance, which was unresolved in the linear one-photon regime. Finally, the influence of intense XUV radiation to the relaxation dynamics of the Ne 2s-3p resonance was investigated by angle-resolved electron spectroscopy, especially be observing

Multiphoton (e,2e) process of hydrogen atom in strong laser field

Energy Technology Data Exchange (ETDEWEB)

Ghosh Deb, S.; Roy, S.; Sinha, C. [Indian Association for the Cultivation of Science, Dept. of Theoretical Physics, Jadavpur, Kolkata (India)

2009-12-15

The dynamics of the electron impact multiphoton ionization of a hydrogen atom in the presence of an intense laser field (e, n gamma e) has been studied theoretically for laser polarization parallel and perpendicular to the incident momentum, with a view to comparing (qualitatively) the results with the recent kinematically complete experiments of Hoehr et al. for the He target. Significant laser modifications are noted in the present doubly (DDCS) and the fully differential multiphoton cross sections (TDCS) for both the geometries (parallel and perpendicular). For most of the explored kinematics (chosen in accordance with the experiment), the present binary peak intensity of the laser-assisted multiphoton TDCS is significantly enhanced with respect to the field free ones, in qualitative agreement with the experiment. Importance of the multiphoton effects is also studied. The multiphoton cross sections in the zeroth order approximation of the ejected electron wavefunction (CV) obeys the Kroll Watson sum rule while it does not hold good in the corresponding first order approximation (MCV). (authors)

Multiphoton ionization processes in strong laser

International Nuclear Information System (INIS)

Krstic, P.

1982-01-01

Multiphoton ionization of hydrogen in ultrastrong laser fields is studied. The previous calculations of this process yield differing result for the transition rate. We show the relations between them and difficulties with each of them. One difficulty is that the finite spatial and time extent of the laser field has been omitted. It is also found that a laser field, which is sufficiently intense to be labeled ultrastrong, makes the electron move relativistically so that it becomes necessary to use Volkov states to describe the electron in the laser field. The transition rate is obtained, using a CO laser as an example, and it is found that the transition rate rises as the laser intensity rises. This is a consequence of the use of relativistic kinematics and is not true nonrelativistically. We also discuss the multiple peaks observed in the energy spectrum of electrons resulting from multiphoton ionization of atoms by lasers. When the laser intensity is large enough for the ponderomotive force to result in appreciable broading of the peaks we show the shape of the broadened peaks contains useful information. We show that the multiphoton ionization probability as a function of laser intensity can be obtained but that the free-free cross sections, which are in principle also obtainable, are probably not obtainable in practice. Finally, we describe the theory of the absorption of more than minimum numbers of photons needed to ionize an atom by an intense laser. The basic approximation used is that the atom is adiabatically deformed by the laser and an impulsive interaction then results in multiphoton absorption. In our first calculation we allow only one resonant excited state to be included in the adiabatic deformation. In our second we also allow the lowest energy continuum to be included. The two results are then compared

Time-resolved computed tomography of the liver: retrospective, multi-phase image reconstruction derived from volumetric perfusion imaging

Energy Technology Data Exchange (ETDEWEB)

Fischer, Michael A.; Kartalis, Nikolaos; Aspelin, Peter; Albiin, Nils; Brismar, Torkel B. [Karolinska University Hospital, Division of Medical Imaging and Technology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm (Sweden); Leidner, Bertil; Svensson, Anders [Karolinska University Hospital, Division of Medical Imaging and Technology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm (Sweden); Karolinska University Hospital Huddinge, Department of Radiology, Stockholm (Sweden)

2014-01-15

To assess feasibility and image quality (IQ) of a new post-processing algorithm for retrospective extraction of an optimised multi-phase CT (time-resolved CT) of the liver from volumetric perfusion imaging. Sixteen patients underwent clinically indicated perfusion CT using 4D spiral mode of dual-source 128-slice CT. Three image sets were reconstructed: motion-corrected and noise-reduced (MCNR) images derived from 4D raw data; maximum and average intensity projections (time MIP/AVG) of the arterial/portal/portal-venous phases and all phases (total MIP/ AVG) derived from retrospective fusion of dedicated MCNR split series. Two readers assessed the IQ, detection rate and evaluation time; one reader assessed image noise and lesion-to-liver contrast. Time-resolved CT was feasible in all patients. Each post-processing step yielded a significant reduction of image noise and evaluation time, maintaining lesion-to-liver contrast. Time MIPs/AVGs showed the highest overall IQ without relevant motion artefacts and best depiction of arterial and portal/portal-venous phases respectively. Time MIPs demonstrated a significantly higher detection rate for arterialised liver lesions than total MIPs/AVGs and the raw data series. Time-resolved CT allows data from volumetric perfusion imaging to be condensed into an optimised multi-phase liver CT, yielding a superior IQ and higher detection rate for arterialised liver lesions than the raw data series. (orig.)

MCNP simulations of a new time-resolved Compton scattering imaging technique

International Nuclear Information System (INIS)

Ilan, Y.

2004-01-01

Medical images of human tissue can be produced using Computed Tomography (CT), Positron Emission Tomography (PET), Ultrasound or Magnetic Resonance Imaging (MRI). In all of the above techniques, in order to get a three-dimensional (3D) image, one has to rotate or move the source, the detectors or the scanned target. This procedure is complicated, time consuming and increases the cost and weight of the scanning equipment. Time resolved optical tomography has been suggested as an alternative to the above conventional methods. This technique implies near infrared light (NIR) and fast time-resolved detectors to obtain a 3D image of the scanned target. However, due to the limited penetration of the NIR light in the tissue, the application of this technique is limited to soft tissue like a female breast or a premature infant brain

Infrared multiphoton dissociation of acrolein. Time-resolved observation of CO ( v = 1) IR emission at 4.7 μm

Science.gov (United States)

Chowdhury, P. K.; Rama Rao, K. V. S.; Mittal, J. P.

1994-02-01

In contrast to the photochemistry of electronically excited acrolein producing vinyl and formyl radicals via CC bond rupture, multiphoton vibrationally excited molecules undergo concerted dissociation generating CO and ethylene. Vibrational excitation in the CO product is detected immediately following the CO 2 laser pulse by observing IR emission at 4.7 μm. The decay of the IR emission was studied as a function of acrolein pressure. A vibrational-vibrational relaxation rate constant of CO ( v=1) by acrolein is found to be 1240 ± 200 Torr -1 s -1.

Denoising time-resolved microscopy image sequences with singular value thresholding

Energy Technology Data Exchange (ETDEWEB)

Furnival, Tom, E-mail: tjof2@cam.ac.uk; Leary, Rowan K., E-mail: rkl26@cam.ac.uk; Midgley, Paul A., E-mail: pam33@cam.ac.uk

2017-07-15

Time-resolved imaging in microscopy is important for the direct observation of a range of dynamic processes in both the physical and life sciences. However, the image sequences are often corrupted by noise, either as a result of high frame rates or a need to limit the radiation dose received by the sample. Here we exploit both spatial and temporal correlations using low-rank matrix recovery methods to denoise microscopy image sequences. We also make use of an unbiased risk estimator to address the issue of how much thresholding to apply in a robust and automated manner. The performance of the technique is demonstrated using simulated image sequences, as well as experimental scanning transmission electron microscopy data, where surface adatom motion and nanoparticle structural dynamics are recovered at rates of up to 32 frames per second. - Highlights: • Correlations in space and time are harnessed to denoise microscopy image sequences. • A robust estimator provides automated selection of the denoising parameter. • Motion tracking and automated noise estimation provides a versatile algorithm. • Application to time-resolved STEM enables study of atomic and nanoparticle dynamics.

Clinical multiphoton tomography and clinical two-photon microendoscopy

Science.gov (United States)

König, Karsten; Bückle, Rainer; Weinigel, Martin; Elsner, Peter; Kaatz, Martin

2009-02-01

We report on applications of high-resolution clinical multiphoton tomography based on the femtosecond laser system DermaInspectTM with its flexible mirror arm in Australia, Asia, and Europe. Applications include early detection of melanoma, in situ tracing of pharmacological and cosmetical compounds including ZnO nanoparticles in the epidermis and upper dermis, the determination of the skin aging index SAAID as well as the study of the effects of anti-aging products. In addition, first clinical studies with novel rigid high-NA two-photon 1.6 mm GRIN microendoscopes have been conducted to study the effect of wound healing in chronic wounds (ulcus ulcera) as well as to perform intrabody imaging with subcellular resolution in small animals.

Multiphoton above threshold effects in strong-field fragmentation

DEFF Research Database (Denmark)

B Madsen, C; Anis, F; B Madsen, L

2012-01-01

We present a study of multiphoton dissociative ionization from molecules. By solving the time-dependent Schrödinger equation for H2+ and projecting the solution onto double continuum scattering states, we observe the correlated electron-nuclear ionization dynamics in detail. We show—for the first...... time—how multiphoton structure prevails as long as one accounts for the energies of all the fragments. Our current work provides a new avenue to analyze strong-field fragmentation that leads to a deeper understanding of the correlated molecular dynamics....

High resolution time- and 2-dimensional space-resolved x-ray imaging of plasmas at NOVA

International Nuclear Information System (INIS)

Landen, O.L.

1992-01-01

A streaked multiple pinhole camera technique, first used by P. Choi et al. to record time- and 2-D space-resolved soft X-ray images of plasma pinches, has been implemented on laser plasmas at NOVA. The instrument is particularly useful for time-resolved imaging of small sources ( 2.5 key imaging, complementing the existing 1--3 key streaked X-ray microscope capabilities at NOVA

Multiphoton ionization/dissociation of osmium tetroxide

International Nuclear Information System (INIS)

Ding, D.; Puretzky, A.A.; Compton, R.N.

1993-01-01

The mechanisms leading to laser multiphoton ionization and dissociation (MPI/MPD) of osmium tetroxide (OsO 4 ) have been investigated from measurements of the kinetic energies of product ions (Os + , Os 2+ , OsO + , O 2 + , O + ) and photoelectrons as a function of the laser wavelength. Neutral channels, intermediate to the dominant Os + ionization channel, such as OsO 4 →OsO 4-n +nO are examined using resonance-enhanced multiphoton ionization (REMPI) of the fast O atoms. Equipartition of the available photon energy among the fragments is observed. The wavelength dependence of the Os + ion signal suggests that one or more of the steps leading to Os + ions involve molecular ions and/or excited neutral atoms. The observed preponderance of very slow ( 2+ is shown to result primarily from REMPI of Os +

Semiclassical analysis of long-wavelength multiphoton processes: The Rydberg atom

International Nuclear Information System (INIS)

Vela-Arevalo, Luz V.; Fox, Ronald F.

2004-01-01

We study the problem of multiphoton processes for intense, long-wavelength irradiation of atomic and molecular electrons. An exact, nonperturbative approach is applied to the standard vector potential coupling Hamiltonian for a three-dimensional hydrogenlike atom in a microwave field treated semiclassically. Multiphoton probability exchange is calculated in both the velocity and the length gauges, by applying the Goeppert-Mayer gauge transformation. The expansion of the time-dependent solution in terms of Floquet states delineates the mechanism of multiphoton transitions. A detailed analysis of the Floquet states and quasienergies as functions of the field parameters allows us to describe the relation between avoided quasienergy crossings and multiphoton probability exchange. We formulate analytical expressions for the variation of quasienergies and Floquet states with respect to the field parameters, and demonstrate that avoided quasienergy crossings are accompanied by dramatic changes in the Floquet states. Analysis of the Floquet states, for small values of the field strength, yields selection rules for the avoided quasienergy crossings. In the case of strong fields, the simultaneous choice of frequency and strength of the field producing an avoided crossing results in improved ionization probability

Multimodal microscopy and the stepwise multi-photon activation fluorescence of melanin

Science.gov (United States)

Lai, Zhenhua

The author's work is divided into three aspects: multimodal microscopy, stepwise multi-photon activation fluorescence (SMPAF) of melanin, and customized-profile lenses (CPL) for on-axis laser scanners, which will be introduced respectively. A multimodal microscope provides the ability to image samples with multiple modalities on the same stage, which incorporates the benefits of all modalities. The multimodal microscopes developed in this dissertation are the Keck 3D fusion multimodal microscope 2.0 (3DFM 2.0), upgraded from the old 3DFM with improved performance and flexibility, and the multimodal microscope for targeting small particles (the "Target" system). The control systems developed for both microscopes are low-cost and easy-to-build, with all components off-the-shelf. The control system have not only significantly decreased the complexity and size of the microscope, but also increased the pixel resolution and flexibility. The SMPAF of melanin, activated by a continuous-wave (CW) mode near-infrared (NIR) laser, has potential applications for a low-cost and reliable method of detecting melanin. The photophysics of melanin SMPAF has been studied by theoretical analysis of the excitation process and investigation of the spectra, activation threshold, and photon number absorption of melanin SMPAF. SMPAF images of melanin in mouse hair and skin, mouse melanoma, and human black and white hairs are compared with images taken by conventional multi-photon fluorescence microscopy (MPFM) and confocal reflectance microscopy (CRM). SMPAF images significantly increase specificity and demonstrate the potential to increase sensitivity for melanin detection compared to MPFM images and CRM images. Employing melanin SMPAF imaging to detect melanin inside human skin in vivo has been demonstrated, which proves the effectiveness of melanin detection using SMPAF for medical purposes. Selective melanin ablation with micrometer resolution has been presented using the Target system

Wavelength dependent photoelectron circular dichroism of limonene studied by femtosecond multiphoton laser ionization and electron-ion coincidence imaging

Science.gov (United States)

Rafiee Fanood, Mohammad M.; Janssen, Maurice H. M.; Powis, Ivan

2016-09-01

Enantiomers of the monoterpene limonene have been investigated by (2 + 1) resonance enhanced multiphoton ionization and photoelectron circular dichroism employing tuneable, circularly polarized femtosecond laser pulses. Electron imaging detection provides 3D momentum measurement while electron-ion coincidence detection can be used to mass-tag individual electrons. Additional filtering, by accepting only parent ion tagged electrons, can be then used to provide discrimination against higher energy dissociative ionization mechanisms where more than three photons are absorbed to better delineate the two photon resonant, one photon ionization pathway. The promotion of different vibrational levels and, tentatively, different electronic ion core configurations in the intermediate Rydberg states can be achieved with different laser excitation wavelengths (420 nm, 412 nm, and 392 nm), in turn producing different state distributions in the resulting cations. Strong chiral asymmetries in the lab frame photoelectron angular distributions are quantified, and a comparison made with a single photon (synchrotron radiation) measurement at an equivalent photon energy.

Imaging by Electrochemical Scanning Tunneling Microscopy and Deconvolution Resolving More Details of Surfaces Nanomorphology

DEFF Research Database (Denmark)

Andersen, Jens Enevold Thaulov

observed in high-resolution images of metallic nanocrystallites may be effectively deconvoluted, as to resolve more details of the crystalline morphology (see figure). Images of surface-crystalline metals indicate that more than a single atomic layer is involved in mediating the tunneling current......Upon imaging, electrochemical scanning tunneling microscopy (ESTM), scanning electrochemical micro-scopy (SECM) and in situ STM resolve information on electronic structures and on surface topography. At very high resolution, imaging processing is required, as to obtain information that relates...... to crystallographic-surface structures. Within the wide range of new technologies, those images surface features, the electrochemical scanning tunneling microscope (ESTM) provides means of atomic resolution where the tip participates actively in the process of imaging. Two metallic surfaces influence ions trapped...

Polarization control of multi-photon absorption under intermediate femtosecond laser field

International Nuclear Information System (INIS)

Cheng Wenjing; Liang Guo; Wu Ping; Liu Pei; Jia Tianqing; Sun Zhenrong; Zhang Shian

2017-01-01

It has been shown that the femtosecond laser polarization modulation is a very simple and well-established method to control the multi-photon absorption process by the light–matter interaction. Previous studies mainly focused on the multi-photon absorption control in the weak field. In this paper, we further explore the polarization control behavior of multi-photon absorption process in the intermediate femtosecond laser field. In the weak femtosecond laser field, the second-order perturbation theory can well describe the non-resonant two-photon absorption process. However, the higher order nonlinear effect (e.g., four-photon absorption) can occur in the intermediate femtosecond laser field, and thus it is necessary to establish new theoretical model to describe the multi-photon absorption process, which includes the two-photon and four-photon transitions. Here, we construct a fourth-order perturbation theory to study the polarization control behavior of this multi-photon absorption under the intermediate femtosecond laser field excitation, and our theoretical results show that the two-photon and four-photon excitation pathways can induce a coherent interference, while the coherent interference is constructive or destructive that depends on the femtosecond laser center frequency. Moreover, the two-photon and four-photon transitions have the different polarization control efficiency, and the four-photon absorption can obtain the higher polarization control efficiency. Thus, the polarization control efficiency of the whole excitation process can be increased or decreased by properly designing the femtosecond laser field intensity and laser center frequency. These studies can provide a clear physical picture for understanding and controlling the multi-photon absorption process in the intermediate femtosecond laser field, and also can provide a theoretical guidance for the future experimental realization. (paper)

Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states

Science.gov (United States)

dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio

2004-03-01

We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n -mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherence and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [ F. Dell’Anno, S. De Siena, and F. Illuminati, 69, 033813 (2004) ], we provide the extension of the nonlinear canonical formalism to multimode systems, we introduce the associated heterodyne multiphoton squeezed states, and we discuss their possible experimental realization.

Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states

International Nuclear Information System (INIS)

Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

2004-01-01

We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n-mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherence and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [F. Dell'Anno, S. De Siena, and F. Illuminati, 69, 033813 (2004)], we provide the extension of the nonlinear canonical formalism to multimode systems, we introduce the associated heterodyne multiphoton squeezed states, and we discuss their possible experimental realization

Signal improvement in multiphoton microscopy by reflection with simple mirrors near the sample

Science.gov (United States)

Rehberg, Markus; Krombach, Fritz; Pohl, Ulrich; Dietzel, Steffen

2010-03-01

In conventional fluorescence or confocal microscopy, emitted light is generated not only in the focal plane but also above and below. The situation is different in multiphoton-induced fluorescence and multiphoton-induced higher harmonic generation. Here, restriction of signal generation to a single focal point permits that all emitted photons can contribute to image formation if collected, regardless of their path through the specimen. Often, the intensity of the emitted light is rather low in biological specimens. We present a method to significantly increase the fraction of photons collected by an epi (backward) detector by placing a simple mirror, an aluminum-coated coverslip, directly under the sample. Samples investigated include fluorescent test slides, collagen gels, and thin-layered, intact mouse skeletal muscles. Quantitative analysis revealed an intensity increase of second- and third-harmonic generated signal in skeletal muscle of nine- and sevenfold respectively, and of fluorescent signal in test slides of up to twofold. Our approach thus allows significant signal improvement also for situations were a forward detection is impossible, e.g., due to the anatomy of animals in intravital microscopy.

Multimodal imaging of vocal fold scarring in a rabbit model by multiphoton microscopy

Science.gov (United States)

Kazarine, Alexei; Bouhabel, Sarah; Douillette, Annie H.; Kost, Karen; Li-Jessen, Nicole Y. K.; Mongeau, Luc; Wiseman, Paul W.

2017-02-01

Vocal fold scarring as a result of injury or disease can lead to voice disorders which can significantly affect the quality of life. During the scarring process, the normally elastic tissue of the vocal fold lamina propria is replaced by a much stiffer collagen-based fibrotic tissue, which impacts the fold's ability to vibrate. Surgical removal of this tissue is often ineffective and can result in further scarring. Injectable biomaterials, a form of tissue engineering, have been proposed as a potential solution to reduce existing scars or prevent scarring altogether. In order to properly evaluate the effectiveness of these new materials, multiphoton microscopy emerges as an effective tool due to its intrinsic multiple label free contrast mechanisms that highlight extracellular matrix elements. In this study, we evaluate the spatial distribution of collagen and elastin fibers in a rabbit model using second harmonic generation (SHG), third harmonic generation (THG) and two photon autofluorescence (TPAF) applied to unlabeled tissue sections. In comparison to traditional methods that rely on histological staining or immunohistochemistry, SHG, THG and TPAF provide a more reliable detection of these native proteins. The evaluation of collagen levels allows us to follow the extent of scarring, while the presence of elastin fibers is thought to be indicative of the level of healing of the injured fold. Using these imaging modalities, we characterize the outcome of injectable biomaterial treatments in order to direct future treatments for tissue engineering.

Use of multi-photon laser-scanning microscopy to describe the distribution of xenobiotic chemicals in fish early life stages

International Nuclear Information System (INIS)

Hornung, Michael W.; Cook, Philip M.; Flynn, Kevin M.; Lothenbach, Doug B.; Johnson, Rodney D.; Nichols, John W.

2004-01-01

To better understand the mechanisms by which persistent bioaccumulative toxicants (PBTs) produce toxicity during fish early life stages (ELS), dose-response relationships need to be understood in relation to the dynamic distribution of chemicals in sensitive tissues. In this study, a multi-photon laser scanning microscope (MPLSM) was used to determine the multi-photon excitation spectra of several polyaromatic hydrocarbons (PAHs) and to describe chemical distribution among tissues during fish ELS. The multi-photon excitation spectra revealed intense fluorescent signal from the model fluorophore, pentamethyl-difluoro-boro-indacene (BODIPY[reg], less signal from benzo[a]pyrene and fluoranthene, and no detectable signal from pyrene. The imaging method was tested by exposing newly fertilized medaka (Oryzias latipes) eggs to BODIPY[reg] or fluoranthene for 6 h, followed by transfer to clean media. Embryos and larvae were then imaged through 5 days post-hatch. The two test chemicals partitioned similarly throughout development and differences in fluorescence intensity among tissues were evident to a depth of several hundred microns. Initially, the most intense signal was observed in the oil droplet within the yolk, while a moderate signal was seen in the portion of the yolk containing the yolk-platelets. As embryonic development progressed, the liver biliary system, gall bladder, and intestinal tract accumulated strong fluorescent signal. After hatch, once the gastrointestinal tract was completely developed, most of the fluorescent signal was cleared. The MPLSM is a useful tool to describe the tissue distribution of fluorescent PBTs during fish ELS

Scanless multitarget-matching multiphoton excitation fluorescence microscopy

Directory of Open Access Journals (Sweden)

Junpeng Qiu

2018-03-01

Full Text Available Using the combination of a reflective blazed grating and a reflective phase-only diffractive spatial light modulator (SLM, scanless multitarget-matching multiphoton excitation fluorescence microscopy (SMTM-MPM was achieved. The SLM shaped an incoming mode-locked, near-infrared Ti:sapphire laser beam into an excitation pattern with addressable shapes and sizes that matched the samples of interest in the field of view. Temporal and spatial focusing were simultaneously realized by combining an objective lens and a blazed grating. The fluorescence signal from illuminated areas was recorded by a two-dimensional sCMOS camera. Compared with a conventional temporal focusing multiphoton microscope, our microscope achieved effective use of the laser power and decreased photodamage with higher axial resolution.

Video-rate resonant scanning multiphoton microscopy: An emerging technique for intravital imaging of the tumor microenvironment

OpenAIRE

Kirkpatrick, Nathaniel D.; Chung, Euiheon; Cook, Daniel C.; Han, Xiaoxing; Gruionu, Gabriel; Liao, Shan; Munn, Lance L.; Padera, Timothy P.; Fukumura, Dai; Jain, Rakesh K.

2012-01-01

The abnormal tumor microenvironment fuels tumor progression, metastasis, immune suppression, and treatment resistance. Over last several decades, developments in and applications of intravital microscopy have provided unprecedented insights into the dynamics of the tumor microenvironment. In particular, intravital multiphoton microscopy has revealed the abnormal structure and function of tumor-associated blood and lymphatic vessels, the role of aberrant tumor matrix in drug delivery, invasion...

Identification of normal and cancerous human colorectal muscularis propria by multiphoton microscopy in different sections

International Nuclear Information System (INIS)

Zhou, Yi; Li, Lianhuang; Zhuo, Shuangmu; Zhu, Xiaoqin; Chen, Jianxin; Chen, Zhifen; Guan, Guoxian; Kang, Deyong

2016-01-01

Multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) as a potential diagnostic tool is attractive. MPM can effectively provide information about morphological and biochemical changes in biological tissues at the molecular level. In this paper, we attempt to identify normal and cancerous human colorectal muscularis propria by multiphoton microscopy in different sections (both in transverse and longitudinal sections). The results show that MPM can display different microstructure changes in the transverse and longitudinal sections of colorectal muscularis propria. MPM also can quantitatively describe the alteration of collagen content between normal and cancerous muscle layers. These are important pathological findings that MPM images can bring more detailed complementary information about tissue architecture and cell morphology through observing the transverse and longitudinal sections of colorectal muscularis propria. This work demonstrates that MPM can be better for identifying the microstructural characteristics of normal and cancerous human colorectal muscularis propria in different sections. (paper)

Identification of normal and cancerous human colorectal muscularis propria by multiphoton microscopy in different sections

Science.gov (United States)

Zhou, Yi; Chen, Zhifen; Kang, Deyong; li, Lianhuang; Zhuo, Shuangmu; Zhu, Xiaoqin; Guan, Guoxian; Chen, Jianxin

2016-01-01

Multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) as a potential diagnostic tool is attractive. MPM can effectively provide information about morphological and biochemical changes in biological tissues at the molecular level. In this paper, we attempt to identify normal and cancerous human colorectal muscularis propria by multiphoton microscopy in different sections (both in transverse and longitudinal sections). The results show that MPM can display different microstructure changes in the transverse and longitudinal sections of colorectal muscularis propria. MPM also can quantitatively describe the alteration of collagen content between normal and cancerous muscle layers. These are important pathological findings that MPM images can bring more detailed complementary information about tissue architecture and cell morphology through observing the transverse and longitudinal sections of colorectal muscularis propria. This work demonstrates that MPM can be better for identifying the microstructural characteristics of normal and cancerous human colorectal muscularis propria in different sections.

Theory of multiphoton ionization of atoms

International Nuclear Information System (INIS)

Szoeke, A.

1986-03-01

A non-perturbative approach to the theory of multiphoton ionization is reviewed. Adiabatic Floquet theory is its first approximation. It explains qualitatively the energy and angular distribution of photoelectrons. In many-electron atoms it predicts collective and inner shell excitation. 14 refs

Time-resolved tomographic images of a relativistic electron beam

International Nuclear Information System (INIS)

Koehler, H.A.; Jacoby, B.A.; Nelson, M.

1984-07-01

We obtained a sequential series of time-resolved tomographic two-dimensional images of a 4.5-MeV, 6-kA, 30-ns electron beam. Three linear fiber-optic arrays of 30 or 60 fibers each were positioned around the beam axis at 0 0 , 61 0 , and 117 0 . The beam interacting with nitrogen at 20 Torr emitted light that was focused onto the fiber arrays and transmitted to a streak camera where the data were recorded on film. The film was digitized, and two-dimensional images were reconstructed using the maximum-entropy tomographic technique. These images were then combined to produce an ultra-high-speed movie of the electron-beam pulse

Site-resolved imaging of a bosonic Mott insulator using ytterbium atoms

Science.gov (United States)

Miranda, Martin; Inoue, Ryotaro; Tambo, Naoki; Kozuma, Mikio

2017-10-01

We demonstrate site-resolved imaging of a strongly correlated quantum system without relying on laser cooling techniques during fluorescence imaging. We observe the formation of Mott shells in the insulating regime and realize thermometry in an atomic cloud. This work proves the feasibility of the noncooled approach and opens the door to extending the detection technology to new atomic species.

Non-invasive assessment of the liver using imaging

Science.gov (United States)

Thorling Thompson, Camilla; Wang, Haolu; Liu, Xin; Liang, Xiaowen; Crawford, Darrell H.; Roberts, Michael S.

2016-12-01

Chronic liver disease causes 2,000 deaths in Australia per year and early diagnosis is crucial to avoid progression to cirrhosis and end stage liver disease. There is no ideal method to evaluate liver function. Blood tests and liver biopsies provide spot examinations and are unable to track changes in function quickly. Therefore better techniques are needed. Non-invasive imaging has the potential to extract increased information over a large sampling area, continuously tracking dynamic changes in liver function. This project aimed to study the ability of three imaging techniques, multiphoton and fluorescence lifetime imaging microscopy, infrared thermography and photoacoustic imaging, in measuring liver function. Collagen deposition was obvious in multiphoton and fluorescence lifetime imaging in fibrosis and cirrhosis and comparable to conventional histology. Infrared thermography revealed a significantly increased liver temperature in hepatocellular carcinoma. In addition, multiphoton and fluorescence lifetime imaging and photoacoustic imaging could both track uptake and excretion of indocyanine green in rat liver. These results prove that non-invasive imaging can extract crucial information about the liver continuously over time and has the potential to be translated into clinic in the assessment of liver disease.

Study the multi-photon absorption process in two types of molecules

International Nuclear Information System (INIS)

Al-azawi, H.R.

1986-01-01

The aim of the present work was to study the multi-photon absorption process in two types of molecules; spherical top such as SF 6 molecules and assymetric top such as CHOOH and C 2 H 4 molecules. This work also aimed to study the effect of buffer gas pressure (Ar), which is transparent to the infrared (IR) laser on the multiphoton absorption of both types of molecules. A pulsed (TEA) CO 2 laser was used as a source which generates multi-lines in the IR-region of the spectrum and an optoacoustic detector was used to detect the energy absorbed by the molecules. In this study, the relaxation process was found to be faster in the heavy molecules than that in the light ones. A limit in the Ar pressure was observed. Below this limit, the gas acted as an active buffer gas and above it, the multi-photon absorption process was quenched. This work also aimed to study the multi-photon absorption spectrum for the CHOOH molecules in the range (1067-1090 cm -1 ). This spectrum was found to be consistent with the linear absorption spectrum obtained for the same range. The density of the vibrational states as a function of the vibrational energy was studied for the molecules SF 6 , CHOOH and C 2 H 4 . The results were used to interpret (i) the difference in the energy absorbed by difference molecules at the same energy density and (ii) the non-linearity in the multi-photon absorption for CHOOH molecules. 1 tab.; 40 figs.; 70 refs

RESOLVE: A new algorithm for aperture synthesis imaging of extended emission in radio astronomy

Science.gov (United States)

Junklewitz, H.; Bell, M. R.; Selig, M.; Enßlin, T. A.

2016-02-01

We present resolve, a new algorithm for radio aperture synthesis imaging of extended and diffuse emission in total intensity. The algorithm is derived using Bayesian statistical inference techniques, estimating the surface brightness in the sky assuming a priori log-normal statistics. resolve estimates the measured sky brightness in total intensity, and the spatial correlation structure in the sky, which is used to guide the algorithm to an optimal reconstruction of extended and diffuse sources. During this process, the algorithm succeeds in deconvolving the effects of the radio interferometric point spread function. Additionally, resolve provides a map with an uncertainty estimate of the reconstructed surface brightness. Furthermore, with resolve we introduce a new, optimal visibility weighting scheme that can be viewed as an extension to robust weighting. In tests using simulated observations, the algorithm shows improved performance against two standard imaging approaches for extended sources, Multiscale-CLEAN and the Maximum Entropy Method.

Multiphoton tomography to detect chemo- and biohazards

Science.gov (United States)

König, Karsten

2015-03-01

In vivo high-resolution multiphoton/CARS tomography provides optical biopsies with 300 nm lateral resolution with chemical fingerprints. Thousands of volunteers and patients have been investigated for early cancer diagnosis, evaluation of anti-ageing cosmetic products, and changes of cellular metabolism by UV exposure and decreased oxygen supply. The skin as the outermost and largest organ is also the major target of CB agents. Current UV-based sensors are useful for bio-aerosol sensing but not for evaluating exposed in vivo skin. Here we evaluate the use of 4D multiphoton/CARS tomographs based on near infrared femtosecond laser radiation, time-correlated single photon counting (FLIM) and white light generation by photonic crystal fibers to detect bio- and chemohazards in human in vivo skin using twophoton fluorescence, SHG, and Raman signals.

Usefulness of Intravital Multiphoton Microscopy in Visualizing Study of Mouse Cochlea and Volume Changes in the Scala Media.

Science.gov (United States)

Ju, Hyun Mi; Lee, Sun Hee; Kong, Tae Hoon; Kwon, Seung-Hae; Choi, Jin Sil; Seo, Young Joon

2017-01-01

Conventional microscopy has limitations in viewing the cochlear microstructures due to three-dimensional spiral structure and the overlying bone. But these issues can be overcome by imaging the cochlea in vitro with intravital multiphoton microscopy (MPM). By using near-infrared lasers for multiphoton excitation, intravital MPM can detect endogenous fluorescence and second harmonic generation of tissues. In this study, we used intravital MPM to visualize various cochlear microstructures without any staining and non-invasively analyze the volume changes of the scala media (SM) without removing the overlying cochlear bone. The intravital MPM images revealed various tissue types, ranging from thin membranes to dense bone, as well as the spiral ganglion beneath the cochlear bone. The two-dimensional, cross-sectional, and serial z-stack intravital MPM images also revealed the spatial dilation of the SM in the temporal bone of pendrin-deficient mice. These findings suggest that intravital MPM might serve as a new method for obtaining microanatomical information regarding the cochlea, similar to standard histopathological analyses in the animal study for the cochlea. Given the capability of intravital MPM for detecting an increase in the volume of the SM in pendrin-deficient mice, it might be a promising new tool for assessing the pathophysiology of hearing loss in the future.

Usefulness of Intravital Multiphoton Microscopy in Visualizing Study of Mouse Cochlea and Volume Changes in the Scala Media

Directory of Open Access Journals (Sweden)

Hyun Mi Ju

2017-07-01

Full Text Available Conventional microscopy has limitations in viewing the cochlear microstructures due to three-dimensional spiral structure and the overlying bone. But these issues can be overcome by imaging the cochlea in vitro with intravital multiphoton microscopy (MPM. By using near-infrared lasers for multiphoton excitation, intravital MPM can detect endogenous fluorescence and second harmonic generation of tissues. In this study, we used intravital MPM to visualize various cochlear microstructures without any staining and non-invasively analyze the volume changes of the scala media (SM without removing the overlying cochlear bone. The intravital MPM images revealed various tissue types, ranging from thin membranes to dense bone, as well as the spiral ganglion beneath the cochlear bone. The two-dimensional, cross-sectional, and serial z-stack intravital MPM images also revealed the spatial dilation of the SM in the temporal bone of pendrin-deficient mice. These findings suggest that intravital MPM might serve as a new method for obtaining microanatomical information regarding the cochlea, similar to standard histopathological analyses in the animal study for the cochlea. Given the capability of intravital MPM for detecting an increase in the volume of the SM in pendrin-deficient mice, it might be a promising new tool for assessing the pathophysiology of hearing loss in the future.

Effects of laser radiation parameters of the infrared multiphoton dissociation of protonated trichloroethylene

International Nuclear Information System (INIS)

Ungureanu, C.; Almasan, V.

1994-01-01

The favorable properties of the infrared multiphoton absorption and dissociation of trichloroethylene-H, (C 2 HCl 3 ), by TEA-CO 2 laser radiation and rapid isotopic exchange between this molecule and water, indicate that it can be a promising further candidate for the final enrichment of heavy water (> 98% D 2 O), by laser method. We present the results obtained in the isotopic selectivity of multiphoton absorption measurements and in the study of the pulse energy and frequency laser radiation influence on the infrared multiphoton dissociation of C 2 HCl 3 in isotopic mixture with C 2 DCl 3 . (Author)

Cellular organization and spectral diversity of GFP-like proteins in live coral cells studied by single and multiphoton imaging and microspectroscopy

Science.gov (United States)

Salih, Anya; Cox, Guy C.; Larkum, Anthony W.

2003-07-01

Tissues of many marine invertebrates of class Anthozoa contain intensely fluorescent or brightly coloured pigments. These pigments belong to a family of photoactive proteins closely related to Green Fluorescent Protein (GFP), and their emissions range from blue to red wavelengths. The great diversity of these pigments has only recently been realised. To investigate the role of these proteins in corals, we have performed an in vivo fluorescent pigment (FP) spectral and cellular distribution analyses in live coral cells using single and multi-photon laser scanning imaging and microspectroscopy. These analyses revealed that even single colour corals contain spectroscopically heterogeneous pigment mixtures, with 2-5 major colour types in the same area of tissue. They were typically arranged in step-wise light emission energy gradients (e.g. blue, green, yellow, red). The successive overlapping emission-excitation spectral profiles of differently coloured FPs suggested that they were suited for sequential energy coupling. Traces of red FPs (emission = 570-660 nm) were present, even in non-red corals. We confirmed that radiative energy transfer could occur between separate granules of blue and green FPs and that energy transfer was inversely proportional to the square of the distance between them. Multi-photon micro-spectrofluorometric analysis gave significantly improved spectral resolution by restricting FP excitation to a single point in the focal plane of the sample. Pigment heterogeneity at small scales within granules suggested that fluorescence resonance energy transfer (FRET) might be occurring, and we confirmed that this was the case. Thus, energy transfer can take place both radiatively and by FRET, probably functioning in photoprotection by dissipation of excessive solar radiation.

Non-descanned multifocal multiphoton microscopy with a multianode photomultiplier tube

International Nuclear Information System (INIS)

Cha, Jae Won; Yew, Elijah Y. S.; Kim, Daekeun; Subramanian, Jaichandar; Nedivi, Elly; So, Peter T. C.

2015-01-01

Multifocal multiphoton microscopy (MMM) improves imaging speed over a point scanning approach by parallelizing the excitation process. Early versions of MMM relied on imaging detectors to record emission signals from multiple foci simultaneously. For many turbid biological specimens, the scattering of emission photons results in blurred images and degrades the signal-to-noise ratio (SNR). We have recently demonstrated that a multianode photomultiplier tube (MAPMT) placed in a descanned configuration can effectively collect scattered emission photons from each focus into their corresponding anodes significantly improving image SNR for highly scattering specimens. Unfortunately, a descanned MMM has a longer detection path resulting in substantial emission photon loss. Optical design constraints in a descanned geometry further results in significant optical aberrations especially for large field-of-view (FOV), high NA objectives. Here, we introduce a non-descanned MMM based on MAPMT that substantially overcomes most of these drawbacks. We show that we improve signal efficiency up to fourfold with limited image SNR degradation due to scattered emission photons. The excitation foci can also be spaced wider to cover the full FOV of the objective with minimal aberrations. The performance of this system is demonstrated by imaging interneuron morphological structures deep in the brains of living mice

Non-descanned multifocal multiphoton microscopy with a multianode photomultiplier tube

Energy Technology Data Exchange (ETDEWEB)

Cha, Jae Won; Yew, Elijah Y. S. [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Kim, Daekeun [Department of Mechanical Engineering, Dankook University (Korea, Republic of); Subramanian, Jaichandar [Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA (United States); Nedivi, Elly [Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA (United States); Departments of Brain and Cognitive Sciences, and Biology, Massachusetts Institute of Technology, Cambridge, MA (United States); So, Peter T. C. [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States)

2015-08-15

Multifocal multiphoton microscopy (MMM) improves imaging speed over a point scanning approach by parallelizing the excitation process. Early versions of MMM relied on imaging detectors to record emission signals from multiple foci simultaneously. For many turbid biological specimens, the scattering of emission photons results in blurred images and degrades the signal-to-noise ratio (SNR). We have recently demonstrated that a multianode photomultiplier tube (MAPMT) placed in a descanned configuration can effectively collect scattered emission photons from each focus into their corresponding anodes significantly improving image SNR for highly scattering specimens. Unfortunately, a descanned MMM has a longer detection path resulting in substantial emission photon loss. Optical design constraints in a descanned geometry further results in significant optical aberrations especially for large field-of-view (FOV), high NA objectives. Here, we introduce a non-descanned MMM based on MAPMT that substantially overcomes most of these drawbacks. We show that we improve signal efficiency up to fourfold with limited image SNR degradation due to scattered emission photons. The excitation foci can also be spaced wider to cover the full FOV of the objective with minimal aberrations. The performance of this system is demonstrated by imaging interneuron morphological structures deep in the brains of living mice.

Thermally activated delayed fluorescence of fluorescein derivative for time-resolved and confocal fluorescence imaging.

Science.gov (United States)

Xiong, Xiaoqing; Song, Fengling; Wang, Jingyun; Zhang, Yukang; Xue, Yingying; Sun, Liangliang; Jiang, Na; Gao, Pan; Tian, Lu; Peng, Xiaojun

2014-07-09

Compared with fluorescence imaging utilizing fluorophores whose lifetimes are in the order of nanoseconds, time-resolved fluorescence microscopy has more advantages in monitoring target fluorescence. In this work, compound DCF-MPYM, which is based on a fluorescein derivative, showed long-lived luminescence (22.11 μs in deaerated ethanol) and was used in time-resolved fluorescence imaging in living cells. Both nanosecond time-resolved transient difference absorption spectra and time-correlated single-photon counting (TCSPC) were employed to explain the long lifetime of the compound, which is rare in pure organic fluorophores without rare earth metals and heavy atoms. A mechanism of thermally activated delayed fluorescence (TADF) that considers the long wavelength fluorescence, large Stokes shift, and long-lived triplet state of DCF-MPYM was proposed. The energy gap (ΔEST) of DCF-MPYM between the singlet and triplet state was determined to be 28.36 meV by the decay rate of DF as a function of temperature. The ΔE(ST) was small enough to allow efficient intersystem crossing (ISC) and reverse ISC, leading to efficient TADF at room temperature. The straightforward synthesis of DCF-MPYM and wide availability of its starting materials contribute to the excellent potential of the compound to replace luminescent lanthanide complexes in future time-resolved imaging technologies.

Evaluation of the resolving power of different angles in MPR images of 16DAS-MDCT

International Nuclear Information System (INIS)

Kimura, Mikio; Usui, Junshi; Nozawa, Takeo

2007-01-01

In this study, we evaluated the resolving power of three-dimensional (3D) multiplanar reformation (MPR) images with various angles by using 16 data acquisition system multi detector row computed tomography (16DAS-MDCT). We reconstructed the MPR images using data with a 0.75 mm slice thickness of the axial image in this examination. To evaluate resolving power, we used an original new phantom (RC phantom) that can be positioned at any slice angle in MPR images. We measured the modulation transfer function (MTF) by using the methods of measuring pre-sampling MTF, and used Fourier transform of image data of the square wave chart. The scan condition and image reconstruction condition that were adopted in this study correspond to the condition that we use for three-dimensional computed tomographic angiography(3D-CTA) examination of the head in our hospital. The MTF of MPR images showed minimum values at slice angles in parallel with the axial slice, and showed maximum values at the sagittal slice and coronal slice angles that are parallel to the Z-axis. With an oblique MPR image, MTF did not change with angle changes in the oblique sagittal slice plane, but in the oblique coronal slice plane, MTF increased as the tilt angle increased from the axial plane to the Z plane. As a result, we could evaluate the resolving power of a head 3D image by measuring the MTF of the axial image and sagittal image or the coronal image. (author)

[Evaluation of the resolving power of different angles in MPR images of 16DAS-MDCT].

Science.gov (United States)

Kimura, Mikio; Usui, Junshi; Nozawa, Takeo

2007-03-20

In this study, we evaluated the resolving power of three-dimensional (3D) multiplanar reformation (MPR) images with various angles by using 16 data acquisition system multi detector row computed tomography (16DAS-MDCT) . We reconstructed the MPR images using data with a 0.75 mm slice thickness of the axial image in this examination. To evaluate resolving power, we used an original new phantom (RC phantom) that can be positioned at any slice angle in MPR images. We measured the modulation transfer function (MTF) by using the methods of measuring pre-sampling MTF, and used Fourier transform of image data of the square wave chart. The scan condition and image reconstruction condition that were adopted in this study correspond to the condition that we use for three-dimensional computed tomographic angiography (3D-CTA) examination of the head in our hospital. The MTF of MPR images showed minimum values at slice angles in parallel with the axial slice, and showed maximum values at the sagittal slice and coronal slice angles that are parallel to the Z-axis. With an oblique MPR image, MTF did not change with angle changes in the oblique sagittal slice plane, but in the oblique coronal slice plane, MTF increased as the tilt angle increased from the axial plane to the Z plane. As a result, we could evaluate the resolving power of a head 3D image by measuring the MTF of the axial image and sagittal image or the coronal image.

Photo-magnetic imaging: resolving optical contrast at MRI resolution

International Nuclear Information System (INIS)

Lin Yuting; Thayer, David; Luk, Alex L; Gulsen, Gultekin; Gao Hao

2013-01-01

In this paper, we establish the mathematical framework of a novel imaging technique, namely photo-magnetic imaging (PMI). PMI uses a laser to illuminate biological tissues and measure the induced temperature variations using magnetic resonance imaging (MRI). PMI overcomes the limitation of conventional optical imaging and allows imaging of the optical contrast at MRI spatial resolution. The image reconstruction for PMI, using a finite-element-based algorithm with an iterative approach, is presented in this paper. The quantitative accuracy of PMI is investigated for various inclusion sizes, depths and absorption values. Then, a comparison between conventional diffuse optical tomography (DOT) and PMI is carried out to illustrate the superior performance of PMI. An example is presented showing that two 2 mm diameter inclusions embedded 4.5 mm deep and located side by side in a 25 mm diameter circular geometry medium are recovered as a single 6 mm diameter object with DOT. However, these two objects are not only effectively resolved with PMI, but their true concentrations are also recovered successfully. (paper)

Multi-photon transitions and Rabi resonance in continuous wave EPR.

Science.gov (United States)

Saiko, Alexander P; Fedaruk, Ryhor; Markevich, Siarhei A

2015-10-01

The study of microwave-radiofrequency multi-photon transitions in continuous wave (CW) EPR spectroscopy is extended to a Rabi resonance condition, when the radio frequency of the magnetic-field modulation matches the Rabi frequency of a spin system in the microwave field. Using the non-secular perturbation theory based on the Bogoliubov averaging method, the analytical description of the response of the spin system is derived for all modulation frequency harmonics. When the modulation frequency exceeds the EPR linewidth, multi-photon transitions result in sidebands in absorption EPR spectra measured with phase-sensitive detection at any harmonic. The saturation of different-order multi-photon transitions is shown to be significantly different and to be sensitive to the Rabi resonance. The noticeable frequency shifts of sidebands are found to be the signatures of this resonance. The inversion of two-photon lines in some spectral intervals of the out-of-phase first-harmonic signal is predicted under passage through the Rabi resonance. The inversion indicates the transition from absorption to stimulated emission or vice versa, depending on the sideband. The manifestation of the primary and secondary Rabi resonance is also demonstrated in the time evolution of steady-state EPR signals formed by all harmonics of the modulation frequency. Our results provide a theoretical framework for future developments in multi-photon CW EPR spectroscopy, which can be useful for samples with long spin relaxation times and extremely narrow EPR lines. Copyright © 2015 Elsevier Inc. All rights reserved.

Application of Negative Curvature Hollow-Core Fiber in an Optical Fiber Sensor Setup for Multiphoton Spectroscopy.

Science.gov (United States)

Popenda, Maciej Andrzej; Stawska, Hanna Izabela; Mazur, Leszek Mateusz; Jakubowski, Konrad; Kosolapov, Alexey; Kolyadin, Anton; Bereś-Pawlik, Elżbieta

2017-10-06

In this paper, an application of negative curvature hollow core fiber (NCHCF) in an all-fiber, multiphoton fluorescence sensor setup is presented. The dispersion parameter (D) of this fiber does not exceed the value of 5 ps/nm × km across the optical spectrum of (680-750) nm, making it well suited for the purpose of multiphoton excitation of biological fluorophores. Employing 1.5 m of this fiber in a simple, all-fiber sensor setup allows us to perform multiphoton experiments without any dispersion compensation methods. Multiphoton excitation of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) with this fiber shows a 6- and 9-fold increase, respectively, in the total fluorescence signal collected when compared with the commercial solution in the form of a hollow-core photonic band gap fiber (HCPBF). To the author's best knowledge, this is the first time an NCHCF was used in an optical-fiber sensor setup for multiphoton fluorescence experiments.

Label-free detection of breast masses using multiphoton microscopy.

Directory of Open Access Journals (Sweden)

Xiufeng Wu

Full Text Available Histopathology forms the gold standard for the diagnosis of breast cancer. Multiphoton microscopy (MPM has been proposed to be a potentially powerful adjunct to current histopathological techniques. A label-free imaging based on two- photon excited fluorescence and second-harmonic generation is developed for differentiating normal breast tissues, benign, as well as breast cancer tissues. Human breast biopsies (including human normal breast tissues, benign as well as breast cancer tissues that are first imaged (fresh, unfixed, and unstained with MPM and are then processed for routine H-E histopathology. Our results suggest that the MPM images, obtained from these unprocessed biopsies, can readily distinguish between benign lesions and breast cancers. In the tissues of breast cancers, MPM showed that the tumor cells displayed marked cellular and nuclear pleomorphism. The tumor cells, characterized by irregular size and shape, enlarged nuclei, and increased nuclear-cytoplasmic ratio, infiltrated into disrupted connective tissue, leading to the loss of second-harmonic generation signals. For breast cancer, MPM diagnosis was 100% correct because the tissues of breast cancers did not have second-harmonic generation signals in MPM imaging. On the contrary, in benign breast masses, second-harmonic generation signals could be seen easily in MPM imaging. These observations indicate that MPM could be an important potential tool to provide label-free noninvasive diagnostic impressions that can guide surgeon in biopsy and patient management.

Clinical coherent anti-Stokes Raman scattering and multiphoton tomography of human skin with a femtosecond laser and photonic crystal fiber

International Nuclear Information System (INIS)

Breunig, Hans Georg; Weinigel, Martin; Bückle, Rainer; Kellner-Höfer, Marcel; König, Karsten; Lademann, Jürgen; Darvin, Maxim E; Sterry, Wolfram

2013-01-01

We report on in vivo coherent anti-Stokes Raman scattering spectroscopy (CARS), two-photon fluorescence and second-harmonic-generation imaging on human skin with a novel multimodal clinical CARS/multiphoton tomograph. CARS imaging is realized by a combination of femtosecond pulses with broadband continuum pulses generated by a photonic crystal fiber. The images reveal the microscopic distribution of (i) non-fluorescent lipids, (ii) endogenous fluorophores and (iii) the collagen network inside the human skin in vivo with subcellular resolution. Examples of healthy as well as cancer-affected skin are presented. (letter)

Clinical coherent anti-Stokes Raman scattering and multiphoton tomography of human skin with a femtosecond laser and photonic crystal fiber

Science.gov (United States)

Breunig, Hans Georg; Weinigel, Martin; Bückle, Rainer; Kellner-Höfer, Marcel; Lademann, Jürgen; Darvin, Maxim E.; Sterry, Wolfram; König, Karsten

2013-02-01

We report on in vivo coherent anti-Stokes Raman scattering spectroscopy (CARS), two-photon fluorescence and second-harmonic-generation imaging on human skin with a novel multimodal clinical CARS/multiphoton tomograph. CARS imaging is realized by a combination of femtosecond pulses with broadband continuum pulses generated by a photonic crystal fiber. The images reveal the microscopic distribution of (i) non-fluorescent lipids, (ii) endogenous fluorophores and (iii) the collagen network inside the human skin in vivo with subcellular resolution. Examples of healthy as well as cancer-affected skin are presented.

Resolving hot spot microstructure using x-ray penumbral imaging (invited)

Science.gov (United States)

Bachmann, B.; Hilsabeck, T.; Field, J.; Masters, N.; Reed, C.; Pardini, T.; Rygg, J. R.; Alexander, N.; Benedetti, L. R.; Döppner, T.; Forsman, A.; Izumi, N.; LePape, S.; Ma, T.; MacPhee, A. G.; Nagel, S.; Patel, P.; Spears, B.; Landen, O. L.

2016-11-01

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

Resolving hot spot microstructure using x-ray penumbral imaging (invited)

Energy Technology Data Exchange (ETDEWEB)

Bachmann, B., E-mail: bachmann2@llnl.gov; Field, J.; Masters, N.; Pardini, T.; Rygg, J. R.; Benedetti, L. R.; Döppner, T.; Izumi, N.; LePape, S.; Ma, T.; MacPhee, A. G.; Nagel, S.; Patel, P.; Spears, B.; Landen, O. L. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hilsabeck, T.; Reed, C.; Alexander, N.; Forsman, A. [General Atomics, San Diego, California 92186 (United States)

2016-11-15

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

Resolving hot spot microstructure using x-ray penumbral imaging (invited).

Science.gov (United States)

Bachmann, B; Hilsabeck, T; Field, J; Masters, N; Reed, C; Pardini, T; Rygg, J R; Alexander, N; Benedetti, L R; Döppner, T; Forsman, A; Izumi, N; LePape, S; Ma, T; MacPhee, A G; Nagel, S; Patel, P; Spears, B; Landen, O L

2016-11-01

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

Resolving hot spot microstructure using x-ray penumbral imaging (invited)

International Nuclear Information System (INIS)

Bachmann, B.; Field, J.; Masters, N.; Pardini, T.; Rygg, J. R.; Benedetti, L. R.; Döppner, T.; Izumi, N.; LePape, S.; Ma, T.; MacPhee, A. G.; Nagel, S.; Patel, P.; Spears, B.; Landen, O. L.; Hilsabeck, T.; Reed, C.; Alexander, N.; Forsman, A.

2016-01-01

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

A new method using multiphoton imaging and morphometric analysis for differentiating chromophobe renal cell carcinoma and oncocytoma kidney tumors

Science.gov (United States)

Wu, Binlin; Mukherjee, Sushmita; Jain, Manu

2016-03-01

Distinguishing chromophobe renal cell carcinoma (chRCC) from oncocytoma on hematoxylin and eosin images may be difficult and require time-consuming ancillary procedures. Multiphoton microscopy (MPM), an optical imaging modality, was used to rapidly generate sub-cellular histological resolution images from formalin-fixed unstained tissue sections from chRCC and oncocytoma.Tissues were excited using 780nm wavelength and emission signals (including second harmonic generation and autofluorescence) were collected in different channels between 390 nm and 650 nm. Granular structure in the cell cytoplasm was observed in both chRCC and oncocytoma. Quantitative morphometric analysis was conducted to distinguish chRCC and oncocytoma. To perform the analysis, cytoplasm and granules in tumor cells were segmented from the images. Their area and fluorescence intensity were found in different channels. Multiple features were measured to quantify the morphological and fluorescence properties. Linear support vector machine (SVM) was used for classification. Re-substitution validation, cross validation and receiver operating characteristic (ROC) curve were implemented to evaluate the efficacy of the SVM classifier. A wrapper feature algorithm was used to select the optimal features which provided the best predictive performance in separating the two tissue types (classes). Statistical measures such as sensitivity, specificity, accuracy and area under curve (AUC) of ROC were calculated to evaluate the efficacy of the classification. Over 80% accuracy was achieved as the predictive performance. This method, if validated on a larger and more diverse sample set, may serve as an automated rapid diagnostic tool to differentiate between chRCC and oncocytoma. An advantage of such automated methods are that they are free from investigator bias and variability.

Collaborative Initiative in Biomedical Imaging to Study Complex Diseases

Energy Technology Data Exchange (ETDEWEB)

Lin, Weili [The University of North Carolina at Chapel Hill; Fiddy, Michael A. [The University of North Carolina at Charlotte

2012-03-31

The work reported addressed these topics: Fluorescence imaging; Optical coherence tomography; X-ray interferometer/phase imaging system; Quantitative imaging from scattered fields, Terahertz imaging and spectroscopy; and Multiphoton and Raman microscopy.

Doubly resonant multiphoton ionization

International Nuclear Information System (INIS)

Crance, M.

1978-01-01

A particular case of doubly resonant multiphoton ionization is theoretically investigated. More precisely, two levels quasi-resonant with two successive harmonics of the field frequency are considered. The method used is based on the effective operator formalism first introduced for this problem by Armstrong, Beers and Feneuille. The main result is to show the possibility of observing large interference effects on the width of the resonances. Moreover this treatment allows us to make more precise the connection between effective operator formalism and standard perturbation theory

High-order multiphoton ionization photoelectron spectroscopy of NO

International Nuclear Information System (INIS)

Carman, H.S. Jr.; Compton, R.N.

1987-01-01

Photoelectron energy angular distributions of NO following three different high-order multiphoton ionization (MPI) schemes have been measured. The 3 + 3 resonantly enhanced multiphoton ionization (REMPI) via the A 2 Σ + (v=O) level yielded a distribution of electron energies corresponding to all accessible vibrational levels (v + =O-6) of the nascent ion. Angular distributions of electrons corresponding to v + =O and v + =3 were significantly different. The 3 + 2 REMPI via the A 2 Σ + (v=1) level produced only one low-energy electron peak (v + =1). Nonresonant MPI at 532 nm yielded a distribution of electron energies corresponding to both four- and five-photon ionization. Prominent peaks in the five-photon photoelectron spectrum (PES) suggest contributions from near-resonant states at the three-photon level. 4 refs., 3 figs

Non-dipole effects in multiphoton ionization of hydrogen atom in short superintense laser fields

Energy Technology Data Exchange (ETDEWEB)

Jobunga, Eric O. [AG Moderne Optik, Institut fuer Physik, Humboldt-Universitaet zu Berlin, Newtonstr. 15, D-12489 Berlin (Germany); Department of Mathematics and Physics, Technical University of Mombasa, P. O. Box 90420-80100, Mombasa (Kenya); Saenz, Alejandro [AG Moderne Optik, Institut fuer Physik, Humboldt-Universitaet zu Berlin, Newtonstr. 15, D-12489 Berlin (Germany)

2014-07-01

The development of novel light sources has enabled the realization of high-precision experiments investigating various non-linear processes in the dynamics of atomic, molecular, and ionic systems interacting with high intense laser pulses. At high intensities or short wavelengths, the analysis of these experiments would definitely require a reliable non-perturbative solution of the time-dependent Schroedinger or Dirac equation. These solutions should consider both the temporal and the spatial intensity variations of the laser pulse.We have solved the non-relativistic time dependent Schroedinger equation for a ground state hydrogen atom interacting with short intense spatially and temporally resolved laser fields corresponding to the multiphoton ATI regime for a monochromatic source with λ= 800 nm. We shall analyse the effects of the A{sup 2} term and the corresponding orders of the multipolar expansion of the transition matrix.

Processing multiphoton states through operation on a single photon: Methods and applications

International Nuclear Information System (INIS)

Lin Qing; He Bing; Bergou, Janos A.; Ren, Yuhang

2009-01-01

Multiphoton states are widely applied in quantum information technology. By the methods presented in this paper, the structure of a multiphoton state in the form of multiple single-photon qubit products can be mapped to a single-photon qudit, which could also be in a separable product with other photons. This makes possible the manipulation of such multiphoton states by processing single-photon states. The optical realization of unknown qubit discrimination [B. He, J. A. Bergou, and Y.-H. Ren, Phys. Rev. A 76, 032301 (2007)] is simplified with the transformation methods. Another application is the construction of quantum logic gates, where the inverse transformations back to the input state spaces are also necessary. We especially show that the modified setups to implement the transformations can realize the deterministic multicontrol gates (including Toffoli gate) operating directly on the products of single-photon qubits.

Multiphoton processes in the field of two-frequency circularly polarized plane electromagnetic waves

International Nuclear Information System (INIS)

Yu, An

1997-01-01

The authors solve Dirac's equation for an electron in the field of a two-frequency plane electromagnetic wave, deriving general formulae for the probabilities of radiation of a photon by the electron, and for the probabilities for pair production by a photon when the two-frequency wave is circularly polarized. In contrast to the case of a monochromatic-plane electromagnetic wave, when an electron is in the field of a two-frequency circularly polarized wave, besides the absorption of multiphotons and emission of simple harmonics of the individual waves, stimulated multiphoton emission processes and various composite harmonic-photon emission processes are occurred: when a high-energy photon is in a such a field, multiphoton processes also follow the pair production processes

Efficient Multiphoton Generation in Waveguide Quantum Electrodynamics

Science.gov (United States)

González-Tudela, A.; Paulisch, V.; Kimble, H. J.; Cirac, J. I.

2017-05-01

Engineering quantum states of light is at the basis of many quantum technologies such as quantum cryptography, teleportation, or metrology among others. Though, single photons can be generated in many scenarios, the efficient and reliable generation of complex single-mode multiphoton states is still a long-standing goal in the field, as current methods either suffer from low fidelities or small probabilities. Here we discuss several protocols which harness the strong and long-range atomic interactions induced by waveguide QED to efficiently load excitations in a collection of atoms, which can then be triggered to produce the desired multiphoton state. In order to boost the success probability and fidelity of each excitation process, atoms are used to both generate the excitations in the rest, as well as to herald the successful generation. Furthermore, to overcome the exponential scaling of the probability of success with the number of excitations, we design a protocol to merge excitations that are present in different internal atomic levels with a polynomial scaling.

Multiphoton processes in isolated atoms and molecules

International Nuclear Information System (INIS)

Sudbo, A.S.

1979-11-01

The theory of coherent excitation of a multilevel quantum mechanical system is developed. Damping of the system is taken into account by the use of a density matrix formalism. General properties of the wave function and/or the density matrix are discussed. The physical implications for the behavior of the system are described, together with possible applications of the formalism, including the infrared multiphoton excitation of molecules, and optical pumping in alkali atoms. Experimental results are presented on the infrared multiphoton dissociation of molecules, followed by a discussion of the general features of this process. The experimental results were obtained using a crossed laser and molecular beam method, and the emphasis is on determining the properties of the dissociating molecule and the dissociation products. The dissociation process is shown to be described very well by the standard statistical theory (RRKM theory) of unimolecular reactions, a brief presentation of which is also included

Time-resolved diffusion tomographic imaging in highly scattering turbid media

Science.gov (United States)

Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Liu, Feng (Inventor); Lax, Melvin (Inventor); Das, Bidyut B. (Inventor)

1998-01-01

A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: X.sup.(k+1).spsp.T =?Y.sup.T W+X.sup.(k).spsp.T .LAMBDA.!?W.sup.T W+.LAMBDA.!.sup.-1 wherein W is a matrix relating output at detector position r.sub.d, at time t, to source at position r.sub.s, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =/ Here Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absoption information.

Additive Manufacture of Three Dimensional Nanocomposite Based Objects through Multiphoton Fabrication

Directory of Open Access Journals (Sweden)

Yaan Liu

2016-09-01

Full Text Available Three-dimensional structures prepared from a gold-polymer composite formulation have been fabricated using multiphoton lithography. In this process, gold nanoparticles were simultaneously formed through photoreduction whilst polymerisation of two possible monomers was promoted. The monomers, trimethylopropane triacrylate (TMPTA and pentaerythritol triacrylate (PETA were mixed with a gold salt, but it was found that the addition of a ruthenium(II complex enhanced both the geometrical uniformity and integrity of the polymerised/reduced material, enabling the first production of 3D gold-polymer structures by single step multiphoton lithography.

Multi-photon microscopy with a low-cost and highly efficient Cr:LiCAF laser

Science.gov (United States)

Sakadić, Sava; Demirbas, Umit; Mempel, Thorsten R.; Moore, Anna; Ruvinskaya, Svetlana; Boas, David A.; Sennaroglu, Alphan; Kartner, Franz X.; Fujimoto, James G.

2009-01-01

Multi-photon microscopy (MPM) is a powerful tool for biomedical imaging, enabling molecular contrast and integrated structural and functional imaging on the cellular and subcellular level. However, the cost and complexity of femtosecond laser sources that are required in MPM are significant hurdles to widespread adoption of this important imaging modality. In this work, we describe femtosecond diode pumped Cr:LiCAF laser technology as a low cost alternative to femtosecond Ti:Sapphire lasers for MPM. Using single mode pump diodes which cost only $150 each, a diode pumped Cr:LiCAF laser generates ~70-fs duration, 1.8-nJ pulses at ~800 nm wavelengths, with a repetition rate of 100 MHz and average output power of 180 mW. Representative examples of MPM imaging in neuroscience, immunology, endocrinology and cancer research using Cr:LiCAF laser technology are presented. These studies demonstrate the potential of this laser source for use in a broad range of MPM applications. PMID:19065223

Spatially Resolved Two-Color Diffusion Measurements in Human Skin Applied to Transdermal Liposome Penetration

DEFF Research Database (Denmark)

Brewer, Jonathan; Bloksgaard, Maria; Kubiak, Jakub

2013-01-01

A multiphoton excitation-based fluorescence fluctuation spectroscopy method, Raster image correlation spectroscopy (RICS), was used to measure the local diffusion coefficients of distinct model fluorescent substances in excised human skin. In combination with structural information obtained by mu......; doi:10.1038/jid.2012.461....

Applications of multiphoton microscopy in the field of colorectal cancer

Science.gov (United States)

Wang, Shu; Li, Lianhuang; Zhu, Xiaoqin; Zheng, Liqin; Zhuo, Shuangmu; Chen, Jianxin

2018-06-01

Multiphoton microscopy (MPM) is a powerful tool for visualizing cellular and subcellular details within living tissue by its unique advantages of being label-free, its intrinsic optical sectioning ability, near-infrared excitation for deep penetration depth into tissue, reduced photobleaching and phototoxicity in the out-of-focus regions, and being capable of providing quantitative information. In this review, we focus on applications of MPM in the field of colorectal cancer, including monitoring cancer progression, detecting tumor metastasis and microenvironment, evaluating the cancer therapy response, and visualizing and ablating pre-invasive cancer cells. We also present one of the major challenges and the future research direction to exploit a colorectal multiphoton endoscope.

Time-resolved imaging of purely valence-electron dynamics during a chemical reaction

DEFF Research Database (Denmark)

Hockett, Paul; Bisgaard, Christer Z.; Clarkin, Owen J.

2011-01-01

Chemical reactions are manifestations of the dynamics of molecular valence electrons and their couplings to atomic motions. Emerging methods in attosecond science can probe purely electronic dynamics in atomic and molecular systems(1-6). By contrast, time-resolved structural-dynamics methods...... such as electron(7-10) or X-ray diffraction(11) and X-ray absorption(12) yield complementary information about the atomic motions. Time-resolved methods that are directly sensitive to both valence-electron dynamics and atomic motions include photoelectron spectroscopy(13-15) and high-harmonic generation(16......,17): in both cases, this sensitivity derives from the ionization-matrix element(18,19). Here we demonstrate a time-resolved molecular-frame photoelectron-angular-distribution (TRMFPAD) method for imaging the purely valence-electron dynamics during a chemical reaction. Specifically, the TRMFPADs measured during...

Modelling of infrared multiphoton absorption and dissociation for design of reactors for isotope separation by lasers

International Nuclear Information System (INIS)

Takeuchi, Kazuo; Nakane, Ryohei; Inoue, Cihiro

1981-01-01

A series of experiments were performed on infrared laser beam absorption (multiphoton absorption) and subsequent dissociation (multiphoton dissociation) of CF 3 Cl to propose models for the design of reactors for isotope separation by lasers. A parallel beam geometry was utilized in batch irradiation experiments to make direct compilation of lumped-parameter data possible. Multiphoton absorption is found to be expressed by a power-law extension of the law of Lambert and by an addition of a new term for buffer gas effect to the law of Beer. For reaction analysis, a method to evaluate the effect of incomplete mixing on apparent reaction rates is first presented. Secondly, multiphoton dissociation of Cf 3 Cl is found to occur in pseudo-first order fashion and the specific reaction rates for different beam fluence are shown to be correlated to the absorbed energy. (author)

One color multi-photon ionization of the Gadolinium atom in near UV region

International Nuclear Information System (INIS)

Kim, Jin Tae; Yi, Jong Hoon; Lhee, Yong Joo; Lee, Jong Min

1999-01-01

We have investigated the states of the gadolinium atom in near ultra-violet (UV) region (∼410 nm) using single photon excitation using resonance ionization mass spectrometry (RIMS). Around 70 transitions among observed 180 single color multi-photon ionization signals have been assigned. Most of the multi-photon processes of the assigned ion signals are through single photon resonant three photon ionization and through two photon resonant three photon ionization. (author)

Dressing effect in multiphoton unimolecular dissociation

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Diaz, P.F.; Garcia-Fernandez, P.

1986-03-01

On the basis of a quantum-statistical model recently discussed, we deal in this paper with the perturbations induced by the intense field of a CO/sub 2/ laser on the levels of the vibrational pattern of a molecule undergoing multiphoton unimolecular dissociation. This perturbational correction is investigated by using a displacement operator technique and the results are interpreted according to the statistical model.

Identification of intramural metastasis in esophageal cancer using multiphoton microscopy

Science.gov (United States)

Xu, Jian; Kang, Deyong; Zhuo, Shuangmu; Zhu, Xiaoqin; Lin, jiangbo; Chen, Jianxin

2017-02-01

Intramural metastasis (IM) of esophageal cancer is defined as metastasis from a primary lesion to the esophageal wall without intraepithelial cancer extension. Esophageal cancer with IM is more common and such cases indicate a poor prognosis. In esophageal surgery, if curative resection is possible, the complete removal of both primary tumor and associated IMs is required. Therefore, accurate diagnosis of IMs in esophageal cancer prior to surgery is of particular importance. Multiphoton microscopy (MPM) with subcellular resolution is well-suited for deep tissue imaging since many endogenous fluorophores of fresh biological tissues are excited through two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). Here, a study to identify IM in fresh tissue section using MPM is reported. In this study, the morphological and spectral differences between IM and surrounding tissue are described. These results show that MPM has the ability to accurately identify IM in esophageal tissues. With improvement of the penetration depth of MPM and the development of multiphton microendoscope, MPM may be a promising imaging technique for preoperative diagnosis of IMs in esophageal cancer in the future.

Photon-Counting Arrays for Time-Resolved Imaging

Directory of Open Access Journals (Sweden)

I. Michel Antolovic

2016-06-01

Full Text Available The paper presents a camera comprising 512 × 128 pixels capable of single-photon detection and gating with a maximum frame rate of 156 kfps. The photon capture is performed through a gated single-photon avalanche diode that generates a digital pulse upon photon detection and through a digital one-bit counter. Gray levels are obtained through multiple counting and accumulation, while time-resolved imaging is achieved through a 4-ns gating window controlled with subnanosecond accuracy by a field-programmable gate array. The sensor, which is equipped with microlenses to enhance its effective fill factor, was electro-optically characterized in terms of sensitivity and uniformity. Several examples of capture of fast events are shown to demonstrate the suitability of the approach.

Conditions for reliable time-resolved dosimetry of electronic portal imaging devices for fixed-gantry IMRT and VMAT

International Nuclear Information System (INIS)

Yeo, Inhwan Jason; Patyal, Baldev; Mandapaka, Anant; Jung, Jae Won; Yi, Byong Yong; Kim, Jong Oh

2013-01-01

Purpose: The continuous scanning mode of electronic portal imaging devices (EPID) that offers time-resolved information has been newly explored for verifying dynamic radiation deliveries. This study seeks to determine operating conditions (dose rate stability and time resolution) under which that mode can be used accurately for the time-resolved dosimetry of intensity-modulated radiation therapy (IMRT) beams.Methods: The authors have designed the following test beams with variable beam holdoffs and dose rate regulations: a 10 × 10 cm open beam to serve as a reference beam; a sliding window (SW) beam utilizing the motion of a pair of multileaf collimator (MLC) leaves outside the 10 × 10 cm jaw; a step and shoot (SS) beam to move the pair in step; a volumetric modulated arc therapy (VMAT) beam. The beams were designed in such a way that they all produce the same open beam output of 10 × 10 cm. Time-resolved ion chamber measurements at isocenter and time-resolved and integrating EPID measurements were performed for all beams. The time-resolved EPID measurements were evaluated through comparison with the ion chamber and integrating EPID measurements, as the latter are accepted procedures. For two-dimensional, time-resolved evaluation, a VMAT beam with an infield MLC travel was designed. Time-resolved EPID measurements and Monte Carlo calculations of such EPID dose images for this beam were performed and intercompared.Results: For IMRT beams (SW and SS), the authors found disagreement greater than 2%, caused by frame missing of the time-resolved mode. However, frame missing disappeared, yielding agreement better than 2%, when the dose rate of irradiation (and thus the frame acquisition rates) reached a stable and planned rate as the dose of irradiation was raised past certain thresholds (a minimum 12 s of irradiation per shoot used for SS IMRT). For VMAT, the authors found that dose rate does not affect the frame acquisition rate, thereby causing no frame missing

Examination of diagnostic features in multiphoton microscopy and optical coherence tomography images of ovarian tumorigenesis in a mouse model

Science.gov (United States)

Watson, Jennifer M.

Ovarian cancer is a deadly disease owing to the non-specific symptoms and suspected rapid progression, leading to frequent late stage detection and poor prognosis. Medical imaging methods such as CT, MRI and ultrasound as well as serum testing for cancer markers have had extremely poor performance for early disease detection. Due to the poor performance of available screening methods, and the impracticality and ineffectiveness of taking tissue biopsies from the ovary, women at high risk for developing ovarian cancer are often advised to undergo prophylactic salpingo-oophorectomy. This surgery results in many side effects and is most often unnecessary since only a fraction of high risk women go on to develop ovarian cancer. Better understanding of the early development of ovarian cancer and characterization of morphological changes associated with early disease could lead to the development of an effective screening test for women at high risk. Optical imaging methods including optical coherence tomography (OCT) and multiphoton microscopy (MPM) are excellent tools for studying disease progression owing to the high resolution and depth sectioning capabilities. Further, these techniques are excellent for optical biopsy because they can image in situ non-destructively. In the studies described in this dissertation OCT and MPM are used to identify cellular and tissue morphological changes associated with early tumor development in a mouse model of ovarian cancer. This work is organized into three specific aims. The first aim is to use the images from the MPM phenomenon of second harmonic generation to quantitatively examine the morphological differences in collagen structure in normal mouse ovarian tissue and mouse ovarian tumors. The second aim is to examine the differences in endogenous two-photon excited fluorescence in normal mouse ovarian tissue and mouse ovarian tumors. The third and final aim is to identify changes in ovarian microstructure resulting from early

Visualization of dermal alteration in skin lesions with discoid lupus erythematosus by multiphoton microscopy

International Nuclear Information System (INIS)

Lin, L H; Yu, H B; Zhu, X Q; Zhuo, S M; Chen, J X; Wang, Y Y; Yang, Y H

2013-01-01

Discoid lupus erythematosus (DLE) is a chronic dermatological disease which lacks valid methods for early diagnosis and therapeutic monitoring. Considering the collagen and elastin disorder due to mucin deposition of DLE, multiphoton microscopy (MPM) imaging techniques were employed to obtain high-resolution collagen and elastin images from the dermis. The content and distribution of collagen and elastin were quantified to characterize the dermal pathological status of skin lesions with DLE in comparison with normal skin. Our results showed a significant difference between skin lesions with DLE and normal skin in terms of the morphological structure of collagen and elastin in the dermis, demonstrating the possibility of MPM for noninvasively tracking the pathological process of DLE even in its early stages and evaluating the therapeutic efficacy at the molecular level. (paper)

Visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals.

Science.gov (United States)

Wang, Baoju; Zhan, Qiuqiang; Zhao, Yuxiang; Wu, Ruitao; Liu, Jing; He, Sailing

2016-01-25

Further development of multiphoton microscopic imaging is confronted with a number of limitations, including high-cost, high complexity and relatively low spatial resolution due to the long excitation wavelength. To overcome these problems, for the first time, we propose visible-to-visible four-photon ultrahigh resolution microscopic imaging by using a common cost-effective 730-nm laser diode to excite the prepared Nd(3+)-sensitized upconversion nanoparticles (Nd(3+)-UCNPs). An ordinary multiphoton scanning microscope system was built using a visible CW diode laser and the lateral imaging resolution as high as 161-nm was achieved via the four-photon upconversion process. The demonstrated large saturation excitation power for Nd(3+)-UCNPs would be more practical and facilitate the four-photon imaging in the application. A sample with fine structure was imaged to demonstrate the advantages of visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals. Combining the uniqueness of UCNPs, the proposed visible-to-visible four-photon imaging would be highly promising and attractive in the field of multiphoton imaging.

Clinical studies of pigmented lesions in human skin by using a multiphoton tomograph

Science.gov (United States)

Balu, Mihaela; Kelly, Kristen M.; Zachary, Christopher B.; Harris, Ronald M.; Krasieva, Tatiana B.; König, Karsten; Tromberg, Bruce J.

2013-02-01

In vivo imaging of pigmented lesions in human skin was performed with a clinical multiphoton microscopy (MPM)-based tomograph (MPTflex, JenLab, Germany). Two-photon excited fluorescence was used for visualizing endogenous fluorophores such as NADH/FAD, keratin, melanin in the epidermal cells and elastin fibers in the dermis. Collagen fibers were imaged by second harmonic generation. Our study involved in vivo imaging of benign melanocytic nevi, atypical nevi and melanoma. The goal of this preliminary study was to identify in vivo the characteristic features and their frequency in pigmented lesions at different stages (benign, atypical and malignant) and to evaluate the ability of in vivo MPM to distinguish atypical nevi from melanoma. Comparison with histopathology was performed for the biopsied lesions. Benign melanocytic nevi were characterized by the presence of nevus cell nests at the epidermal-dermal junction. In atypical nevi, features such as lentiginous hyperplasia, acanthosis and architectural disorder were imaged. Cytological atypia was present in all the melanoma lesions imaged, showing the strongest correlation with malignancy. The MPM images demonstrated very good correlation with corresponding histological images, suggesting that MPM could be a promising tool for in vivo non-invasive pigmented lesion diagnosis, particularly distinguishing atypical nevi from melanoma.

Time-resolved photoelectron imaging using a femtosecond UV laser and a VUV free-electron laser

OpenAIRE

Liu, S. Y.; Ogi, Yoshihiro; Fuji, Takao; Nishizawa, Kiyoshi; Horio, Takuya; Mizuno, Tomoya; Kohguchi, Hiroshi; Nagasono, Mitsuru; Togashi, Tadashi; Tono, Kensuke; Yabashi, Makina; Senba, Yasunori; Ohashi, Haruhiko; Kimura, Hiroaki; Ishikawa, Tetsuya

2010-01-01

A time-resolved photoelectron imaging using a femtosecond ultraviolet (UV) laser and a vacuum UV freeelectron laser is presented. Ultrafast internal conversion and intersystem crossing in pyrazine in a supersonic molecular beam were clearly observed in the time profiles of photoioinzation intensity and time-dependent photoelectron images.

High-intensity power-resolved radiation imaging of an operational nuclear reactor.

Science.gov (United States)

Beaumont, Jonathan S; Mellor, Matthew P; Villa, Mario; Joyce, Malcolm J

2015-10-09

Knowledge of the neutron distribution in a nuclear reactor is necessary to ensure the safe and efficient burnup of reactor fuel. Currently these measurements are performed by in-core systems in what are extremely hostile environments and in most reactor accident scenarios it is likely that these systems would be damaged. Here we present a compact and portable radiation imaging system with the ability to image high-intensity fast-neutron and gamma-ray fields simultaneously. This system has been deployed to image radiation fields emitted during the operation of a TRIGA test reactor allowing a spatial visualization of the internal reactor conditions to be obtained. The imaged flux in each case is found to scale linearly with reactor power indicating that this method may be used for power-resolved reactor monitoring and for the assay of ongoing nuclear criticalities in damaged nuclear reactors.

Generalized Multiphoton Quantum Interference

Directory of Open Access Journals (Sweden)

Max Tillmann

2015-10-01

Full Text Available Nonclassical interference of photons lies at the heart of optical quantum information processing. Here, we exploit tunable distinguishability to reveal the full spectrum of multiphoton nonclassical interference. We investigate this in theory and experiment by controlling the delay times of three photons injected into an integrated interferometric network. We derive the entire coincidence landscape and identify transition matrix immanants as ideally suited functions to describe the generalized case of input photons with arbitrary distinguishability. We introduce a compact description by utilizing a natural basis that decouples the input state from the interferometric network, thereby providing a useful tool for even larger photon numbers.

Identifying Two Common Types of Breast Benign Diseases Based on Multiphoton Microscopy

Directory of Open Access Journals (Sweden)

Yan Wu

2018-01-01

Full Text Available Multiphoton microscopy has attracted increasing attention and investigations in the field of breast cancer, based on two-photon excited fluorescence (TPEF and second-harmonic generation (SHG. However, the incidence of breast benign diseases is about 5 to 10 times higher than breast cancer; up to 30% of women suffer from breast benign diseases and require treatment at some time in their lives. Thus, in this study, MPM was applied to image fibroadenoma and fibrocystic lesion, which are two of the most common breast benign diseases. The results show that MPM has the capability to identify the microstructure of lobule and stroma in normal breast tissue, the interaction of compressed ducts with surrounding collagen fiber in fibroadenoma, and the architecture of cysts filled with cystic fluid in fibrocystic disease. These findings indicate that, with integration of MPM into currently accepted clinical imaging system, it has the potential to make a real-time diagnosis of breast benign diseases in vivo, as well as breast cancer.

Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states

Science.gov (United States)

dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio

2004-03-01

Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [F. Dell’Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states.

Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states

International Nuclear Information System (INIS)

Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

2004-01-01

Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [F. Dell'Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states

Multi-photon microscope driven by novel green laser pump

DEFF Research Database (Denmark)

Marti, Dominik; Djurhuus, Martin; Jensen, Ole Bjarlin

2016-01-01

Multi-photon microscopy is extensively used in research due to its superior possibilities when compared to other microscopy modalities. The technique also has the possibility to advance diagnostics in clinical applications, due to its capabilities complementing existing technology in a multimodal...

Polarization control of intermediate state absorption in resonance-mediated multi-photon absorption process

International Nuclear Information System (INIS)

Xu, Shuwu; Yao, Yunhua; Jia, Tianqing; Ding, Jingxin; Zhang, Shian; Sun, Zhenrong; Huang, Yunxia

2015-01-01

We theoretically and experimentally demonstrate the control of the intermediate state absorption in an (n + m) resonance-mediated multi-photon absorption process by the polarization-modulated femtosecond laser pulse. An analytical solution of the intermediate state absorption in a resonance-mediated multi-photon absorption process is obtained based on the time-dependent perturbation theory. Our theoretical results show that the control efficiency of the intermediate state absorption by the polarization modulation is independent of the laser intensity when the transition from the intermediate state to the final state is coupled by the single-photon absorption, but will be affected by the laser intensity when this transition is coupled by the non-resonant multi-photon absorption. These theoretical results are experimentally confirmed via a two-photon fluorescence control in (2 + 1) resonance-mediated three-photon absorption of Coumarin 480 dye and a single-photon fluorescence control in (1 + 2) resonance-mediated three-photon absorption of IR 125 dye. (paper)

Space-Time Quantum Imaging

Directory of Open Access Journals (Sweden)

Ronald E. Meyers

2015-03-01

Full Text Available We report on an experimental and theoretical investigation of quantum imaging where the images are stored in both space and time. Ghost images of remote objects are produced with either one or two beams of chaotic laser light generated by a rotating ground glass and two sensors measuring the reference field and bucket field at different space-time points. We further observe that the ghost images translate depending on the time delay between the sensor measurements. The ghost imaging experiments are performed both with and without turbulence. A discussion of the physics of the space-time imaging is presented in terms of quantum nonlocal two-photon analysis to support the experimental results. The theoretical model includes certain phase factors of the rotating ground glass. These experiments demonstrated a means to investigate the time and space aspects of ghost imaging and showed that ghost imaging contains more information per measured photon than was previously recognized where multiple ghost images are stored within the same ghost imaging data sets. This suggests new pathways to explore quantum information stored not only in multi-photon coincidence information but also in time delayed multi-photon interference. The research is applicable to making enhanced space-time quantum images and videos of moving objects where the images are stored in both space and time.

Differentiating fibroadenoma and ductal carcinoma in situ from normal breast tissue by multiphoton microscopy

Science.gov (United States)

Nie, Yuting; Wu, Yan; Lian, Yuane; Fu, Fangmeng; Wang, Chuan; Chen, Jianxin

2014-09-01

Fibroadenoma (FA) is the most common benign tumor of the female breast and several studies have reported that women with it have increased risk of breast cancer. While the ductal carcinoma in situ (DCIS) is a very early form of breast cancer. Thus, early detections of FA and DCIS are critical for improving breast tumor outcome and survival. In this paper, we use multiphoton microscopy (MPM) to obtain the high-contrast images of fresh, unfixed, unstained human breast specimens (normal breast tissue, FA and DCIS). Our results show that MPM has the ability to identify the characteristics of FA and DCIS including changes of duct architecture and collagen morphology. These results are consistent with the histological results. With the advancement of MPM, the technique has potential ability to serve as a real-time noninvasive imaging tool for early detection of breast tumor.

Visualizing liver anatomy, physiology and pharmacology using multiphoton microscopy.

Science.gov (United States)

Wang, Haolu; Liang, Xiaowen; Gravot, Germain; Thorling, Camilla A; Crawford, Darrell H G; Xu, Zhi Ping; Liu, Xin; Roberts, Michael S

2017-01-01

Multiphoton microscopy (MPM) has become increasingly popular and widely used in both basic and clinical liver studies over the past few years. This technology provides insights into deep live tissues with less photobleaching and phototoxicity, which helps us to better understand the cellular morphology, microenvironment, immune responses and spatiotemporal dynamics of drugs and therapeutic cells in the healthy and diseased liver. This review summarizes the principles, opportunities, applications and limitations of MPM in hepatology. A key emphasis is on the use of fluorescence lifetime imaging (FLIM) to add additional quantification and specificity to the detection of endogenous fluorescent species in the liver as well as exogenous molecules and nanoparticles that are applied to the liver in vivo. We anticipate that in the near future MPM-FLIM will advance our understanding of the cellular and molecular mechanisms of liver diseases, and will be evaluated from bench to bedside, leading to real-time histology of human liver diseases. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fundamental studies of molecular multiphoton ionization

International Nuclear Information System (INIS)

Miller, J.C.; Compton, R.N.

1984-04-01

For several years the authors have performed fundamental studies of molecular multiphoton ionization (MPI). We will present a potpourri of techniques and results chosen to illustrate the interesting complexities of molecular MPI. Techniques used include time-of-flight mass spectroscopy, photoelectron spectroscopy, supersonic expansion cooling of molecular beams, harmonic generation, two-color laser MPI, and polarization spectroscopy. Whenever possible the relevance of these results to resonance ionization spectroscopy schemes will be delineated. 23 references, 10 figures

Multiphoton dissociation of polyatomic molecules

International Nuclear Information System (INIS)

Schulz, P.A.

1979-10-01

The dynamics of infrared multiphoton excitation and dissociation of SF 6 was investigated under collision free conditions by a crossed laser-molecular beam method. In order to understand the excitation mechanism and to elucidate the requirements of laser intensity and energy fluence, a series of experiments were carried out to measure the dissociation yield dependences on energy fluence, vibrational temperature of SF 6 , the pulse duration of the CO 2 laser and the frequency in both one and two laser experiments. Translational energy distributions of the SF 5 dissociation product measured by time of flight and angular distributions and the dissociation lifetime of excited SF 6 as inferred from the observation of secondary dissociation of SF 5 into SF 4 and F during the laser pulse suggest that the dynamics of dissociation of excited molecules is dominated by complete energy randomization and rapid intramolecular energy transfer on a nanosecond timescale, and can be adequately described by RRKM theory. An improved phenomenological model including the initial intensity dependent excitation, a rate equation describing the absorption and stimulated emission of single photons, and the unimolecular dissociation of excited molecules is constructed based on available experimental results. The model shows that the energy fluence of the laser determines the excitation of molecules in the quasi-continuum and the excess energy with which molecules dissociate after the laser pulse. The role played by the laser intensity in multiphoton dissociation is more significant than just that of overcoming the intensity dependent absorption in the lowest levels. 63 references

2008 Multiphoton Processes Gordon Research Conferences - June 8-13, 2008

Energy Technology Data Exchange (ETDEWEB)

Mette B. Gaarde

2009-08-28

In 2008 the Gordon Research Conference on Multiphoton Processes is held for the 14th time. The meeting continues to evolve as it embraces both the rapid technological and intellectual growth in the field as well as the multi-disciplinary expertise of the participants. This time the sessions will focus on: (1) Attosecond Science; (2) Free-electron laser experiments and theory; (3) Ultrafast dynamics of molecules; (4) Laser control of molecules; (5) Ultrafast imaging; (6) Super-high intensity and x-rays; (7) Strong field processes in molecules; and (8) Control atoms with light and vice versa. The scientific program will blur traditional disciplinary boundaries as the presenters and discussion leaders involve chemists, physicists, and optical engineers, representing both experiment and theory. The broad range of expertise and different perspectives of attendees should provide a stimulating and unique environment for solving problems and developing new ideas in this rapidly evolving field.

Non-invasive in vivo characterization of skin wound healing using label-free multiphoton microscopy (Conference Presentation)

Science.gov (United States)

Jones, Jake D.; Majid, Fariah; Ramser, Hallie; Quinn, Kyle P.

2017-02-01

Non-healing ulcerative wounds, such as diabetic foot ulcers, are challenging to diagnose and treat due to their numerous possible etiologies and the variable efficacy of advanced wound care products. Thus, there is a critical need to develop new quantitative biomarkers and diagnostic technologies that are sensitive to wound status in order to guide care. The objective of this study was to evaluate the utility of label-free multiphoton microscopy for characterizing wound healing dynamics in vivo and identifying potential differences in diabetic wounds. We isolated and measured an optical redox ratio of FAD/(NADH+FAD) autofluorescence to provide three-dimensional maps of local cellular metabolism. Using a mouse model of wound healing, in vivo imaging at the wound edge identified a significant decrease in the optical redox ratio of the epidermis (p≤0.0103) between Days 3 through 14 compared to Day 1. This decrease in redox ratio coincided with a decrease in NADH fluorescence lifetime and thickening of the epithelium, collectively suggesting a sensitivity to keratinocyte hyperproliferation. In contrast to normal wounds, we have found that keratinocytes from diabetic wounds remain in a proliferative state at later time points with a lower redox ratio at the wound edge. Microstructural organization and composition was also measured from second harmonic generation imaging of collagen and revealed differences between diabetic and non-diabetic wounds. Our work demonstrates label-free multiphoton microscopy offers potential to provide non-invasive structural and functional biomarkers associated with different stages of skin wound healing, which may be used to detect delayed healing and guide treatment.

Multiphoton photodegradation of indocyanine green: Solvent protolysis effect

Energy Technology Data Exchange (ETDEWEB)

Fuyuki, Masanori, E-mail: mn.fuyuki@kio.ac.jp

2016-02-15

The multiphoton photodegradation mechanism of indocyanine green (ICG) was investigated by using femtosecond near-infrared (NIR) pump and probe pulses. In the pump fluence region from 2 mJ/cm{sup 2} to 4 mJ/cm{sup 2}, the photodegradation rate was higher in acetic acid than in ethanol, and the rate was proportional to pump fluence to the 2.3th power in acetic acid and the 3.9th in ethanol. Considering that the degree of auto-protolysis of acetic acid is much higher than that of ethanol, the experimental results indicate that self-ionized solvent molecules played an essential role in the degradation of ICG molecules excited by NIR multiphoton process. - Highlights: • Photodegradation of ICG by femtosecond near-infrared pulses. • Photodegradation rate of ICG was higher in acetic acid than in ethanol. • Photodegradation rate was proportional to pump fluence to 2.3th power in acetic acid. • Photodegradation rate was proportional to pump fluence to 3.9th power in ethanol. • Self-ionized solvent molecules promoted ICG photodegradation in acetic acid.

Thermally activated delayed fluorescence organic dots for two-photon fluorescence lifetime imaging

Science.gov (United States)

He, Tingchao; Ren, Can; Li, Zhuohua; Xiao, Shuyu; Li, Junzi; Lin, Xiaodong; Ye, Chuanxiang; Zhang, Junmin; Guo, Lihong; Hu, Wenbo; Chen, Rui

2018-05-01

Autofluorescence is a major challenge in complex tissue imaging when molecules present in the biological tissue compete with the fluorophore. This issue may be resolved by designing organic molecules with long fluorescence lifetimes. The present work reports the two-photon absorption (TPA) properties of a thermally activated delayed fluorescence (TADF) molecule with carbazole as the electron donor and dicyanobenzene as the electron acceptor (i.e., 4CzIPN). The results indicate that 4CzIPN exhibits a moderate TPA cross-section (˜9 × 10-50 cm4 s photon-1), high fluorescence quantum yield, and a long fluorescence lifetime (˜1.47 μs). 4CzIPN was compactly encapsulated into an amphiphilic copolymer via nanoprecipitation to achieve water-soluble organic dots. Interestingly, 4CzIPN organic dots have been utilized in applications involving two-photon fluorescence lifetime imaging (FLIM). Our work aptly demonstrates that TADF molecules are promising candidates of nonlinear optical probes for developing next-generation multiphoton FLIM applications.

Multiphotonic Confocal Microscopy 3D imaging: Application to mantle sulfides in sub-arc environment (Avacha Volcano, Kamchatka)

Science.gov (United States)

Antoine, Bénard; Luc-Serge, Doucet; Sabine, Palle; Dmitri A., Ionov

2010-05-01

Petrogenetic relations in igneous rocks are usually studied in natural samples using classical optical microscopy and subsequent geochemical data acquisition. Multiphotonic Laser Scanning Confocal Microscopy (MLSCM) can be a powerful tool to section geological materials optically with sub-micrometric resolution and then generate a three-dimensional (3D) reconstruction (ca. 106 μm3 stack). MLSCM is used here to investigate textural relations of Monosulfide Solid Solution (MSS) with silicate phases in fresh spinel harzburgite xenoliths from the andesitic Avacha volcano (Kamchatka, Russia). The xenoliths contain MSS disseminated in olivine and orthopyroxene (opx) neoblasts as well as MSS-rich quenched magmatic opx veins [1]. First, Reflection Mode (RM) was tested on vein sulfides in resin-impregnated thick (120 μm) polished rock sections. Then we used a combination of Differential Interference Contrast (DIC) with a transmitted light detector, two photons-excited fluorescence (2PEF) and Second Harmonic Generation (SHG). Sequential imaging feature of the Leica TCS-SP2 software was applied. The excitation laser used for 2PEF was a COHERENT MIRA 900 with a 76Hz repetition rate and 800nm wavelength. Image stacks were analysed using ImageJ software [2]. The aim of the tests was to try to discriminate sulfides in silicate matrix as a tool for a better assessment of equilibrium conditions between the two phases. Preliminary results show that Fe-Ni rich MSS from vein and host rock have a strong auto-fluorescence in the Near UV-VIS domain (392-715 nm) whereas silicate matrix is only revealed through DIC. SHG is obtained only from dense nanocentrosymmetrical structures such as embedded medium (organic matter like glue and resin). The three images were recorded sequentially enabling efficient discrimination between the different components of the rock slices. RM permits reconstruction of the complete 3D structure of the rock slice. High resolution (ca. 0.2 μm along X-Y axis vs

Influence of rotation on multiphoton processes in HF

International Nuclear Information System (INIS)

Broeckhove, J.; Feyen, B.; Van Leuven, P.

1994-01-01

In this contribution, the authors are concerned with the role of rotational motion in multiphoton processes induced by a laser field of high intensity. The authors use the pseudospectral split operator method for the propagation of the quantum wave-function. The rotation is treated by decomposition of the HF wave-function in its angular momentum components

Time Resolved Shadowgraph Images of Silicon during Laser Ablation: Shockwaves and Particle Generation

International Nuclear Information System (INIS)

Liu, C Y; Mao, X L; Greif, R; Russo, R E

2007-01-01

Time resolved shadowgraph images were recorded of shockwaves and particle ejection from silicon during laser ablation. Particle ejection and expansion were correlated to an internal shockwave resonating between the shockwave front and the target surface. The number of particles ablated increased with laser energy and was related to the crater volume

Time Resolved Shadowgraph Images of Silicon during Laser Ablation:Shockwaves and Particle Generation

Energy Technology Data Exchange (ETDEWEB)

Liu, C.Y.; Mao, X.L.; Greif, R.; Russo, R.E.

2006-05-06

Time resolved shadowgraph images were recorded of shockwaves and particle ejection from silicon during laser ablation. Particle ejection and expansion were correlated to an internal shockwave resonating between the shockwave front and the target surface. The number of particles ablated increased with laser energy and was related to the crater volume.

Ponderomotive effects in multiphoton pair production

Science.gov (United States)

Kohlfürst, Christian; Alkofer, Reinhard

2018-02-01

The Dirac-Heisenberg-Wigner formalism is employed to investigate electron-positron pair production in cylindrically symmetric but otherwise spatially inhomogeneous, oscillating electric fields. The oscillation frequencies are hereby tuned to obtain multiphoton pair production in the nonperturbative threshold regime. An effective mass, as well as a trajectory-based semiclassical analysis, is introduced in order to interpret the numerical results for the distribution functions as well as for the particle yields and spectra. The results, including the asymptotic particle spectra, display clear signatures of ponderomotive forces.

Fast, free-breathing, in vivo fetal imaging using time-resolved 3D MRI technique: preliminary results.

Science.gov (United States)

Liu, Jing; Glenn, Orit A; Xu, Duan

2014-04-01

Fetal MR imaging is very challenging due to the movement of fetus and the breathing motion of the mother. Current clinical protocols involve quick 2D scouting scans to determine scan plane and often several attempts to reorient the scan plane when the fetus moves. This makes acquisition of fetal MR images clinically challenging and results in long scan times in order to obtain images that are of diagnostic quality. Compared to 2D imaging, 3D imaging of the fetus has many advantages such as higher SNR and ability to reformat images in multiple planes. However, it is more sensitive to motion and challenging for fetal imaging due to irregular fetal motion in addition to maternal breathing and cardiac motion. This aim of this study is to develop a fast 3D fetal imaging technique to resolve the challenge of imaging the moving fetus. This 3D imaging sequence has multi-echo radial sampling in-plane and conventional Cartesian encoding through plane, which provides motion robustness and high data acquisition efficiency. The utilization of a golden-ratio based projection profile allows flexible time-resolved image reconstruction with arbitrary temporal resolution at arbitrary time points as well as high signal-to-noise and contrast-to-noise ratio. The nice features of the developed image technique allow the 3D visualization of the movements occurring throughout the scan. In this study, we applied this technique to three human subjects for fetal MRI and achieved promising preliminary results of fetal brain, heart and lung imaging.

Study on infrared multiphoton excitation of the linear triatomic molecule by the Lie-algebra approach

International Nuclear Information System (INIS)

Feng, H.; Zheng, Y.; Ding, S.

2007-01-01

Infrared multiphoton vibrational excitation of the linear triatomic molecule has been studied using the quadratic anharmonic Lie-algebra model, unitary transformations, and Magnus approximation. An explicit Lie-algebra expression for the vibrational transition probability is obtained by using a Lie-algebra approach. This explicit Lie-algebra expressions for time-evolution operator and vibrational transition probabilities make the computation clearer and easier. The infrared multiphoton vibrational excitation of the DCN linear tri-atomic molecule is discussed as an example

Multiphoton minimal inertia scanning for fast acquisition of neural activity signals

Science.gov (United States)

Schuck, Renaud; Go, Mary Ann; Garasto, Stefania; Reynolds, Stephanie; Dragotti, Pier Luigi; Schultz, Simon R.

2018-04-01

Objective. Multi-photon laser scanning microscopy provides a powerful tool for monitoring the spatiotemporal dynamics of neural circuit activity. It is, however, intrinsically a point scanning technique. Standard raster scanning enables imaging at subcellular resolution; however, acquisition rates are limited by the size of the field of view to be scanned. Recently developed scanning strategies such as travelling salesman scanning (TSS) have been developed to maximize cellular sampling rate by scanning only select regions in the field of view corresponding to locations of interest such as somata. However, such strategies are not optimized for the mechanical properties of galvanometric scanners. We thus aimed to develop a new scanning algorithm which produces minimal inertia trajectories, and compare its performance with existing scanning algorithms. Approach. We describe here the adaptive spiral scanning (SSA) algorithm, which fits a set of near-circular trajectories to the cellular distribution to avoid inertial drifts of galvanometer position. We compare its performance to raster scanning and TSS in terms of cellular sampling frequency and signal-to-noise ratio (SNR). Main Results. Using surrogate neuron spatial position data, we show that SSA acquisition rates are an order of magnitude higher than those for raster scanning and generally exceed those achieved by TSS for neural densities comparable with those found in the cortex. We show that this result also holds true for in vitro hippocampal mouse brain slices bath loaded with the synthetic calcium dye Cal-520 AM. The ability of TSS to ‘park’ the laser on each neuron along the scanning trajectory, however, enables higher SNR than SSA when all targets are precisely scanned. Raster scanning has the highest SNR but at a substantial cost in number of cells scanned. To understand the impact of sampling rate and SNR on functional calcium imaging, we used the Cramér-Rao Bound on evoked calcium traces recorded

Time Domain Filtering of Resolved Images of Sgr A{sup ∗}

Energy Technology Data Exchange (ETDEWEB)

Shiokawa, Hotaka; Doeleman, Sheperd S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gammie, Charles F. [Department of Physics, University of Illinois, 1110 West Green Street, Urbana, IL 61801 (United States)

2017-09-01

The goal of the Event Horizon Telescope (EHT) is to provide spatially resolved images of Sgr A*, the source associated with the Galactic Center black hole. Because Sgr A* varies on timescales that are short compared to an EHT observing campaign, it is interesting to ask whether variability contains information about the structure and dynamics of the accretion flow. In this paper, we introduce “time-domain filtering,” a technique to filter time fluctuating images with specific temporal frequency ranges and to demonstrate the power and usage of the technique by applying it to mock millimeter wavelength images of Sgr A*. The mock image data is generated from the General Relativistic Magnetohydrodynamic (GRMHD) simulation and the general relativistic ray-tracing method. We show that the variability on each line of sight is tightly correlated with a typical radius of emission. This is because disk emissivity fluctuates on a timescale of the order of the local orbital period. Time-domain filtered images therefore reflect the model dependent emission radius distribution, which is not accessible in time-averaged images. We show that, in principle, filtered data have the power to distinguish between models with different black-hole spins, different disk viewing angles, and different disk orientations in the sky.

O2 rotational temperature measurements in an atmospheric air microdischarge by radar resonance-enhanced multiphoton ionization

International Nuclear Information System (INIS)

Sawyer, Jordan; Wu, Yue; Zhang, Zhili; Adams, Steven F.

2013-01-01

Nonintrusive spatially resolved rotational temperature measurements in an atmospheric air microdischarge are presented. The measurements were based on coherent microwave Rayleigh scattering (Radar) from resonance-enhanced multiphoton ionization of molecular oxygen. The open air DC microdischarge source operated in a stable “normal-glow” mode and pin-to-pin electrodes spaced 1.3 mm apart. The second harmonic of a tunable dye laser beam was focused between the two electrodes and scanned between 286 and 288 nm. Coherent microwave Rayleigh scattering was used to collect the two-photon rotational spectra of O 2 at C 3 Π(v = 2)←X 3 Σ(v′ = 0) transitions. The Boltzmann plots from analyses of the O 2 rotational lines determined local rotational temperatures at various axial locations between the electrodes. The molecular oxygen rotational temperature varied from ∼1150 K to ∼1350 K within the discharge area. The measurements had an accuracy of ∼±50 K.

O2 rotational temperature measurements in an atmospheric air microdischarge by radar resonance-enhanced multiphoton ionization

Science.gov (United States)

Sawyer, Jordan; Wu, Yue; Zhang, Zhili; Adams, Steven F.

2013-06-01

Nonintrusive spatially resolved rotational temperature measurements in an atmospheric air microdischarge are presented. The measurements were based on coherent microwave Rayleigh scattering (Radar) from resonance-enhanced multiphoton ionization of molecular oxygen. The open air DC microdischarge source operated in a stable "normal-glow" mode and pin-to-pin electrodes spaced 1.3 mm apart. The second harmonic of a tunable dye laser beam was focused between the two electrodes and scanned between 286 and 288 nm. Coherent microwave Rayleigh scattering was used to collect the two-photon rotational spectra of O2 at C3Π(v = 2)←X3Σ(v' = 0) transitions. The Boltzmann plots from analyses of the O2 rotational lines determined local rotational temperatures at various axial locations between the electrodes. The molecular oxygen rotational temperature varied from ˜1150 K to ˜1350 K within the discharge area. The measurements had an accuracy of ˜±50 K.

Resonance Enhanced Multi-photon Spectroscopy of DNA

Science.gov (United States)

Ligare, Marshall Robert

For over 50 years DNA has been studied to better understand its connection to life and evolution. These past experiments have led to our understanding of its structure and function in the biological environment but the interaction of DNA with UV radiation at the molecular level is still not very well understood. Unique mechanisms in nucleobase chromaphores protect us from adverse chemical reactions after UV absorption. Studying these processes can help develop theories for prebiotic chemistry and the possibility of alternative forms of DNA. Using resonance enhanced multi-photon spectroscopic techniques in the gas phase allow for the structure and dynamics of individual nucleobases to be studied in detail. Experiments studying different levels of structure/complexity with relation to their biological function are presented. Resonant IR multiphoton dissociation spectroscopy in conjunction with molecular mechanics and DFT calculations are used to determine gas phase structures of anionic nucleotide clusters. A comparison of the identified structures with known biological function shows how the hydrogen bonding of the nucleotides and their clusters free of solvent create favorable structures for quick incorporation into enzymes such as DNA polymerase. Resonance enhanced multi-photon ionization (REMPI) spectroscopy techniques such as resonant two photon ionization (R2PI) and IR-UV double resonance are used to further elucidate the structure and excited state dynamics of the bare nucleobases thymine and uracil. Both exhibit long lived excited electronic states that have been implicated in DNA photolesions which can ultimately lead to melanoma and carcinoma. Our experimental data in comparison with many quantum chemical calculations suggest a new picture for the dynamics of thymine and uracil in the gas phase. A high probability of UV absorption from a vibrationally hot ground state to the excited electronic state shows that the stability of thymine and uracil comes from

Computational code in atomic and nuclear quantum optics: Advanced computing multiphoton resonance parameters for atoms in a strong laser field

Science.gov (United States)

Glushkov, A. V.; Gurskaya, M. Yu; Ignatenko, A. V.; Smirnov, A. V.; Serga, I. N.; Svinarenko, A. A.; Ternovsky, E. V.

2017-10-01

The consistent relativistic energy approach to the finite Fermi-systems (atoms and nuclei) in a strong realistic laser field is presented and applied to computing the multiphoton resonances parameters in some atoms and nuclei. The approach is based on the Gell-Mann and Low S-matrix formalism, multiphoton resonance lines moments technique and advanced Ivanov-Ivanova algorithm of calculating the Green’s function of the Dirac equation. The data for multiphoton resonance width and shift for the Cs atom and the 57Fe nucleus in dependence upon the laser intensity are listed.

Multiphoton effects in laser-assisted ionization of a helium atom by electron impact

Energy Technology Data Exchange (ETDEWEB)

Ghosh Deb, S.; Sinha, C. [Department of Theoretical Physics, Indian association for the Cultivation of Science, Jadavpur, Kokata (India)

2010-11-15

The dynamics of the electron impact multiphoton ionization of a He atom in the presence of an intense laser field (n{gamma}{sub e}, 2e) is studied theoretically for laser polarization (||{sup l}) and perpendicular to the incident momentum. The triple differential (TDCS) as well as the double differential (DDCS) cross sections are studied for the coplanar asymmetric geometry. The results are compared with the only available kinematically complete experiment at high incident energy (1000 eV). Significant laser modification (enhancement) is noted due to multiphoton effects in the present binary and recoil peak intensities of the TDCS for both the geometries, in qualitative agreement with the experiment. In the single photon case, the net effect of the laser field is to suppress the field free (FF) TDCS as well as the DDCS in the zeroth order approximation of the ejected electron wave function (CV), while in the first order (MCV), the cross sections are found to be enhanced. The CV multiphoton cross sections obey the famous Kroll Watson (KW) sum rule while the latter does not hold good in the corresponding MCV approximation. (authors)

Photometric Modeling of Simulated Surace-Resolved Bennu Images

Science.gov (United States)

Golish, D.; DellaGiustina, D. N.; Clark, B.; Li, J. Y.; Zou, X. D.; Bennett, C. A.; Lauretta, D. S.

2017-12-01

The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) is a NASA mission to study and return a sample of asteroid (101955) Bennu. Imaging data from the mission will be used to develop empirical surface-resolved photometric models of Bennu at a series of wavelengths. These models will be used to photometrically correct panchromatic and color base maps of Bennu, compensating for variations due to shadows and photometric angle differences, thereby minimizing seams in mosaicked images. Well-corrected mosaics are critical to the generation of a global hazard map and a global 1064-nm reflectance map which predicts LIDAR response. These data products directly feed into the selection of a site from which to safely acquire a sample. We also require photometric correction for the creation of color ratio maps of Bennu. Color ratios maps provide insight into the composition and geological history of the surface and allow for comparison to other Solar System small bodies. In advance of OSIRIS-REx's arrival at Bennu, we use simulated images to judge the efficacy of both the photometric modeling software and the mission observation plan. Our simulation software is based on USGS's Integrated Software for Imagers and Spectrometers (ISIS) and uses a synthetic shape model, a camera model, and an empirical photometric model to generate simulated images. This approach gives us the flexibility to create simulated images of Bennu based on analog surfaces from other small Solar System bodies and to test our modeling software under those conditions. Our photometric modeling software fits image data to several conventional empirical photometric models and produces the best fit model parameters. The process is largely automated, which is crucial to the efficient production of data products during proximity operations. The software also produces several metrics on the quality of the observations themselves, such as surface coverage and the

Local crystallography analysis for atomically resolved scanning tunneling microscopy images

International Nuclear Information System (INIS)

Lin, Wenzhi; Li, Qing; Belianinov, Alexei; Gai, Zheng; Baddorf, Arthur P; Pan, Minghu; Jesse, Stephen; Kalinin, Sergei V; Sales, Brian C; Sefat, Athena

2013-01-01

Scanning probe microscopy has emerged as a powerful and flexible tool for atomically resolved imaging of surface structures. However, due to the amount of information extracted, in many cases the interpretation of such data is limited to being qualitative and semi-quantitative in nature. At the same time, much can be learned from local atom parameters, such as distances and angles, that can be analyzed and interpreted as variations of local chemical bonding, or order parameter fields. Here, we demonstrate an iterative algorithm for indexing and determining atomic positions that allows the analysis of inhomogeneous surfaces. This approach is further illustrated by local crystallographic analysis of several real surfaces, including highly ordered pyrolytic graphite and an Fe-based superconductor FeTe 0.55 Se 0.45 . This study provides a new pathway to extract and quantify local properties for scanning probe microscopy images. (paper)

Nanostructures based on quantum dots for application in promising methods of single- and multiphoton imaging and diagnostics

Science.gov (United States)

Nabiev, I. R.

2017-01-01

Molecules recognizing biomarkers of diseases (monoclonal antibodies (monoABs)) are often too large for biomedical applications, and the conditions that are used to bind them with nanolabels lead to disordered orientation of monoABs with respect to the nanoparticle surface. Extremely small nanoprobes, designed via oriented conjugation of quantum dots (QDs) with single-domain antibodies (sdABs) derived from the immunoglobulin of llama and produced in the E. coli culture, have a hydrodynamic diameter less than 12 nm and contain equally oriented sdAB molecules on the surface of each QD. These nanoprobes exhibit excellent specificity and sensitivity in quantitative determination of a small number of cells expressing biomarkers. In addition, the higher diffusion coefficient of sdABs makes it possible to perform immunohistochemical analysis in bulk tissue, inaccessible for conventional monoABs. The necessary conditions for implementing high-quality immunofluorescence diagnostics are a high specificity of labeling and clear differences between the fluorescence of nanoprobes and the autofluorescence of tissues. Multiphoton micros-copy with excitation in the near-IR spectral range, which is remote from the range of tissue autofluorescence excitation, makes it possible to solve this problem and image deep layers in biological tissues. The two-photon absorption cross sections of CdSe/ZnS QDs conjugated with sdABs exceed the corresponding values for organic fluorophores by several orders of magnitude. These nanoprobes provide clear discrimination between the regions of tumor and normal tissues with a ratio of the sdAB fluorescence to the tissue autofluorescence upon two-photon excitation exceeding that in the case of single-photon excitation by a factor of more than 40. The data obtained indicate that the sdAB-QD conjugates used as labels provide the same, or even better, quality as the "gold standard" of immunohistochemical diagnostics. The developed nanoprobes are expected to

Semiclassical analysis of long-wavelength multiphoton processes: The periodically driven harmonic oscillator

International Nuclear Information System (INIS)

Fox, Ronald F.; Vela-Arevalo, Luz V.

2002-01-01

The problem of multiphoton processes for intense, long-wavelength irradiation of atomic and molecular electrons is presented. The recently developed method of quasiadiabatic time evolution is used to obtain a nonperturbative analysis. When applied to the standard vector potential coupling, an exact auxiliary equation is obtained that is in the electric dipole coupling form. This is achieved through application of the Goeppert-Mayer gauge. While the analysis to this point is general and aimed at microwave irradiation of Rydberg atoms, a Floquet analysis of the auxiliary equation is presented for the special case of the periodically driven harmonic oscillator. Closed form expressions for a complete set of Floquet states are obtained. These are used to demonstrate that for the oscillator case there are no multiphoton resonances

Experimental REMPI [Resonance Enhanced Multiphoton Ionization] studies of small molecules

International Nuclear Information System (INIS)

Dehmer, J.L.; Dehmer, P.M.; Pratt, S.T.; O'Halloran, M.A.; Tomkins, F.S.

1986-01-01

Resonance Enhanced Multiphoton Ionization (REMPI) utilizes tunable dye lasers to ionize an atom or molecule by first preparing an excited state by multiphoton absorption and then ionizing that state before it can decay. This process is highly selective with respect to both the initial and resonant intermediate states of the target, and it can be extremely sensitive. In addition, the products of the REMPI process can be detected as needed by analyzing the resulting electrons, ions, fluorescence, or by additional REMPI. This points to a number of exciting opportunities for both basic and applied science. On the applied side, REMPI has great potential as an ultrasensitive, highly selective detector for trace, reactive, or transient species. On the basic side, REMPI affords an unprecedented means of exploring excited state physics and chemistry at the quantum-state-specific level. We shall give an overview together with examples of current studies of excited molecular states to illustrate the principles of and prospects for REMPI. 27 refs., 3 figs

Time resolved, 2-D hard X-ray imaging of relativistic electron-beam target interactions on ETA-II

International Nuclear Information System (INIS)

Crist, C.E.; Sampayan, S.; Westenskow, G.; Caporaso, G.; Houck, T.; Weir, J.; Trimble, D.; Krogh, M.

1998-01-01

Advanced radiographic applications require a constant source size less than 1 mm. To study the time history of a relativistic electron beam as it interacts with a bremsstrahlung converter, one of the diagnostics they use is a multi-frame time-resolved hard x-ray camera. They are performing experiments on the ETA-II accelerator at Lawrence Livermore National Laboratory to investigate details of the electron beam/converter interactions. The camera they are using contains 6 time-resolved images, each image is a 5 ns frame. By starting each successive frame 10 ns after the previous frame, they create a 6-frame movie from the hard x-rays produced from the interaction of the 50-ns electron beam pulse

Temporally resolved imaging on quenching and re-ignition of nanosecond underwater discharge

Directory of Open Access Journals (Sweden)

Yong Yang

2012-12-01

Full Text Available This paper presents the temporally resolved images of plasma discharge in de-ionized water. The discharge was produced by high voltage pulses with 0.3 ns rise time and 10 ns duration. The temporal resolution of the imaging system was one nanosecond. A unique three-stage process, including a fast ignition at the leading edge of the pulse, quenching at the plateau of the pulse, and self re-ignition at the trailing edge of the pulse, was observed in a single pulse cycle. The maximum measured propagation velocity of the plasma discharge was about 1000 km/s. The possibility of direct ionization in water under high reduced electric field conditions was discussed.

Multiphoton absorption coefficients in solids: an universal curve

International Nuclear Information System (INIS)

Brandi, H.S.; Araujo, C.B. de

1983-04-01

An universal curve for the frequency dependence of the multiphoton absorption coefficient is proposed based on a 'non-perturbative' approach. Specific applications have been made to obtain two, three, four and five photons absorption coefficient in different materials. Properly scaling of the two photon absorption coefficient and the use of the universal curve yields results for the higher order absorption coefficients in good agreement with the experimental data. (Author) [pt

Quantitative depth resolved microcirculation imaging with optical coherence tomography angiography (Part ΙΙ): Microvascular network imaging.

Science.gov (United States)

Gao, Wanrong

2017-04-17

In this work, we review the main phenomena that have been explored in OCT angiography to image the vessels of the microcirculation within living tissues with the emphasis on how the different processing algorithms were derived to circumvent specific limitations. Parameters are then discussed that can quantitatively describe the depth-resolved microvascular network for possible clinic diagnosis applications. Finally,future directions in continuing OCT development are discussed. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Statistical properties of multiphoton time-dependent three-boson coupled oscillators

Czech Academy of Sciences Publication Activity Database

Abdalla, M. S.; Peřina, Jan; Křepelka, Jaromír

2006-01-01

Roč. 23, č. 6 (2006), s. 1146-1160 ISSN 0740-3224 R&D Projects: GA MŠk(CZ) OC P11.003 Institutional research plan: CEZ:AV0Z10100522 Keywords : quantum statistic * coupled oscillators * multiphoton Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.002, year: 2006

In vivo 3D measurement of moxifloxacin and gatifloxacin distributions in the mouse cornea using multiphoton microscopy

OpenAIRE

Lee, Seunghun; Lee, Jun Ho; Park, Jin Hyoung; Yoon, Yeoreum; Chung, Wan Kyun; Tchah, Hungwon; Kim, Myoung Joon; Kim, Ki Hean

2016-01-01

Moxifloxacin and gatifloxacin are fourth-generation fluoroquinolone antibiotics used in the clinic to prevent or treat ocular infections. Their pharmacokinetics in the cornea is usually measured from extracted ocular fluids or tissues, and in vivo direct measurement is difficult. In this study multiphoton microscopy (MPM), which is a 3D optical microscopic technique based on multiphoton fluorescence, was applied to the measurement of moxifloxacin and gatifloxacin distribution in the cornea. I...

EVIDENCE FOR DUST CLEARING THROUGH RESOLVED SUBMILLIMETER IMAGING

International Nuclear Information System (INIS)

Brown, J. M.; Blake, G. A.; Qi, C.; Wilner, D. J.; Dullemond, C. P.; Williams, J. P.

2009-01-01

Mid-infrared spectrophotometric observations have revealed a small subclass of circumstellar disks with spectral energy distributions (SEDs) suggestive of large inner gaps with low dust content. However, such data provide only an indirect and model-dependent method of finding central holes. Imaging of protoplanetry disks provides an independent check of SED modeling. We present here the direct characterization of three 33-47 AU radii inner gaps, in the disks around LkHα 330, SR 21N, and HD 135344B, via 340 GHz (880 μm) dust continuum aperture synthesis observations obtained with the Submillimeter Array (SMA). The large gaps are fully resolved at ∼0.''3 by the SMA data and mostly empty of dust, with less than (1-7.5) x 10 -6 M sun of fine grained solids inside the holes. Gas (as traced by atomic accretion markers and CO 4.7 μm rovibrational emission) is still present in the inner regions of all three disks. For each, the inner hole exhibits a relatively steep rise in dust emission to the outer disk, a feature more likely to originate from the gravitational influence of a companion body than from a process expected to show a more shallow gradient like grain growth. Importantly, the good agreement between the spatially resolved data and spectrophotometry-based models lends confidence to current interpretations of SEDs, wherein the significant dust emission deficits arise from disks with inner gaps or holes. Further SED-based searches can therefore be expected to yield numerous additional candidates that can be examined at high spatial resolution.

View-sharing in keyhole imaging: Partially compressed central k-space acquisition in time-resolved MRA at 3.0 T

International Nuclear Information System (INIS)

Hadizadeh, Dariusch R.; Gieseke, Juergen; Beck, Gabriele; Geerts, Liesbeth; Kukuk, Guido M.; Bostroem, Azize; Urbach, Horst; Schild, Hans H.; Willinek, Winfried A.

2011-01-01

Introduction: Time-resolved contrast-enhanced magnetic resonance (MR) angiography (CEMRA) of the intracranial vasculature has proved its clinical value for the evaluation of cerebral vascular disease in cases where both flow hemodynamics and morphology are important. The purpose of this study was to evaluate a combination of view-sharing with keyhole imaging to increase spatial and temporal resolution of time-resolved CEMRA at 3.0 T. Methods: Alternating view-sharing was combined with randomly segmented k-space ordering, keyhole imaging, partial Fourier and parallel imaging (4DkvsMRA). 4DkvsMRA was evaluated using varying compression factors (80-100) resulting in spatial resolutions ranging from (1.1 x 1.1 x 1.4) to (0.96 x 0.96 x 0.95) mm 3 and temporal resolutions ranging from 586 ms/dynamic scan - 288 ms/dynamic scan in three protocols in 10 healthy volunteers and seven patients (17 subjects). DSA correlation was available in four patients with cerebral arteriovenous malformations (cAVMs) and one patient with cerebral teleangiectasia. Results: 4DkvsMRA was successfully performed in all subjects and showed clear depiction of arterial and venous phases with diagnostic image quality. At the maximum view-sharing compression factor (=100), a 'flickering' artefact was observed. Conclusion: View-sharing in keyhole imaging allows for increased spatial and temporal resolution in time-resolved MRA.

View-sharing in keyhole imaging: Partially compressed central k-space acquisition in time-resolved MRA at 3.0 T

Energy Technology Data Exchange (ETDEWEB)

Hadizadeh, Dariusch R., E-mail: Dariusch.Hadizadeh@ukb.uni-bonn.de [University of Bonn, Department of Radiology, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany); Gieseke, Juergen [University of Bonn, Department of Radiology, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany); Philips Healthcare, Best (Netherlands); Beck, Gabriele; Geerts, Liesbeth [Philips Healthcare, Best (Netherlands); Kukuk, Guido M. [University of Bonn, Department of Radiology, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany); Bostroem, Azize [Department of Neurosurgery, Sigmund-Freud-Strasse 25, 53127 Bonn, Deutschland (Germany); Urbach, Horst; Schild, Hans H.; Willinek, Winfried A. [University of Bonn, Department of Radiology, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany)

2011-11-15

Introduction: Time-resolved contrast-enhanced magnetic resonance (MR) angiography (CEMRA) of the intracranial vasculature has proved its clinical value for the evaluation of cerebral vascular disease in cases where both flow hemodynamics and morphology are important. The purpose of this study was to evaluate a combination of view-sharing with keyhole imaging to increase spatial and temporal resolution of time-resolved CEMRA at 3.0 T. Methods: Alternating view-sharing was combined with randomly segmented k-space ordering, keyhole imaging, partial Fourier and parallel imaging (4DkvsMRA). 4DkvsMRA was evaluated using varying compression factors (80-100) resulting in spatial resolutions ranging from (1.1 x 1.1 x 1.4) to (0.96 x 0.96 x 0.95) mm{sup 3} and temporal resolutions ranging from 586 ms/dynamic scan - 288 ms/dynamic scan in three protocols in 10 healthy volunteers and seven patients (17 subjects). DSA correlation was available in four patients with cerebral arteriovenous malformations (cAVMs) and one patient with cerebral teleangiectasia. Results: 4DkvsMRA was successfully performed in all subjects and showed clear depiction of arterial and venous phases with diagnostic image quality. At the maximum view-sharing compression factor (=100), a 'flickering' artefact was observed. Conclusion: View-sharing in keyhole imaging allows for increased spatial and temporal resolution in time-resolved MRA.

Line broadening in multiphoton processes with a resonant intermediate transition

International Nuclear Information System (INIS)

Wang, C.C.; James, J.V.; Xia, J.

1983-01-01

The linewidth of the excitation spectrum for multiphoton ionization is found to be broadened much more severely than the cascade fluorescence originating from the resonant intermediate level. These results are due to the mutual effects of the ionizing and resonating transitions, which are not properly accounted for in perturbative treatments

Deep imaging: how much of the proteome does current top-down technology already resolve?

Directory of Open Access Journals (Sweden)

Elise P Wright

Full Text Available Effective proteome analyses are based on interplay between resolution and detection. It had been claimed that resolution was the main factor limiting the use of two-dimensional gel electrophoresis. Improved protein detection now indicates that this is unlikely to be the case. Using a highly refined protocol, the rat brain proteome was extracted, resolved, and detected. In order to overcome the stain saturation threshold, high abundance protein species were excised from the gel following standard imaging. Gels were then imaged again using longer exposure times, enabling detection of lower abundance, less intensely stained protein species. This resulted in a significant enhancement in the detection of resolved proteins, and a slightly modified digestion protocol enabled effective identification by standard mass spectrometric methods. The data indicate that the resolution required for comprehensive proteome analyses is already available, can assess multiple samples in parallel, and preserve critical information concerning post-translational modifications. Further optimization of staining and detection methods promises additional improvements to this economical, widely accessible and effective top-down approach to proteome analysis.

Multiphoton atomic ionization in the field of a very short laser pulse

International Nuclear Information System (INIS)

Popov, V.S.

2001-01-01

Closed analytic expressions are derived for the probability of multiphoton atomic and ionic ionization in a variable electric field E(t), which are applicable for arbitrary Keldysh parameters γ. Dependencies of the ionization probability and photoelectron pulse spectrum on the shape of a very short laser pulse are analyzed. Examples of pulse fields of various forms, including a modulated light pulse with a Gaussian or Lorentz envelope, are considered in detail. The interference effect in the photoelectron energy spectrum during atomic ionization by a periodic field of a general form is examined. The range of applicability of the adiabatic approximation in the multiphoton ionization theory is discussed. The imaginary time method is used in the calculations, which allows the probability of particle tunneling through oscillating barriers to be effectively calculated

Femtosecond Light Source for Phase-Controlled Multiphoton Ionization

International Nuclear Information System (INIS)

Sokolov, A. V.; Walker, D. R.; Yavuz, D. D.; Yin, G. Y.; Harris, S. E.

2001-01-01

We describe a femtosecond Raman light source with more than an octave of optical bandwidth. We use this source to demonstrate phase control of multiphoton ionization under conditions where ionization requires eleven photons of the lowest frequency of the spectrum or five photons of the highest frequency. The nonlinearity of the photoionization process allows us to characterize the light source. Experiment-to-theory comparison implies generation of a near single-cycle waveform

An instrument for small-animal imaging using time-resolved diffuse and fluorescence optical methods

International Nuclear Information System (INIS)

Montcel, Bruno; Poulet, Patrick

2006-01-01

We describe time-resolved optical methods that use diffuse near-infrared photons to image the optical properties of tissues and their inner fluorescent probe distribution. The assembled scanner uses picosecond laser diodes at 4 wavelengths, an 8-anode photo-multiplier tube and time-correlated single photon counting. Optical absorption and reduced scattering images as well as fluorescence emission images are computed from temporal profiles of diffuse photons. This method should improve the spatial resolution and the quantification of fluorescence signals. We used the diffusion approximation of the radiation transport equation and the finite element method to solve the forward problem. The inverse problem is solved with an optimization algorithm such as ART or conjugate gradient. The scanner and its performances are presented, together with absorption, scattering and fluorescent images obtained with it

Advanced femtosecond lasers enable new developments in non-linear imaging and functional studies in neuroscience, biology and medical applications (Conference Presentation)

Science.gov (United States)

Arrigoni, Marco; McCoy, Darryl

2016-03-01

In the last few years Multiphoton Excitation Microscopy witnessed a mutation from tool for imaging cellular structures in living animals deeper than other high-resolution techniques, into an instrument for monitoring functionality and even stimulating or inhibiting inter-cellular signalling. This paradigm shift has been enabled primarily by the development of genetically encoded probes like Ca indicators (GECI) and Opsins for optogenetics inhibition and stimulation. These developments will hopefully enable the understanding of how local network of hundreds or thousands of neurons operate in response to actual tasks or induced stimuli. Imaging, monitoring signals and activating neurons, all on a millisecond time scale, requires new laser tools providing a combination of wavelengths, higher powers and operating regimes different from the ones traditionally used for classic multiphoton imaging. The other key development in multiphoton techniques relates to potential diagnostic and clinical applications where non-linear imaging could provide all optical marker-free replacement of H and E techniques and even intra-operative guidance for procedures like cancer surgery. These developments will eventually drive the development of specialized laser sources where compact size, ease of use, beam delivery and cost are primary concerns. In this talk we will discuss recent laser product developments targeting the various applications of multiphoton imaging, as fiber lasers and other new type of lasers gradually gain popularity and their own space, side-by-side or as an alternative to conventional titanium sapphire femtosecond lasers.

Time-resolved echo-shared parallel MRA of the lung: observer preference study of image quality in comparison with non-echo-shared sequences

International Nuclear Information System (INIS)

Fink, C.; Puderbach, M.; Zaporozhan, J.; Plathow, C.; Kauczor, H.-U.; Ley, S.

2005-01-01

The aim of this study was to evaluate the image quality of time-resolved echo-shared parallel MRA of the lung. The pulmonary vasculature of nine patients (seven females, two males; median age: 44 years) with pulmonary disease was examined using a time-resolved MRA sequence combining echo sharing with parallel imaging (time-resolved echo-shared angiography technique, or TREAT). The sharpness of the vessel borders, conspicuousness of peripheral lung vessels, artifact level, and overall image quality of TREAT was assessed independently by four readers in a side-by-side comparison with non-echo-shared time-resolved parallel MRA data (pMRA) previously acquired in the same patients. Furthermore, the SNR of pulmonary arteries (PA) and veins (PV) achieved with both pulse sequences was compared. The mean voxel size of TREAT MRA was decreased by 24% compared with the non-echo-shared MRA. Regarding the sharpness of the vessel borders, conspicuousness of peripheral lung vessels, and overall image quality the TREAT sequence was rated superior in 75-76% of all cases. If the TREAT images were preferred over the pMRA images, the advantage was rated as major in 61-71% of all cases. The level of artifacts was not increased with the TREAT sequence. The mean interobserver agreement for all categories ranged between fair (artifact level) and good (overall image quality). The maximum SNR of TREAT did not differ from non-echo-shared parallel MRA (PA: TREAT: 273±45; pMRA: 280±71; PV: TREAT: 273±33; pMRA: 258±62). TREAT achieves a higher spatial resolution than non-echo-shared parallel MRA which is also perceived as an improved image quality. (orig.)

Design, Fabrication and Computational Characterization of a 3D Micro-Valve Built by Multi-Photon Polymerization

Directory of Open Access Journals (Sweden)

Stratos Galanopoulos

2014-08-01

Full Text Available We report on the design, modeling and fabrication by multi-photon polymerization of a complex medical fluidic device. The physical dimensions of the built micro-valve prototype are compared to those of its computer-designed model. Important fabrication issues such as achieving high dimensional resolution and ability to control distortion due to shrinkage are presented and discussed. The operational performance of both multi-photon and CAD-created models under steady blood flow conditions was evaluated and compared through computational fluid dynamics analysis.

Monitoring the effect of mechanical stress on mesenchymal stem cell collagen production by multiphoton microscopy

Science.gov (United States)

Chen, Wei-Liang; Chang, Chia-Cheng; Chiou, Ling-Ling; Li, Tsung-Hsien; Liu, Yuan; Lee, Hsuan-Shu; Dong, Chen-Yuan

2008-02-01

Tissue engineering is emerging as a promising method for repairing damaged tissues. Due to cartilage's common wear and injury, in vitro production of cartilage replacements have been an active area of research. Finding the optimal condition for the generation of the collagen matrix is crucial in reproducing cartilages that closely match those found in human. Using multiphoton autofluorescence and second-harmonic generation (SHG) microscopy we monitored the effect of mechanical stress on mesenchymal stem cell collagen production. Bone marrow mesenchymal stem cells in the form of pellets were cultured and periodically placed under different mechanical stress by centrifugation over a period of four weeks. The differently stressed samples were imaged several times during the four week period, and the collagen production under different mechanical stress is characterized.

Beyond the Floquet theorem: generalized Floquet formalisms and quasienergy methods for atomic and molecular multiphoton processes in intense laser fields

International Nuclear Information System (INIS)

Chu, S.-I.; Telnov, D.A.

2004-01-01

The advancement of high-power and short-pulse laser technology in the past two decades has generated considerable interest in the study of multiphoton and very high-order nonlinear optical processes of atomic and molecular systems in intense and superintense laser fields, leading to the discovery of a host of novel strong-field phenomena which cannot be understood by the conventional perturbation theory. The Floquet theorem and the time-independent Floquet Hamiltonian method are powerful theoretical framework for the study of bound-bound multiphoton transitions driven by periodically time-dependent fields. However, there are a number of significant strong-field processes cannot be directly treated by the conventional Floquet methods. In this review article, we discuss several recent developments of generalized Floquet theorems, formalisms, and quasienergy methods, beyond the conventional Floquet theorem, for accurate nonperturbative treatment of a broad range of strong-field atomic and molecular processes and phenomena of current interests. Topics covered include (a) artificial intelligence (AI)-most-probable-path approach (MPPA) for effective treatment of ultralarge Floquet matrix problem; (b) non-Hermitian Floquet formalisms and complex quasienergy methods for nonperturbative treatment of bound-free and free-free processes such as multiphoton ionization (MPI) and above-threshold ionization (ATI) of atoms and molecules, multiphoton dissociation (MPD) and above-threshold dissociation (ATD) of molecules, chemical bond softening and hardening, charge-resonance enhanced ionization (CREI) of molecular ions, and multiple high-order harmonic generation (HHG), etc.; (c) many-mode Floquet theorem (MMFT) for exact treatment of multiphoton processes in multi-color laser fields with nonperiodic time-dependent Hamiltonian; (d) Floquet-Liouville supermatrix (FLSM) formalism for exact nonperturbative treatment of time-dependent Liouville equation (allowing for relaxations and

Beyond the Floquet theorem: generalized Floquet formalisms and quasienergy methods for atomic and molecular multiphoton processes in intense laser fields

Science.gov (United States)

Chu, Shih-I.; Telnov, Dmitry A.

2004-02-01

The advancement of high-power and short-pulse laser technology in the past two decades has generated considerable interest in the study of multiphoton and very high-order nonlinear optical processes of atomic and molecular systems in intense and superintense laser fields, leading to the discovery of a host of novel strong-field phenomena which cannot be understood by the conventional perturbation theory. The Floquet theorem and the time-independent Floquet Hamiltonian method are powerful theoretical framework for the study of bound-bound multiphoton transitions driven by periodically time-dependent fields. However, there are a number of significant strong-field processes cannot be directly treated by the conventional Floquet methods. In this review article, we discuss several recent developments of generalized Floquet theorems, formalisms, and quasienergy methods, beyond the conventional Floquet theorem, for accurate nonperturbative treatment of a broad range of strong-field atomic and molecular processes and phenomena of current interests. Topics covered include (a) artificial intelligence (AI)-most-probable-path approach (MPPA) for effective treatment of ultralarge Floquet matrix problem; (b) non-Hermitian Floquet formalisms and complex quasienergy methods for nonperturbative treatment of bound-free and free-free processes such as multiphoton ionization (MPI) and above-threshold ionization (ATI) of atoms and molecules, multiphoton dissociation (MPD) and above-threshold dissociation (ATD) of molecules, chemical bond softening and hardening, charge-resonance enhanced ionization (CREI) of molecular ions, and multiple high-order harmonic generation (HHG), etc.; (c) many-mode Floquet theorem (MMFT) for exact treatment of multiphoton processes in multi-color laser fields with nonperiodic time-dependent Hamiltonian; (d) Floquet-Liouville supermatrix (FLSM) formalism for exact nonperturbative treatment of time-dependent Liouville equation (allowing for relaxations and

Time-resolved diode laser infrared absorption spectroscopy of the nascent HCl in the infrared laser chemistry of 1,2-dichloro-1,1-difluoroethane

Science.gov (United States)

Dietrich, Peter; Quack, Martin; Seyfang, George

1990-04-01

The IR multiphoton excitation and the frequency, fluence and intensity dependence of the IR-laser chemical yields of CF 2ClCH 2Cl have been studied in the fluence range of 1 to 10 J cm -2 yielding a steady-state constant k(st)/ I=0.74×10 6 s -1 MW -1 cm 2 which is approximately independent of intensity. Time-resolved IR absorption spectroscopy with diode laser sources has been used to observe the nascent HCl during the first few 100 ns indicating a population inversion between the levels ν=1, J=4 and ν=2, J=5. At low reactant pressures ( p⩽10 Pa) the time-resolved measurement gives a steady-state rate constant consistent with the theoretical result adjusted to the static yield measurements. The capability of state-selective and time-resolved IR spectroscopy is thus demonstrated, giving real-time determinations of rate constants.

Coherent enhancement of resonance-mediated multiphoton absorption

International Nuclear Information System (INIS)

Zhang, Shian; Zhang, Hui; Jia, Tianqing; Wang, Zugeng; Sun, Zhenrong

2010-01-01

In this paper, we theoretically investigate the coherent enhancement of resonance-mediated (2+2) four-photon absorption. It is found that by shaping the spectral phase with a π phase step, the resonance-mediated (2+2) four-photon transition probability can be enhanced. Furthermore, the coherent enhancement dependences on the detuning between the two two-photon absorptions, laser spectral bandwidth and laser centre frequency are explicitly discussed and analysed. We believe these theoretical results may play an important role in enhancing more complex resonance-mediated multiphoton absorption processes.

Whole-head functional brain imaging of neonates at cot-side using time-resolved diffuse optical tomography

Science.gov (United States)

Dempsey, Laura A.; Cooper, Robert J.; Powell, Samuel; Edwards, Andrea; Lee, Chuen-Wai; Brigadoi, Sabrina; Everdell, Nick; Arridge, Simon; Gibson, Adam P.; Austin, Topun; Hebden, Jeremy C.

2015-07-01

We present a method for acquiring whole-head images of changes in blood volume and oxygenation from the infant brain at cot-side using time-resolved diffuse optical tomography (TR-DOT). At UCL, we have built a portable TR-DOT device, known as MONSTIR II, which is capable of obtaining a whole-head (1024 channels) image sequence in 75 seconds. Datatypes extracted from the temporal point spread functions acquired by the system allow us to determine changes in absorption and reduced scattering coefficients within the interrogated tissue. This information can then be used to define clinically relevant measures, such as oxygen saturation, as well as to reconstruct images of relative changes in tissue chromophore concentration, notably those of oxy- and deoxyhaemoglobin. Additionally, the effective temporal resolution of our system is improved with spatio-temporal regularisation implemented through a Kalman filtering approach, allowing us to image transient haemodynamic changes. By using this filtering technique with intensity and mean time-of-flight datatypes, we have reconstructed images of changes in absorption and reduced scattering coefficients in a dynamic 2D phantom. These results demonstrate that MONSTIR II is capable of resolving slow changes in tissue optical properties within volumes that are comparable to the preterm head. Following this verification study, we are progressing to imaging a 3D dynamic phantom as well as the neonatal brain at cot-side. Our current study involves scanning healthy babies to demonstrate the quality of recordings we are able to achieve in this challenging patient population, with the eventual goal of imaging functional activation and seizures.

Multiphoton ionization as a probe of molecular photofragmentation: statistical and dynamical energy partitioning in the multiphoton dissociation of nitromethane

International Nuclear Information System (INIS)

Rockney, B.H.

1982-01-01

Multiphoton ionization (MPI) appears in its first use as a probe of laser-induced photofragmentation. Specifically, MPI here reveals the internal and translational energy content of the nascent fragments from the infrared multiphoton dissociation (MPD) of nitromethane (CH 3 NO 2 ). The apparatus for this work consists of a pulsed supersonic molecular beam crossed by two pulsed and focused lasers - a CO 2 laser to induce collision-free unimolecular dissociation of CH 3 NO 2 , and a tunable dye laser following immediately to ionize selectively one of the pair of dissociation fragments for detection by a mass spectrometer and particle multiplier. A computer simulation of each fragment's MPI spectrum, a series of four photon resonances to members of the npsigma/sub u/ Rydberg state of NO 2 and three photon resonances to two vibrational members of the #betta# 1 Rydberg state of CH 3 , aids in determining the fragment's internal energy content. The dye laser is delayed and its focus is traced through a small quarter circle centered at the focus of the CO 2 laser. The flight times of the fragments from the point of dissociation and their laboratory scattering angular distributions at fixed ionizing laser wavelength provide their center of mass recoil velocity distributions. The energy deposited in the fragments evidences a striking mixture of statistical and dynamical energy partitioning. The statistical RRKM theory of unimolecular decomposition accurately predicts the amount of internal energy found in the fragments

Accelerated echo-planar J-resolved spectroscopic imaging in the human brain using compressed sensing: a pilot validation in obstructive sleep apnea.

Science.gov (United States)

Sarma, M K; Nagarajan, R; Macey, P M; Kumar, R; Villablanca, J P; Furuyama, J; Thomas, M A

2014-06-01

Echo-planar J-resolved spectroscopic imaging is a fast spectroscopic technique to record the biochemical information in multiple regions of the brain, but for clinical applications, time is still a constraint. Investigations of neural injury in obstructive sleep apnea have revealed structural changes in the brain, but determining the neurochemical changes requires more detailed measurements across multiple brain regions, demonstrating a need for faster echo-planar J-resolved spectroscopic imaging. Hence, we have extended the compressed sensing reconstruction of prospectively undersampled 4D echo-planar J-resolved spectroscopic imaging to investigate metabolic changes in multiple brain locations of patients with obstructive sleep apnea and healthy controls. Nonuniform undersampling was imposed along 1 spatial and 1 spectral dimension of 4D echo-planar J-resolved spectroscopic imaging, and test-retest reliability of the compressed sensing reconstruction of the nonuniform undersampling data was tested by using a brain phantom. In addition, 9 patients with obstructive sleep apnea and 11 healthy controls were investigated by using a 3T MR imaging/MR spectroscopy scanner. Significantly reduced metabolite differences were observed between patients with obstructive sleep apnea and healthy controls in multiple brain regions: NAA/Cr in the left hippocampus; total Cho/Cr and Glx/Cr in the right hippocampus; total NAA/Cr, taurine/Cr, scyllo-Inositol/Cr, phosphocholine/Cr, and total Cho/Cr in the occipital gray matter; total NAA/Cr and NAA/Cr in the medial frontal white matter; and taurine/Cr and total Cho/Cr in the left frontal white matter regions. The 4D echo-planar J-resolved spectroscopic imaging technique using the nonuniform undersampling-based acquisition and compressed sensing reconstruction in patients with obstructive sleep apnea and healthy brain is feasible in a clinically suitable time. In addition to brain metabolite changes previously reported by 1D MR

Generating multiphoton Greenberger-Horne-Zeilinger states with weak cross-Kerr nonlinearity

International Nuclear Information System (INIS)

Jin, Guang-Sheng; Lin, Yuan; Wu, Biao

2007-01-01

We propose a scheme to generate polarization-entangled multiphoton Greenberger-Horne-Zeilinger states with weak cross-Kerr nonlinearity based on controlled bus rotation and subsequent homodyne measurement. Our method is simple in operation and has high success probabilities with near perfect fidelities in an ideal case

3D imaging of intrinsic crystalline defects in zinc oxide by spectrally resolved two-photon fluorescence microscopy

Science.gov (United States)

Al-Tabich, A.; Inami, W.; Kawata, Y.; Jablonski, R.; Worasawat, S.; Mimura, H.

2017-05-01

We present a method for three-dimensional intrinsic defect imaging in zinc oxide (ZnO) by spectrally resolved two-photon fluorescence microscopy, based on the previously presented method of observing a photoluminescence distribution in wide-gap semiconductor crystals [Noor et al., Appl. Phys. Lett. 92(16), 161106 (2008)]. A tightly focused light beam radiated by a titanium-sapphire laser is used to obtain a two-photon excitation of selected area of the ZnO sample. Photoluminescence intensity of a specific spectral range is then selected by optical band pass filters and measured by a photomultiplier tube. Reconstruction of the specimen image is done by scanning the volume of interest by a piezoelectric positioning stage and measuring the spectrally resolved photoluminescence intensity at each point. The method has been proved to be effective at locating intrinsic defects of the ZnO crystalline structure in the volume of the crystal. The method was compared with other defect imaging and 3D imaging techniques like scanning tunneling microscopy and confocal microscopy. In both cases, our method shows superior penetration abilities and, as the only method, allows location of the defects of the chosen type in 3D. In this paper, we present the results of oxygen vacancies and zinc antisites imaging in ZnO nanorods.

Multiphoton ionization of the hydrogen atom by a circularly polarized electromagnetic field

International Nuclear Information System (INIS)

Prepelitsa, O.B.

1999-01-01

This paper examines the multiphoton ionization of the ground state of the hydrogen atom in the field of a circularly polarized intense electromagnetic wave. To describe the states of photoelectrons, quasiclassical wave functions are introduced that partially allow for the effect of an intense electromagnetic wave and that of the Coulomb potential. Expressions are derived for the angular and energy distributions of photoelectrons with energies much lower than the ionization potential of an unperturbed atom. It is found that, due to allowance for the Coulomb potential in the wave function of the final electron states, the transition probability near the ionization threshold tends to a finite value. In addition, the well-known selection rules for multiphoton transitions in a circularly polarized electromagnetic field are derived in a natural way. Finally, the results are compared with those obtained in the Keldysh-Faisal-Reiss approximation

vuv fluorescence from selective high-order multiphoton excitation of N2

International Nuclear Information System (INIS)

Coffee, Ryan N.; Gibson, George N.

2004-01-01

Recent fluorescence studies suggest that ultrashort pulse laser excitation may be highly selective. Selective high-intensity laser excitation holds important consequences for the physics of multiphoton processes. To establish the extent of this selectivity, we performed a detailed comparative study of the vacuum ultraviolet fluorescence resulting from the interaction of N 2 and Ar with high-intensity infrared ultrashort laser pulses. Both N 2 and Ar reveal two classes of transitions, inner-valence ns ' l ' . From their pressure dependence, we associate each transition with either plasma or direct laser excitation. Furthermore, we qualitatively confirm such associations with the time dependence of the fluorescence signal. Remarkably, only N 2 presents evidence of direct laser excitation. This direct excitation produces ionic nitrogen fragments with inner-valence (2s) holes, two unidentified transitions, and one molecular transition, the N 2 + :X 2 Σ g + 2 Σ u + . We discuss these results in the light of a recently proposed model for multiphoton excitation

Time-resolved blood flow measurement in the in vivo mouse model by optical frequency domain imaging

Science.gov (United States)

Walther, Julia; Mueller, Gregor; Meissner, Sven; Cimalla, Peter; Homann, Hanno; Morawietz, Henning; Koch, Edmund

2009-07-01

In this study, we demonstrate that phase-resolved Doppler optical frequency domain imaging (OFDI) is very suitable to quantify the pulsatile blood flow within a vasodynamic measurement in the in vivo mouse model. For this, an OFDI-system with a read-out rate of 20 kHz and a center wavelength of 1320 nm has been used to image the time-resolved murine blood flow in 300 μμm vessels. Because OFDI is less sensitive to fringe washout due to axial sample motion, it is applied to analyze the blood flow velocities and the vascular dynamics in six-week-old C57BL/6 mice compared to one of the LDLR knockout strain kept under sedentary conditions or with access to voluntary wheel running. We have shown that the systolic as well as the diastolic phase of the pulsatile arterial blood flow can be well identified at each vasodynamic state. Furthermore, the changes of the flow velocities after vasoconstriction and -dilation were presented and interpreted in the entire physiological context. With this, the combined measurement of time-resolved blood flow and vessel diameter provides the basis to analyze the vascular function and its influence on the blood flow of small arteries of different mouse strains in response to different life styles.

Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media

Science.gov (United States)

Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Gayen, Swapan K. (Inventor)

2000-01-01

A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =/ Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absorption information. An algorithm, which combines a two dimensional (2D) matrix inversion with a one-dimensional (1D) Fourier transform inversion is used to obtain images of three dimensional hidden objects in turbid scattering media.

Multi-photon processes brought about by a laser; Processus multiphotoniques provoques par un laser

Energy Technology Data Exchange (ETDEWEB)

Nelson, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

We calculate the critical intensity characterizing the multiphoton processes. The multiphoton effects corresponding to the Compton scattering, the Bremsstrahlung, the photoelectric effect are investigated. The cross sections are evaluated. We show how the introduction of a refractive index, in clothing the photons, allows the elimination of the infrared divergence. The theory seems consistent with experiment. (author) [French] Nous calculons l'intensite critique caracterisant les processus multiphotoniques. Les effets multiphotoniques correspondant a la diffusion Compton, au bremsstrahlung, a l'effet photoelectrique sont etudies. Les sections efficaces sont evaluees. Nous montrons comment l'introduction d'un indice de refraction, en habillant les photons, permet d'eliminer les divergences infra-rouges. La theorie semble compatible avec l'experience. (auteur)

Multiphoton absorption probabilities in strong laser fields with application to H-

International Nuclear Information System (INIS)

Mu, X.; University of Oregon, Eugene, OR

1990-01-01

The commonly used Keldysh multiphoton ionization rate is shown to follow from the zeroth-order approximation of an exact expression, based on the formal time-independent theory of scattering. The formulation is applied to the loosely bound H - system; good agreement is obtained with a recent experimental measurement

Investigations of multiphoton excitation and ionization in a short range potential

International Nuclear Information System (INIS)

Susskind, S.M.; Cowley, S.C.; Valeo, E.J.

1989-02-01

We introduce an approach to the study of excitation and ionization for a system with a short range potential. In particular, analytical and numerical results are presented for the multiphoton ionization rate, under strong field conditions, of an electron confined by a δ-function potential. 9 refs., 3 figs

Investigations of multiphoton excitation and ionization in a short range potential

Energy Technology Data Exchange (ETDEWEB)

Susskind, S.M.; Cowley, S.C.; Valeo, E.J.

1989-02-01

We introduce an approach to the study of excitation and ionization for a system with a short range potential. In particular, analytical and numerical results are presented for the multiphoton ionization rate, under strong field conditions, of an electron confined by a delta-function potential. 9 refs., 3 figs.

Contrast in atomically resolved EF-SCEM imaging

Energy Technology Data Exchange (ETDEWEB)

Wang, Peng [National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093 (China); D’Alfonso, Adrian J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Hashimoto, Ayako [Surface Physics and Structure Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, 305-0047 (Japan); Electron Microscopy Station, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003 (Japan); Morgan, Andrew J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Takeguchi, Masaki [Surface Physics and Structure Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Electron Microscopy Station, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003 (Japan); Mitsuishi, Kazutaka [Surface Physics and Structure Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, 305-0047 (Japan); Electron Microscopy Station, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003 (Japan); Shimojo, Masayuki [Department of Materials Science and Engineering, Shibaura Institute of Technology, 3-7-5, Toyosu, Koto-ku, Tokyo, 135-8548 (Japan); Kirkland, Angus I. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Allen, Leslie J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Nellist, Peter D., E-mail: peter.nellist@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

2013-11-15

Energy-filtered scanning confocal electron microscopy (EF-SCEM) is a technique that uses the reduced depth of field of an aberration-corrected transmission electron microscope to provide three-dimensional (3D) compositional information. Using a silicon sample in the <110> orientation, we show that EF-SCEM image data can be recorded that shows lattice resolution in the plane perpendicular to the incident beam direction. The confocal effect is demonstrated through the reduction of the mean intensity as the confocal plane is displaced from the sample mid-plane, unlike optical sectioning in high-angle annular dark-field scanning transmission electron microscopy (STEM). Simulations of the EF-SCEM data show agreement with the experimental data, and allow the interpretability of the data to be explored. The effects of channelling, absorption and delocalisation complicate the quantitative and qualitative interpretation of the data, highlighting the need for matching to simulations. Finally the effects of the finite detector pin-hole aperture size are explored, and we show that the EF-SCEM contrast in the plane perpendicular to the beam direction starts to resemble that of a STEM spectrum imaging experiment as the aperture size increases. - Highlights: • Atomically resolved energy-filtered scanning confocal electron microscopy (EF-SCEM) is demonstrated. • The confocal effect is demonstrated through the reduction of the mean intensity as the confocal plane is displaced from the sample mid-plane. • Simulations show agreement with the experimental data. • The effects of channelling, absorption and delocalisation complicate the quantitative and qualitative interpretation of the data. • The effects of the finite detector pin-hole aperture size are explored.

Contrast in atomically resolved EF-SCEM imaging

International Nuclear Information System (INIS)

Wang, Peng; D’Alfonso, Adrian J.; Hashimoto, Ayako; Morgan, Andrew J.; Takeguchi, Masaki; Mitsuishi, Kazutaka; Shimojo, Masayuki; Kirkland, Angus I.; Allen, Leslie J.; Nellist, Peter D.

2013-01-01

Energy-filtered scanning confocal electron microscopy (EF-SCEM) is a technique that uses the reduced depth of field of an aberration-corrected transmission electron microscope to provide three-dimensional (3D) compositional information. Using a silicon sample in the orientation, we show that EF-SCEM image data can be recorded that shows lattice resolution in the plane perpendicular to the incident beam direction. The confocal effect is demonstrated through the reduction of the mean intensity as the confocal plane is displaced from the sample mid-plane, unlike optical sectioning in high-angle annular dark-field scanning transmission electron microscopy (STEM). Simulations of the EF-SCEM data show agreement with the experimental data, and allow the interpretability of the data to be explored. The effects of channelling, absorption and delocalisation complicate the quantitative and qualitative interpretation of the data, highlighting the need for matching to simulations. Finally the effects of the finite detector pin-hole aperture size are explored, and we show that the EF-SCEM contrast in the plane perpendicular to the beam direction starts to resemble that of a STEM spectrum imaging experiment as the aperture size increases. - Highlights: • Atomically resolved energy-filtered scanning confocal electron microscopy (EF-SCEM) is demonstrated. • The confocal effect is demonstrated through the reduction of the mean intensity as the confocal plane is displaced from the sample mid-plane. • Simulations show agreement with the experimental data. • The effects of channelling, absorption and delocalisation complicate the quantitative and qualitative interpretation of the data. • The effects of the finite detector pin-hole aperture size are explored

Spatially resolved chemical analysis of cicada wings using laser-ablation electrospray ionization (LAESI) imaging mass spectrometry (IMS).

Science.gov (United States)

Román, Jessica K; Walsh, Callee M; Oh, Junho; Dana, Catherine E; Hong, Sungmin; Jo, Kyoo D; Alleyne, Marianne; Miljkovic, Nenad; Cropek, Donald M

2018-03-01

Laser-ablation electrospray ionization (LAESI) imaging mass spectrometry (IMS) is an emerging bioanalytical tool for direct imaging and analysis of biological tissues. Performing ionization in an ambient environment, this technique requires little sample preparation and no additional matrix, and can be performed on natural, uneven surfaces. When combined with optical microscopy, the investigation of biological samples by LAESI allows for spatially resolved compositional analysis. We demonstrate here the applicability of LAESI-IMS for the chemical analysis of thin, desiccated biological samples, specifically Neotibicen pruinosus cicada wings. Positive-ion LAESI-IMS accurate ion-map data was acquired from several wing cells and superimposed onto optical images allowing for compositional comparisons across areas of the wing. Various putative chemical identifications were made indicating the presence of hydrocarbons, lipids/esters, amines/amides, and sulfonated/phosphorylated compounds. With the spatial resolution capability, surprising chemical distribution patterns were observed across the cicada wing, which may assist in correlating trends in surface properties with chemical distribution. Observed ions were either (1) equally dispersed across the wing, (2) more concentrated closer to the body of the insect (proximal end), or (3) more concentrated toward the tip of the wing (distal end). These findings demonstrate LAESI-IMS as a tool for the acquisition of spatially resolved chemical information from fragile, dried insect wings. This LAESI-IMS technique has important implications for the study of functional biomaterials, where understanding the correlation between chemical composition, physical structure, and biological function is critical. Graphical abstract Positive-ion laser-ablation electrospray ionization mass spectrometry coupled with optical imaging provides a powerful tool for the spatially resolved chemical analysis of cicada wings.

Comparison of in vivo and ex vivo laser scanning microscopy and multiphoton tomography application for human and porcine skin imaging

Energy Technology Data Exchange (ETDEWEB)

Darvin, M E; Richter, H; Zhu, Y J; Meinke, M C; Knorr, F; Lademann, J [Center of Experimental and Applied Cutaneous Physiology, Department of Dermatology, Venerology and Allergology, Charité - Universitätsmedizin Berlin (Germany); Gonchukov, S A [National Research Nuclear University ' ' MEPhI' ' (Russian Federation); Koenig, K [JenLab GmbH, Schillerstr. 1, 07745 Jena (Germany)

2014-07-31

Two state-of-the-art microscopic optical methods, namely, confocal laser scanning microscopy in the fluorescence and reflectance regimes and multiphoton tomography in the autofluorescence and second harmonic generation regimes, are compared for porcine skin ex vivo and healthy human skin in vivo. All skin layers such as stratum corneum (SC), stratum spinosum (SS), stratum basale (SB), papillary dermis (PD) and reticular dermis (RD) as well as transition zones between these skin layers are measured noninvasively at a high resolution, using the above mentioned microscopic methods. In the case of confocal laser scanning microscopy (CLSM), measurements in the fluorescence regime were performed by using a fluorescent dye whose topical application on the surface is well suited for the investigation of superficial SC and characterisation of the skin barrier function. For investigations of deeply located skin layers, such as SS, SB and PD, the fluorescent dye must be injected into the skin, which markedly limits fluorescence measurements using CLSM. In the case of reflection CLSM measurements, the obtained results can be compared to the results of multiphoton tomography (MPT) for all skin layers excluding RD. CLSM cannot distinguish between dermal collagen and elastin measuring their superposition in the RD. By using MPT, it is possible to analyse the collagen and elastin structures separately, which is important for the investigation of anti-aging processes. The resolution of MPT is superior to CLSM. The advantages and limitations of both methods are discussed and the differences and similarities between human and porcine skin are highlighted. (laser biophotonics)

Comparison of in vivo and ex vivo laser scanning microscopy and multiphoton tomography application for human and porcine skin imaging

Science.gov (United States)

Darvin, M. E.; Richter, H.; Zhu, Y. J.; Meinke, M. C.; Knorr, F.; Gonchukov, S. A.; Koenig, K.; Lademann, J.

2014-07-01

Two state-of-the-art microscopic optical methods, namely, confocal laser scanning microscopy in the fluorescence and reflectance regimes and multiphoton tomography in the autofluorescence and second harmonic generation regimes, are compared for porcine skin ex vivo and healthy human skin in vivo. All skin layers such as stratum corneum (SC), stratum spinosum (SS), stratum basale (SB), papillary dermis (PD) and reticular dermis (RD) as well as transition zones between these skin layers are measured noninvasively at a high resolution, using the above mentioned microscopic methods. In the case of confocal laser scanning microscopy (CLSM), measurements in the fluorescence regime were performed by using a fluorescent dye whose topical application on the surface is well suited for the investigation of superficial SC and characterisation of the skin barrier function. For investigations of deeply located skin layers, such as SS, SB and PD, the fluorescent dye must be injected into the skin, which markedly limits fluorescence measurements using CLSM. In the case of reflection CLSM measurements, the obtained results can be compared to the results of multiphoton tomography (MPT) for all skin layers excluding RD. CLSM cannot distinguish between dermal collagen and elastin measuring their superposition in the RD. By using MPT, it is possible to analyse the collagen and elastin structures separately, which is important for the investigation of anti-aging processes. The resolution of MPT is superior to CLSM. The advantages and limitations of both methods are discussed and the differences and similarities between human and porcine skin are highlighted.

Comparison of in vivo and ex vivo laser scanning microscopy and multiphoton tomography application for human and porcine skin imaging

International Nuclear Information System (INIS)

Darvin, M E; Richter, H; Zhu, Y J; Meinke, M C; Knorr, F; Lademann, J; Gonchukov, S A; Koenig, K

2014-01-01

Two state-of-the-art microscopic optical methods, namely, confocal laser scanning microscopy in the fluorescence and reflectance regimes and multiphoton tomography in the autofluorescence and second harmonic generation regimes, are compared for porcine skin ex vivo and healthy human skin in vivo. All skin layers such as stratum corneum (SC), stratum spinosum (SS), stratum basale (SB), papillary dermis (PD) and reticular dermis (RD) as well as transition zones between these skin layers are measured noninvasively at a high resolution, using the above mentioned microscopic methods. In the case of confocal laser scanning microscopy (CLSM), measurements in the fluorescence regime were performed by using a fluorescent dye whose topical application on the surface is well suited for the investigation of superficial SC and characterisation of the skin barrier function. For investigations of deeply located skin layers, such as SS, SB and PD, the fluorescent dye must be injected into the skin, which markedly limits fluorescence measurements using CLSM. In the case of reflection CLSM measurements, the obtained results can be compared to the results of multiphoton tomography (MPT) for all skin layers excluding RD. CLSM cannot distinguish between dermal collagen and elastin measuring their superposition in the RD. By using MPT, it is possible to analyse the collagen and elastin structures separately, which is important for the investigation of anti-aging processes. The resolution of MPT is superior to CLSM. The advantages and limitations of both methods are discussed and the differences and similarities between human and porcine skin are highlighted. (laser biophotonics)

Triple-color super-resolution imaging of live cells: resolving submicroscopic receptor organization in the plasma membrane.

Science.gov (United States)

Wilmes, Stephan; Staufenbiel, Markus; Lisse, Domenik; Richter, Christian P; Beutel, Oliver; Busch, Karin B; Hess, Samuel T; Piehler, Jacob

2012-05-14

In living color: efficient intracellular covalent labeling of proteins with a photoswitchable dye using the HaloTag for dSTORM super-resolution imaging in live cells is described. The dynamics of cellular nanostructures at the plasma membrane were monitored with a time resolution of a few seconds. In combination with dual-color FPALM imaging, submicroscopic receptor organization within the context of the membrane skeleton was resolved. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bi-dimensional arrays of SPAD for time-resolved single photon imaging

International Nuclear Information System (INIS)

Tudisco, S.; Lanzano, L.; Musumeci, F.; Neri, L.; Privitera, S.; Scordino, A.; Condorelli, G.; Fallica, G.; Mazzillo, M.; Sanfilippo, D.; Valvo, G.

2009-01-01

Many scientific areas like astronomy, biophysics, biomedicine, nuclear and plasma science, etc. are interested in the development of a new time-resolved single photon imaging device. Such a device represents today one of the most challenging goals in the field of photonics. In collaboration with Catania R and D staff of ST-Microelectronics (STM) we created, during the last few years, a new avalanche photosensor-Single Photon Avalanche Diode (SPAD) able to detect and count, with excellent performance, single photons. Further we will discuss the possible realization of a single photon imaging device through the many elements integration (bi-dimensional arrays) of SPADs. In order to achieve the goal, it is also important to develop an appropriate readout strategy able to address the time information of each individual sensor and in order to read a great number of elements easily. First prototypes were designed and manufactured by STM and the results are reported here. In the paper we will discuss in particular: (i) sensor performance (gain, photodetection efficiency, timing, after-pulsing, etc.); (ii) array performance (layout, cross-talk, etc.); (iii) readout strategy (quenching, electronics), and (iv) first imaging results (general performance).

Identification of the boundary between normal breast tissue and invasive ductal carcinoma during breast-conserving surgery using multiphoton microscopy

Science.gov (United States)

Deng, Tongxin; Nie, Yuting; Lian, Yuane; Wu, Yan; Fu, Fangmeng; Wang, Chuan; Zhuo, Shuangmu; Chen, Jianxin

2014-11-01

Breast-conserving surgery has become an important way of surgical treatment for breast cancer worldwide nowadays. Multiphoton microscopy (MPM) has the ability to noninvasively visualize tissue architectures at the cellular level using intrinsic fluorescent molecules in biological tissues without the need for fluorescent dye. In this study, MPM is used to image the microstructures of terminal duct lobular unit (TDLU), invasive ductal carcinoma and the boundary region between normal and cancerous breast tissues. Our study demonstrates that MPM has the ability to not only reveal the morphological changes of the cuboidal epithelium, basement membrane and interlobular stroma but also identify the boundary between normal breast tissue and invasive ductal carcinoma, which correspond well to the Hematoxylin and Eosin (H and E) images. Predictably, MPM can monitor surgical margins in real time and provide considerable accuracy for resection of breast cancerous tissues intraoperatively. With the development of miniature, real-time MPM imaging technology, MPM should have great application prospects during breast-conserving surgery.

Deflection evaluation using time-resolved radiography

International Nuclear Information System (INIS)

Fry, D.A.; Lucero, J.P.

1990-01-01

Time-resolved radiography is the creation of an x-ray image for which both the start-exposure and stop-exposure times are known with respect to the event under study. The combination of image and timing are used to derive information about the event. The authors have applied time-resolved radiography to evaluate motions of explosive-driven events. In the particular application discussed in this paper, the author's intent is to measure maximum deflections of the components involved. Exposures are made during the time just before to just after the event of interest occurs. A smear or blur of motion out to its furthest extent is recorded on the image. Comparison of the dynamic images with static images allows deflection measurements to be made

Rotationally resolved photodetachment spectrum of OH{sup -}, exposed with velocity-map imaging

Energy Technology Data Exchange (ETDEWEB)

Gibson, S T; Cavanagh, S J; Lewis, B R, E-mail: Stephen.Gibson@anu.edu.a, E-mail: Steven.Cavanagh@anu.edu.a [Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2009-11-01

The photodetachment spectrum of OH{sup -} has been measured using velocity-map imaging for the detection of photoelectrons. The relative electron kinetic-energy resolution, determined to be ({Delta}E/E) = 0.5%, resolves individual rotational transitions, including R3(0) that defines the electron affinity. Previously unobserved, N-, O-, S-, T-branch transitions are also revealed. The angular anisotropy parameters in general exhibit values consistent with electron detachment from O{sup -}, {beta} {approx} -0.8, except for the S, T branches which are significantly more isotropic, with {beta} {approx} -0.4.

Non-perturbative methods applied to multiphoton ionization

International Nuclear Information System (INIS)

Brandi, H.S.; Davidovich, L.; Zagury, N.

1982-09-01

The use of non-perturbative methods in the treatment of atomic ionization is discussed. Particular attention is given to schemes of the type proposed by Keldysh where multiphoton ionization and tunnel auto-ionization occur for high intensity fields. These methods are shown to correspond to a certain type of expansion of the T-matrix in the intra-atomic potential; in this manner a criterium concerning the range of application of these non-perturbative schemes is suggested. A brief comparison between the ionization rate of atoms in the presence of linearly and circularly polarized light is presented. (Author) [pt

Time-resolved absorption measurements on OMEGA

International Nuclear Information System (INIS)

Jaanimagi, P.A.; DaSilva, L.; Delettrez, J.; Gregory, G.G.; Richardson, M.C.

1986-01-01

Time-resolved measurements of the incident laser light that is scattered and/or refracted from targets irradiated by the 24 uv-beam OMEGA laser at LLE, have provided some interesting features related to time-resolved absorption. The decrease in laser absorption characteristic of irradiating a target that implodes during the laser pulse has been observed. The increase in absorption expected as the critical density surface moves from a low to a high Z material in the target has also been noted. The detailed interpretation of these results is made through comparisons with simulation using the code LILAC, as well as with streak data from time-resolved x-ray imaging and spectroscopy. In addition, time and space-resolved imaging of the scattered light yields information on laser irradiation uniformity conditions on the target. The report consists of viewgraphs

Electron energy spectrum and maximum disruption angle under multi-photon beamstrahlung

Energy Technology Data Exchange (ETDEWEB)

Yokoya, Kaoru; Chen, Pisin

1989-03-01

The final electron energy spectrum under multi-photon beamstrahlung process is derived analytically in the classical and the intermediate regimes. The maximum disruption angle from the low energy tail of the spectrum is also estimated. The results are then applied to the TLC and the CLIC parameters. 6 refs., 1 fig., 1 tab.

High Resolution Multiphoton Ionization/Dissociation of Molecular Beam of Acetone from 582.60 to 585.80 nm

Science.gov (United States)

Mejia-Ospino, Enrique; Garcia, Gladis; Guerrero, Alfonso; Alvarez, Ignacio; Cisneros, Carmen

2003-05-01

Multiphoton ionization and dissociation of a jet supersonic of acetone at wavelength from 582.60 to 585.80 nm is studied using a Nd:YAG-OPO (optical parametric oscillator) system coupled to time-of-flight mass spectrometer. We present high-resolution (1.5 cm-1) three-photon resonance multiphoton spectra of the acetone 3s CH3CO+), (CH3+) and (COH+), being CH3COCH3+ ---> CH3CO+ + CH3 the more likely channel. The molecular and acetyl ions are observed practically in overall wavelength range.

All-optical bidirectional neural interfacing using hybrid multiphoton holographic optogenetic stimulation.

Science.gov (United States)

Paluch-Siegler, Shir; Mayblum, Tom; Dana, Hod; Brosh, Inbar; Gefen, Inna; Shoham, Shy

2015-07-01

Our understanding of neural information processing could potentially be advanced by combining flexible three-dimensional (3-D) neuroimaging and stimulation. Recent developments in optogenetics suggest that neurophotonic approaches are in principle highly suited for noncontact stimulation of network activity patterns. In particular, two-photon holographic optical neural stimulation (2P-HONS) has emerged as a leading approach for multisite 3-D excitation, and combining it with temporal focusing (TF) further enables axially confined yet spatially extended light patterns. Here, we study key steps toward bidirectional cell-targeted 3-D interfacing by introducing and testing a hybrid new 2P-TF-HONS stimulation path for accurate parallel optogenetic excitation into a recently developed hybrid multiphoton 3-D imaging system. The system is shown to allow targeted all-optical probing of in vitro cortical networks expressing channelrhodopsin-2 using a regeneratively amplified femtosecond laser source tuned to 905 nm. These developments further advance a prospective new tool for studying and achieving distributed control over 3-D neuronal circuits both in vitro and in vivo.

Controlling the optical bistability beyond the multi-photon resonance condition in a three-level closed-loop atomic system

International Nuclear Information System (INIS)

Mahmoudi, Mohammad; Nozari, Narges; Vafafard, Azar; Sahrai, Mostafa

2012-01-01

We investigate the optical bistability behavior of a three-level closed-loop atomic system beyond the multi-photon resonance condition. Using the Floquet decomposition, we solve the time-dependent equations of motion, beyond the multi-photon resonance condition. By identifying the different scattering processes contributing to the medium response, it is shown that in general the optical bistability behavior of the system is not phase-dependent. The phase dependence is due to the scattering of the driving and coupling fields into the probe field at a frequency, which, in general, differs from the probe field frequency. - Highlights: → We investigate optical bistability of a three-level closed-loop atomic system, beyond the multi-photon resonance condition. → By applying Floquet decomposition to the equation of motion, the different scattering processes contributing to the medium response are determined. → It is shown that the phase dependence of optical bistability arises from the scattering of the driving and coupling fields into the probe field frequency.

Hotspot related plasmon assisted multiphoton photocurrents in metal-insulator-metal junctions

Energy Technology Data Exchange (ETDEWEB)

Differt, Dominik; Pfeiffer, Walter [Universitaet Bielefeld, Universitaetsstr. 25, 33615 Bielefeld (Germany); Diesing, Detlef [Universitaet Duisburg-Essen, Universitaetsstr. 5, 45117 Essen (Germany)

2011-07-01

Scanning photocurrent microscopy of metal-insulator-metal junctions (MIM) is used to investigate the mechanisms of femtosecond multiphoton photocurrent injection at liquid nitrogen temperature. The locally induced multiphoton photocurrent in a Ag-TaO-Ta MIM junction is measured in a scanning microscope cryostat under focused illumination (5{mu}m focus diameter, 800 nm, 30 fs, 80 MHz repetition rate). The intensity dependence reveals a mixture of two-photon and three-photon processes that are responsible for the photocurrent. Its lateral variation shows hotspot-like behaviour with significant magnitude variations on a 100 to 200 nm length scale. Assuming an injection current duration of 40fs the peak injection current density of about 10{sup 4} A cm{sup -2} is estimated - 10{sup 6} times higher than that for 400 nm continuous wave illumination slightly below the damage threshold. The simultaneously measured extinction of the incident radiation reveals a 20 to 30% increased absorption at the hotspots. We attribute the local photocurrent enhancement to the defect-assisted excitation of surface plasmon polaritons at the silver electrode leading to an enhanced local excitation.

Highly time-resolved imaging of combustion and pyrolysis product concentrations in solid fuel combustion: NO formation in a burning cigarette.

Science.gov (United States)

Zimmermann, Ralf; Hertz-Schünemann, Romy; Ehlert, Sven; Liu, Chuan; McAdam, Kevin; Baker, Richard; Streibel, Thorsten

2015-02-03

The highly dynamic, heterogeneous combustion process within a burning cigarette was investigated by a miniaturized extractive sampling probe (microprobe) coupled to photoionization mass spectrometry using soft laser single photon ionization (SPI) for online real-time detection of molecular ions of combustion and pyrolysis products. Research cigarettes smoked by a smoking machine are used as a reproducible model system for solid-state biomass combustion, which up to now is not addressable by current combustion-diagnostic tools. By combining repetitively recorded online measurement sequences from different sampling locations in an imaging approach, highly time- and space-resolved quantitative distribution maps of, e.g., nitrogen monoxide, benzene, and oxygen concentrations were obtained at a near microscopic level. The obtained quantitative distribution maps represent a time-resolved, movie-like imaging of the respective compound's formation and destruction zones in the various combustion and pyrolysis regions of a cigarette during puffing. Furthermore, spatially resolved kinetic data were ascertainable. The here demonstrated methodology can also be applied to various heterogenic combustion/pyrolysis or reaction model systems, such as fossil- or biomass-fuel pellet combustion or to a positional resolved analysis of heterogenic catalytic reactions.

Static and time-resolved 10-1000 keV x-ray imaging detector options for NIF

International Nuclear Information System (INIS)

Landen, O.L.; Bell, P.M.; McDonald, J.W.; Park, H.-S.; Weber, F.; Moody, J.D.; Lowry, M.E.; Stewart, R.E.

2004-01-01

High energy (>10 keV) x-ray self-emission imaging and radiography will be essential components of many NIF high energy density physics experiments. In preparation for such experiments, we have evaluated the pros and cons of various static [x-ray film, bare charge-coupled device (CCD), and scintillator + CCD] and time-resolved (streaked and gated) 10-1000 keV detectors

Temporal shaping of nanosecond CO2 laser pulses in multiphoton saturable absorbers

International Nuclear Information System (INIS)

Haglund, R.F. Jr.

1981-01-01

It was shown that substantial temporal distortion of nanosecond 10.6 μm laser pulses occurs in traversing multiphoton saturable absorbers. The risetime and pulse delay effects appear to depend both on fluence and wavelength, and to be qualitatively consistent with predictions of a simple two-level absorption model

Multi-Photon Absorption Spectra: A Comparison Between Transmittance Change and Fluorescence Methods

Science.gov (United States)

2015-05-21

AFRL-OSR-VA-TR-2015-0134 multi-photon absorption spectra Cleber Mendonca INSTITUTO DE FISICA DE SAO CARLOS Final Report 05/21/2015 DISTRIBUTION A...5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Instituto de Fisica de Sao Carlos - Universidade de Sao Paulo Av

CMOS Time-Resolved, Contact, and Multispectral Fluorescence Imaging for DNA Molecular Diagnostics

Directory of Open Access Journals (Sweden)

Nan Guo

2014-10-01

Full Text Available Instrumental limitations such as bulkiness and high cost prevent the fluorescence technique from becoming ubiquitous for point-of-care deoxyribonucleic acid (DNA detection and other in-field molecular diagnostics applications. The complimentary metal-oxide-semiconductor (CMOS technology, as benefited from process scaling, provides several advanced capabilities such as high integration density, high-resolution signal processing, and low power consumption, enabling sensitive, integrated, and low-cost fluorescence analytical platforms. In this paper, CMOS time-resolved, contact, and multispectral imaging are reviewed. Recently reported CMOS fluorescence analysis microsystem prototypes are surveyed to highlight the present state of the art.

Time-resolved autofluorescence imaging of human donor retina tissue from donors with significant extramacular drusen.

Science.gov (United States)

Schweitzer, Dietrich; Gaillard, Elizabeth R; Dillon, James; Mullins, Robert F; Russell, Stephen; Hoffmann, Birgit; Peters, Sven; Hammer, Martin; Biskup, Christoph

2012-06-08

Time and spectrally resolved measurements of autofluorescence have the potential to monitor metabolism at the cellular level. Fluorophores that emit with the same fluorescence intensity can be discriminated from each other by decay time of fluorescence intensity after pulsed excitation. We performed time-resolved autofluorescence measurements on fundus samples from a donor with significant extramacular drusen. Tissue sections from two human donors were prepared and imaged with a laser scanning microscope. The sample was excited with a titanium-sapphire laser, which was tuned to 860 nm, and frequency doubled by a BBO crystal to 430 nm. The repetition rate was 76 MHz and the pulse width was 170 femtoseconds (fs). The time-resolved autofluorescence was recorded simultaneously in 16 spectral channels (445-605 nm) and bi-exponentially fitted. RPE can be discriminated clearly from Bruch's membrane, drusen, and choroidal connective tissue by fluorescence lifetime. In RPE, bright fluorescence of lipofuscin could be detected with a maximum at 510 nm and extending beyond 600 nm. The lifetime was 385 ps. Different types of drusen were found. Most of them did not contain lipofuscin and exhibited a weak fluorescence, with a maximum at 470 nm. The lifetime was 1785 picoseconds (ps). Also, brightly emitting lesions, presumably representing basal laminar deposits, with fluorescence lifetimes longer than those recorded in RPE could be detected. The demonstrated differentiation of fluorescent structures by their fluorescence decay time is important for interpretation of in vivo measurements by the new fluorescence lifetime imaging (FLIM) ophthalmoscopy on healthy subjects as well as on patients.

Dirac Equation in (1 +1 )-Dimensional Curved Spacetime and the Multiphoton Quantum Rabi Model

Science.gov (United States)

Pedernales, J. S.; Beau, M.; Pittman, S. M.; Egusquiza, I. L.; Lamata, L.; Solano, E.; del Campo, A.

2018-04-01

We introduce an exact mapping between the Dirac equation in (1 +1 )-dimensional curved spacetime (DCS) and a multiphoton quantum Rabi model (QRM). A background of a (1 +1 )-dimensional black hole requires a QRM with one- and two-photon terms that can be implemented in a trapped ion for the quantum simulation of Dirac particles in curved spacetime. We illustrate our proposal with a numerical analysis of the free fall of a Dirac particle into a (1 +1 )-dimensional black hole, and find that the Zitterbewegung effect, measurable via the oscillatory trajectory of the Dirac particle, persists in the presence of gravity. From the duality between the squeezing term in the multiphoton QRM and the metric coupling in the DCS, we show that gravity generates squeezing of the Dirac particle wave function.

Time-resolved spectroscopic imaging reveals the fundamentals of cellular NADH fluorescence.

Science.gov (United States)

Li, Dong; Zheng, Wei; Qu, Jianan Y

2008-10-15

A time-resolved spectroscopic imaging system is built to study the fluorescence characteristics of nicotinamide adenine dinucleotide (NADH), an important metabolic coenzyme and endogenous fluorophore in cells. The system provides a unique approach to measure fluorescence signals in different cellular organelles and cytoplasm. The ratios of free over protein-bound NADH signals in cytosol and nucleus are slightly higher than those in mitochondria. The mitochondrial fluorescence contributes about 70% of overall cellular fluorescence and is not a completely dominant signal. Furthermore, NADH signals in mitochondria, cytosol, and the nucleus respond to the changes of cellular activity differently, suggesting that cytosolic and nuclear fluorescence may complicate the well-known relationship between mitochondrial fluorescence and cellular metabolism.

Wide-field time-resolved luminescence imaging and spectroscopy to decipher obliterated documents in forensic science

Science.gov (United States)

Suzuki, Mototsugu; Akiba, Norimitsu; Kurosawa, Kenji; Kuroki, Kenro; Akao, Yoshinori; Higashikawa, Yoshiyasu

2016-01-01

We applied a wide-field time-resolved luminescence (TRL) method with a pulsed laser and a gated intensified charge coupled device (ICCD) for deciphering obliterated documents for use in forensic science. The TRL method can nondestructively measure the dynamics of luminescence, including fluorescence and phosphorescence lifetimes, which prove to be useful parameters for image detection. First, we measured the TRL spectra of four brands of black porous-tip pen inks on paper to estimate their luminescence lifetimes. Next, we acquired the TRL images of 12 obliterated documents at various delay times and gate times of the ICCD. The obliterated contents were revealed in the TRL images because of the difference in the luminescence lifetimes of the inks. This method requires no pretreatment, is nondestructive, and has the advantage of wide-field imaging, which makes it is easy to control the gate timing. This demonstration proves that TRL imaging and spectroscopy are powerful tools for forensic document examination.

Full optical model of micro-endoscope with optical coherence microscopy, multiphoton microscopy and visible capabilities

Science.gov (United States)

Vega, David; Kiekens, Kelli C.; Syson, Nikolas C.; Romano, Gabriella; Baker, Tressa; Barton, Jennifer K.

2018-02-01

While Optical Coherence Microscopy (OCM), Multiphoton Microscopy (MPM), and narrowband imaging are powerful imaging techniques that can be used to detect cancer, each imaging technique has limitations when used by itself. Combining them into an endoscope to work in synergy can help achieve high sensitivity and specificity for diagnosis at the point of care. Such complex endoscopes have an elevated risk of failure, and performing proper modelling ensures functionality and minimizes risk. We present full 2D and 3D models of a multimodality optical micro-endoscope to provide real-time detection of carcinomas, called a salpingoscope. The models evaluate the endoscope illumination and light collection capabilities of various modalities. The design features two optical paths with different numerical apertures (NA) through a single lens system with a scanning optical fiber. The dual path is achieved using dichroic coatings embedded in a triplet. A high NA optical path is designed to perform OCM and MPM while a low NA optical path is designed for the visible spectrum to navigate the endoscope to areas of interest and narrowband imaging. Different tests such as the reflectance profile of homogeneous epithelial tissue were performed to adjust the models properly. Light collection models for the different modalities were created and tested for efficiency. While it is challenging to evaluate the efficiency of multimodality endoscopes, the models ensure that the system is design for the expected light collection levels to provide detectable signal to work for the intended imaging.

Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

NARCIS (Netherlands)

Meng, C.; Janssen, M.H.M.

2015-01-01

Here, we report on femtosecond ion imaging experiments to measure the density profile of a pulsed supersonic molecular beam. Ion images are measured for both a molecular beam and bulk gas under identical experimental conditions via femtosecond multiphoton ionization of Xe atoms. We report the

Design and synthesis of hyperstructured molecules based on cyclophosphazene core for multiphoton absorption

International Nuclear Information System (INIS)

Naik, K. Praveen Kumar; Sreeramulu, V.; Ramya, E.; Muralidharan, K.; Rao, D. Narayana

2016-01-01

Cyclophosphazene based hyperstructured molecules were synthesized through simple nucleophilic substitution reactions. All these molecules were characterized by multinuclear NMR, MALDI and HRMS spectral data. Third order nonlinear optical properties of the hyperstructured molecules were measured using Z-scan technique with 532 nm, picosecond (ps) laser and 800 nm, femtosecond (fs) laser pulses. The molecules showed reverse saturable absorption on excitation at both 532 nm and 800 nm, which could be attributed to the two-photon absorption (2 PA) and three-photon absorption (3 PA), respectively. The 2 PA and 3 PA cross section values exhibited by the molecules based on cyclophosphazene are as high as 527 GM and 1.86 × 10"−"7"6 cm"−"6 s"2 photon"−"1, respectively. The 2PA, 3PA coefficients and optical limiting properties make them suitable candidates for nonlinear optical devices in the visible and near IR range. - Graphical abstract: The hyperstructured molecules based on cyclophosphazene core were synthesized and used for multiphoton absorption. Open aperture Z-scan curves of hyper structured molecules at the excitation of (a) picosecond laser and (b) femtosecond laser representing multiphoton absorption properties are reported. - Highlights: • Two hyperstructured molecules based on cyclophosphazene core are designed for multiphoton absorption. • NLO properties are measured using Z-scan technique at 532 nm and 800 nm wavelengths. • The molecules were tested for the optical limiting applications at 532 nm and 800 nm laser pulses.

Design and synthesis of hyperstructured molecules based on cyclophosphazene core for multiphoton absorption

Energy Technology Data Exchange (ETDEWEB)

Naik, K. Praveen Kumar [School of Chemistry, University of Hyderabad, Hyderabad 500046 India (India); Sreeramulu, V. [School of Physics, University of Hyderabad, Hyderabad 500046 India (India); CNR-IFN CSMFO Laboratory, Via alla Cascata, 56/C Povo, Trento (Italy); Ramya, E. [School of Physics, University of Hyderabad, Hyderabad 500046 India (India); Muralidharan, K., E-mail: murali@uohyd.ac.in [School of Chemistry, University of Hyderabad, Hyderabad 500046 India (India); Rao, D. Narayana [School of Physics, University of Hyderabad, Hyderabad 500046 India (India)

2016-09-01

Cyclophosphazene based hyperstructured molecules were synthesized through simple nucleophilic substitution reactions. All these molecules were characterized by multinuclear NMR, MALDI and HRMS spectral data. Third order nonlinear optical properties of the hyperstructured molecules were measured using Z-scan technique with 532 nm, picosecond (ps) laser and 800 nm, femtosecond (fs) laser pulses. The molecules showed reverse saturable absorption on excitation at both 532 nm and 800 nm, which could be attributed to the two-photon absorption (2 PA) and three-photon absorption (3 PA), respectively. The 2 PA and 3 PA cross section values exhibited by the molecules based on cyclophosphazene are as high as 527 GM and 1.86 × 10{sup −76} cm{sup −6} s{sup 2} photon{sup −1}, respectively. The 2PA, 3PA coefficients and optical limiting properties make them suitable candidates for nonlinear optical devices in the visible and near IR range. - Graphical abstract: The hyperstructured molecules based on cyclophosphazene core were synthesized and used for multiphoton absorption. Open aperture Z-scan curves of hyper structured molecules at the excitation of (a) picosecond laser and (b) femtosecond laser representing multiphoton absorption properties are reported. - Highlights: • Two hyperstructured molecules based on cyclophosphazene core are designed for multiphoton absorption. • NLO properties are measured using Z-scan technique at 532 nm and 800 nm wavelengths. • The molecules were tested for the optical limiting applications at 532 nm and 800 nm laser pulses.

Color capable sub-pixel resolving optofluidic microscope and its application to blood cell imaging for malaria diagnosis.

Directory of Open Access Journals (Sweden)

Seung Ah Lee

Full Text Available Miniaturization of imaging systems can significantly benefit clinical diagnosis in challenging environments, where access to physicians and good equipment can be limited. Sub-pixel resolving optofluidic microscope (SROFM offers high-resolution imaging in the form of an on-chip device, with the combination of microfluidics and inexpensive CMOS image sensors. In this work, we report on the implementation of color SROFM prototypes with a demonstrated optical resolution of 0.66 µm at their highest acuity. We applied the prototypes to perform color imaging of red blood cells (RBCs infected with Plasmodium falciparum, a particularly harmful type of malaria parasites and one of the major causes of death in the developing world.

Resonance-enhanced multiphoton ionization (REMPI) spectroscopy of p-chlorofluorobenzene

Science.gov (United States)

Tuttle, William D.; Gardner, Adrian M.; Wright, Timothy G.

2017-09-01

The S1 ← S0 (A˜1 B2 ← X˜1 A1) electronic transition of para-chlorofluorobenzene has been investigated using resonance-enhanced multiphoton ionization (REMPI) spectroscopy. Assignment of the vibrational structure has been achieved by comparison with corresponding spectra of related molecules, via quantum chemical calculations, and via shifts in bands between the spectra of the 35Cl and 37Cl isotopologues. In addition, we have also partially reassigned a previously-published spectrum of para-dichlorobenzene.

Design and implementation of a sensitive high-resolution nonlinear spectral imaging microscope

NARCIS (Netherlands)

Palero, Jonathan A.; Latouche, Gwendal; de Bruijn, Henriëtte S.; van der Ploeg van den Heuvel, Angélique; Sterenborg, Henricus J. C. M.; Gerritsen, Hans C.

2008-01-01

Live tissue nonlinear microscopy based on multiphoton autofluorescence and second harmonic emission originating from endogenous fluorophores and noncentrosymmetric-structured proteins is rapidly gaining interest in biomedical applications. The advantage of this technique includes high imaging

Resolving the HD 100546 Protoplanetary System with the Gemini Planet Imager: Evidence for Multiple Forming, Accreting Planets

OpenAIRE

Currie, Thayne; Cloutier, Ryan; Brittain, Sean; Grady, Carol; Burrows, Adam; Muto, Takayuki; Kenyon, Scott J.; Kuchner, Marc J.

2015-01-01

We report Gemini Planet Imager H band high-contrast imaging/integral field spectroscopy and polarimetry of the HD 100546, a 10 $Myr$-old early-type star recently confirmed to host a thermal infrared bright (super)jovian protoplanet at wide separation, HD 100546 b. We resolve the inner disk cavity in polarized light, recover the thermal-infrared (IR) bright arm, and identify one additional spiral arm. We easily recover HD 100546 b and show that much of its emission originates an unresolved, po...

Recoil effects in multiphoton electron-positron pair creation

International Nuclear Information System (INIS)

Krajewska, K.; Kaminski, J. Z.

2010-01-01

Triply differential probability rates for electron-positron pair creation in laser-nucleus collisions, calculated within the S-matrix approach, are investigated as functions of the nuclear recoil. Pronounced enhancements of differential probability rates of multiphoton pair production are found for a nonzero momentum transfer from the colliding nucleus. The corresponding rates show a very dramatic dependence on the polarization of the laser field impinging on the nucleus; only for a linearly polarized light are the multiphoton rates for electron-positron pair production considerably large. We focus therefore on this case. Our numerical results for different geometries of the reaction particles demonstrate that, for the linearly polarized laser field of an infinite extent (which is a good approximation for femtosecond laser pulses), the pair creation is far more efficient if the nucleus is detected in the direction of the laser-field propagation. The corresponding angular distributions of the created particles show that the high-energy pairs are predominantly produced in the plane spanned by the polarization vector and the laser-field propagation direction, while the low-energy pairs are rather spread around the latter of the two directions. The enhancement of differential probability rates at each energy sector, defined by the four-momentum conservation relation, is observed with varying the energy of the produced particles. The total probability rates of pair production are also evaluated and compared with the corresponding results for the case when one disregards the recoil effect. A tremendous enhancement of the total probability rates of the electron-positron pair creation is observed if one takes into account the nuclear recoil.

Approach to quantify human dermal skin aging using multiphoton laser scanning microscopy

Science.gov (United States)

Puschmann, Stefan; Rahn, Christian-Dennis; Wenck, Horst; Gallinat, Stefan; Fischer, Frank

2012-03-01

Extracellular skin structures in human skin are impaired during intrinsic and extrinsic aging. Assessment of these dermal changes is conducted by subjective clinical evaluation and histological and molecular analysis. We aimed to develop a new parameter for the noninvasive quantitative determination of dermal skin alterations utilizing the high-resolution three-dimensional multiphoton laser scanning microscopy (MPLSM) technique. To quantify structural differences between chronically sun-exposed and sun-protected human skin, the respective collagen-specific second harmonic generation and the elastin-specific autofluorescence signals were recorded in young and elderly volunteers using the MPLSM technique. After image processing, the elastin-to-collagen ratio (ELCOR) was calculated. Results show that the ELCOR parameter of volar forearm skin significantly increases with age. For elderly volunteers, the ELCOR value calculated for the chronically sun-exposed temple area is significantly augmented compared to the sun-protected upper arm area. Based on the MPLSM technology, we introduce the ELCOR parameter as a new means to quantify accurately age-associated alterations in the extracellular matrix.

Studies of atmospheric molecules by multiphoton spectroscopy

International Nuclear Information System (INIS)

Johnson, P.M.

1990-12-01

Resonance ionization processes can play an important role in understanding molecules important in combustion processes. They are a reflection of the dynamic as well as the static properties of atomic and molecular species. Due to the sequential or quasisequential nature of photon absorption in resonant multiphoton events, the lifetimes of the intermediate states play an essential role in the overall cross-sections if they are short enough to be competitive with subsequent photon interactions. In molecules this is particularly important because there are many dissociative and other radiationless pathways which can contribute to a competitive channel. Under those conditions it should be possible to obtain information about the nature of the dynamics of the intermediate state form the multiphoton ionization process. This will involve looking at not only the ionization cross-section but also other observables such as the kinetic energy of the ejected electrons and possibly the distribution of fragment ions produced in the ionization event. Whether the ionization amplitude is affected or not, the time scales of the dynamic events which alter the ionization path can vary over a large range from the femtoseconds of dissociation to the microseconds of some radiationless transitions in large molecules. When the competing channel has a time scale shorter than the laser pulse length, the kinetics of the ionization are intimately tied into the precise nature of the laser pulse. For time scales longer than the laser pulse, pump-probe ionization schemes in which one laser prepares a state while another does the ionization provide a particularly simple method for investigating the dynamics of the intermediate state. Here the author discusses examples from each of these regimes. CO 2 and pyrazine are examined. 6 refs., 6 figs

Comparative study of Nd(3+) emission from 4f2 5d and 4f3 configurations induced by multiphotonic process in YLF, GLF and LLF crystals

International Nuclear Information System (INIS)

Librantz, Andre Felipe Henriques

2000-01-01

Nd 3+ ultraviolet fluorescence induced by multiphotonic laser excitations was studied in Nd-doped YLiF 4 (YLF) and LuLiF 4 (LLF) crystals by using the time resolved spectroscopy technique. The UV luminescences are due to transitions between the 4f 2 5d and the 4f 3 electronic configurations of Nd 3+ ions. The 4f 2 5d configuration can be reached by direct pumping the UV transition or by multiphotonic excitation, both processes give raise to the UV emission band with a structure due to the strong phonon coupling, expected for a 5d orbital involvement in the transition. The multiphotonic excitation process is due to three photons (532 nm) sequential absorptions of 532 nm-photons by metastable levels of the 4f 3 configuration splitted by crystalline local field. The sequential excitation of Nd by the pumping laser is attributed to the 4 I 9/2 +532nm → 4 G 7/2 ground state absorption followed by the 4 G 7/2 +532 nm →2 F 5/2 and 2 F 5/2 +532 nm → 4f 2 5d excited state absorptions. The UV emissions due to 4f 2 5d configuration are parity allowed, having lifetime of 35 ns in contrast to UV emissions from 4f 3 configuration which are induced by two absorption steps and are parity forbidden showing longer lifetime of 8μs and narrow tines. The polarization effects of the UV emissions were studied and their behavior are dependent on the excited state configuration involving or not the 5d orbital. The allowed UV emissions positions were affected by the host variation more than the ones originating from the 4f 3 configuration as expected. The electronic energy of the 4f 2 5d configuration shifts to lower energy when increasing the crystal field. (author)

Multiscale Vision Model Highlights Spontaneous Glial Calcium Waves Recorded by 2-Photon Imaging in Brain Tissue

DEFF Research Database (Denmark)

Brazhe, Alexey; Mathiesen, Claus; Lauritzen, Martin

2013-01-01

Intercellular glial calcium waves constitute a signaling pathway which can be visualized by fluorescence imaging of cytosolic Ca2+ changes. However, there is a lack of procedures for sensitive and reliable detection of calcium waves in noisy multiphoton imaging data. Here we extend multiscale...

Real-time visualization of melanin granules in normal human skin using combined multiphoton and reflectance confocal microscopy.

Science.gov (United States)

Majdzadeh, Ali; Lee, Anthony M D; Wang, Hequn; Lui, Harvey; McLean, David I; Crawford, Richard I; Zloty, David; Zeng, Haishan

2015-05-01

Recent advances in biomedical optics have enabled dermal and epidermal components to be visualized at subcellular resolution and assessed noninvasively. Multiphoton microscopy (MPM) and reflectance confocal microscopy (RCM) are noninvasive imaging modalities that have demonstrated promising results in imaging skin micromorphology, and which provide complementary information regarding skin components. This study assesses whether combined MPM/RCM can visualize intracellular and extracellular melanin granules in the epidermis and dermis of normal human skin. We perform MPM and RCM imaging of in vivo and ex vivo skin in the infrared domain. The inherent three-dimensional optical sectioning capability of MPM/RCM is used to image high-contrast granular features across skin depths ranging from 50 to 90 μm. The optical images thus obtained were correlated with conventional histologic examination including melanin-specific staining of ex vivo specimens. MPM revealed highly fluorescent granular structures below the dermal-epidermal junction (DEJ) region. Histochemical staining also demonstrated melanin-containing granules that correlate well in size and location with the granular fluorescent structures observed in MPM. Furthermore, the MPM fluorescence excitation wavelength and RCM reflectance of cell culture-derived melanin were equivalent to those of the granules. This study suggests that MPM can noninvasively visualize and quantify subepidermal melanin in situ. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

High-resolution, time-resolved MRA provides superior definition of lower-extremity arterial segments compared to 2D time-of-flight imaging.

Science.gov (United States)

Thornton, F J; Du, J; Suleiman, S A; Dieter, R; Tefera, G; Pillai, K R; Korosec, F R; Mistretta, C A; Grist, T M

2006-08-01

To evaluate a novel time-resolved contrast-enhanced (CE) projection reconstruction (PR) magnetic resonance angiography (MRA) method for identifying potential bypass graft target vessels in patients with Class II-IV peripheral vascular disease. Twenty patients (M:F = 15:5, mean age = 58 years, range = 48-83 years), were recruited from routine MRA referrals. All imaging was performed on a 1.5 T MRI system with fast gradients (Signa LX; GE Healthcare, Waukesha, WI). Images were acquired with a novel technique that combined undersampled PR with a time-resolved acquisition to yield an MRA method with high temporal and spatial resolution. The method is called PR hyper time-resolved imaging of contrast kinetics (PR-hyperTRICKS). Quantitative and qualitative analyses were used to compare two-dimensional (2D) time-of-flight (TOF) and PR-hyperTRICKS in 13 arterial segments per lower extremity. Statistical analysis was performed with the Wilcoxon signed-rank test. Fifteen percent (77/517) of the vessels were scored as missing or nondiagnostic with 2D TOF, but were scored as diagnostic with PR-hyperTRICKS. Image quality was superior with PR-hyperTRICKS vs. 2D TOF (on a four-point scale, mean rank = 3.3 +/- 1.2 vs. 2.9 +/- 1.2, P < 0.0001). PR-hyperTRICKS produced images with high contrast-to-noise ratios (CNR) and high spatial and temporal resolution. 2D TOF images were of inferior quality due to moderate spatial resolution, inferior CNR, greater flow-related artifacts, and absence of temporal resolution. PR-hyperTRICKS provides superior preoperative assessment of lower limb ischemia compared to 2D TOF.

Rotational averaging of multiphoton absorption cross sections

Energy Technology Data Exchange (ETDEWEB)

Friese, Daniel H., E-mail: daniel.h.friese@uit.no; Beerepoot, Maarten T. P.; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry, University of Tromsø — The Arctic University of Norway, N-9037 Tromsø (Norway)

2014-11-28

Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

Variational methods for high-order multiphoton processes

International Nuclear Information System (INIS)

Gao, B.; Pan, C.; Liu, C.; Starace, A.F.

1990-01-01

Methods for applying the variationally stable procedure for Nth-order perturbative transition matrix elements of Gao and Starace [Phys. Rev. Lett. 61, 404 (1988); Phys. Rev. A 39, 4550 (1989)] to multiphoton processes involving systems other than atomic H are presented. Three specific cases are discussed: one-electron ions or atoms in which the electron--ion interaction is described by a central potential; two-electron ions or atoms in which the electronic states are described by the adiabatic hyperspherical representation; and closed-shell ions or atoms in which the electronic states are described by the multiconfiguration Hartree--Fock representation. Applications are made to the dynamic polarizability of He and the two-photon ionization cross section of Ar

Time-resolved Particle Image Velocimetry measurements of the 3D random Richtmyer-Meshkov Instability

Science.gov (United States)

Sewell, Everest; Krivets, Vitaliy; Jacobs, Jeffrey

2017-11-01

The vertical shock tube at the University of Arizona is used to perform experiments on the multi-mode three-dimensional Richtmyer-Meshkov Instability (RMI). An interface of air and sulfur hexafluoride is formed in a counter flow configuration, and is excited using voice coils to produce faraday-like multi-modal perturbations.This interface is shock accelerated by an approximately Mach 1.2 shockwave to form the RMI. Time resolved Particle Image Velocimetry (PIV) is used to perform analysis of the evolving instability.

Super-nonlinear fluorescence microscopy for high-contrast deep tissue imaging

Science.gov (United States)

Wei, Lu; Zhu, Xinxin; Chen, Zhixing; Min, Wei

2014-02-01

Two-photon excited fluorescence microscopy (TPFM) offers the highest penetration depth with subcellular resolution in light microscopy, due to its unique advantage of nonlinear excitation. However, a fundamental imaging-depth limit, accompanied by a vanishing signal-to-background contrast, still exists for TPFM when imaging deep into scattering samples. Formally, the focusing depth, at which the in-focus signal and the out-of-focus background are equal to each other, is defined as the fundamental imaging-depth limit. To go beyond this imaging-depth limit of TPFM, we report a new class of super-nonlinear fluorescence microscopy for high-contrast deep tissue imaging, including multiphoton activation and imaging (MPAI) harnessing novel photo-activatable fluorophores, stimulated emission reduced fluorescence (SERF) microscopy by adding a weak laser beam for stimulated emission, and two-photon induced focal saturation imaging with preferential depletion of ground-state fluorophores at focus. The resulting image contrasts all exhibit a higher-order (third- or fourth- order) nonlinear signal dependence on laser intensity than that in the standard TPFM. Both the physical principles and the imaging demonstrations will be provided for each super-nonlinear microscopy. In all these techniques, the created super-nonlinearity significantly enhances the imaging contrast and concurrently extends the imaging depth-limit of TPFM. Conceptually different from conventional multiphoton processes mediated by virtual states, our strategy constitutes a new class of fluorescence microscopy where high-order nonlinearity is mediated by real population transfer.

Star-shaped ladder-type ter(p-phenylene)s for efficient multiphoton absorption.

Science.gov (United States)

Guo, Lei; Li, King Fai; Wong, Man Shing; Cheah, Kok Wai

2013-05-04

Star-shaped ladder-type ter(p-phenylene)s exhibit remarkably efficient multiphoton absorption properties with 2PA cross-section up to 2579 GM at 700 nm and 3PA cross-section up to 3.35 × 10(-76) cm(6) s(2) in the femtosecond regime for a blue-emissive molecule despite having such a short π-conjugated framework.

Effects of multi-photon interferences from internally generated fields in strongly resonant systems

International Nuclear Information System (INIS)

Deng, Lu; Payne, Marvin G.; Garrett, William R.

2006-01-01

In studies of various nonlinear optical phenomena, strong resonant features in the atomic or molecular response to multi-photon driven processes have been used to greatly enhance the visibility of otherwise weak higher-order processes. However, there are well defined circumstances where a multi-photon-resonant response of a target system leads to the generation of one or more new electromagnetic fields that can drastically change the overall system response from what would be expected from the imposed laser fields alone. New effects can occur and dominate some aspects of the nonlinear optical response because of the constructive or destructive interference between transition amplitudes along multiple excitation pathways between a given set of optically coupled states, where one of the pathways involve internally generated field(s). Under destructive interference some resonant enhancements can become completely canceled (suppressed). This review focuses on the class of optical interference effects associated with internally generated fields, that have been found to be capable of influencing a very significant number of basic physical phenomena in gas or vapor phase systems. It provides a historical overview of experimental and theoretical developments and a modern understanding of the underlying physics and its various manifestations that include: suppression of multi-photon excitation processes, suppression of stimulated emissions (Raman, hyper-Raman, and optically pumped stimulated emissions), saturation of parametric wave-mixing, pressure and beam-geometry dependent shifting of multi-photon-resonant absorption lines, and the suppression of Autler-Townes splitting and ac-stark shifts. Additionally, optical interference effects in some modern contexts, such as achieving multi-photon induced transparency, establishing single-photon self-interference based induced transparency, and generating entangled single photon states, are reviewed

Measurement of absorption spectrum of deuterium oxide (D2O) and its application to signal enhancement in multiphoton microscopy at the 1700-nm window

International Nuclear Information System (INIS)

Wang, Yuxin; Wen, Wenhui; Wang, Kai; Wang, Ke; Zhai, Peng; Qiu, Ping

2016-01-01

1700-nm window has been demonstrated to be a promising excitation window for deep-tissue multiphoton microscopy (MPM). Long working-distance water immersion objective lenses are typically used for deep-tissue imaging. However, absorption due to immersion water at 1700 nm is still high and leads to dramatic decrease in signals. In this paper, we demonstrate measurement of absorption spectrum of deuterium oxide (D 2 O) from 1200 nm to 2600 nm, covering the three low water-absorption windows potentially applicable for deep-tissue imaging (1300 nm, 1700 nm, and 2200 nm). We apply this measured result to signal enhancement in MPM at the 1700-nm window. Compared with water immersion, D 2 O immersion enhances signal levels in second-harmonic generation imaging, 3-photon fluorescence imaging, and third-harmonic generation imaging by 8.1, 24.8, and 24.7 times with 1662-nm excitation, in good agreement with theoretical calculation based on our absorption measurement. This suggests D 2 O a promising immersion medium for deep-tissue imaging

Velocity landscape correlation resolves multiple flowing protein populations from fluorescence image time series.

Science.gov (United States)

Pandžić, Elvis; Abu-Arish, Asmahan; Whan, Renee M; Hanrahan, John W; Wiseman, Paul W

2018-02-16

Molecular, vesicular and organellar flows are of fundamental importance for the delivery of nutrients and essential components used in cellular functions such as motility and division. With recent advances in fluorescence/super-resolution microscopy modalities we can resolve the movements of these objects at higher spatio-temporal resolutions and with better sensitivity. Previously, spatio-temporal image correlation spectroscopy has been applied to map molecular flows by correlation analysis of fluorescence fluctuations in image series. However, an underlying assumption of this approach is that the sampled time windows contain one dominant flowing component. Although this was true for most of the cases analyzed earlier, in some situations two or more different flowing populations can be present in the same spatio-temporal window. We introduce an approach, termed velocity landscape correlation (VLC), which detects and extracts multiple flow components present in a sampled image region via an extension of the correlation analysis of fluorescence intensity fluctuations. First we demonstrate theoretically how this approach works, test the performance of the method with a range of computer simulated image series with varying flow dynamics. Finally we apply VLC to study variable fluxing of STIM1 proteins on microtubules connected to the plasma membrane of Cystic Fibrosis Bronchial Epithelial (CFBE) cells. Copyright © 2018 Elsevier Inc. All rights reserved.

Time-resolved photoelectron spectrometry of a dephasing process in pyrazine

International Nuclear Information System (INIS)

Pavlov, R.L.; Pavlov, L.I.; Delchev, Ya.I.; Pavlova, S.I.

2001-01-01

The first femtosecond time-resolved photoelectron imaging (PEI) is presented. The method is characterized by photoionization of NO and further applied to ultrafast dephasing in pyrazine. Intermediate case behaviour in radiationless transition is clearly observed in time-resolved photoelectron kinetic energy distribution. Femtosecond PEI is with much improved efficiency than conventional photoelectron spectroscopies. It is anticipated that the unifield approach of time-resolved photoelectron and photoion imaging opens the possibility of observing photon-induced dynamics in real time

Characterizing germania concentration and structure in fiber soot using multiphoton microscopy and spectroscopy technology

Science.gov (United States)

Chen, Minghan; Li, Ming-Jun; Liu, Anping

2015-02-01

Germania doping is commonly used in the core of optical fiber due to its advantages compared to other materials such as superior transparency in near-infrared telecommunication wavelength region. During fiber preform manufacturing using the outside vapor deposition (OVD) process, Ge is doped into a silica soot preform by chemical vapor deposition. Since the Ge doping concentration profile is directly correlated with the fiber refractive index profile, its characterization is critical for the fiber industry. Electron probe micro-analyzer (EPMA) is a conventional analysis method for characterizing the Ge concentration profile. However, it requires extensive sample preparation and lengthy measurement. In this paper, a multiphoton microscopy technique is utilized to measure the Ge doping profile based on the multiphoton fluorescence intensity of the soot layers. Two samples, one with ramped and another with stepped Ge doping profiles were prepared for measurements. Measured results show that the technique is capable of distinguishing ramped and stepped Ge doping profiles with good accuracy. In the ramped soot sample, a sharp increment of doping level was observed in about 2 mm range from soot edge followed by a relative slow gradient doping accretion. As for the stepped doping sample, step sizes ranging from around 1 mm (at soot edge) to 3 mm (at soot center) were observed. All the measured profiles are in close agreement with that of the EPMA measurements. In addition, both multiphoton fluorescence (around 420 nm) and sharp second harmonic generations (at 532 nm) were observed, which indicates the co-existence of crystal and amorphous GeO2.

Multiphoton tomography of astronauts

Science.gov (United States)

König, Karsten; Weinigel, Martin; Pietruszka, Anna; Bückle, Rainer; Gerlach, Nicole; Heinrich, Ulrike

2015-03-01

Weightlessness may impair the astronaut's health conditions. Skin impairments belong to the most frequent health problems during space missions. Within the Skin B project, skin physiological changes during long duration space flights are currently investigated on three European astronauts that work for nearly half a year at the ISS. Measurements on the hydration, the transepidermal water loss, the surface structure, elasticity and the tissue density by ultrasound are conducted. Furthermore, high-resolution in vivo histology is performed by multiphoton tomography with 300 nm spatial and 200 ps temporal resolution. The mobile certified medical tomograph with a flexible 360° scan head attached to a mechano-optical arm is employed to measure two-photon autofluorescence and SHG in the volar forearm of the astronauts. Modification of the tissue architecture and of the fluorescent biomolecules NAD(P)H, keratin, melanin and elastin are detected as well as of SHG-active collagen. Thinning of the vital epidermis, a decrease of the autofluoresence intensity, an increase in the long fluorescence lifetime, and a reduced skin ageing index SAAID based on an increased collagen level in the upper dermis have been found. Current studies focus on recovery effects.

Three-photon imaging of ovarian cancer

Science.gov (United States)

Barton, Jennifer K.; Amirsolaimani, Babak; Rice, Photini; Hatch, Kenneth; Kieu, Khanh

2016-02-01

Optical imaging methods have the potential to detect ovarian cancer at an early, curable stage. Optical imaging has the disadvantage that high resolution techniques require access to the tissue of interest, but miniature endoscopes that traverse the natural orifice of the reproductive tract, or access the ovaries and fallopian tubes through a small incision in the vagina wall, can provide a minimally-invasive solution. We have imaged both rodent and human ovaries and fallopian tubes with a variety of endoscope-compatible modalities. The recent development of fiber-coupled femtosecond lasers will enable endoscopic multiphoton microscopy (MPM). We demonstrated two- and three-photon excited fluorescence (2PEF, 3PEF), and second- and third-harmonic generation microscopy (SHG, THG) in human ovarian and fallopian tube tissue. A study was undertaken to understand the mechanisms of contrast in these images. Six patients (normal, cystadenoma, and ovarian adenocarcinoma) provided ovarian and fallopian tube biopsies. The tissue was imaged with three-dimensional optical coherence tomography, multiphoton microscopy, and frozen for histological sectioning. Tissue sections were stained with hematoxylin and eosin, Masson's trichrome, and Sudan black. Approximately 1 μm resolution images were obtained with an excitation source at 1550 nm. 2PEF signal was absent. SHG signal was mainly from collagen. 3PEF and THG signal came from a variety of sources, including a strong signal from fatty connective tissue and red blood cells. Adenocarcinoma was characterized by loss of SHG signal, whereas cystic abnormalities showed strong SHG. There was limited overlap of two- and three- photon signals, suggesting that three-photon imaging can provide additional information for early diagnosis of ovarian cancer.

Wide-field spectrally resolved quantitative fluorescence imaging system: toward neurosurgical guidance in glioma resection

Science.gov (United States)

Xie, Yijing; Thom, Maria; Ebner, Michael; Wykes, Victoria; Desjardins, Adrien; Miserocchi, Anna; Ourselin, Sebastien; McEvoy, Andrew W.; Vercauteren, Tom

2017-11-01

In high-grade glioma surgery, tumor resection is often guided by intraoperative fluorescence imaging. 5-aminolevulinic acid-induced protoporphyrin IX (PpIX) provides fluorescent contrast between normal brain tissue and glioma tissue, thus achieving improved tumor delineation and prolonged patient survival compared with conventional white-light-guided resection. However, commercially available fluorescence imaging systems rely solely on visual assessment of fluorescence patterns by the surgeon, which makes the resection more subjective than necessary. We developed a wide-field spectrally resolved fluorescence imaging system utilizing a Generation II scientific CMOS camera and an improved computational model for the precise reconstruction of the PpIX concentration map. In our model, the tissue's optical properties and illumination geometry, which distort the fluorescent emission spectra, are considered. We demonstrate that the CMOS-based system can detect low PpIX concentration at short camera exposure times, while providing high-pixel resolution wide-field images. We show that total variation regularization improves the contrast-to-noise ratio of the reconstructed quantitative concentration map by approximately twofold. Quantitative comparison between the estimated PpIX concentration and tumor histopathology was also investigated to further evaluate the system.

Optimized respiratory-resolved motion-compensated 3D Cartesian coronary MR angiography.

Science.gov (United States)

Correia, Teresa; Ginami, Giulia; Cruz, Gastão; Neji, Radhouene; Rashid, Imran; Botnar, René M; Prieto, Claudia

2018-04-22

To develop a robust and efficient reconstruction framework that provides high-quality motion-compensated respiratory-resolved images from free-breathing 3D whole-heart Cartesian coronary magnetic resonance angiography (CMRA) acquisitions. Recently, XD-GRASP (eXtra-Dimensional Golden-angle RAdial Sparse Parallel MRI) was proposed to achieve 100% scan efficiency and provide respiratory-resolved 3D radial CMRA images by exploiting sparsity in the respiratory dimension. Here, a reconstruction framework for Cartesian CMRA imaging is proposed, which provides respiratory-resolved motion-compensated images by incorporating 2D beat-to-beat translational motion information to increase sparsity in the respiratory dimension. The motion information is extracted from interleaved image navigators and is also used to compensate for 2D translational motion within each respiratory phase. The proposed Optimized Respiratory-resolved Cartesian Coronary MR Angiography (XD-ORCCA) method was tested on 10 healthy subjects and 2 patients with cardiovascular disease, and compared against XD-GRASP. The proposed XD-ORCCA provides high-quality respiratory-resolved images, allowing clear visualization of the right and left coronary arteries, even for irregular breathing patterns. Compared with XD-GRASP, the proposed method improves the visibility and sharpness of both coronaries. Significant differences (p respiratory phases with larger motion amplitudes and subjects with irregular breathing patterns. A robust respiratory-resolved motion-compensated framework for Cartesian CMRA has been proposed and tested in healthy subjects and patients. The proposed XD-ORCCA provides high-quality images for all respiratory phases, independently of the regularity of the breathing pattern. © 2018 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Multiphoton crosslinking for biocompatible 3D printing of type I collagen.

Science.gov (United States)

Bell, Alex; Kofron, Matthew; Nistor, Vasile

2015-09-03

Multiphoton fabrication is a powerful technique for three-dimensional (3D) printing of structures at the microscale. Many polymers and proteins have been successfully structured and patterned using this method. Type I collagen comprises a large part of the extracellular matrix for most tissue types and is a widely used cellular scaffold material for tissue engineering. Current methods for creating collagen tissue scaffolds do not allow control of local geometry on a cellular scale. This means the environment experienced by cells may be made up of the native material but unrelated to native cellular-scale structure. In this study, we present a novel method to allow multiphoton crosslinking of type I collagen with flavin mononucleotide photosensitizer. The method detailed allows full 3D printing of crosslinked structures made from unmodified type I collagen and uses only demonstrated biocompatible materials. Resolution of 1 μm for both standing lines and high-aspect ratio gaps between structures is demonstrated and complex 3D structures are fabricated. This study demonstrates a means for 3D printing with one of the most widely used tissue scaffold materials. High-resolution, 3D control of the fabrication of collagen scaffolds will facilitate higher fidelity recreation of the native extracellular environment for engineered tissues.

Microscopic time-resolved imaging of singlet oxygen by delayed fluorescence in living cells.

Science.gov (United States)

Scholz, Marek; Dědic, Roman; Hála, Jan

2017-11-08

Singlet oxygen is a highly reactive species which is involved in a number of processes, including photodynamic therapy of cancer. Its very weak near-infrared emission makes imaging of singlet oxygen in biological systems a long-term challenge. We address this challenge by introducing Singlet Oxygen Feedback Delayed Fluorescence (SOFDF) as a novel modality for semi-direct microscopic time-resolved wide-field imaging of singlet oxygen in biological systems. SOFDF has been investigated in individual fibroblast cells incubated with a well-known photosensitizer aluminium phthalocyanine tetrasulfonate. The SOFDF emission from the cells is several orders of magnitude stronger and much more readily detectable than the very weak near-infrared phosphorescence of singlet oxygen. Moreover, the analysis of SOFDF kinetics enables us to estimate the lifetimes of the involved excited states. Real-time SOFDF images with micrometer spatial resolution and submicrosecond temporal-resolution have been recorded. Interestingly, a steep decrease in the SOFDF intensity after the photodynamically induced release of a photosensitizer from lysosomes has been demonstrated. This effect could be potentially employed as a valuable diagnostic tool for monitoring and dosimetry in photodynamic therapy.

Characterizing multi-photon quantum interference with practical light sources and threshold single-photon detectors

Science.gov (United States)

Navarrete, Álvaro; Wang, Wenyuan; Xu, Feihu; Curty, Marcos

2018-04-01

The experimental characterization of multi-photon quantum interference effects in optical networks is essential in many applications of photonic quantum technologies, which include quantum computing and quantum communication as two prominent examples. However, such characterization often requires technologies which are beyond our current experimental capabilities, and today's methods suffer from errors due to the use of imperfect sources and photodetectors. In this paper, we introduce a simple experimental technique to characterize multi-photon quantum interference by means of practical laser sources and threshold single-photon detectors. Our technique is based on well-known methods in quantum cryptography which use decoy settings to tightly estimate the statistics provided by perfect devices. As an illustration of its practicality, we use this technique to obtain a tight estimation of both the generalized Hong‑Ou‑Mandel dip in a beamsplitter with six input photons and the three-photon coincidence probability at the output of a tritter.

Application of a high-repetition-rate laser diagnostic system for single-cycle-resolved imaging in internal combustion engines.

Science.gov (United States)

Hult, Johan; Richter, Mattias; Nygren, Jenny; Aldén, Marcus; Hultqvist, Anders; Christensen, Magnus; Johansson, Bengt

2002-08-20

High-repetition-rate laser-induced fluorescence measurements of fuel and OH concentrations in internal combustion engines are demonstrated. Series of as many as eight fluorescence images, with a temporal resolution ranging from 10 micros to 1 ms, are acquired within one engine cycle. A multiple-laser system in combination with a multiple-CCD camera is used for cycle-resolved imaging in spark-ignition, direct-injection stratified-charge, and homogeneous-charge compression-ignition engines. The recorded data reveal unique information on cycle-to-cycle variations in fuel transport and combustion. Moreover, the imaging system in combination with a scanning mirror is used to perform instantaneous three-dimensional fuel-concentration measurements.

Time-resolved magnetic imaging in an aberration-corrected, energy-filtered photoemission electron microscope

International Nuclear Information System (INIS)

Nickel, F.; Gottlob, D.M.; Krug, I.P.; Doganay, H.; Cramm, S.; Kaiser, A.M.; Lin, G.; Makarov, D.; Schmidt, O.G.

2013-01-01

We report on the implementation and usage of a synchrotron-based time-resolving operation mode in an aberration-corrected, energy-filtered photoemission electron microscope. The setup consists of a new type of sample holder, which enables fast magnetization reversal of the sample by sub-ns pulses of up to 10 mT. Within the sample holder current pulses are generated by a fast avalanche photo diode and transformed into magnetic fields by means of a microstrip line. For more efficient use of the synchrotron time structure, we developed an electrostatic deflection gating mechanism capable of beam blanking within a few nanoseconds. This allows us to operate the setup in the hybrid bunch mode of the storage ring facility, selecting one or several bright singular light pulses which are temporally well-separated from the normal high-intensity multibunch pulse pattern. - Highlights: • A new time-resolving operation mode in photoemission electron microscopy is shown. • Our setup works within an energy-filtered, aberration-corrected PEEM. • A new gating system for bunch selection using synchrotron radiation is developed. • An alternative magnetic excitation system is developed. • First tr-imaging using an energy-filtered, aberration-corrected PEEM is shown

Protocol for generating multiphoton entangled states from quantum dots in the presence of nuclear spin fluctuations

DEFF Research Database (Denmark)

Denning, Emil Vosmar; Iles-Smith, Jake; McCutcheon, Dara P. S.

2017-01-01

Multiphoton entangled states are a crucial resource for many applications inquantum information science. Semiconductor quantum dots offer a promising route to generate such states by mediating photon-photon correlations via a confinedelectron spin, but dephasing caused by the host nuclear spin...... environment typically limits coherence (and hence entanglement) between photons to the spin T2* time of a few nanoseconds. We propose a protocol for the deterministic generation of multiphoton entangled states that is inherently robust against the dominating slow nuclear spin environment fluctuations, meaning...... that coherence and entanglement is instead limited only by the much longer spin T2 time of microseconds. Unlike previous protocols, the present schemeallows for the generation of very low error probability polarisation encoded three-photon GHZ states and larger entangled states, without the need for spin echo...

Nanosecond Time-Resolved Microscopic Gate-Modulation Imaging of Polycrystalline Organic Thin-Film Transistors

Science.gov (United States)

Matsuoka, Satoshi; Tsutsumi, Jun'ya; Matsui, Hiroyuki; Kamata, Toshihide; Hasegawa, Tatsuo

2018-02-01

We develop a time-resolved microscopic gate-modulation (μ GM ) imaging technique to investigate the temporal evolution of the channel current and accumulated charges in polycrystalline pentacene thin-film transistors (TFTs). A time resolution of as high as 50 ns is achieved by using a fast image-intensifier system that could amplify a series of instantaneous optical microscopic images acquired at various time intervals after the stepped gate bias is switched on. The differential images obtained by subtracting the gate-off image allows us to acquire a series of temporal μ GM images that clearly show the gradual propagation of both channel charges and leaked gate fields within the polycrystalline channel layers. The frontal positions for the propagations of both channel charges and leaked gate fields coincide at all the time intervals, demonstrating that the layered gate dielectric capacitors are successively transversely charged up along the direction of current propagation. The initial μ GM images also indicate that the electric field effect is originally concentrated around a limited area with a width of a few micrometers bordering the channel-electrode interface, and that the field intensity reaches a maximum after 200 ns and then decays. The time required for charge propagation over the whole channel region with a length of 100 μ m is estimated at about 900 ns, which is consistent with the measured field-effect mobility and the temporal-response model for organic TFTs. The effect of grain boundaries can be also visualized by comparison of the μ GM images for the transient and the steady states, which confirms that the potential barriers at the grain boundaries cause the transient shift in the accumulated charges or the transient accumulation of additional charges around the grain boundaries.

Examination of excited state populations in sputtering using Multiphoton Resonance Ionization

International Nuclear Information System (INIS)

Kimock, F.M.; Baxter, J.P.; Pappas, D.L.; Kobrin, P.H.; Winograd, N.

1984-01-01

Multiphoton Resonance Ionization has been employed to study the populations of excited state atoms ejected from ion bombarded metal surfaces. Preliminary investigations have focused on three model systems: aluminum, indium and cobalt. In this paper the authors examine the effect of primary ion energy (2 to 12 keV Ar + ) on excited state yields for these three systems. The influence of the sample matrix on excited state populations of sputtered atoms is also discussed

Yield and enrichment studies of C-13 isotope by multi-photon ...

Indian Academy of Sciences (India)

Abstract. Multi-photon dissociation of Freon-22 (CF2HCl) at low temperatures has been carried out to separate the C-13 isotope using a TEA CO2 laser. Yield and enrichment of C-13 isotope in the product C2F4 are studied at 9P(22) laser line as a function of temperature (–50°C to 30°C). It is observed that at a given fluence ...

Evaluation of Elastin/Collagen Content in Human Dermis in-Vivo by Multiphoton Tomography—Variation with Depth and Correlation with Aging

Directory of Open Access Journals (Sweden)

Jean-Christophe Pittet

2014-08-01

Full Text Available The aim of this study was to evaluate the influence of the depth of the dermis on the measured collagen and elastin levels and to establish the correlation between the amount of these two extracellular matrix (ECM components and age. Multiphoton Microscopy (MPM that measures the autofluorescence (AF and second harmonic generation (SHG was used to quantify the levels of elastin and collagen and to determine the SAAID (SHG-to-AF Aging Index of Dermis at two different skin depths. A 50 MHz ultrasound scanner was used for the calculation of the Sub Epidermal Non Echogenic Band (SENEB. The measurements of the skin mechanical properties were done with a cutometer. All measurements were performed on two groups of 30 healthy female volunteers. The MPM showed a decrease of the quantity of collagen and elastin as a function of depth of the dermis as well as age. The SAAID was lower for the older skin in the deeper dermis. Ultrasound imaging revealed a significant decrease of SENEB as a function of aging. The mechanical properties confirmed a loss of cutaneous elasticity and firmness. Although multiphoton microscopy is a powerful technique to study the characteristics of the dermis and its age-related damage, the location of the measurements (depth remains very important for the validation of these variations. These variations do not seem to be homogeneous according to the part of the dermis that is studied.

A single-shot nonlinear autocorrelation approach for time-resolved physics in the vacuum ultraviolet spectral range

International Nuclear Information System (INIS)

Rompotis, Dimitrios

2016-02-01

In this work, a single-shot temporal metrology scheme operating in the vacuum-extreme ultraviolet spectral range has been designed and experimentally implemented. Utilizing an anti-collinear geometry, a second-order intensity autocorrelation measurement of a vacuum ultraviolet pulse can be performed by encoding temporal delay information on the beam propagation coordinate. An ion-imaging time-of-flight spectrometer, offering micrometer resolution has been set-up for this purpose. This instrument enables the detection of a magnified image of the spatial distribution of ions exclusively generated by direct two-photon absorption in the combined counter-propagating pulse focus and thus obtain the second-order intensity autocorrelation measurement on a single-shot basis. Additionally, an intense VUV light source based on high-harmonic generation has been experimentally realized. It delivers intense sub-20 fs Ti:Sa fifth-harmonic pulses utilizing a loose-focusing geometry in a long Ar gas cell. The VUV pulses centered at 161.8 nm reach pulse energies of 1.1 μJ per pulse, while the corresponding pulse duration is measured with a second-order, fringe-resolved autocorrelation scheme to be 18 ± 1 fs on average. Non-resonant, two-photon ionization of Kr and Xe and three-photon ionization of Ne verify the fifth-harmonic pulse intensity and indicate the feasibility of multi-photon VUV pump/VUV probe studies of ultrafast atomic and molecular dynamics. Finally, the extended functionally of the counter-propagating pulse metrology approach is demonstrated by a single-shot VUV pump/VUV probe experiment aiming at the investigation of ultrafast dissociation dynamics of O 2 excited in the Schumann-Runge continuum at 162 nm.

Time- and energy resolved photoemission electron microscopy-imaging of photoelectron time-of-flight analysis by means of pulsed excitations

International Nuclear Information System (INIS)

Oelsner, Andreas; Rohmer, Martin; Schneider, Christian; Bayer, Daniela; Schoenhense, Gerd; Aeschlimann, Martin

2010-01-01

The present work enlightens the developments in time- and energy resolved photoemission electron microscopy over the past few years. We describe basic principles of the technique and demonstrate different applications. An energy- and time-filtering photoemission electron microscopy (PEEM) for real-time spectroscopic imaging can be realized either by a retarding field or hemispherical energy analyzer or by using time-of-flight optics with a delay line detector. The latter method has the advantage of no data loss at all as all randomly incoming particles are measured not only by position but also by time. This is of particular interest for pump-probe experiments in the femtosecond and attosecond time scale where space charge processes drastically limit the maximum number of photoemitted electrons per laser pulse. This work focuses particularly on time-of-flight analysis using a novel delay line detector. Time and energy resolved PEEM instruments with delay line detectors enable 4D imaging (x, y, Δt, E Kin ) on a true counting basis. This allows a broad range of applications from real-time observation of dynamic phenomena at surfaces to fs time-of-flight spectro-microscopy and even aberration correction. By now, these time-of-flight analysis instruments achieve intrinsic time resolutions of 108 ps absolute and 13.5 ps relative. Very high permanent measurement speeds of more than 4 million events per second in random detection regimes have been realized using a standard USB2.0 interface. By means of this performance, the time-resolved PEEM technique enables to display evolutions of spatially resolved (<25 nm) and temporal sliced images life on any modern computer. The method allows dynamics investigations of variable electrical, magnetic, and optical near fields at surfaces and great prospects in dynamical adaptive photoelectron optics. For dynamical processes in the ps time scale such as magnetic domain wall movements, the time resolution of the delay line detectors

Impurity mapping in sulphide minerals using Time-resolved Ion Beam Induced Current imaging

International Nuclear Information System (INIS)

Laird, Jamie S.; Johnson, Brett C.; Ganesan, Kumaravelu; Kandasamy, Sasikaran; Davidson, Garry; Borg, Stacey; Ryan, Chris G.

2010-01-01

The semiconducting properties and charge transport within natural minerals like pyrite are postulated to drive certain geochemical processes which can lead to precious metal ore genesis. In this paper we outline electrical measurements on mineral samples and present spatio-temporally resolved Ion Beam Induced Charge or Current studies on a Schottky pyrite junction. Au-Schottky contacts were fabricated in regions selected by thermoelectric and 4-point probe resistivity measurements. The complexity in charge transport due to impurity variations results in imaging contrast which is deemed important for fluid electrochemistry. The relevance of understanding charge collection in pyrite in the context of complex geochemical processes is briefly discussed.

Visualizing Angiogenesis by Multiphoton Microscopy In Vivo in Genetically Modified 3D-PLGA/nHAp Scaffold for Calvarial Critical Bone Defect Repair.

Science.gov (United States)

Li, Jian; Jahr, Holger; Zheng, Wei; Ren, Pei-Gen

2017-09-07

The reconstruction of critically sized bone defects remains a serious clinical problem because of poor angiogenesis within tissue-engineered scaffolds during repair, which gives rise to a lack of sufficient blood supply and causes necrosis of the new tissues. Rapid vascularization is a vital prerequisite for new tissue survival and integration with existing host tissue. The de novo generation of vasculature in scaffolds is one of the most important steps in making bone regeneration more efficient, allowing repairing tissue to grow into a scaffold. To tackle this problem, the genetic modification of a biomaterial scaffold is used to accelerate angiogenesis and osteogenesis. However, visualizing and tracking in vivo blood vessel formation in real-time and in three-dimensional (3D) scaffolds or new bone tissue is still an obstacle for bone tissue engineering. Multiphoton microscopy (MPM) is a novel bio-imaging modality that can acquire volumetric data from biological structures in a high-resolution and minimally-invasive manner. The objective of this study was to visualize angiogenesis with multiphoton microscopy in vivo in a genetically modified 3D-PLGA/nHAp scaffold for calvarial critical bone defect repair. PLGA/nHAp scaffolds were functionalized for the sustained delivery of a growth factor pdgf-b gene carrying lentiviral vectors (LV-pdgfb) in order to facilitate angiogenesis and to enhance bone regeneration. In a scaffold-implanted calvarial critical bone defect mouse model, the blood vessel areas (BVAs) in PHp scaffolds were significantly higher than in PH scaffolds. Additionally, the expression of pdgf-b and angiogenesis-related genes, vWF and VEGFR2, increased correspondingly. MicroCT analysis indicated that the new bone formation in the PHp group dramatically improved compared to the other groups. To our knowledge, this is the first time multiphoton microscopy was used in bone tissue-engineering to investigate angiogenesis in a 3D bio-degradable scaffold in

Ionisation of hydrogen-like atoms by a multiphoton absorption process

International Nuclear Information System (INIS)

Gontier, Y.; Trahin, M.

1967-01-01

The general expression for the amplitude of the probability of ionisation by a multiphoton absorption process is derived. Its non-relativistic limit is taken and the bipolar approximation is used for calculating the ionisation cross-section of hydrogen-like atoms. This latter involves the summation over intermediate virtual states by means of: a) a recursion relationship concerning angular functions, b) a particular technique which when applied to radial functions makes it possible to solve a system of inhomogeneous first-order differential equations. (authors) [fr

Resonance-enhanced multiphoton ionization photoelectron spectroscopy of even-parity autoionizing Rydberg states of atomic sulphur

NARCIS (Netherlands)

Woutersen, S.; de Milan, J.B.; de Lange, C.A.; Buma, W.J.

1997-01-01

Several previously unobserved Rydberg states of the sulphur atom above the lowest ionization threshold are identified and assigned using (2 + 1) resonance-enhanced multiphoton-ionization photoelectron spectroscopy. All states were accessed by two-photon transitions from either the 3P ground or the

Infrared multiphoton absorption and decomposition

International Nuclear Information System (INIS)

Evans, D.K.; McAlpine, R.D.

1984-01-01

The discovery of infrared laser induced multiphoton absorption (IRMPA) and decomposition (IRMPD) by Isenor and Richardson in 1971 generated a great deal of interest in these phenomena. This interest was increased with the discovery by Ambartzumian, Letokhov, Ryadbov and Chekalin that isotopically selective IRMPD was possible. One of the first speculations about these phenomena was that it might be possible to excite a particular mode of a molecule with the intense infrared laser beam and cause decomposition or chemical reaction by channels which do not predominate thermally, thus providing new synthetic routes for complex chemicals. The potential applications to isotope separation and novel chemistry stimulated efforts to understand the underlying physics and chemistry of these processes. At ICOMP I, in 1977 and at ICOMP II in 1980, several authors reviewed the current understandings of IRMPA and IRMPD as well as the particular aspect of isotope separation. There continues to be a great deal of effort into understanding IRMPA and IRMPD and we will briefly review some aspects of these efforts with particular emphasis on progress since ICOMP II. 31 references

Multiphoton ionization of (Xe)n and (NO)n clusters using a picosecond laser

International Nuclear Information System (INIS)

Smith, D.B.; Miller, J.C.

1989-01-01

Mass-resolved multiphoton ionization (MPI) spectroscopy is an established technique for detecting and analyzing van der Waals molecules and larger clusters. MPI spectroscopy provides excellent detection sensitivity, moderately high resolution, and selectivity among cluster species. In addition to information provided by the analysis of photoions following MPI, photoelectron spectroscopy can reveal details regarding the structure of ionic states. Unfortunately, the technique is limited by its tendency to produce extensive fragmentation. Fragmentation is also a problem with other ionization techniques (e.g., electron impact ionization), but the intense laser beams required for MPI cause additional dissociation channels to become available. These channels include absorption of additional photons by parent ions (ion ladder mechanism), absorption of additional photons by fragment ions (ladder switching mechanism), and resonances with dissociative states in the neutral manifold. The existence of these dissociation channels can preclude the use of MPI spectroscopy in many situations. Recently, MPI studies of stable molecules using picosecond lasers (pulse length = 1 - 10 ps) have indicated that limitations due to fragmentation might be subdued. With picosecond lasers, dissociation mechanisms can be altered and in some cases fragmentation can be eliminated or reduced. Additional photon absorption competes effectively with dissociation channels when a very short laser pulse or, perhaps more importantly, a sufficiently high peak-power is used. In the case where ionic absorption and fragmentation occurs, it has been shown that picosecond MPI might favor the ion ladder mechanism rather than the ladder switching mechanism

In vivo multiphoton-microscopy of picosecond-laser-induced optical breakdown in human skin.

Science.gov (United States)

Balu, Mihaela; Lentsch, Griffin; Korta, Dorota Z; König, Karsten; Kelly, Kristen M; Tromberg, Bruce J; Zachary, Christopher B

2017-08-01

Improvements in skin appearance resulting from treatment with fractionated picosecond-lasers have been noted, but optimizing the treatment efficacy depends on a thorough understanding of the specific skin response. The development of non-invasive laser imaging techniques in conjunction with laser therapy can potentially provide feedback for guidance and optimizing clinical outcome. The purpose of this study was to demonstrate the capability of multiphoton microscopy (MPM), a high-resolution, label-free imaging technique, to characterize in vivo the skin response to a fractionated non-ablative picosecond-laser treatment. Two areas on the arm of a volunteer were treated with a fractionated picosecond laser at the Dermatology Clinic, UC Irvine. The skin response to treatment was imaged in vivo with a clinical MPM-based tomograph at 3 hours and 24 hours after treatment and seven additional time points over a 4-week period. MPM revealed micro-injuries present in the epidermis. Pigmented cells were particularly damaged in the process, suggesting that melanin is likely the main absorber for laser induced optical breakdown. Damaged individual cells were distinguished as early as 3 hours post pico-laser treatment with the 532 nm wavelength, and 24 hours post-treatment with both 532 and 1064 nm wavelengths. At later time points, clusters of cellular necrotic debris were imaged across the treated epidermis. After 24 hours of treatment, inflammatory cells were imaged in the proximity of epidermal micro-injuries. The epidermal injuries were exfoliated over a 4-week period. This observational and descriptive pilot study demonstrates that in vivo MPM imaging can be used non-invasively to provide label-free contrast for describing changes in human skin following a fractionated non-ablative laser treatment. The results presented in this study represent the groundwork for future longitudinal investigations on an expanded number of subjects to understand the response to treatment

Sequestration of Antimony on Calcite Observed by Time-Resolved Nanoscale Imaging.

Science.gov (United States)

Renard, François; Putnis, Christine V; Montes-Hernandez, German; King, Helen E; Breedveld, Gijs D; Okkenhaug, Gudny

2018-01-02

Antimony, which has damaging effects on the human body and the ecosystem, can be released into soils, ground-, and surface waters either from ore minerals that weather in near surface environments, or due to anthropogenic releases from waste rich in antimony, a component used in batteries, electronics, ammunitions, plastics, and many other industrial applications. Here, we show that dissolved Sb can interact with calcite, a widespread carbonate mineral, through a coupled dissolution-precipitation mechanism. The process is imaged in situ, at room temperature, at the nanometer scale by using an atomic force microscope equipped with a flow-through cell. Time-resolved imaging allowed following the coupled process of calcite dissolution, nucleation of precipitates at the calcite surface and growth of these precipitates. Sb(V) forms a precipitate, whereas Sb(III) needs to be oxidized to Sb(V) before being incorporated in the new phase. Scanning-electron microscopy and Raman spectroscopy allowed identification of the precipitates as two different calcium-antimony phases (Ca 2 Sb 2 O 7 ). This coupled dissolution-precipitation process that occurs in a boundary layer at the calcite surface can sequester Sb as a solid phase on calcite, which has environmental implications as it may reduce the mobility of this hazardous compound in soils and groundwaters.

Picosecond multiphoton ionization of atomic and molecular clusters

International Nuclear Information System (INIS)

Miller, J.C.; Smith, D.B.

1990-01-01

High peak-power picosecond laser pulses have been used for the first time to effect nonresonant or resonant multiphoton ionization (MPI) of clusters generated in a supersonic nozzle expansion. The resulting ions are subsequently detected and characterized by time-of-flight mass spectroscopy. Specifically, we present results involving MPI of clusters of xenon and nitric oxide. Previous MPI studies of many molecular clusters using nanosecond lasers have not been successful in observing the parent ion, presumably due to fast dissociation channels. It is proposed that the present technique is a new and rather general ionization source for cluster studies which is complementary to electron impact but may, in addition, provide unique spectroscopic or dynamical information. 23 refs., 5 figs

Examination of excited state populations in sputtering using multiphoton resonance ionization

International Nuclear Information System (INIS)

Kimock, F.M.; Baxter, J.P.; Pappas, D.L.; Kobrin, P.H.; Winograd, N.

1984-01-01

Multiphoton Resonance Ionization has been employed to study the populations of excited state atoms ejected from ion bombarded metal surfaces. Preliminary investigations have focused on three model systems: aluminum, indium and cobalt. In this paper we examine the effect of primary ion energy (2 to 12 keV Ar + ) on excited state yields for these three systems. The influence of the sample matrix on excited state populations of sputtered atoms is also discussed. 8 refs., 4 figs

Atomic-structure effects in strong-field multiphoton detachment and ionization

International Nuclear Information System (INIS)

AAberg, T.; Mu, X.; Ruscheinski, J.; Crasemann, B.

1994-01-01

Above-threshold photoelectron detachment and ionization spectra are investigated theoretically in the tunneling and over-barrier regime as a function of wavelength (≥ 1.064 μm) and polarization of the electromagnetic field. It is found that the zeros in the initial-state wave function can drastically affect the shape of the high-energy photoelectron distribution. The phenomenon is not predicted by tunneling and related models and hence can test their validity and reveal whether Keldysh-type theories are in general applicable to strong-field multiphoton dynamics. (orig.)

Electron-Nuclear Energy Sharing in Above-Threshold Multiphoton Dissociative Ionization of H2

DEFF Research Database (Denmark)

Wu, J.; Kunitski, M.; Pitzer, M.

2013-01-01

We report experimental observation of the energy sharing between electron and nuclei in above-threshold multiphoton dissociative ionization of H2 by strong laser fields. The absorbed photon energy is shared between the ejected electron and nuclei in a correlated fashion, resulting in multiple...... diagonal lines in their joint energy spectrum governed by the energy conservation of all fragment particles....

Multi-photon creation and single-photon annihilation of electron-positron pairs

Energy Technology Data Exchange (ETDEWEB)

Hu, Huayu

2011-04-27

In this thesis we study multi-photon e{sup +}e{sup -} pair production in a trident process, and singlephoton e{sup +}e{sup -} pair annihilation in a triple interaction. The pair production is considered in the collision of a relativistic electron with a strong laser beam, and calculated within the theory of laser-dressed quantum electrodynamics. A regularization method is developed systematically for the resonance problem arising in the multi-photon process. Total production rates, positron spectra, and relative contributions of different reaction channels are obtained in various interaction regimes. Our calculation shows good agreement with existing experimental data from SLAC, and adds further insights into the experimental findings. Besides, we study the process in a manifestly nonperturbative domain, whose accessibility to future all-optical experiments based on laser acceleration is shown. In the single-photon e{sup +}e{sup -} pair annihilation, the recoil momentum is absorbed by a spectator particle. Various kinematic configurations of the three incoming particles are examined. Under certain conditions, the emitted photon exhibits distinct angular and polarization distributions which could facilitate the detection of the process. Considering an equilibrium relativistic e{sup +}e{sup -} plasma, it is found that the single-photon process becomes the dominant annihilation channel for plasma temperatures above 3 MeV. Multi-particle correlation effects are therefore essential for the e{sup +}e{sup -} dynamics at very high density. (orig.)

Multi-photon creation and single-photon annihilation of electron-positron pairs

International Nuclear Information System (INIS)

Hu, Huayu

2011-01-01

In this thesis we study multi-photon e + e - pair production in a trident process, and singlephoton e + e - pair annihilation in a triple interaction. The pair production is considered in the collision of a relativistic electron with a strong laser beam, and calculated within the theory of laser-dressed quantum electrodynamics. A regularization method is developed systematically for the resonance problem arising in the multi-photon process. Total production rates, positron spectra, and relative contributions of different reaction channels are obtained in various interaction regimes. Our calculation shows good agreement with existing experimental data from SLAC, and adds further insights into the experimental findings. Besides, we study the process in a manifestly nonperturbative domain, whose accessibility to future all-optical experiments based on laser acceleration is shown. In the single-photon e + e - pair annihilation, the recoil momentum is absorbed by a spectator particle. Various kinematic configurations of the three incoming particles are examined. Under certain conditions, the emitted photon exhibits distinct angular and polarization distributions which could facilitate the detection of the process. Considering an equilibrium relativistic e + e - plasma, it is found that the single-photon process becomes the dominant annihilation channel for plasma temperatures above 3 MeV. Multi-particle correlation effects are therefore essential for the e + e - dynamics at very high density. (orig.)

Femtosecond Time-resolved Optical Polarigraphy (FTOP)

International Nuclear Information System (INIS)

Aoshima, S.; Fujimoto, M.; Hosoda, M.; Tsuchiya, Y.

2000-01-01

A novel time-resolved imaging technique named FTOP (Femtosecond Time-resolved Optical Polarigraphy) for visualizing the ultrafast propagation dynamics of intense light pulses in a medium has been proposed and demonstrated. Femtosecond snapshot images can be created with a high spatial resolution by imaging only the polarization components of the probe pulse; these polarization components change due to the instantaneous birefringence induced by the pump pulse in the medium. Ultrafast temporal changes in the two-dimensional spatial distribution of the optical pulse intensity were clearly visualized in consecutive images by changing the delay between the pump and probe. We observe that several filaments appear and then come together before the vacuum focus due to nonlinear effects in air. We also prove that filamentation dynamics such as the formation position and the propagation behavior are complex and are strongly affected by the pump energy. The results collected clearly show that this method FTOP succeeds for the first time in directly visualizing the ultrafast dynamics of the self-modulated nonlinear propagation of light. (author)

Single photon and multiphoton events with missing energy in $e^{+} e^{-}$ collisions at LEP

CERN Document Server

Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, M; Doria, A; Dova, M T; Duchesneau, D; Duda, M; Echenard, B; Eline, A; El-Hage, A; El-Mamouni, H; Engler, A; Eppling, F J; Extermann, P; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, M; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, F; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Nisati, A; Novák, T; Nowak, H; Ofierzynski, R A; Organtini, G; Pal, I; Palomares, C; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosenbleck, C; Rosier-Lees, S; Roth, S; Rubio, J A; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Schäfer, C; Shchegelskii, V; Schopper, Herwig Franz; Schotanus, D J; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wang, Q; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M

2004-01-01

Single- and multi-photon events with missing energy are selected in 619/pb of data collected by the L3 detector at LEP at centre-of-mass energies between 189GeV and 209GeV. The cross sections of the process e^+e^- -> nu nu gamma (gamma) are found to be in agreement with the Standard Model expectations, and the number of light neutrino species is determined, including lower energy data, to be N_nu = 2.98 +/- 0.05 +/- 0.04. Selection results are also given in the form of tables which can be used to test future models involving single- and multi-photon signatures at LEP. These final states are also predicted by models with large extra dimensions and by several supersymmetric models. No evidence for such models is found. Among others, lower limits between 1.5TeV and 0.65TeV are set, at 95% confidence level, on the new scale of gravity for the number of extra dimensions between 2 and 8.

Observation of multiphoton detachment of the H/sup -/ ion

International Nuclear Information System (INIS)

Tang, C.Y.; Harris, P.G.; Mohagheghi, A.H.; Los Alamos National Laboratory, Los Alamos, New Mexico 87545; Cohen Mechanical Design, Broomall, Pennsylvania 19008; The University of Connecticut, Storrs, Connecticut 06268; Western Washington University, Bellingham, Washington 98225)

1989-01-01

We have observed nonresonant multiphoton electron detachment of H/sup -/ ions in moderately intense (a few tens of GW/cm 2 ) laser fields. A well-collimated beam of H/sup -/ ions with an energy of 581 MeV was intersected by focused 10.6-μm radiation from a pulsed CO 2 laser. The center-of-mass photon energy was tuned using the relativistic Doppler shift so that the minimum number of simultaneous photons required for electron detachment ranged from three to sixteen. Definite signals were observed for the minimum photon number ranging from three to eight. Our preliminary results show evidence for structure in the relative total cross section

The study of multiphoton ionization processes in hydrogen atoms

International Nuclear Information System (INIS)

Mohammad, M.A.

1981-01-01

In this thesis we investigate theoretically the multiphoton ionization of hydrogen atoms based on perturbation theory.The main problem in the numorical evaluation is the appearance of infinite summation over the matrix element and energy denominators of the intermediate state in the formula for ionization cross section.Our numerical result is in excellent agreement with other workers.In the last part of the thesis we have again calculated the two photon ionization of hydrogen atoms using momentum translation approximation of Reiss.The method in general is in fair agreement with other calculations but dose not show the resonance behaviour.(2 tabs., 1 fig., 45 refs.)

Emerging biomedical applications of time-resolved fluorescence spectroscopy

Science.gov (United States)

Lakowicz, Joseph R.; Szmacinski, Henryk; Koen, Peter A.

1994-07-01

Time-resolved fluorescence spectroscopy is presently regarded as a research tool in biochemistry, biophysics, and chemical physics. Advances in laser technology, the development of long-wavelength probes, and the use of lifetime-based methods are resulting in the rapid migration of time-resolved fluorescence to the clinical chemistry lab, to the patient's bedside, to flow cytometers, to the doctor's office, and even to home health care. Additionally, time-resolved imaging is now a reality in fluorescence microscopy, and will provide chemical imaging of a variety of intracellular analytes and/or cellular phenomena. In this overview paper we attempt to describe some of the opportunities available using chemical sensing based on fluorescence lifetimes, and to predict those applications of lifetime-based sensing which are most likely in the near future.

Multiphoton amplitude in a constant background field

Science.gov (United States)

Ahmad, Aftab; Ahmadiniaz, Naser; Corradini, Olindo; Kim, Sang Pyo; Schubert, Christian

2018-01-01

In this contribution, we present our recent compact master formulas for the multiphoton amplitudes of a scalar propagator in a constant background field using the worldline fomulation of quantum field theory. The constant field has been included nonperturbatively, which is crucial for strong external fields. A possible application is the scattering of photons by electrons in a strong magnetic field, a process that has been a subject of great interest since the discovery of astrophysical objects like radio pulsars, which provide evidence that magnetic fields of the order of 1012G are present in nature. The presence of a strong external field leads to a strong deviation from the classical scattering amplitudes. We explicitly work out the Compton scattering amplitude in a magnetic field, which is a process of potential relevance for astrophysics. Our final result is compact and suitable for numerical integration.

Generation of a multi-photon Greenberger-Horne-Zeilinger state with linear optical elements and photon detectors

International Nuclear Information System (INIS)

Zou, X B; Pahlke, K; Mathis, W

2005-01-01

We present a scheme to generate a multi-photon Greenberger-Horne-Zeilinger (GHZ) state by using single-photon sources, linear optical elements and photon detectors. Such a maximum entanglement has wide applications in the demonstration of quantum nonlocality and quantum information processing

Time-Resolved Particle Image Velocimetry Measurements with Wall Shear Stress and Uncertainty Quantification for the FDA Nozzle Model.

Science.gov (United States)

Raben, Jaime S; Hariharan, Prasanna; Robinson, Ronald; Malinauskas, Richard; Vlachos, Pavlos P

2016-03-01

We present advanced particle image velocimetry (PIV) processing, post-processing, and uncertainty estimation techniques to support the validation of computational fluid dynamics analyses of medical devices. This work is an extension of a previous FDA-sponsored multi-laboratory study, which used a medical device mimicking geometry referred to as the FDA benchmark nozzle model. Experimental measurements were performed using time-resolved PIV at five overlapping regions of the model for Reynolds numbers in the nozzle throat of 500, 2000, 5000, and 8000. Images included a twofold increase in spatial resolution in comparison to the previous study. Data was processed using ensemble correlation, dynamic range enhancement, and phase correlations to increase signal-to-noise ratios and measurement accuracy, and to resolve flow regions with large velocity ranges and gradients, which is typical of many blood-contacting medical devices. Parameters relevant to device safety, including shear stress at the wall and in bulk flow, were computed using radial basis functions. In addition, in-field spatially resolved pressure distributions, Reynolds stresses, and energy dissipation rates were computed from PIV measurements. Velocity measurement uncertainty was estimated directly from the PIV correlation plane, and uncertainty analysis for wall shear stress at each measurement location was performed using a Monte Carlo model. Local velocity uncertainty varied greatly and depended largely on local conditions such as particle seeding, velocity gradients, and particle displacements. Uncertainty in low velocity regions in the sudden expansion section of the nozzle was greatly reduced by over an order of magnitude when dynamic range enhancement was applied. Wall shear stress uncertainty was dominated by uncertainty contributions from velocity estimations, which were shown to account for 90-99% of the total uncertainty. This study provides advancements in the PIV processing methodologies over

Virtual Hematoxylin and Eosin Transillumination Microscopy Using Epi-Fluorescence Imaging.

Science.gov (United States)

Giacomelli, Michael G; Husvogt, Lennart; Vardeh, Hilde; Faulkner-Jones, Beverly E; Hornegger, Joachim; Connolly, James L; Fujimoto, James G

2016-01-01

We derive a physically realistic model for the generation of virtual transillumination, white light microscopy images using epi-fluorescence measurements from thick, unsectioned tissue. We demonstrate this technique by generating virtual transillumination H&E images of unsectioned human breast tissue from epi-fluorescence multiphoton microscopy data. The virtual transillumination algorithm is shown to enable improved contrast and color accuracy compared with previous color mapping methods. Finally, we present an open source implementation of the algorithm in OpenGL, enabling real-time GPU-based generation of virtual transillumination microscopy images using conventional fluorescence microscopy systems.

Imaging of nitric oxide in nitrergic neuromuscular neurotransmission in the gut.

Directory of Open Access Journals (Sweden)

Hemant S Thatte

Full Text Available Numerous functional studies have shown that nitrergic neurotransmission plays a central role in peristalsis and sphincter relaxation throughout the gut and impaired nitrergic neurotransmission has been implicated in clinical disorders of all parts of the gut. However, the role of nitric oxide (NO as a neurotransmitter continues to be controversial because: 1 the cellular site of production during neurotransmission is not well established; 2 NO may interacts with other inhibitory neurotransmitter candidates, making it difficult to understand its precise role.Imaging NO can help resolve many of the controversies regarding the role of NO in nitrergic neurotransmission. Imaging of NO and its cellular site of production is now possible. NO forms quantifiable fluorescent compound with diaminofluorescein (DAF and allows imaging of NO with good specificity and sensitivity in living cells. In this report we describe visualization and regulation of NO and calcium (Ca(2+ in the myenteric nerve varicosities during neurotransmission using multiphoton microscopy. Our results in mice gastric muscle strips provide visual proof that NO is produced de novo in the nitrergic nerve varicosities upon nonadrenergic noncholinergic (NANC nerve stimulation. These studies show that NO is a neurotransmitter rather than a mediator. Changes in NO production in response to various pharmacological treatments correlated well with changes in slow inhibitory junction potential of smooth muscles.Dual imaging and electrophysiologic studies provide visual proof that during nitrergic neurotransmission NO is produced in the nerve terminals. Such studies may help define whether NO production or its signaling pathway is responsible for impaired nitrergic neurotransmission in pathological states.

Multi-photon UV photolysis of gaseous polycyclic aromatic hydrocarbons: Extinction spectra and dynamics

Energy Technology Data Exchange (ETDEWEB)

Walsh, A. J.; Gash, E. W.; Mansfield, M. W. D. [Physics Department, University College Cork, Cork (Ireland); Ruth, A. A. [Physics Department, University College Cork, Cork (Ireland); Environmental Research Institute, University College Cork, Cork (Ireland)

2013-08-07

The extinction spectra of static naphthalene and static biphenylene vapor, each buffered with a noble gas at room temperature, were measured as a function of time in the region between 390 and 850 nm after UV multi-photon laser photolysis at 308 nm. Employing incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS), the spectra were found to be unstructured with a general lack of isolated features suggesting that the extinction was not solely based on absorption but was in fact dominated by scattering from particles formed in the photolysis of the respective polycyclic aromatic hydrocarbon. Following UV multi-photon photolysis, the extinction dynamics of the static (unstirred) closed gas-phase system exhibits extraordinary quasi-periodic and complex oscillations with periods ranging from seconds to many minutes, persisting for up to several hours. Depending on buffer gas type and pressure, several types of dynamical responses could be generated (classified as types I, II, and III). They were studied as a function of temperature and chamber volume for different experimental conditions and possible explanations for the oscillations are discussed. A conclusive model for the observed phenomena has not been established. However, a number of key hypotheses have made based on the measurements in this publication: (a) Following the multi-photon UV photolysis of naphthalene (or biphenylene), particles are formed on a timescale not observable using IBBCEAS. (b) The observed temporal behavior cannot be described on basis of a chemical reaction scheme alone. (c) The pressure dependence of the system's responses is due to transport phenomena of particles in the chamber. (d) The size distribution and the refractive indices of particles are time dependent and evolve on a timescale of minutes to hours. The rate of particle coagulation, involving coalescent growth and particle agglomeration, affects the observed oscillations. (e) The walls of the chamber act as a

Multiphoton dissociation and thermal unimolecular reactions induced by infrared lasers

International Nuclear Information System (INIS)

Dai, H.L.

1981-04-01

Multiphoton dissociation (MPD) of ethyl chloride was studied using a tunable 3.3 μm laser to excite CH stretches. The absorbed energy increases almost linearly with fluence, while for 10 μm excitation there is substantial saturation. Much higher dissociation yields were observed for 3.3 μm excitation than for 10 μm excitation, reflecting bottlenecking in the discrete region of 10 μm excitation. The resonant nature of the excitation allows the rate equations description for transitions in the quasicontinuum and continuum to be extended to the discrete levels. Absorption cross sections are estimated from ordinary ir spectra. A set of cross sections which is constant or slowly decreasing with increasing vibrational excitation gives good fits to both absorption and dissociation yield data. The rate equations model was also used to quantitatively calculate the pressure dependence of the MPD yield of SF 6 caused by vibrational self-quenching. Between 1000-3000 cm -1 of energy is removed from SF 6 excited to approx. > 60 kcal/mole by collision with a cold SF 6 molecule at gas kinetic rate. Calculation showed the fluence dependence of dissociation varies strongly with the gas pressure. Infrared multiphoton excitation was applied to study thermal unimolecular reactions. With SiF 4 as absorbing gas for the CO 2 laser pulse, transient high temperature pulses were generated in a gas mixture. IR fluorescence from the medium reflected the decay of the temperature. The activation energy and the preexponential factor of the reactant dissociation were obtained from a phenomenological model calculation. Results are presented in detail

An enhancement of spin polarization by multiphoton pumping in semiconductors

Energy Technology Data Exchange (ETDEWEB)

Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

2011-08-15

Highlights: {yields} Multiphoton pumping and spin generation in semiconductors. {yields} Optical selection rules for inter-band transitions. {yields} Calculations of spin polarization using band-energy model and the second order perturbation theory. {yields} Enhancement of the electronic spin polarization. - Abstract: A pump-probe spectroscopic study has been carried out in zinc-blende bulk semiconductors. In the semiconductor samples, a spin-polarized carrier population is produced by the absorption of a monochromatic circularly polarized light beam with two-photon energy above the direct band gap in bulk semiconductors. The production of a carrier population with a net spin is a consequence of the optical selection rules for the heavy-hole and light-hole valence-to-conduction band transitions. This production is probed by the spin-dependent transmission of the samples in the time domain. The spin polarization of the conduction-band-electrons in dependences of delay of the probe beam as well as of pumping photon energy is estimated. The spin polarization is found to depolarize rapidly for pumping energy larger than the energy gap of the split-off band to the conduction band. From the polarization decays, the spin relaxation times are also estimated. Compared to one-photon pumping, the results, however, show that an enhancement of the spin-polarization is achieved by multiphoton excitation of the samples. The experimental results are compared with those obtained in calculations using second order perturbation theory of the spin transport model. A good agreement between experiment and theory is obtained. The observed results are discussed in details.

An enhancement of spin polarization by multiphoton pumping in semiconductors

International Nuclear Information System (INIS)

Miah, M. Idrish

2011-01-01

Highlights: → Multiphoton pumping and spin generation in semiconductors. → Optical selection rules for inter-band transitions. → Calculations of spin polarization using band-energy model and the second order perturbation theory. → Enhancement of the electronic spin polarization. - Abstract: A pump-probe spectroscopic study has been carried out in zinc-blende bulk semiconductors. In the semiconductor samples, a spin-polarized carrier population is produced by the absorption of a monochromatic circularly polarized light beam with two-photon energy above the direct band gap in bulk semiconductors. The production of a carrier population with a net spin is a consequence of the optical selection rules for the heavy-hole and light-hole valence-to-conduction band transitions. This production is probed by the spin-dependent transmission of the samples in the time domain. The spin polarization of the conduction-band-electrons in dependences of delay of the probe beam as well as of pumping photon energy is estimated. The spin polarization is found to depolarize rapidly for pumping energy larger than the energy gap of the split-off band to the conduction band. From the polarization decays, the spin relaxation times are also estimated. Compared to one-photon pumping, the results, however, show that an enhancement of the spin-polarization is achieved by multiphoton excitation of the samples. The experimental results are compared with those obtained in calculations using second order perturbation theory of the spin transport model. A good agreement between experiment and theory is obtained. The observed results are discussed in details.

Multiphoton ionization of atomic cesium

International Nuclear Information System (INIS)

Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

1984-01-01

We describe experimental studies of resonantly enhanced multi-photon ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photo-electron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photo-ionization signal. For both ns and np states the ''field induced'' MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength

Exact results for emission from one and two atoms in an ideal cavity at multiphoton resonance

International Nuclear Information System (INIS)

Fam Le Kien; Shumovskij, A.S.; Tran Quang.

1987-01-01

The emission from the system of one or two two-level atoms in an ideal cavity with one mode at mutiphoton resonance is examined. Exact results for the two-time dipole correlation function and the time-dependent spectra of multiphoton-induced fluorescence are presented

Search for anomalous multiphoton production at 100-300 GeV

International Nuclear Information System (INIS)

Burke, D.L.; Gustafson, H.R.; Jones, L.W.; Longo, M.J.

1975-01-01

A search for anomalous multiphoton production in neutron-CH 2 collisions has been carried out at Fermilab. Both anomalous γ events as might be produced in the annihilation of a magnetic monopole pair, as well as events with smaller opening angles, such as those observed in cosmic ray emulsions by Schein et al. and others were sought. No evidence for either type of event was found. An upper limit approximately 2.7 μb is placed on the production cross section for 'Schein' events or approximately10 -2 that deduced from the cosmic ray data. (Auth.)

A RESOLVED NEAR-INFRARED IMAGE OF THE INNER CAVITY IN THE GM Aur TRANSITIONAL DISK

Energy Technology Data Exchange (ETDEWEB)

Oh, Daehyeon; Yang, Yi [Department of Astronomical Science, SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan); Hashimoto, Jun; Kusakabe, Nobuhiko [Astrobiology Center of NINS 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan); Carson, Joseph C. [Department of Physics and Astronomy, College of Charleston 66 George Street, Charleston, SC 29424 (United States); Janson, Markus [Department of Astronomy, Stockholm University, AlbaNova University Center SE-106 91 Stockholm (Sweden); Kwon, Jungmi; Nakagawa, Takao [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Mayama, Satoshi [The Center for the Promotion of Integrated Sciences, SOKENDAI (The Graduate University for Advanced Studies), Shonan International Village, Hayama-cho, Miura-gun, Kanagawa 240-0193 (Japan); Uyama, Taichi [Department of Astronomy, The University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Kudo, Tomoyuki; Currie, Thayne [Subaru Telescope, National Astronomical Observatory of Japan 650 North A’ohoku Place, Hilo, HI 96720 (United States); Abe, Lyu [Laboratoire Lagrange (UMR 7293), Universite de Nice-Sophia Antipolis, CNRS, Observatoire de la Coted’azur 28 avenue Valrose, F-06108 Nice Cedex 2 (France); Akiyama, Eiji [National Astronomical Observatory of Japan 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan); Brandner, Wolfgang [Max Planck Institute for Astronomy, Köonigstuhl 17, D-69117 Heidelberg (Germany); Brandt, Timothy D.; Feldt, Markus [Astrophysics Department, Institute for Advanced Study Princeton, NJ (United States); Goto, Miwa [Universitats-Sternwarte Munchen, Ludwig-Maximilians-Universitat, Scheinerstr. 1, D-81679 Munchen (Germany); Grady, Carol A. [Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center Greenbelt, MD 20771 (United States); and others

2016-11-01

We present high-contrast H -band polarized intensity (PI) images of the transitional disk around the young solar-like star GM Aur. The near-infrared direct imaging of the disk was derived by polarimetric differential imaging using the Subaru 8.2 m Telescope and HiCIAO. An angular resolution and an inner working angle of 0.″07 and r ∼ 0.″05, respectively, were obtained. We clearly resolved a large inner cavity, with a measured radius of 18 ± 2 au, which is smaller than that of a submillimeter interferometric image (28 au). This discrepancy in the cavity radii at near-infrared and submillimeter wavelengths may be caused by a 3–4 M {sub Jup} planet about 20 au away from the star, near the edge of the cavity. The presence of a near-infrared inner cavity is a strong constraint on hypotheses for inner cavity formation in a transitional disk. A dust filtration mechanism has been proposed to explain the large cavity in the submillimeter image, but our results suggest that this mechanism must be combined with an additional process. We found that the PI slope of the outer disk is significantly different from the intensity slope obtained from HST /NICMOS, and this difference may indicate the grain growth process in the disk.

Effects of uniform dc electric fields on multiphoton ionization of cesium atoms

International Nuclear Information System (INIS)

Klots, C.E.; Compton, R.N.

1985-01-01

Multiphoton ionization of cesium atoms shows pronounced two-photon resonances at the nd states and, to a much smaller extent, at the ns states. A dc electric field augments the ns resonances and, for a complementary reason, induces resonances at the np and nf levels. A scaling law for field-induced signals, as a function of principal quantum number, is reported. Field ionization of high Rydberg states is also conveniently studied and quantified with our technique

Multiphoton ionization and fragmentation study of acetone using 308 nm laser radiation

Science.gov (United States)

Liu Houxiang, Li Shutao, Han Jingcheng, Zhu Rong, Guan Yifu, Wu Cunkai

1988-10-01

Multiphoton ionization and fragmentation (MPI-F) of acetone molecules using 308 nm laser radiation was studied by using a molecular beam and quadrupole mass spectrometer. The ion peaks of acetone molecule appear at m/e=15 and 43, corresponding to the two fragments CH3+ and CH3CO+. It is considered that these two ions are, respectively, formed by direct (2+1) and 2-photon ionization of methyl and acetyl radicals, generated by photodissociation of acetone molecule.

Binary-space-partitioned images for resolving image-based visibility.

Science.gov (United States)

Fu, Chi-Wing; Wong, Tien-Tsin; Tong, Wai-Shun; Tang, Chi-Keung; Hanson, Andrew J

2004-01-01

We propose a novel 2D representation for 3D visibility sorting, the Binary-Space-Partitioned Image (BSPI), to accelerate real-time image-based rendering. BSPI is an efficient 2D realization of a 3D BSP tree, which is commonly used in computer graphics for time-critical visibility sorting. Since the overall structure of a BSP tree is encoded in a BSPI, traversing a BSPI is comparable to traversing the corresponding BSP tree. BSPI performs visibility sorting efficiently and accurately in the 2D image space by warping the reference image triangle-by-triangle instead of pixel-by-pixel. Multiple BSPIs can be combined to solve "disocclusion," when an occluded portion of the scene becomes visible at a novel viewpoint. Our method is highly automatic, including a tensor voting preprocessing step that generates candidate image partition lines for BSPIs, filters the noisy input data by rejecting outliers, and interpolates missing information. Our system has been applied to a variety of real data, including stereo, motion, and range images.

Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

International Nuclear Information System (INIS)

Liu, Yuzhu; Knopp, Gregor; Qin, Chaochao; Gerber, Thomas

2015-01-01

Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S 2 to S 1 is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S 2 state to the vibrationally hot S 1 state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S 1 state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding

Multiphoton transitions in semiconductors in the non-perturbative approach

International Nuclear Information System (INIS)

Iqbal, M.Z.; Hassan, A.R.

1987-09-01

Transition rates for multiphoton absorption via direct band-to-band excitation have been calculated using a non-perturbative approach due to Jones and Reiss, based on the Volkov type final state wave functions. Both cases of parabolic and non-parabolic energy bands have been included in our calculations. Absorption coefficients have been obtained for the cases of plane polarized and circularly polarized light. In particular, two-photon absorption coefficients are derived for the two cases of polarization for the parabolic band approximation as well as for non-parabolic bands and compared with the results based on perturbation theory. Numerical estimates of the two photon absorption coefficients resulting from our calculations are also provided. (author). 10 refs, 1 tab

Non-invasive imaging of skin cancer with fluorescence lifetime imaging using two photon tomography

Science.gov (United States)

Patalay, Rakesh; Talbot, Clifford; Alexandrov, Yuriy; Munro, Ian; Breunig, Hans Georg; König, Karsten; Warren, Sean; Neil, Mark A. A.; French, Paul M. W.; Chu, Anthony; Stamp, Gordon W.; Dunsby, Christopher

2011-07-01

Multispectral fluorescence lifetime imaging (FLIM) using two photon microscopy as a non-invasive technique for the diagnosis of skin lesions is described. Skin contains fluorophores including elastin, keratin, collagen, FAD and NADH. This endogenous contrast allows tissue to be imaged without the addition of exogenous agents and allows the in vivo state of cells and tissues to be studied. A modified DermaInspect® multiphoton tomography system was used to excite autofluorescence at 760 nm in vivo and on freshly excised ex vivo tissue. This instrument simultaneously acquires fluorescence lifetime images in four spectral channels between 360-655 nm using time-correlated single photon counting and can also provide hyperspectral images. The multispectral fluorescence lifetime images were spatially segmented and binned to determine lifetimes for each cell by fitting to a double exponential lifetime model. A comparative analysis between the cellular lifetimes from different diagnoses demonstrates significant diagnostic potential.

3D Printer Generated Tissue iMolds for Cleared Tissue Using Single- and Multi-Photon Microscopy for Deep Tissue Evaluation.

Science.gov (United States)

Miller, Sean J; Rothstein, Jeffrey D

2017-01-01

Pathological analyses and methodology has recently undergone a dramatic revolution. With the creation of tissue clearing methods such as CLARITY and CUBIC, groups can now achieve complete transparency in tissue samples in nano-porous hydrogels. Cleared tissue is then imagined in a semi-aqueous medium that matches the refractive index of the objective being used. However, one major challenge is the ability to control tissue movement during imaging and to relocate precise locations post sequential clearing and re-staining. Using 3D printers, we designed tissue molds that fit precisely around the specimen being imaged. First, images are taken of the specimen, followed by importing and design of a structural mold, then printed with affordable plastics by a 3D printer. With our novel design, we have innovated tissue molds called innovative molds (iMolds) that can be generated in any laboratory and are customized for any organ, tissue, or bone matter being imaged. Furthermore, the inexpensive and reusable tissue molds are made compatible for any microscope such as single and multi-photon confocal with varying stage dimensions. Excitingly, iMolds can also be generated to hold multiple organs in one mold, making reconstruction and imaging much easier. Taken together, with iMolds it is now possible to image cleared tissue in clearing medium while limiting movement and being able to relocate precise anatomical and cellular locations on sequential imaging events in any basic laboratory. This system provides great potential for screening widespread effects of therapeutics and disease across entire organ systems.

Impulsive IR-multiphoton dissociation of acrolein: observation of non-statistical product vibrational excitation in CO ( v=1-12) by time resolved IR fluorescence spectroscopy

Science.gov (United States)

Chowdhury, P. K.

2000-10-01

On IR-multiphoton excitation, vibrationally highly excited acrolein molecules undergo concerted dissociation generating CO and ethylene. The vibrationally excited products, CO and ethylene, are detected immediately following the CO 2 laser pulse by observing IR fluorescence at 4.7 and 3.2 μm, respectively. The nascent CO is formed with significant vibrational excitation, with a Boltzmann population distribution for v=1-12 levels corresponding to T v=12 950±50 K. The average vibrational energy in the product CO is found to be 26 kcal mol -1, in contrast to its statistical share of 5 kcal mol -1, available from the product energy distribution. The nascent vibrationally excited ethylene either dissociates by absorbing further infrared laser photons from the tail of the CO 2 laser pulse or relaxes by collisional deactivation. Ethylene IR-fluorescence excitation spectrum showed a structure in the quasi-continuum, with a facile resonance at 10.53 μm corresponding to the 10P(14) CO 2 laser line, which explains the higher acetylene yield observed at a higher pressure. A hydrogen atom transfer mechanism followed by C-C impulsive break in the acrolein transition state may be responsible for such non-statistical product energy distribution.

Time-Resolved Diffuse Optical Spectroscopy and Imaging Using Solid-State Detectors: Characteristics, Present Status, and Research Challenges.

Science.gov (United States)

Alayed, Mrwan; Deen, M Jamal

2017-09-14

Diffuse optical spectroscopy (DOS) and diffuse optical imaging (DOI) are emerging non-invasive imaging modalities that have wide spread potential applications in many fields, particularly for structural and functional imaging in medicine. In this article, we review time-resolved diffuse optical imaging (TR-DOI) systems using solid-state detectors with a special focus on Single-Photon Avalanche Diodes (SPADs) and Silicon Photomultipliers (SiPMs). These TR-DOI systems can be categorized into two types based on the operation mode of the detector (free-running or time-gated). For the TR-DOI prototypes, the physical concepts, main components, figures-of-merit of detectors, and evaluation parameters are described. The performance of TR-DOI prototypes is evaluated according to the parameters used in common protocols to test DOI systems particularly basic instrumental performance (BIP). In addition, the potential features of SPADs and SiPMs to improve TR-DOI systems and expand their applications in the foreseeable future are discussed. Lastly, research challenges and future developments for TR-DOI are discussed for each component in the prototype separately and also for the entire system.

Virtual Hematoxylin and Eosin Transillumination Microscopy Using Epi-Fluorescence Imaging.

Directory of Open Access Journals (Sweden)

Michael G Giacomelli

Full Text Available We derive a physically realistic model for the generation of virtual transillumination, white light microscopy images using epi-fluorescence measurements from thick, unsectioned tissue. We demonstrate this technique by generating virtual transillumination H&E images of unsectioned human breast tissue from epi-fluorescence multiphoton microscopy data. The virtual transillumination algorithm is shown to enable improved contrast and color accuracy compared with previous color mapping methods. Finally, we present an open source implementation of the algorithm in OpenGL, enabling real-time GPU-based generation of virtual transillumination microscopy images using conventional fluorescence microscopy systems.

Depth-resolved imaging of colon tumor using optical coherence tomography and fluorescence laminar optical tomography (Conference Presentation)

Science.gov (United States)

Tang, Qinggong; Frank, Aaron; Wang, Jianting; Chen, Chao-wei; Jin, Lily; Lin, Jon; Chan, Joanne M.; Chen, Yu

2016-03-01

Early detection of neoplastic changes remains a critical challenge in clinical cancer diagnosis and treatment. Many cancers arise from epithelial layers such as those of the gastrointestinal (GI) tract. Current standard endoscopic technology is unable to detect those subsurface lesions. Since cancer development is associated with both morphological and molecular alterations, imaging technologies that can quantitative image tissue's morphological and molecular biomarkers and assess the depth extent of a lesion in real time, without the need for tissue excision, would be a major advance in GI cancer diagnostics and therapy. In this research, we investigated the feasibility of multi-modal optical imaging including high-resolution optical coherence tomography (OCT) and depth-resolved high-sensitivity fluorescence laminar optical tomography (FLOT) for structural and molecular imaging. APC (adenomatous polyposis coli) mice model were imaged using OCT and FLOT and the correlated histopathological diagnosis was obtained. Quantitative structural (the scattering coefficient) and molecular imaging parameters (fluorescence intensity) from OCT and FLOT images were developed for multi-parametric analysis. This multi-modal imaging method has demonstrated the feasibility for more accurate diagnosis with 87.4% (87.3%) for sensitivity (specificity) which gives the most optimal diagnosis (the largest area under receiver operating characteristic (ROC) curve). This project results in a new non-invasive multi-modal imaging platform for improved GI cancer detection, which is expected to have a major impact on detection, diagnosis, and characterization of GI cancers, as well as a wide range of epithelial cancers.

Resolving plate structure across the seismogenic zone in Cascadia from onshore-offshore receiver function imaging

Science.gov (United States)

Audet, P.; Schaeffer, A. J.

2017-12-01

Studies of the forearc structure in the Cascadia subduction zone using teleseismic P-wave receiver function have resolved structures associated with deep fluid cycling, such as the basalt-to-eclogite reaction and fluid overpressure within the subducting oceanic crust, as well as the serpentinization of the forearc mantle wedge. Unfortunately, the updip extent of the over-pressured zone, and therefore the possible control on the transition from episodic slow slip to seismic slip, occurs offshore and is not resolved in those studies. The Cascadia Initiative (CI) has provided an opportunity to extend this work to the locked zone using teleseismic receiver functions from the deployment of a dense line of ocean-bottom seismograph stations offshore of Washington State, from the trench to the coastline. Here we calculate P-wave receiver functions using data from offshore (CI) and onshore (CAFE) broadband seismic stations. These data clearly show the various scattered phases associated with a dipping low-velocity layer that was identified in previous studies as the downgoing oceanic crust. These signals are difficult to untangle offshore because they arrive at similar times. We process receiver functions using a modified common-conversion point (CCP) stacking technique that uses a coherency filter to optimally stack images obtained from the three main scattered phases. The resulting image shows along-dip variations in the character of the seismic discontinuities associated with the top and bottom of the low-velocity layer. Combined with focal depth information of regular and low-frequency earthquakes, these variations may reflect changes in the material properties of the megathrust across the seismogenic zone in Cascadia.

Techniques used to increase the resolving power of magnetic ...

African Journals Online (AJOL)

Magnetic resonance imaging is a method which can be used to obtain highly detailed and clear images of organs inside the body. The objective of this article is evaluation of techniques used to increase the resolving power of magnetic resonance images. The use of gradient techniques with high functionality will increase ...

A multiphoton objective design with incorporated beam splitter for enhanced fluorescence collection.

Science.gov (United States)

McMullen, Jesse D; Zipfel, Warren R

2010-03-15

We present a de novo design of an objective for use in multi-photon (MPM) and second harmonic generation (SHG) microscopy. This objective was designed to have a large field of view (FOV), while maintaining a moderate numerical aperture (NA) and relative straight forward construction. A dichroic beam splitter was incorporated within the objective itself allowing for an increase in the front aperture of the objective and corresponding enhancement of the solid angle of collected emission by an order of magnitude over existing designs.

BENCHMARKING THE OPTICAL RESOLVING POWER OF UAV BASED CAMERA SYSTEMS

Directory of Open Access Journals (Sweden)

H. Meißner

2017-08-01

Full Text Available UAV based imaging and 3D object point generation is an established technology. Some of the UAV users try to address (very highaccuracy applications, i.e. inspection or monitoring scenarios. In order to guarantee such level of detail and accuracy high resolving imaging systems are mandatory. Furthermore, image quality considerably impacts photogrammetric processing, as the tie point transfer, mandatory for forming the block geometry, fully relies on the radiometric quality of images. Thus, empirical testing of radiometric camera performance is an important issue, in addition to standard (geometric calibration, which normally is covered primarily. Within this paper the resolving power of ten different camera/lens installations has been investigated. Selected systems represent different camera classes, like DSLRs, system cameras, larger format cameras and proprietary systems. As the systems have been tested in wellcontrolled laboratory conditions and objective quality measures have been derived, individual performance can be compared directly, thus representing a first benchmark on radiometric performance of UAV cameras. The results have shown, that not only the selection of appropriate lens and camera body has an impact, in addition the image pre-processing, i.e. the use of a specific debayering method, significantly influences the final resolving power.

Experimental quantum teleportation and multiphoton entanglement via interfering narrowband photon sources

International Nuclear Information System (INIS)

Yang Jian; Zhang Han; Peng Chengzhi; Chen Zengbing; Bao Xiaohui; Chen Shuai; Pan Jianwei

2009-01-01

In this paper, we report a realization of synchronization-free quantum teleportation and narrowband three-photon entanglement through interfering narrowband photon sources. Since both the single-photon and the entangled photon pair utilized are completely autonomous, it removes the requirement of high-demanding synchronization techniques in long-distance quantum communication with pulsed spontaneous parametric down-conversion sources. The frequency linewidth of the three-photon entanglement realized is on the order of several MHz, which matches the requirement of atomic ensemble based quantum memories. Such a narrowband multiphoton source will have applications in some advanced quantum communication protocols and linear optical quantum computation.

Velocity Field Measurements of Human Coughing Using Time Resolved Particle Image Velocimetry

Science.gov (United States)

Khan, T.; Marr, D. R.; Higuchi, H.; Glauser, M. N.

2003-11-01

Quantitative fluid mechanics analysis of human coughing has been carried out using new Time Resolved Particle Image Velocimetry (TRPIV). The study involves measurement of velocity vector time-histories and velocity profiles. It is focused on the average normal human coughing. Some work in the past on cough mechanics has involved measurement of flow rates, tidal volumes and sub-glottis pressure. However, data of unsteady velocity vector field of the exiting highly time-dependent jets is not available. In this study, human cough waveform data are first acquired in vivo using conventional respiratory instrumentation for various volunteers of different gender/age groups. The representative waveform is then reproduced with a coughing/breathing simulator (with or without a manikin) for TRPIV measurements and analysis. The results of this study would be useful not only for designing of indoor air quality and heating, ventilation and air conditioning systems, but also for devising means of protection against infectious diseases.

Time-resolved Chemical Imaging of Molecules by High-order Harmonics and Ultrashort Rescattering Electrons

Energy Technology Data Exchange (ETDEWEB)

Lin, Chii Dong [Kansas State Univ., Manhattan, KS (United States)

2016-03-21

Directly monitoring atomic motion during a molecular transformation with atomic-scale spatio-temporal resolution is a frontier of ultrafast optical science and physical chemistry. Here we provide the foundation for a new imaging method, fixed-angle broadband laser-induced electron scattering, based on structural retrieval by direct one-dimensional Fourier transform of a photoelectron energy distribution observed along the polarization direction of an intense ultrafast light pulse. The approach exploits the scattering of a broadband wave packet created by strong-field tunnel ionization to self-interrogate the molecular structure with picometre spatial resolution and bond specificity. With its inherent femtosecond resolution, combining our technique with molecular alignment can, in principle, provide the basis for time-resolved tomography for multi-dimensional transient structural determination.

Revealing of photon-number splitting attack on quantum key distribution system by photon-number resolving devices

International Nuclear Information System (INIS)

Gaidash, A A; Egorov, V I; Gleim, A V

2016-01-01

Quantum cryptography allows distributing secure keys between two users so that any performed eavesdropping attempt would be immediately discovered. However, in practice an eavesdropper can obtain key information from multi-photon states when attenuated laser radiation is used as a source of quantum states. In order to prevent actions of an eavesdropper, it is generally suggested to implement special cryptographic protocols, like decoy states or SARG04. In this paper, we describe an alternative method based on monitoring photon number statistics after detection. We provide a useful rule of thumb to estimate approximate order of difference of expected distribution and distribution in case of attack. Formula for calculating a minimum value of total pulses or time-gaps to resolve attack is shown. Also formulas for actual fraction of raw key known to Eve were derived. This method can therefore be used with any system and even combining with mentioned special protocols. (paper)

Multiphoton Absorption Order of CsPbBr3 As Determined by Wavelength-Dependent Nonlinear Optical Spectroscopy.

Science.gov (United States)

Saouma, Felix O; Stoumpos, Constantinos C; Kanatzidis, Mercouri G; Kim, Yong Soo; Jang, Joon I

2017-10-05

CsPbBr 3 is a direct-gap semiconductor where optical absorption takes place across the fundamental bandgap, but this all-inorganic halide perovskite typically exhibits above-bandgap emission when excited over an energy level, lying above the conduction-band minimum. We probe this bandgap anomaly using wavelength-dependent multiphoton absorption spectroscopy and find that the fundamental gap is strictly two-photon forbidden, rendering it three-photon absorption (3PA) active. Instead, two-photon absorption (2PA) commences when the two-photon energy is resonant with the optical gap, associated with the level causing the anomaly. We determine absolute nonlinear optical dispersion over this 3PA-2PA region, which can be explained by two-band models in terms of the optical gap. The polarization dependence of 3PA and 2PA is also measured and explained by the relevant selection rules. CsPbBr 3 is highly luminescent under multiphoton absorption at room temperature with marked polarization and wavelength dependence at the 3PA-2PA crossover and therefore has potential for nonlinear optical applications.

Quantitative Time-Resolved Fluorescence Imaging of Androgen Receptor and Prostate-Specific Antigen in Prostate Tissue Sections.

Science.gov (United States)

Krzyzanowska, Agnieszka; Lippolis, Giuseppe; Helczynski, Leszek; Anand, Aseem; Peltola, Mari; Pettersson, Kim; Lilja, Hans; Bjartell, Anders

2016-05-01

Androgen receptor (AR) and prostate-specific antigen (PSA) are expressed in the prostate and are involved in prostate cancer (PCa). The aim of this study was to develop reliable protocols for reproducible quantification of AR and PSA in benign and malignant prostate tissue using time-resolved fluorescence (TRF) imaging techniques. AR and PSA were detected with TRF in tissue microarrays from 91 PCa patients. p63/ alpha-methylacyl-CoA racemase (AMACR) staining on consecutive sections was used to categorize tissue areas as benign or cancerous. Automated image analysis was used to quantify staining intensity. AR intensity was significantly higher in AMACR+ and lower in AMACR- cancer areas as compared with benign epithelium. The PSA intensity was significantly lower in cancer areas, particularly in AMACR- glands. The AR/PSA ratio varied significantly in the AMACR+ tumor cells as compared with benign glands. There was a trend of more rapid disease progression in patients with higher AR/PSA ratios in the AMACR- areas. This study demonstrates the feasibility of developing reproducible protocols for TRF imaging and automated image analysis to study the expression of AR and PSA in benign and malignant prostate. It also highlighted the differences in AR and PSA protein expression within AMACR- and AMACR+ cancer regions. © 2016 The Histochemical Society.

Size effects in van der Waals clusters studied by spin and angle-resolved electron spectroscopy and multi-coincidence ion imaging

International Nuclear Information System (INIS)

Rolles, D; Pesic, Z D; Zhang, H; Bilodeau, R C; Bozek, J D; Berrah, N

2007-01-01

We have studied the valence and inner-shell photoionization of free rare-gas clusters by means of angle and spin resolved photoelectron spectroscopy and momentum resolving electron-multi-ion coincidence spectroscopy. The electron measurements probe the evolution of the photoelectron angular distribution and spin polarization parameters as a function of photon energy and cluster size, and reveal a strong cluster size dependence of the photoelectron angular distributions in certain photon energy regions. In contrast, the spin polarization parameter of the cluster photoelectrons is found to be very close to the atomic value for all covered photon energies and cluster sizes. The ion imaging measurements, which probe the fragmentation dynamics of multiply charged van der Waals clusters, also exhibit a pronounced cluster size dependence

Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

Energy Technology Data Exchange (ETDEWEB)

Liu, Yuzhu, E-mail: yuzhu.liu@gmail.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Knopp, Gregor [Paul Scherrer Institute, Villigen 5232 (Switzerland); Qin, Chaochao [Department of Physics, Henan Normal University, Xinxiang 453007 (China); Gerber, Thomas [Paul Scherrer Institute, Villigen 5232 (Switzerland)

2015-01-13

Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S{sub 2} to S{sub 1} is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S{sub 2} state to the vibrationally hot S{sub 1} state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S{sub 1} state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding.

Photothermal optical coherence tomography for depth-resolved imaging of mesenchymal stem cells via single wall carbon nanotubes

Science.gov (United States)

Subhash, Hrebesh M.; Connolly, Emma; Murphy, Mary; Barron, Valerie; Leahy, Martin

2014-03-01

The progress in stem cell research over the past decade holds promise and potential to address many unmet clinical therapeutic needs. Tracking stem cell with modern imaging modalities are critically needed for optimizing stem cell therapy, which offers insight into various underlying biological processes such as cell migration, engraftment, homing, differentiation, and functions etc. In this study we report the feasibility of photothermal optical coherence tomography (PT-OCT) to image human mesenchymal stem cells (hMSCs) labeled with single-walled carbon nanotubes (SWNTs) for in vitro cell tracking in three dimensional scaffolds. PT-OCT is a functional extension of conventional OCT with extended capability of localized detection of absorbing targets from scattering background to provide depth-resolved molecular contrast imaging. A 91 kHz line rate, spectral domain PT-OCT system at 1310nm was developed to detect the photothermal signal generated by 800nm excitation laser. In general, MSCs do not have obvious optical absorption properties and cannot be directly visualized using PT-OCT imaging. However, the optical absorption properties of hMSCs can me modified by labeling with SWNTs. Using this approach, MSC were labeled with SWNT and the cell distribution imaged in a 3D polymer scaffold using PT-OCT.

High-resolution, 2- and 3-dimensional imaging of uncut, unembedded tissue biopsy samples.

Science.gov (United States)

Torres, Richard; Vesuna, Sam; Levene, Michael J

2014-03-01

Despite continuing advances in tissue processing automation, traditional embedding, cutting, and staining methods limit our ability for rapid, comprehensive visual examination. These limitations are particularly relevant to biopsies for which immediate therapeutic decisions are most necessary, faster feedback to the patient is desired, and preservation of tissue for ancillary studies is most important. The recent development of improved tissue clearing techniques has made it possible to consider use of multiphoton microscopy (MPM) tools in clinical settings, which could address difficulties of established methods. To demonstrate the potential of MPM of cleared tissue for the evaluation of unembedded and uncut pathology samples. Human prostate, liver, breast, and kidney specimens were fixed and dehydrated by using traditional histologic techniques, with or without incorporation of nucleic acid fluorescent stains into dehydration steps. A benzyl alcohol/benzyl benzoate clearing protocol was substituted for xylene. Multiphoton microscopy was performed on a home-built system. Excellent morphologic detail was achievable with MPM at depths greater than 500 μm. Pseudocoloring produced images analogous to hematoxylin-eosin-stained images. Concurrent second-harmonic generation detection allowed mapping of collagen. Subsequent traditional section staining with hematoxylin-eosin did not reveal any detrimental morphologic effects. Sample immunostains on renal tissue showed preservation of normal reactivity. Complete reconstructions of 1-mm cubic samples elucidated 3-dimensional architectural organization. Multiphoton microscopy on cleared, unembedded, uncut biopsy specimens shows potential as a practical clinical tool with significant advantages over traditional histology while maintaining compatibility with gold standard techniques. Further investigation to address remaining implementation barriers is warranted.

Single Photon Counting Performance and Noise Analysis of CMOS SPAD-Based Image Sensors

Science.gov (United States)

Dutton, Neale A. W.; Gyongy, Istvan; Parmesan, Luca; Henderson, Robert K.

2016-01-01

SPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub-electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width (PSW) of single photon peaks in a photon counting histogram (PCH). The technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold quanta image sensor (QIS) theory. Finally, various single and multiple photon spatio-temporal oversampling techniques are reviewed. PMID:27447643

Time-resolved diffuse optical tomographic imaging for the provision of both anatomical and functional information about biological tissue

Science.gov (United States)

Zhao, Huijuan; Gao, Feng; Tanikawa, Yukari; Homma, Kazuhiro; Yamada, Yukio

2005-04-01

We present in vivo images of near-infrared (NIR) diffuse optical tomography (DOT) of human lower legs and forearm to validate the dual functions of a time-resolved (TR) NIR DOT in clinical diagnosis, i.e., to provide anatomical and functional information simultaneously. The NIR DOT system is composed of time-correlated single-photon-counting channels, and the image reconstruction algorithm is based on the modified generalized pulsed spectral technique, which effectively incorporates the TR data with reasonable computation time. The reconstructed scattering images of both the lower legs and the forearm revealed their anatomies, in which the bones were clearly distinguished from the muscles. In the absorption images, some of the blood vessels were observable. In the functional imaging, a subject was requested to do handgripping exercise to stimulate physiological changes in the forearm tissue. The images of oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentration changes in the forearm were obtained from the differential images of the absorption at three wavelengths between the exercise and the rest states, which were reconstructed with a differential imaging scheme. These images showed increases in both blood volume and oxyhemoglobin concentration in the arteries and simultaneously showed hypoxia in the corresponding muscles. All the results have demonstrated the capability of TR NIR DOT by reconstruction of the absolute images of the scattering and the absorption with a high spatial resolution that finally provided both the anatomical and functional information inside bulky biological tissues.

Comparison of analytical and Monte Carlo calculations of multi-photon effects in bremsstrahlung emission by high-energy electrons

DEFF Research Database (Denmark)

Mangiarotti, Alessio; Sona, Pietro; Ballestrero, Sergio

2012-01-01

Approximate analytical calculations of multi-photon effects in the spectrum of total radiated energy by high-energy electrons crossing thin targets are compared to the results of Monte Carlo type simulations. The limits of validity of the analytical expressions found in the literature are establi...

Spatially resolved D-T(2) correlation NMR of porous media.

Science.gov (United States)

Zhang, Yan; Blümich, Bernhard

2014-05-01

Within the past decade, 2D Laplace nuclear magnetic resonance (NMR) has been developed to analyze pore geometry and diffusion of fluids in porous media on the micrometer scale. Many objects like rocks and concrete are heterogeneous on the macroscopic scale, and an integral analysis of microscopic properties provides volume-averaged information. Magnetic resonance imaging (MRI) resolves this spatial average on the contrast scale set by the particular MRI technique. Desirable contrast parameters for studies of fluid transport in porous media derive from the pore-size distribution and the pore connectivity. These microscopic parameters are accessed by 1D and 2D Laplace NMR techniques. It is therefore desirable to combine MRI and 2D Laplace NMR to image functional information on fluid transport in porous media. Because 2D Laplace resolved MRI demands excessive measuring time, this study investigates the possibility to restrict the 2D Laplace analysis to the sum signals from low-resolution pixels, which correspond to pixels of similar amplitude in high-resolution images. In this exploratory study spatially resolved D-T2 correlation maps from glass beads and mortar are analyzed. Regions of similar contrast are first identified in high-resolution images to locate corresponding pixels in low-resolution images generated with D-T2 resolved MRI for subsequent pixel summation to improve the signal-to-noise ratio of contrast-specific D-T2 maps. This method is expected to contribute valuable information on correlated sample heterogeneity from the macroscopic and the microscopic scales in various types of porous materials including building materials and rock. Copyright © 2014 Elsevier Inc. All rights reserved.

Ultrafast biophotonics

CERN Document Server

Vasa, P

2016-01-01

This book presents emerging contemporary optical techniques of ultrafast science which have opened entirely new vistas for probing biological entities and processes. The spectrum reaches from time-resolved imaging and multiphoton microscopy to cancer therapy and studies of DNA damage. The book displays interdisciplinary research at the interface of physics and biology. Emerging topics on the horizon are also discussed, like the use of squeezed light, frequency combs and terahertz imaging as the possibility of mimicking biological systems. The book is written in a manner to make it readily accessible to researchers, postgraduate biologists, chemists, engineers, and physicists and students of optics, biomedical optics, photonics and biotechnology.

SPATIALLY RESOLVED M-BAND EMISSION FROM IO’S LOKI PATERA–FIZEAU IMAGING AT THE 22.8 m LBT

Energy Technology Data Exchange (ETDEWEB)

Conrad, Albert; Veillet, Christian [LBT Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Kleer, Katherine de; Pater, Imke de [University of California at Berkeley, Berkeley, CA 94720 (United States); Leisenring, Jarron; Defrère, Denis; Hinz, Philip; Skemer, Andy [University of Arizona, 1428 E. University Blvd., Tucson, AZ 85721 (United States); Camera, Andrea La; Bertero, Mario; Boccacci, Patrizia [DIBRIS, University of Genoa, Via Dodecaneso 35, I-16146 Genova (Italy); Arcidiacono, Carmelo [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Hofmann, Karl-Heinz; Schertl, Dieter; Weigelt, Gerd [Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, D-53121 Bonn (Germany); Kürster, Martin [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Rathbun, Julie [Planetary Science Institute, 1700 E. Fort Lowell, Tucson, AZ 85719 (United States); Skrutskie, Michael [University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Spencer, John [Southwest Research Institute, 1050 Walnut Ste. Suite 300, Boulder, CO 80302 (United States); Woodward, Charles E., E-mail: aconrad@lbto.org [Minnesota Institute for Astrophysics, 116 Church St., Minneapolis, MN 55455 (United States)

2015-05-15

The Large Binocular Telescope Interferometer mid-infrared camera, LMIRcam, imaged Io on the night of 2013 December 24 UT and detected strong M-band (4.8 μm) thermal emission arising from Loki Patera. The 22.8 m baseline of the Large Binocular Telescope provides an angular resolution of ∼32 mas (∼100 km at Io) resolving the Loki Patera emission into two distinct maxima originating from different regions within Loki’s horseshoe lava lake. This observation is consistent with the presence of a high-temperature source observed in previous studies combined with an independent peak arising from cooling crust from recent resurfacing. The deconvolved images also reveal 15 other emission sites on the visible hemisphere of Io including two previously unidentified hot spots.

Identifying and quantifying the stromal fibrosis in muscularis propria of colorectal carcinoma by multiphoton microscopy

Science.gov (United States)

Chen, Sijia; Yang, Yinghong; Jiang, Weizhong; Feng, Changyin; Chen, Zhifen; Zhuo, Shuangmu; Zhu, Xiaoqin; Guan, Guoxian; Chen, Jianxin

2014-10-01

The examination of stromal fibrosis within colorectal cancer is overlooked, not only because the routine pathological examinations seem to focus more on tumour staging and precise surgical margins, but also because of the lack of efficient diagnostic methods. Multiphoton microscopy (MPM) can be used to study the muscularis stroma of normal and colorectal carcinoma tissue at the molecular level. In this work, we attempt to show the feasibility of MPM for discerning the microstructure of the normal human rectal muscle layer and fibrosis colorectal carcinoma tissue practicably. Three types of muscularis propria stromal fibrosis beneath the colorectal cancer infiltration were first observed through the MPM imaging system by providing intercellular microstructural details in fresh, unstained tissue samples. Our approach also presents the capability of quantifying the extent of stromal fibrosis from both amount and orientation of collagen, which may further characterize the severity of fibrosis. By comparing with the pathology analysis, these results show that the MPM has potential advantages in becoming a histological tool for detecting the stromal fibrosis and collecting prognosis evidence, which may guide subsequent therapy procedures for patients into good prognosis.

Decomposition of time-resolved tomographic PIV

NARCIS (Netherlands)

Schmid, P.J.; Violato, D.; Scarano, F.

2012-01-01

An experimental study has been conducted on a transitional water jet at a Reynolds number of Re = 5,000. Flow fields have been obtained by means of time-resolved tomographic particle image velocimetry capturing all relevant spatial and temporal scales. The measured threedimensional flow fields have

Multiphoton ionization of atomic cesium

International Nuclear Information System (INIS)

Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

1984-01-01

We describe experimental studies of resonantly enhanced multiphoton ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photoelectron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photoionization signal. For both ns and np states the field induced MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength. Finally, we note that the classical two-photon field-ionization threshold is lower for the case in which the laser polarization and the electric field are parallel than it is when they are perpendicular. 22 references, 11 figures

In vivo imaging of extracellular matrix remodeling by tumor-associated fibroblasts

DEFF Research Database (Denmark)

Perentes, Jean Y; McKee, Trevor D; Ley, Carsten D

2009-01-01

Here we integrated multiphoton laser scanning microscopy and the registration of second harmonic generation images of collagen fibers to overcome difficulties in tracking stromal cell-matrix interactions for several days in live mice. We show that the matrix-modifying hormone relaxin increased...... tumor-associated fibroblast (TAF) interaction with collagen fibers by stimulating beta1-integrin activity, which is necessary for fiber remodeling by matrix metalloproteinases....

Quantitative, depth-resolved determination of particle motion using multi-exposure, spatial frequency domain laser speckle imaging.

Science.gov (United States)

Rice, Tyler B; Kwan, Elliott; Hayakawa, Carole K; Durkin, Anthony J; Choi, Bernard; Tromberg, Bruce J

2013-01-01

Laser Speckle Imaging (LSI) is a simple, noninvasive technique for rapid imaging of particle motion in scattering media such as biological tissue. LSI is generally used to derive a qualitative index of relative blood flow due to unknown impact from several variables that affect speckle contrast. These variables may include optical absorption and scattering coefficients, multi-layer dynamics including static, non-ergodic regions, and systematic effects such as laser coherence length. In order to account for these effects and move toward quantitative, depth-resolved LSI, we have developed a method that combines Monte Carlo modeling, multi-exposure speckle imaging (MESI), spatial frequency domain imaging (SFDI), and careful instrument calibration. Monte Carlo models were used to generate total and layer-specific fractional momentum transfer distributions. This information was used to predict speckle contrast as a function of exposure time, spatial frequency, layer thickness, and layer dynamics. To verify with experimental data, controlled phantom experiments with characteristic tissue optical properties were performed using a structured light speckle imaging system. Three main geometries were explored: 1) diffusive dynamic layer beneath a static layer, 2) static layer beneath a diffuse dynamic layer, and 3) directed flow (tube) submerged in a dynamic scattering layer. Data fits were performed using the Monte Carlo model, which accurately reconstructed the type of particle flow (diffusive or directed) in each layer, the layer thickness, and absolute flow speeds to within 15% or better.

Characterization of a time-resolved non-contact scanning diffuse optical imaging system exploiting fast-gated single-photon avalanche diode detection

Energy Technology Data Exchange (ETDEWEB)

Di Sieno, Laura, E-mail: laura.disieno@polimi.it; Dalla Mora, Alberto; Contini, Davide [Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Wabnitz, Heidrun; Macdonald, Rainer [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany); Pifferi, Antonio [Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Mazurenka, Mikhail [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany); Hannoversches Zentrum für Optische Technologien, Nienburger Str. 17, 30167 Hannover (Germany); Hoshi, Yoko [Department of Biomedical Optics, Medical Photonics Research Center, Hamamatsu University School of Medicine, Hamamatsu 431-3192 (Japan); Boso, Gianluca; Tosi, Alberto [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Becker, Wolfgang [Becker and Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Martelli, Fabrizio [Dipartimento di Fisica e Astronomia dell’Università degli Studi di Firenze, Via G. Sansone 1, Sesto Fiorentino, Firenze 50019 (Italy)

2016-03-15

We present a system for non-contact time-resolved diffuse reflectance imaging, based on small source-detector distance and high dynamic range measurements utilizing a fast-gated single-photon avalanche diode. The system is suitable for imaging of diffusive media without any contact with the sample and with a spatial resolution of about 1 cm at 1 cm depth. In order to objectively assess its performances, we adopted two standardized protocols developed for time-domain brain imagers. The related tests included the recording of the instrument response function of the setup and the responsivity of its detection system. Moreover, by using liquid turbid phantoms with absorbing inclusions, depth-dependent contrast and contrast-to-noise ratio as well as lateral spatial resolution were measured. To illustrate the potentialities of the novel approach, the characteristics of the non-contact system are discussed and compared to those of a fiber-based brain imager.

Characterization of a time-resolved non-contact scanning diffuse optical imaging system exploiting fast-gated single-photon avalanche diode detection

International Nuclear Information System (INIS)

Di Sieno, Laura; Dalla Mora, Alberto; Contini, Davide; Wabnitz, Heidrun; Macdonald, Rainer; Pifferi, Antonio; Mazurenka, Mikhail; Hoshi, Yoko; Boso, Gianluca; Tosi, Alberto; Becker, Wolfgang; Martelli, Fabrizio

2016-01-01

We present a system for non-contact time-resolved diffuse reflectance imaging, based on small source-detector distance and high dynamic range measurements utilizing a fast-gated single-photon avalanche diode. The system is suitable for imaging of diffusive media without any contact with the sample and with a spatial resolution of about 1 cm at 1 cm depth. In order to objectively assess its performances, we adopted two standardized protocols developed for time-domain brain imagers. The related tests included the recording of the instrument response function of the setup and the responsivity of its detection system. Moreover, by using liquid turbid phantoms with absorbing inclusions, depth-dependent contrast and contrast-to-noise ratio as well as lateral spatial resolution were measured. To illustrate the potentialities of the novel approach, the characteristics of the non-contact system are discussed and compared to those of a fiber-based brain imager.

Time-resolved image analysis for turbulent flows

NARCIS (Netherlands)

Kähler, C.J.; Cierpka, C.; Scharnowski, S.; Manhart, M.; Sciacchitano, A.; Lynch, K.; Scarano, F.; Wieneke, B.; Willert, C.; Jeon, Y. J.; Chatellier, L.; Augereau, L.; Tremblais, B.; David, L.

2013-01-01

Classical Particle Image Velocimetry (PIV) uses two representations of the particle image distribution to determine the displacement of the particle image pattern by spatial cross-correlation. The accuracy and the robustness are however limited by the fact that only two representations at t and t

Development of resonance-enhanced multiphoton ionization system

International Nuclear Information System (INIS)

Naik, P.D.; Upadhyaya, Hari P.; Kumar, Awadhesh; Bajaj, P.N.; Sinha, A.K.; Bhatt, S.; Gupta, M.D.P.

2009-05-01

Radiation and Photochemistry Division has developed a Molecular Beam-Resonance Enhanced Multiphoton Ionization-Time-of-Flight spectrometer, a highly sensitive and selective analytical detection system, for investigation of photodissociation dynamics of isolated molecules. In this system, the molecular beam is intersected in the extraction region of a Wiley-McLaren type Time-of-Flight mass spectrometer by the photolysis laser beam, propagating perpendicular to both the molecular beams and the Time-of-Flight tube. The probe (ionization) laser beam counter propagating to the photolysis beam, ionizes the stable products and the radicals produced on photodissociation. The important features of the system, namely, the resolution and the detection limit, have been determined from the studies of aniline molecular beam, generated by seeding 1% aniline in helium. For the present configuration, using one metre long flight tube, the resolution has been found to be about 400, and detection limit is better than 106 species per cm 3 . The integrity of the set-up is obtained from the photodissociation dynamics studies of bromoform. (author)

Free digital image analysis software helps to resolve equivocal scores in HER2 immunohistochemistry.

Science.gov (United States)

Helin, Henrik O; Tuominen, Vilppu J; Ylinen, Onni; Helin, Heikki J; Isola, Jorma

2016-02-01

Evaluation of human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) is subject to interobserver variation and lack of reproducibility. Digital image analysis (DIA) has been shown to improve the consistency and accuracy of the evaluation and its use is encouraged in current testing guidelines. We studied whether digital image analysis using a free software application (ImmunoMembrane) can assist in interpreting HER2 IHC in equivocal 2+ cases. We also compared digital photomicrographs with whole-slide images (WSI) as material for ImmunoMembrane DIA. We stained 750 surgical resection specimens of invasive breast cancers immunohistochemically for HER2 and analysed staining with ImmunoMembrane. The ImmunoMembrane DIA scores were compared with the originally responsible pathologists' visual scores, a researcher's visual scores and in situ hybridisation (ISH) results. The originally responsible pathologists reported 9.1 % positive 3+ IHC scores, for the researcher this was 8.4 % and for ImmunoMembrane 9.5 %. Equivocal 2+ scores were 34 % for the pathologists, 43.7 % for the researcher and 10.1 % for ImmunoMembrane. Negative 0/1+ scores were 57.6 % for the pathologists, 46.8 % for the researcher and 80.8 % for ImmunoMembrane. There were six false positive cases, which were classified as 3+ by ImmunoMembrane and negative by ISH. Six cases were false negative defined as 0/1+ by IHC and positive by ISH. ImmunoMembrane DIA using digital photomicrographs and WSI showed almost perfect agreement. In conclusion, digital image analysis by ImmunoMembrane can help to resolve a majority of equivocal 2+ cases in HER2 IHC, which reduces the need for ISH testing.

IR and visible luminescence studies in the infrared multiphoton dissociation of 1,2-dibromo-1,1-difluoroethane

Science.gov (United States)

Pushpa, K. K.; Kumar, Awadhesh; Vatsa, R. K.; Naik, P. D.; Annaji Rao, K.; Mittal, J. P.; Parthasarathy, V.; Sarkar, S. K.

1995-07-01

The infrared multiphoton dissociation of 1,2-dibromo-1,1-difluoroethane gives rise to IR and visible luminescence. Vibrationally excited parent molecules dissociate via two primary channels yielding bromine and vibrationally excited HBr. The strong visible emission observed between 350 to 750 nm has been assigned to electronically excited carbene CF 2Br CH.

S-matrix analysis of vibrational and alignment effects in intense-field multiphoton ionization of molecules

International Nuclear Information System (INIS)

Requate, A.

2007-03-01

Theoretical analysis of the vibrational excitation of small molecules during multiphoton ionization in intense laser fields of optical and infrared frequencies. Analysis of the alignment dependence of the electron impact ionization of diatomic molecules in the presence of an intense laser field as the final step in the process of Nonsequential Double Ionization. Quantum mechanical description using S-matrix theory in Strong Field Approximation (SFA), i.e. beyond perturbation theory. (orig.)

S-matrix analysis of vibrational and alignment effects in intense-field multiphoton ionization of molecules

Energy Technology Data Exchange (ETDEWEB)

Requate, A

2007-03-15

Theoretical analysis of the vibrational excitation of small molecules during multiphoton ionization in intense laser fields of optical and infrared frequencies. Analysis of the alignment dependence of the electron impact ionization of diatomic molecules in the presence of an intense laser field as the final step in the process of Nonsequential Double Ionization. Quantum mechanical description using S-matrix theory in Strong Field Approximation (SFA), i.e. beyond perturbation theory. (orig.)

Identification of tumor cells infiltrating into connective tissue in esophageal cancer by multiphoton microscopy

Science.gov (United States)

Xu, Jian; Jiang, Liwei; Kang, Deyong; Wu, Xuejing; Xu, Meifang; Zhuo, Shuangmu; Zhu, Xiaoqin; Lin, Jiangbo; Chen, Jianxin

2016-10-01

Esophageal cancer is one of the most common malignancies of the gastrointestinal cancers and carries poorer prognosis than other gastrointestinal cancers. In general practice, the depth of tumor infiltration in esophageal wall is crucial to establishing appropriate treatment plan which is established by detecting the tumor infiltration depth. Connective tissue is one of the main structures that form the esophageal wall. So, identification of tumor cells infiltrating into connective tissue is helping for detecting the tumor infiltration depth. Our aim is to evaluate whether multiphoton microscopy (MPM) can be used to detect tumor cells infiltrating into connective tissue in the esophageal cancer. MPM is well-suited for real-time detecting morphologic and cellular changes in fresh tissues since many endogenous fluorophores of fresh tissues are excited through two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). In this work, microstructure of tumor cells and connective tissue are first studied. Then, morphological changes of collagen fibers after the infiltration of tumor cells are shown. These results show that MPM has the ability to detect tumor cells infiltrating into connective tissue in the esophageal cancer. In the future, MPM may be a promising imaging technique for detecting tumor cells in esophageal cancer.

Time-resolved imaging of flyer dynamics for femtosecond laser-induced backward transfer of solid polymer thin films

Energy Technology Data Exchange (ETDEWEB)

Feinaeugle, M., E-mail: m.feinaeugle@utwente.nl [Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Gregorčič, P. [Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000, Ljubljana (Slovenia); Heath, D.J. [Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Mills, B., E-mail: bm602@orc.soton.ac.uk [Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Eason, R.W. [Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom)

2017-02-28

Highlights: • Laser-induced backward transfer was investigated by time-resolved shadowgraphy. • Flyer velocity was a function of carrier, donor thickness, delay and fluence. • We investigated the fluence window for intact transfer and the role of the receiver. • Donor-crater profile variation was studied for different ejection regimes. • Conditions for intact and fragmented flyers were determined. - Abstract: We have studied the transfer regimes and dynamics of polymer flyers from laser-induced backward transfer (LIBT) via time-resolved shadowgraphy. Imaging of the flyer ejection phase of LIBT of 3.8 μm and 6.4 μm thick SU-8 polymer films on germanium and silicon carrier substrates was performed over a time delay range of 1.4–16.4 μs after arrival of the laser pulse. The experiments were carried out with 150 fs, 800 nm pulses spatially shaped using a digital micromirror device, and laser fluences of up to 3.5 J/cm{sup 2} while images were recorded via a CCD camera and a spark discharge lamp. Velocities of flyers found in the range of 6–20 m/s, and the intact and fragmented ejection regimes, were a function of donor thickness, carrier and laser fluence. The crater profile of the donor after transfer and the resulting flyer profile indicated different flyer ejection modes for Si carriers and high fluences. The results contribute to better understanding of the LIBT process, and help to determine experimental parameters for successful LIBT of intact deposits.

Automated three-dimensional tracking of the left ventricular myocardium in time-resolved and dose-modulated cardiac CT images using deformable image registration.

Science.gov (United States)

Gupta, Vikas; Lantz, Jonas; Henriksson, Lilian; Engvall, Jan; Karlsson, Matts; Persson, Anders; Ebbers, Tino

Assessment of myocardial deformation from time-resolved cardiac computed tomography (4D CT) would augment the already available functional information from such an examination without incurring any additional costs. A deformable image registration (DIR) based approach is proposed to allow fast and automatic myocardial tracking in clinical 4D CT images. Left ventricular myocardial tissue displacement through a cardiac cycle was tracked using a B-spline transformation based DIR. Gradient of such displacements allowed Lagrangian strain estimation with respect to end-diastole in clinical 4D CT data from ten subjects with suspected coronary artery disease. Dice similarity coefficient (DSC), point-to-curve error (PTC), and tracking error were used to assess the tracking accuracy. Wilcoxon signed rank test provided significance of tracking errors. Topology preservation was verified using Jacobian of the deformation. Reliability of estimated strains and torsion (normalized twist angle) was tested in subjects with normal function by comparing them with normal strain in the literature. Comparison with manual tracking showed high accuracy (DSC: 0.99±0.05; PTC: 0.56mm±0.47 mm) and resulted in determinant(Jacobian)>0 for all subjects, indicating preservation of topology. Average radial (0.13 mm), angular (0.64) and longitudinal (0.10 mm) tracking errors for the entire cohort were not significant (p > 0.9). For patients with normal function, average strain [circumferential, radial, longitudinal] and peak torsion estimates were: [-23.5%, 31.1%, -17.2%] and 7.22°, respectively. These estimates were in conformity with the reported normal ranges in the existing literature. Accurate wall deformation tracking and subsequent strain estimation are feasible with the proposed method using only routine time-resolved 3D cardiac CT. Copyright © 2018 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Minimum resolvable power contrast model

Science.gov (United States)

Qian, Shuai; Wang, Xia; Zhou, Jingjing

2018-01-01

Signal-to-noise ratio and MTF are important indexs to evaluate the performance of optical systems. However,whether they are used alone or joint assessment cannot intuitively describe the overall performance of the system. Therefore, an index is proposed to reflect the comprehensive system performance-Minimum Resolvable Radiation Performance Contrast (MRP) model. MRP is an evaluation model without human eyes. It starts from the radiance of the target and the background, transforms the target and background into the equivalent strips,and considers attenuation of the atmosphere, the optical imaging system, and the detector. Combining with the signal-to-noise ratio and the MTF, the Minimum Resolvable Radiation Performance Contrast is obtained. Finally the detection probability model of MRP is given.

Photoleucine Survives Backbone Cleavage by Electron Transfer Dissociation. A Near-UV Photodissociation and Infrared Multiphoton Dissociation Action Spectroscopy Study

Czech Academy of Sciences Publication Activity Database

Shaffer, C. J.; Martens, J.; Marek, Aleš; Oomens, J.; Tureček, F.

2016-01-01

Roč. 27, č. 7 (2016), s. 1176-1185 ISSN 1044-0305 Institutional support: RVO:61388963 Keywords : peptide ions * electron transfer dissociation * photoleucine label * near-UV photodissociation * infrared multiphoton dissociation action spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.786, year: 2016

Multiphoton Rabi oscillations between highly excited Stark states of potassium

International Nuclear Information System (INIS)

He Yonglin

2011-01-01

We have applied a nonperturbative resonant theory to study the Rabi frequency of microwave multiphoton transitions between two Rydberg states of potassium in a static electric field. The Stark electric dipole moments used to calculate the Rabi frequency are determined by the Stark states' wave functions, which are obtained by the diagonalization method. The frequencies of the Rabi oscillations are in good agreement with either experimental ones or ones calculated by the time-dependent close-coupling method and the Floquet theory. Furthermore, we are able to show that the size of avoided crossings between the (n+2)s and (n,3) states can be predicted from the Stark electric dipole moment and the difference of the two Stark states' energy at a given resonance.

Microwave multiphoton excitation of helium Rydberg atoms: The analogy with atomic collisions

International Nuclear Information System (INIS)

van de Water, W.; van Leeuwen, K.A.H.; Yoakum, S.; Galvez, E.J.; Moorman, L.; Bergeman, T.; Sauer, B.E.; Koch, P.M.

1989-01-01

We study multiphoton transitions in helium Rydberg atoms subjected to a microwave electric field of fixed frequency but varying intensity. For each principal quantum number in the range n=25--32, the n 3 S to n 3 (L>2), n=25--32, transition probability exhibits very sharp structures as a function of the field amplitude. Their positions could be reproduced precisely using a Floquet Hamiltonian for the interaction between atom and field. Their shapes are determined by the transients of field turn-on and turn-off in a way that makes a close analogy with the theory of slow atomic collisions

Search for Multiphoton Signatures of a Higgs Boson

Energy Technology Data Exchange (ETDEWEB)

Atramentov, Oleksiy Vladimirovich [Iowa State Univ., Ames, IA (United States)

2006-07-01

In this thesis we describe a search for a fermiophobic Higgs boson in 3γ+X events. The study has been performed on 0.83 fb^-1 of data collected with the D0 detector that resides at one of the interaction regions of the Tevatron collider, the world's highest energy accelerator. This study was motivated by a fairly recent phenomenological paper [33] where it was noticed that in certain class of models (2HDM Type I and THM) the multi-photon final states like this one become detectable at the luminosity that has been collected by the D0 experiment by 2006. The mechanism that permits such final state becomes available when the conventional higgs production mechanism (higgs strahlung) are suppressed. This leads to the fact that Higgs boson with mass (m_hf < 90 GeV/c²) lower than the current limit has not been excluded.

Multiphoton spectral analysis of benzo[a]pyrene uptake and metabolism in a rat liver cell line

International Nuclear Information System (INIS)

Barhoumi, Rola; Mouneimne, Youssef; Ramos, Ernesto; Morisseau, Christophe; Hammock, Bruce D.; Safe, Stephen; Parrish, Alan R.; Burghardt, Robert C.

2011-01-01

Dynamic analysis of the uptake and metabolism of polycyclic aromatic hydrocarbons (PAHs) and their metabolites within live cells in real time has the potential to provide novel insights into genotoxic and non-genotoxic mechanisms of cellular injury caused by PAHs. The present work, combining the use of metabolite spectra generated from metabolite standards using multiphoton spectral analysis and an 'advanced unmixing process', identifies and quantifies the uptake, partitioning, and metabolite formation of one of the most important PAHs (benzo[a]pyrene, BaP) in viable cultured rat liver cells over a period of 24 h. The application of the advanced unmixing process resulted in the simultaneous identification of 8 metabolites in live cells at any single time. The accuracy of this unmixing process was verified using specific microsomal epoxide hydrolase inhibitors, glucuronidation and sulfation inhibitors as well as several mixtures of metabolite standards. Our findings prove that the two-photon microscopy imaging surpasses the conventional fluorescence imaging techniques and the unmixing process is a mathematical technique that seems applicable to the analysis of BaP metabolites in living cells especially for analysis of changes of the ultimate carcinogen benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide. Therefore, the combination of the two-photon acquisition with the unmixing process should provide important insights into the cellular and molecular mechanisms by which BaP and other PAHs alter cellular homeostasis.

MONSTIR II: A 32-channel, multispectral, time-resolved optical tomography system for neonatal brain imaging

Energy Technology Data Exchange (ETDEWEB)

Cooper, Robert J., E-mail: robert.cooper@ucl.ac.uk; Magee, Elliott; Everdell, Nick; Magazov, Salavat; Varela, Marta; Airantzis, Dimitrios; Gibson, Adam P.; Hebden, Jeremy C. [Biomedical Optics Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT (United Kingdom)

2014-05-15

We detail the design, construction and performance of the second generation UCL time-resolved optical tomography system, known as MONSTIR II. Intended primarily for the study of the newborn brain, the system employs 32 source fibres that sequentially transmit picosecond pulses of light at any four wavelengths between 650 and 900 nm. The 32 detector channels each contain an independent photo-multiplier tube and temporally correlated photon-counting electronics that allow the photon transit time between each source and each detector position to be measured with high temporal resolution. The system's response time, temporal stability, cross-talk, and spectral characteristics are reported. The efficacy of MONSTIR II is demonstrated by performing multi-spectral imaging of a simple phantom.

Complex EUV imaging reflectometry: spatially resolved 3D composition determination and dopant profiling with a tabletop 13nm source

Science.gov (United States)

Porter, Christina L.; Tanksalvala, Michael; Gerrity, Michael; Miley, Galen P.; Esashi, Yuka; Horiguchi, Naoto; Zhang, Xiaoshi; Bevis, Charles S.; Karl, Robert; Johnsen, Peter; Adams, Daniel E.; Kapteyn, Henry C.; Murnane, Margaret M.

2018-03-01

With increasingly 3D devices becoming the norm, there is a growing need in the semiconductor industry and in materials science for high spatial resolution, non-destructive metrology techniques capable of determining depth-dependent composition information on devices. We present a solution to this problem using ptychographic coherent diffractive imaging (CDI) implemented using a commercially available, tabletop 13 nm source. We present the design, simulations, and preliminary results from our new complex EUV imaging reflectometer, which uses coherent 13 nm light produced by tabletop high harmonic generation. This tool is capable of determining spatially-resolved composition vs. depth profiles for samples by recording ptychographic images at multiple incidence angles. By harnessing phase measurements, we can locally and nondestructively determine quantities such as device and thin film layer thicknesses, surface roughness, interface quality, and dopant concentration profiles. Using this advanced imaging reflectometer, we can quantitatively characterize materials-sciencerelevant and industry-relevant nanostructures for a wide variety of applications, spanning from defect and overlay metrology to the development and optimization of nano-enhanced thermoelectric or spintronic devices.

The multiphoton ionization of uranium hexafluoride

International Nuclear Information System (INIS)

Armstrong, D.P.

1992-05-01

Multiphoton ionization (MPI) time-of-flight mass spectroscopy and photoelectron spectroscopy studies of UF 6 have been conducted using focused light from the Nd:YAG laser fundamental (λ=1064 nm) and its harmonics (λ=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF x + fragment ions even at the lowest laser power densities at which signal could be detected. The laser power dependence of U n+ ions signals indicates that saturation can occur for many of the steps required for their ionization. In general, the doubly-charged uranium ion (U 2+ ) intensity is much greater than that of the singly-charged uranium ion (U + ). For the case of the tunable dye laser experiments, the U n+ (n = 1- 4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The dominance of the U 2+ ion and the absence or very small intensities of UF x + fragments, along with the unsaturated wavelength dependence, indicate that mechanisms may exist other than ionization of bare U atoms after the stepwise photodissociation of F atoms from the parent molecule

Visible luminescence studies in the infrared multiphoton dissociation of 1,2-dichloro-1,1-difluoroethane

Science.gov (United States)

Pushpa, K. K.; Kumar, Awadesh; Naik, P. D.; Annaji Rao, K.; Parthasarathy, V.; Sarkar, S. K.; Mittal, J. P.

1997-11-01

A strong visible luminescence was observed in the CO 2 laser induced infrared multiphoton dissociation of 1,2-dichloro-1,1-difluoroethane. The emission observed between 350-750 nm is attributed to electronically excited carbene CF 2ClCH. The temporal profile of this luminescence was studied as a function of laser pulse duration, pulse energy, excitation frequency and substrate pressure. A suitable dissociation mechanism is presented considering various channels of IRMPD of this molecule.

Real-time histology in liver disease using multiphoton microscopy with fluorescence lifetime imaging

OpenAIRE

Wang, Haolu; Liang, Xiaowen; Mohammed, Yousuf H.; Thomas, James A.; Bridle, Kim R.; Thorling, Camilla A.; Grice, Jeffrey E.; Xu, Zhi Ping; Liu, Xin; Crawford, Darrell H. G.; Roberts, Michael S.

2015-01-01

Conventional histology with light microscopy is essential in the diagnosis of most liver diseases. Recently, a concept of real-time histology with optical biopsy has been advocated. In this study, live mice livers (normal, with fibrosis, steatosis, hepatocellular carcinoma and ischemia-reperfusion injury) were imaged by MPM-FLIM for stain-free real-time histology. The acquired MPM-FLIM images were compared with conventional histological images. MPM-FLIM imaged subsurface cellular and subcellu...

Absorption Mode FT-ICR Mass Spectrometry Imaging

Energy Technology Data Exchange (ETDEWEB)

Smith, Donald F.; Kilgour, David P.; Konijnenburg, Marco; O' Connor, Peter B.; Heeren, Ronald M.

2013-12-03

Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here we present the first use of absorption mode for Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image and then these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode ?Datacubes? for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.

Imaging time-resolved electrothermal atomization laser-excited atomic fluorescence spectrometry for determination of mercury in seawater.

Science.gov (United States)

Le Bihan, Alain; Cabon, Jean-Yves; Deschamps, Laure; Giamarchi, Philippe

2011-06-15

In this study, direct determination of mercury at the nanogram per liter level in the complex seawater matrix by imaging time-resolved electrothermal atomization laser-excited atomic fluorescence spectrometry (ITR-ETA-LEAFS) is described. In the case of mercury, the use of a nonresonant line for fluorescence detection with only one laser excitation is not possible. For measurements at the 253.652 nm resonant line, scattering phenomena have been minimized by eliminating the simultaneous vaporization of salts and by using temporal resolution and the imaging mode of the camera. Electrothermal conditions (0.1 M oxalic acid as matrix modifier, low atomization temperature) have been optimized in order to suppress chemical interferences and to obtain a good separation of specific signal and seawater background signal. For ETA-LEAFS, a specific response has been obtained for Hg with the use of time resolution. Moreover, an important improvement of the detection limit has been obtained by selecting, from the furnace image, pixels collecting the lowest number of scattered photons. Using optimal experimental conditions, a detection limit of 10 ng L(-1) for 10 μL of sample, close to the lowest concentration level of total Hg in the open ocean, has been obtained.

Experimental Visualizations of a Generic Launch Vehicle Flow Field: Time-Resolved Shadowgraph and Infrared Imaging

Science.gov (United States)

Garbeff, Theodore J., II; Panda, Jayanta; Ross, James C.

2017-01-01

Time-Resolved shadowgraph and infrared (IR) imaging were performed to investigate off-body and on-body flow features of a generic, 'hammer-head' launch vehicle geometry previously tested by Coe and Nute (1962). The measurements discussed here were one part of a large range of wind tunnel test techniques that included steady-state pressure sensitive paint (PSP), dynamic PSP, unsteady surface pressures, and unsteady force measurements. Image data was captured over a Mach number range of 0.6 less than or equal to M less than or equal to 1.2 at a Reynolds number of 3 million per foot. Both shadowgraph and IR imagery were captured in conjunction with unsteady pressures and forces and correlated with IRIG-B timing. High-speed shadowgraph imagery was used to identify wake structure and reattachment behind the payload fairing of the vehicle. Various data processing strategies were employed and ultimately these results correlated well with the location and magnitude of unsteady surface pressure measurements. Two research grade IR cameras were positioned to image boundary layer transition at the vehicle nose and flow reattachment behind the payload fairing. The poor emissivity of the model surface treatment (fast PSP) proved to be challenging for the infrared measurement. Reference image subtraction and contrast limited adaptive histogram equalization (CLAHE) were used to analyze this dataset. Ultimately turbulent boundary layer transition was observed and located forward of the trip dot line at the model sphere-cone junction. Flow reattachment location was identified behind the payload fairing in both steady and unsteady thermal data. As demonstrated in this effort, recent advances in high-speed and thermal imaging technology have modernized classical techniques providing a new viewpoint for the modern researcher

Photolysis of NO2 at multiple wavelengths in the spectral region 200-205 nm - A velocity map imaging study

NARCIS (Netherlands)

Coroiu, A.M.; Parker, D.H.; Groenenboom, G.C.; Barr, J.; Novalbos, I.T.; Whitaker, B.J.

2006-01-01

A study of the photodissociation dynamics of NO2 in the 200-205 nm region using resonance enhanced multiphoton ionization (REMPI) in conjunction with the velocity map imaging technique is presented. We chose this region because it allowed the use of a single laser to photodissociate the NO2 molecule

Excitation-resolved cone-beam x-ray luminescence tomography.

Science.gov (United States)

Liu, Xin; Liao, Qimei; Wang, Hongkai; Yan, Zhuangzhi

2015-07-01

Cone-beam x-ray luminescence computed tomography (CB-XLCT), as an emerging imaging technique, plays an important role in in vivo small animal imaging studies. However, CB-XLCT suffers from low-spatial resolution due to the ill-posed nature of reconstruction. We improve the imaging performance of CB-XLCT by using a multiband excitation-resolved imaging scheme combined with principal component analysis. To evaluate the performance of the proposed method, the physical phantom experiment is performed with a custom-made XLCT/XCT imaging system. The experimental results validate the feasibility of the method, where two adjacent nanophosphors (with an edge-to-edge distance of 2.4 mm) can be located.

Controlling the transmitted information of a multi-photon interacting with a single-Cooper pair box

International Nuclear Information System (INIS)

Kadry, Heba; Abdel-Aty, Abdel-Haleem; Zakaria, Nordin; Cheong, Lee Yen

2014-01-01

We study a model of a multi-photon interaction of a single Cooper pair box with a cavity field. The exchange of the information using this system is studied. We quantify the fidelity of the transmitted information. The effect of the system parameters (detuning parameter, field photons, state density and mean photon number) in the fidelity of the transmitted information is investigated. We found that the fidelity of the transmitted information can be controlled using the system parameters

Controlling the transmitted information of a multi-photon interacting with a single-Cooper pair box

Energy Technology Data Exchange (ETDEWEB)

Kadry, Heba, E-mail: hkadry1@yahoo.com; Abdel-Aty, Abdel-Haleem, E-mail: hkadry1@yahoo.com; Zakaria, Nordin, E-mail: hkadry1@yahoo.com [Computer and Information Science Department, Universiti Teknologi Petronas, Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Cheong, Lee Yen [Fundamental and Applied Science Department, Universiti Teknologi Petronas, Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

2014-10-24

We study a model of a multi-photon interaction of a single Cooper pair box with a cavity field. The exchange of the information using this system is studied. We quantify the fidelity of the transmitted information. The effect of the system parameters (detuning parameter, field photons, state density and mean photon number) in the fidelity of the transmitted information is investigated. We found that the fidelity of the transmitted information can be controlled using the system parameters.

Roles of Tunneling, Multiphoton Ionization, and Cascade Ionization for Femtosecond Optical Breakdown in Aqueous Media

Science.gov (United States)

2009-09-01

This implies that a kinetic energy of Ecrit = 1.5 ~ is required for impact ionization [Kai00, Ret04]. The excess energy of 0.5  ~ that remains... Ecrit because the impact ioni- zation rate increases with kinetic energy [Arn92, Kai00, Kel60, Ret04]. To consider both factors, we assume that the...but then neglect it in their theoretical treatment of breakdown [Spa81]. The first comprehensive rate equation model including multiphoton and

Pilot Assessment of Brain Metabolism in Perinatally HIV-Infected Youths Using Accelerated 5D Echo Planar J-Resolved Spectroscopic Imaging.

Science.gov (United States)

Iqbal, Zohaib; Wilson, Neil E; Keller, Margaret A; Michalik, David E; Church, Joseph A; Nielsen-Saines, Karin; Deville, Jaime; Souza, Raissa; Brecht, Mary-Lynn; Thomas, M Albert

2016-01-01

To measure cerebral metabolite levels in perinatally HIV-infected youths and healthy controls using the accelerated five dimensional (5D) echo planar J-resolved spectroscopic imaging (EP-JRESI) sequence, which is capable of obtaining two dimensional (2D) J-resolved spectra from three spatial dimensions (3D). After acquisition and reconstruction of the 5D EP-JRESI data, T1-weighted MRIs were used to classify brain regions of interest for HIV patients and healthy controls: right frontal white (FW), medial frontal gray (FG), right basal ganglia (BG), right occipital white (OW), and medial occipital gray (OG). From these locations, respective J-resolved and TE-averaged spectra were extracted and fit using two different quantitation methods. The J-resolved spectra were fit using prior knowledge fitting (ProFit) while the TE-averaged spectra were fit using the advanced method for accurate robust and efficient spectral fitting (AMARES). Quantitation of the 5D EP-JRESI data using the ProFit algorithm yielded significant metabolic differences in two spatial locations of the perinatally HIV-infected youths compared to controls: elevated NAA/(Cr+Ch) in the FW and elevated Asp/(Cr+Ch) in the BG. Using the TE-averaged data quantified by AMARES, an increase of Glu/(Cr+Ch) was shown in the FW region. A strong negative correlation (r 0.6) were shown between Asp/(Cr+Ch) and CD4 counts in the FG and BG. The complimentary results using ProFit fitting of J-resolved spectra and AMARES fitting of TE-averaged spectra, which are a subset of the 5D EP-JRESI acquisition, demonstrate an abnormal energy metabolism in the brains of perinatally HIV-infected youths. This may be a result of the HIV pathology and long-term combinational anti-retroviral therapy (cART). Further studies of larger perinatally HIV-infected cohorts are necessary to confirm these findings.

High contrast imaging and flexible photomanipulation for quantitative in vivo multiphoton imaging with polygon scanning microscope.

Science.gov (United States)

Li, Yongxiao; Montague, Samantha J; Brüstle, Anne; He, Xuefei; Gillespie, Cathy; Gaus, Katharina; Gardiner, Elizabeth E; Lee, Woei Ming

2018-02-28

In this study, we introduce two key improvements that overcome limitations of existing polygon scanning microscopes while maintaining high spatial and temporal imaging resolution over large field of view (FOV). First, we proposed a simple and straightforward means to control the scanning angle of the polygon mirror to carry out photomanipulation without resorting to high speed optical modulators. Second, we devised a flexible data sampling method directly leading to higher image contrast by over 2-fold and digital images with 100 megapixels (10 240 × 10 240) per frame at 0.25 Hz. This generates sub-diffraction limited pixels (60 nm per pixels over the FOV of 512 μm) which increases the degrees of freedom to extract signals computationally. The unique combined optical and digital control recorded fine fluorescence recovery after localized photobleaching (r ~10 μm) within fluorescent giant unilamellar vesicles and micro-vascular dynamics after laser-induced injury during thrombus formation in vivo. These new improvements expand the quantitative biological-imaging capacity of any polygon scanning microscope system. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

First Resolved Images of the Mira AB Symbiotic Binary at Centimeter Wavelengths

OpenAIRE

Matthews, Lynn D.; Karovska, Margarita

2005-01-01

We report the first spatially resolved radio continuum measurements of the Mira AB symbiotic binary system, based on observations obtained with the Very Large Array (VLA). This is the first time that a symbiotic binary has been resolved unambiguously at centimeter wavelengths. We describe the results of VLA monitoring of both stars over a ten month period, together with constraints on their individual spectral energy distributions, variability, and radio emission mechanisms. The emission from...

Time-resolved X-ray transmission microscopy on magnetic microstructures

International Nuclear Information System (INIS)

Puzic, Aleksandar

2007-01-01

Three excitation schemes were designed for stroboscopic imaging of magnetization dynamics with time-resolved magnetic transmission X-ray microscopy (TR-MTXM). These techniques were implemented into two types of X-ray microscopes, namely the imaging transmission X-ray microscope (ITXM) and the scanning transmission X-ray microscope (STXM), both installed at the electron storage ring of the Advanced Light Source in Berkeley, USA. Circular diffraction gratings (Fresnel zone plates) used in both microscopes as focusing and imaging elements presently allow for lateral resolution down to 30 nm. Magnetic imaging is performed by using the X-ray magnetic circular dichroism (XMCD) as element specific contrast mechanism. The developed methods have been successfully applied to the experimental investigation of magnetization dynamics in ferromagnetic microstructures. A temporal resolution well below 100 ps was achieved. A conventional pump-probe technique was implemented first. The dynamic response of the magnetization excited by a broadband pulsed magnetic field was imaged spatially resolved using focused X-ray flashes. As a complementary method, the spatially resolved ferromagnetic resonance (SR-FMR) technique was developed for experimental study of magnetization dynamics in the frequency domain. As a third excitation mode, the burst excitation was implemented. The performance and efficiency of the developed methods have been demonstrated by imaging the local magnetization dynamics in laterally patterned ferromagnetic thin-film elements and three-layer stacks. The existence of multiple eigenmodes in the excitation spectra of ferromagnetic microstructures has been verified by using the pump-probe technique. Magnetostatic spin waves were selectively excited and detected with a time resolution of 50 ps using the SR-FMR technique. Thorough analysis of 20 in most cases independently prepared samples has verified that vortices which exhibit a low-amplitude switching of their core

Direct measurements of multi-photon induced nonlinear lattice dynamics in semiconductors via time-resolved x-ray scattering.

Science.gov (United States)

Williams, G Jackson; Lee, Sooheyong; Walko, Donald A; Watson, Michael A; Jo, Wonhuyk; Lee, Dong Ryeol; Landahl, Eric C

2016-12-22

Nonlinear optical phenomena in semiconductors present several fundamental problems in modern optics that are of great importance for the development of optoelectronic devices. In particular, the details of photo-induced lattice dynamics at early time-scales prior to carrier recombination remain poorly understood. We demonstrate the first integrated measurements of both optical and structural, material-dependent quantities while also inferring the bulk impulsive strain profile by using high spatial-resolution time-resolved x-ray scattering (TRXS) on bulk crystalline gallium arsenide. Our findings reveal distinctive laser-fluence dependent crystal lattice responses, which are not described by previous TRXS experiments or models. The initial linear expansion of the crystal upon laser excitation stagnates at a laser fluence corresponding to the saturation of the free carrier density before resuming expansion in a third regime at higher fluences where two-photon absorption becomes dominant. Our interpretations of the lattice dynamics as nonlinear optical effects are confirmed by numerical simulations and by additional measurements in an n-type semiconductor that allows higher-order nonlinear optical processes to be directly observed as modulations of x-ray diffraction lineshapes.

Techniques for depth-resolved imaging through turbid media including coherence-gated imaging

International Nuclear Information System (INIS)

Dunsby, C; French, P M W

2003-01-01

This article aims to review the panoply of techniques for realising optical imaging through turbid media such as biological tissue. It begins by briefly discussing optical scattering and outlines the various approaches that have been developed to image through scattering media including spatial filtering, time-gated imaging and coherence-based techniques. The discussion includes scanning and wide-field techniques and concentrates on techniques to discriminate in favour of unscattered ballistic light although imaging with scattered light is briefly reviewed. Wide-field coherence-gated imaging techniques are discussed in some detail with particular emphasis placed on techniques to achieve real-time high-resolution three-dimensional imaging including through turbid media, providing rapid whole-field acquisition and high depth and transverse spatial resolution images. (topical review)

Insights on proximity effect and multiphoton induced luminescence from gold nanospheres in far field optical microscopy

Energy Technology Data Exchange (ETDEWEB)

Borglin, Johan [Biomedical Photonics Group, Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, 412 96 Gothenburg (Sweden); Department of Physics, University of Gothenburg, Kemivägen 10, 412 96 Gothenburg (Sweden); Guldbrand, Stina [Department of Physics, University of Gothenburg, Kemivägen 10, 412 96 Gothenburg (Sweden); Evenbratt, Hanne [Pharmaceutical Technology, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, 412 96 Gothenburg (Sweden); Kirejev, Vladimir; Ericson, Marica B., E-mail: marica.ericson@chem.gu.se [Biomedical Photonics Group, Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, 412 96 Gothenburg (Sweden); Grönbeck, Henrik [Department of Applied Physics, Chalmers University of Technology, Kemivägen 9, 412 96 Gothenburg (Sweden)

2015-12-07

Gold nanoparticles can be visualized in far-field multiphoton laser-scanning microscopy (MPM) based on the phenomena of multiphoton induced luminescence (MIL). This is of interest for biomedical applications, e.g., for cancer diagnostics, as MPM allows for working in the near-infrared (NIR) optical window of tissue. It is well known that the aggregation of particles causes a redshift of the plasmon resonance, but its implications for MIL applying far-field MPM should be further exploited. Here, we explore MIL from 10 nm gold nanospheres that are chemically deposited on glass substrates in controlled coverage gradients using MPM operating in NIR range. The substrates enable studies of MIL as a function of inter-particle distance and clustering. It was shown that MIL was only detected from areas on the substrates where the particle spacing was less than one particle diameter, or where the particles have aggregated. The results are interpreted in the context that the underlying physical phenomenon of MIL is a sequential two-photon absorption process, where the first event is driven by the plasmon resonance. It is evident that gold nanospheres in this size range have to be closely spaced or clustered to exhibit detectable MIL using far-field MPM operating in the NIR region.

Controllable surfaces of path interference in the multiphoton ionization of atoms by a weak trichromatic field

International Nuclear Information System (INIS)

Mercouris, Theodoros; Nicolaides, Cleanthes A

2005-01-01

Multiphoton detachment rates for the H - 1 S ground state irradiated by a weak trichromatic ac field consisting of the fundamental frequency ω 0.272 eV and its second, third or fourth higher harmonics were computed from first principles. The weak intensities are in the range of 10 7 -10 8 W cm -2 . The calculations incorporated systematically electronic structure and electron correlation effects. They were done by implementing a time-independent, nonperturbative many-electron, many-photon theory (MEMPT) which obtains cycle-averaged complex eigenvalues, whose real part gives the field-induced energy shift, Δ, and the imaginary part is the multiphoton ionization rate, Γ. Through analysis, plausible arguments and computation, we show that when the intensities are weak the dependence of Γ on phase differences is simple. Specifically, Γs are depicted in the form of plane surfaces, with minor ripples due to higher order ionization paths, in terms of trigonometric functions of the phase differences. This dependence is likely to be applicable to other atomic systems as well, and to provide a definition of the weak field regime in the trichromatic case. When the field intensities are such that higher order ionization paths become important, these dependences break down and we reach the strong field regime

Insights on proximity effect and multiphoton induced luminescence from gold nanospheres in far field optical microscopy

International Nuclear Information System (INIS)

Borglin, Johan; Guldbrand, Stina; Evenbratt, Hanne; Kirejev, Vladimir; Ericson, Marica B.; Grönbeck, Henrik

2015-01-01

Gold nanoparticles can be visualized in far-field multiphoton laser-scanning microscopy (MPM) based on the phenomena of multiphoton induced luminescence (MIL). This is of interest for biomedical applications, e.g., for cancer diagnostics, as MPM allows for working in the near-infrared (NIR) optical window of tissue. It is well known that the aggregation of particles causes a redshift of the plasmon resonance, but its implications for MIL applying far-field MPM should be further exploited. Here, we explore MIL from 10 nm gold nanospheres that are chemically deposited on glass substrates in controlled coverage gradients using MPM operating in NIR range. The substrates enable studies of MIL as a function of inter-particle distance and clustering. It was shown that MIL was only detected from areas on the substrates where the particle spacing was less than one particle diameter, or where the particles have aggregated. The results are interpreted in the context that the underlying physical phenomenon of MIL is a sequential two-photon absorption process, where the first event is driven by the plasmon resonance. It is evident that gold nanospheres in this size range have to be closely spaced or clustered to exhibit detectable MIL using far-field MPM operating in the NIR region

Waveguide-integrated single- and multi-photon detection at telecom wavelengths using superconducting nanowires

International Nuclear Information System (INIS)

Ferrari, Simone; Kahl, Oliver; Kovalyuk, Vadim; Goltsman, Gregory N.; Korneev, Alexander; Pernice, Wolfram H. P.

2015-01-01

We investigate single- and multi-photon detection regimes of superconducting nanowire detectors embedded in silicon nitride nanophotonic circuits. At near-infrared wavelengths, simultaneous detection of up to three photons is observed for 120 nm wide nanowires biased far from the critical current, while narrow nanowires below 100 nm provide efficient single photon detection. A theoretical model is proposed to determine the different detection regimes and to calculate the corresponding internal quantum efficiency. The predicted saturation of the internal quantum efficiency in the single photon regime agrees well with plateau behavior observed at high bias currents

Waveguide-integrated single- and multi-photon detection at telecom wavelengths using superconducting nanowires

Energy Technology Data Exchange (ETDEWEB)

Ferrari, Simone; Kahl, Oliver [Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76132 (Germany); Kovalyuk, Vadim [Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76132 (Germany); Department of Physics, Moscow State Pedagogical University, Moscow 119992 (Russian Federation); Goltsman, Gregory N. [Department of Physics, Moscow State Pedagogical University, Moscow 119992 (Russian Federation); National Research University Higher School of Economics, 20 Myasnitskaya Ulitsa, Moscow 101000 (Russian Federation); Korneev, Alexander [Department of Physics, Moscow State Pedagogical University, Moscow 119992 (Russian Federation); Moscow Institute of Physics and Technology (State University), Moscow 141700 (Russian Federation); Pernice, Wolfram H. P., E-mail: wolfram.pernice@kit.edu [Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76132 (Germany); Department of Physics, University of Münster, 48149 Münster (Germany)

2015-04-13

We investigate single- and multi-photon detection regimes of superconducting nanowire detectors embedded in silicon nitride nanophotonic circuits. At near-infrared wavelengths, simultaneous detection of up to three photons is observed for 120 nm wide nanowires biased far from the critical current, while narrow nanowires below 100 nm provide efficient single photon detection. A theoretical model is proposed to determine the different detection regimes and to calculate the corresponding internal quantum efficiency. The predicted saturation of the internal quantum efficiency in the single photon regime agrees well with plateau behavior observed at high bias currents.

Influence of evanescent waves on the voxel profile in multipulse multiphoton polymerization nanofabrication

International Nuclear Information System (INIS)

Li Wei; Cao Tianxiang; Zhai Zhaohui; Yu Xuanyi; Zhang Xinzheng; Xu Jingjun

2013-01-01

The relationship between the profile of the structures obtained by multiphoton polymerization and the optical parameters of nanofabrication systems has been studied theoretically for a multipulse scheme. We find that the profile of sub-wavelength structures is greatly affected by the evanescent waves affect. Not only is the photocured polymer voxel affected by the beam profile, but the beam propagation behavior is influenced by the photocured polymer voxel. This gives us a new view of matter–light interactions in multipulse polymerization process, which is useful to the accurate control of the nanofabrication profile and the selection of new nanofabrication materials. (paper)

In vivo detection of basal cell carcinoma: comparison of a reflectance confocal microscope and a multiphoton tomograph

Science.gov (United States)

Ulrich, Martina; Klemp, Marisa; Darvin, Maxim E.; König, Karsten; Lademann, Jürgen; Meinke, Martina C.

2013-06-01

The standard diagnostic procedure for basal cell carcinoma (BCC) is invasive tissue biopsy with time-consuming histological examination. To reduce the number of biopsies, noninvasive optical methods have been developed providing high-resolution skin examination. We present direct comparison of a reflectance confocal microscope (RLSM) and a multiphoton tomograph (MPT) for BCC diagnosis. Both systems are applied to nine patients prior to surgery, and the results are analyzed, including histological results. Both systems prove suitable for detecting typical characteristics of BCC in various stages. The RLSM allows large horizontal overview images to be obtained, enabling the investigator to find the regions of interest quickly, e.g., BCC nests. Elongated cells and palisading structures are easily recognized using both methods. Due to the higher resolution, changes in nucleus diameter or cytoplasm could be visualized with the MPT. Therefore, the nucleus diameter, nucleus/cytoplasm ratio, and cell density are estimated for normal and BCC cells using the MPT. The nucleus of elongated BCC cells is significantly longer than other measured normal skin cells, whereas the cell density and nucleus/cytoplasm ratio of BCC cannot be significantly distinguished from granular cells.

Two-photon emission and multiphoton absorption by atoms

International Nuclear Information System (INIS)

Mu, X.

1988-01-01

This thesis consists of investigations of two problems concerning photon-atom interactions. The first topic deals with two-photon transitions in atomic inner shells. An independent-particle model has been used to describe the two-photon transitions between different inner-shell electron states. The first relativistic self-consistent-field calculation of these transition rates in Ag, Mo, and Xe has been carried out. The theoretical results are compared with recent measurements. Good agreement with measured rates is found except in some cases where more reliable experiments still need to be done. The second topic is multiphoton multiionization of atoms. The maximum entropy principle has been employed in this theoretical investigation. A detailed statistical analysis of measured ionic charge distributions produced in strong laser pulses has been carried out. The results of this analysis indicates that the charge-state distribution is a Poissonian, rather than the binomial which prevails under infrared radiation, and hence that ionization occurs stepwise during the pulse. This result is shown to be consistent with experimental data

A phasor approach analysis of multiphoton FLIM measurements of three-dimensional cell culture models

Science.gov (United States)

Lakner, P. H.; Möller, Y.; Olayioye, M. A.; Brucker, S. Y.; Schenke-Layland, K.; Monaghan, M. G.

2016-03-01

Fluorescence lifetime imaging microscopy (FLIM) is a useful approach to obtain information regarding the endogenous fluorophores present in biological samples. The concise evaluation of FLIM data requires the use of robust mathematical algorithms. In this study, we developed a user-friendly phasor approach for analyzing FLIM data and applied this method on three-dimensional (3D) Caco-2 models of polarized epithelial luminal cysts in a supporting extracellular matrix environment. These Caco-2 based models were treated with epidermal growth factor (EGF), to stimulate proliferation in order to determine if FLIM could detect such a change in cell behavior. Autofluorescence from nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) in luminal Caco-2 cysts was stimulated by 2-photon laser excitation. Using a phasor approach, the lifetimes of involved fluorophores and their contribution were calculated with fewer initial assumptions when compared to multiexponential decay fitting. The phasor approach simplified FLIM data analysis, making it an interesting tool for non-experts in numerical data analysis. We observed that an increased proliferation stimulated by EGF led to a significant shift in fluorescence lifetime and a significant alteration of the phasor data shape. Our data demonstrates that multiphoton FLIM analysis with the phasor approach is a suitable method for the non-invasive analysis of 3D in vitro cell culture models qualifying this method for monitoring basic cellular features and the effect of external factors.

Non-contact measurement of partial gas pressure and distribution of elemental composition using energy-resolved neutron imaging

Directory of Open Access Journals (Sweden)

A. S. Tremsin

2017-01-01

Full Text Available Neutron resonance absorption imaging is a non-destructive technique that can characterize the elemental composition of a sample by measuring nuclear resonances in the spectrum of a transmitted beam. Recent developments in pixelated time-of-flight imaging detectors coupled with pulsed neutron sources pose new opportunities for energy-resolved imaging. In this paper we demonstrate non-contact measurements of the partial pressure of xenon and krypton gases encapsulated in a steel pipe while simultaneously passing the neutron beam through high-Z materials. The configuration was chosen as a proof of principle demonstration of the potential to make non-destructive measurement of gas composition in nuclear fuel rods. The pressure measured from neutron transmission spectra (∼739 ± 98 kPa and ∼751 ± 154 kPa for two Xe resonances is in relatively good agreement with the pressure value of ∼758 ± 21 kPa measured by a pressure gauge. This type of imaging has been performed previously for solids with a spatial resolution of ∼ 100 μm. In the present study it is demonstrated that the high penetration capability of epithermal neutrons enables quantitative mapping of gases encapsulate within high-Z materials such as steel, tungsten, urania and others. This technique may be beneficial for the non-destructive testing of bulk composition of objects (such as spent nuclear fuel assemblies and others containing various elements opaque to other more conventional imaging techniques. The ability to image the gaseous substances concealed within solid materials also allows non-destructive leak testing of various containers and ultimately measurement of gas partial pressures with sub-mm spatial resolution.

Polarization-resolved optical response of plasmonic particle-on-film nanocavities

Science.gov (United States)

Zhang, Q.; Li, G.-C.; Lo, T. W.; Lei, D. Y.

2018-02-01

Placing a metal nanoparticle atop a metal film forms a plasmonic particle-on-film nanocavity. Such a nanocavity supports strong plasmonic coupling that results in rich hybridized plasmon modes, rendering the cavity a versatile platform for exploiting a wide range of plasmon-enhanced spectroscopy applications. In this paper, we fully address the polarization-resolved, orientation-dependent far-field optical responses of plasmonic monomer- and dimer-on-film nanocavities by numerical simulations and experiments. With polarization-resolved dark-field spectroscopy, the distinct plasmon resonances of these nanocavities are clearly determined from their scattering spectra. Moreover, the radiation patterns of respective plasmon modes, which are often mixed together in common dark-field imaging, can be unambiguously resolved with our proposed quasi-multispectral imaging method. Explicitly, the radiation pattern of the monomer-on-film nanocavity gradually transitions from a solid spot in the green imaging channel to a doughnut ring in the red channel when tuning the excitation polarization from parallel to perpendicular to the sample surface. This observation holds true for the plasmonic dimer-on-film nanocavity with the dimer axis aligned in the incidence plane; when the dimer axis is normal to the incidence plane, the pattern transitions from a solid spot to a doughnut ring both in the red channel. These studies not only demonstrate a flexible polarization control over the optical responses of plasmonic particle-on-film nanostructures but also enrich the optical tool kit for far-field imaging and spectroscopy characterization of various plasmonic nanostructures.

On the separation of enantiomers of 1,1,1,2-tetrafluoroiodoethane by IR multiphoton excitation

International Nuclear Information System (INIS)

Pochert, J.; Quack, M.; Seyfang, G.

2002-01-01

The first attempt to separate enantiomers of chiral molecules using IR-multiphoton excitation with circularly polarized light is reported. 1,1,1,2-Tetrafuoroiodoethane CF 3 CHFI has been chosen as its IR-spectroscopy and its IR-photochemistry is well characterized by our previous work. A theoretical model based on a master equation is presented to predict the enrichment factor. The experimental results show that the experimental sensitivity must be improved to reach the limit of the theoretical prediction. (author)

Time-resolved brightness measurements by streaking

Science.gov (United States)

Torrance, Joshua S.; Speirs, Rory W.; McCulloch, Andrew J.; Scholten, Robert E.

2018-03-01

Brightness is a key figure of merit for charged particle beams, and time-resolved brightness measurements can elucidate the processes involved in beam creation and manipulation. Here we report on a simple, robust, and widely applicable method for the measurement of beam brightness with temporal resolution by streaking one-dimensional pepperpots, and demonstrate the technique to characterize electron bunches produced from a cold-atom electron source. We demonstrate brightness measurements with 145 ps temporal resolution and a minimum resolvable emittance of 40 nm rad. This technique provides an efficient method of exploring source parameters and will prove useful for examining the efficacy of techniques to counter space-charge expansion, a critical hurdle to achieving single-shot imaging of atomic scale targets.

Imaging photoelectrons formed in strong laser fields

International Nuclear Information System (INIS)

Helm, H.; Dyer, M.J.; Saeed, M.; Huestis, D.L.

1993-01-01

An instrument capable of characterizing the angular correlation and energy distribution of products from photoionization of single atoms or molecules will be described. An external electric field is used to project individual charged particles generated in multiphoton ionization from the focal volume onto two-dimensional detectors. Digital images are recorded for each laser shot and summed. These images provide a direct view of the angular nodal plants of the photoelectrons and they can be analyzed to represent the spatial and energy distributions in the form of a polar plot, f(E,Θ). We discuss the application of this instrument to short pulse photoionization of rare gases and molecular hydrogen at visible and UV wavelengths at intensities ranging from 10 13 to 10 15 W/cm 2

Optical drug monitoring: photoacoustic imaging of nanosensors to monitor therapeutic lithium in vivo.

Science.gov (United States)

Cash, Kevin J; Li, Chiye; Xia, Jun; Wang, Lihong V; Clark, Heather A

2015-02-24

Personalized medicine could revolutionize how primary care physicians treat chronic disease and how researchers study fundamental biological questions. To realize this goal, we need to develop more robust, modular tools and imaging approaches for in vivo monitoring of analytes. In this report, we demonstrate that synthetic nanosensors can measure physiologic parameters with photoacoustic contrast, and we apply that platform to continuously track lithium levels in vivo. Photoacoustic imaging achieves imaging depths that are unattainable with fluorescence or multiphoton microscopy. We validated the photoacoustic results that illustrate the superior imaging depth and quality of photoacoustic imaging with optical measurements. This powerful combination of techniques will unlock the ability to measure analyte changes in deep tissue and will open up photoacoustic imaging as a diagnostic tool for continuous physiological tracking of a wide range of analytes.

Use of three-dimensional time-resolved phase-contrast magnetic resonance imaging with vastly undersampled isotropic projection reconstruction to assess renal blood flow in a renal cell carcinoma patient treated with sunitinib: a case report.

Science.gov (United States)

Takayama, Tatsuya; Takehara, Yasuo; Sugiyama, Masataka; Sugiyama, Takayuki; Ishii, Yasuo; Johnson, Kevin E; Wieben, Oliver; Wakayama, Tetsuya; Sakahara, Harumi; Ozono, Seiichiro

2014-08-14

New imaging modalities to assess the efficacy of drugs that have molecular targets remain under development. Here, we describe for the first time the use of time-resolved three-dimensional phase-contrast magnetic resonance imaging to monitor changes in blood supply to a tumor during sunitinib treatment in a patient with localized renal cell carcinoma. A 43-year-old Japanese woman with a tumor-bearing but functional single kidney presented at our hospital in July 2012. Computed tomography and magnetic resonance imaging revealed a cT1aN0M0 renal cell carcinoma embedded in the upper central region of the left kidney. She was prescribed sunitinib as neoadjuvant therapy for 8 months, and then underwent partial nephrectomy. Tumor monitoring during this time was done using time-resolved three-dimensional phase-contrast magnetic resonance imaging, a recent technique which specifically measures blood flow in the various vessels of the kidney. This imaging allowed visualization of the redistribution of renal blood flow during treatment, and showed that flow to the tumor was decreased and flows to other areas increased. Of note, this change occurred in the absence of any change in tumor size. The ability of time-resolved three-dimensional phase-contrast magnetic resonance imaging to provide quantitative information on blood supply to tumors may be useful in monitoring the efficacy of sunitinib treatment.

Comments on advanced, time-resolved imaging techniques for free-electron laser (FEL) experiments

Energy Technology Data Exchange (ETDEWEB)

Lumpkin, A.H.

1992-01-01

An extensive set of time-resolved imaging experiments has been performed on rf-linac driven free-electron lasers (FELs) over the past few years. These experiments have addressed both micropulse and macropulse timescales on both the charged-particle beam and the wiggler/undulator outputs (spontaneous emission and lasing). A brief review of first measurements on photoinjecter micropulse elongation, submacropulse phase slew in drive lasers, submacropulse wavelength shifts in lasers, etc. is presented. This is followed by discussions of new measurements of 35-MeV electron beam micropulse bunch length (<10 ps) using optical transition radiation, some of the first single bend synchrotron radiation beam profile measurements at gamma <80, and comments on the low-jitter synchroscan streak camera tuner. These techniques will be further developed on the 200-650 MeV linac test stand at the Advanced Photon Source (APS) in the next few years. Such techniques should be adaptable to many of the present FEL designs and to some aspects of the next generation of light sources.

Comments on advanced, time-resolved imaging techniques for free-electron laser (FEL) experiments

Energy Technology Data Exchange (ETDEWEB)

Lumpkin, A.H.

1992-11-01

An extensive set of time-resolved imaging experiments has been performed on rf-linac driven free-electron lasers (FELs) over the past few years. These experiments have addressed both micropulse and macropulse timescales on both the charged-particle beam and the wiggler/undulator outputs (spontaneous emission and lasing). A brief review of first measurements on photoinjecter micropulse elongation, submacropulse phase slew in drive lasers, submacropulse wavelength shifts in lasers, etc. is presented. This is followed by discussions of new measurements of 35-MeV electron beam micropulse bunch length (<10 ps) using optical transition radiation, some of the first single bend synchrotron radiation beam profile measurements at gamma <80, and comments on the low-jitter synchroscan streak camera tuner. These techniques will be further developed on the 200-650 MeV linac test stand at the Advanced Photon Source (APS) in the next few years. Such techniques should be adaptable to many of the present FEL designs and to some aspects of the next generation of light sources.

Lucas–Kanade fluid trajectories for time-resolved PIV

International Nuclear Information System (INIS)

Yegavian, Robin; Leclaire, Benjamin; Illoul, Cédric; Losfeld, Gilles; Champagnat, Frédéric

2016-01-01

We introduce a new method for estimating fluid trajectories in time-resolved PIV. It relies on a Lucas–Kanade paradigm and consists in a simple and direct extension of a two-frame estimation with FOLKI-PIV (Champagnat et al 2011 Exp. Fluids 50 1169–82). The so-called Lucas–Kanade Fluid Trajectories (LKFT) are assumed to be polynomial in time, and are found as the minimizer of a global functional, in which displacements are sought so as to match the intensities of a series of images pairs in the sequence, in the least-squares sense. All pairs involve the central image, similar to other recent time-resolved approaches (FTC (Lynch and Scarano 2013 Meas. Sci. Technol . 24 035305) and FTEE (Jeon et al 2014 Exp. Fluids 55 1–16)). As switching from a two-frame to a time-resolved objective simply amounts to adding terms in a functional, no significant additional algorithmic element is required. Similar to FOLKI-PIV the method is very well suited for GPU acceleration, which is an important feature as computational complexity increases with the image sequence size. Tests on synthetic data exhibiting peak-locking show that increasing the image sequence size strongly reduces both associated bias and random error, and that LKFT has a remaining total error comparable to that of FTEE on this case. Results on case B of the third PIV challenge (Stanislas et al 2008 Exp. Fluids 45 27–71) also show its ability to drastically reduce the error in situations with low signal-to-noise ratio. These results are finally confirmed on experimental images acquired in the near-field of a low Reynolds number jet. Strong reductions in peak-locking, spatial and temporal noise compared to two-frame estimation are also observed, on the displacement components themselves, as well as on spatial or temporal derivatives, such as vorticity and material acceleration. (paper)

Photoionization of excited molecular states using multiphoton excitation techniques

International Nuclear Information System (INIS)

Dehmer, P.M.; Pratt, S.T.; Dehmer, J.L.

1984-01-01

Photoelectron spectra are reported for three photon resonant, four photon ionization of H 2 via the B 1 Σ + /sub u/, v = 7 (J = 2,4) and C 1 Pi/sub u/, v = 0-4 (J = 1) levels and of N 2 via the o 3 1 Pi/sub u/, v = 1,2, b 1 Pi/sub u/, v = 3-5, and c 1 Pi/sub u/, v = 0 levels. The results reflect both the spectroscopy and the dynamics of photoionization of excited molecular states and are discussed in terms of the selection rules for photoionization and the relative probabilities of photoionization from Rydberg and valence states. In some cases, in accordance with the Franck-Condon principle, the results demonstrate that resonant multiphoton ionization through Rydberg states may be a powerful technique for the production of electronic, vibrational, and rotational state selected ions. However, in other cases, systematic departures from Franck-Condon factors are observed, which reflect the more subtle dynamics of excited state photoionization

Multi-photon absorption limits to heralded single photon sources

Science.gov (United States)

Husko, Chad A.; Clark, Alex S.; Collins, Matthew J.; De Rossi, Alfredo; Combrié, Sylvain; Lehoucq, Gaëlle; Rey, Isabella H.; Krauss, Thomas F.; Xiong, Chunle; Eggleton, Benjamin J.

2013-01-01

Single photons are of paramount importance to future quantum technologies, including quantum communication and computation. Nonlinear photonic devices using parametric processes offer a straightforward route to generating photons, however additional nonlinear processes may come into play and interfere with these sources. Here we analyse spontaneous four-wave mixing (SFWM) sources in the presence of multi-photon processes. We conduct experiments in silicon and gallium indium phosphide photonic crystal waveguides which display inherently different nonlinear absorption processes, namely two-photon (TPA) and three-photon absorption (ThPA), respectively. We develop a novel model capturing these diverse effects which is in excellent quantitative agreement with measurements of brightness, coincidence-to-accidental ratio (CAR) and second-order correlation function g(2)(0), showing that TPA imposes an intrinsic limit on heralded single photon sources. We build on these observations to devise a new metric, the quantum utility (QMU), enabling further optimisation of single photon sources. PMID:24186400

Multiphoton ionization photoelectron spectroscopy of xenon: Experiment and theory

International Nuclear Information System (INIS)

Bajic, S.J.; Compton, R.N.; Tang, X.; L'Huiller, A.; Lambropoulos, P.

1988-11-01

Photoelectron energy and angular distributions for resonantly enhanced multiphoton ionization (REMPI) of xenon via the three-photon-allowed 7s[3/2] 1 0 and 5d[3/2] 1 0 states have been studied both experimentally and theoretically. The electron kinetic energy spectra give the probability of leaving Xe + in either the 2 P/sub 1/2/ or 2 P/sub 3/2/ core. The measured branching ratio for leaving each ionic core is used to test the theoretical description of the REMPI process. Measurements of both the angular distributions and the [3+1] REMPI via the 5d state are adequately reproduced by multichannel quantum defect theory. However, measurements of angular distributions for the electrons resulting from [3+1] via the 7s[3/2] 1 0 state into Xe + 2 P/sub 3/2/ (core preserving) or Xe + 2 P/sub 1/2/ (core changing) are in striking disagreement with theory. 1 ref., 2 figs

Permutational symmetries for coincidence rates in multimode multiphotonic interferometry

Science.gov (United States)

Khalid, Abdullah; Spivak, Dylan; Sanders, Barry C.; de Guise, Hubert

2018-06-01

We obtain coincidence rates for passive optical interferometry by exploiting the permutational symmetries of partially distinguishable input photons, and our approach elucidates qualitative features of multiphoton coincidence landscapes. We treat the interferometer input as a product state of any number of photons in each input mode with photons distinguished by their arrival time. Detectors at the output of the interferometer count photons from each output mode over a long integration time. We generalize and prove the claim of Tillmann et al. [Phys. Rev. X 5, 041015 (2015), 10.1103/PhysRevX.5.041015] that coincidence rates can be elegantly expressed in terms of immanants. Immanants are functions of matrices that exhibit permutational symmetries and the immanants appearing in our coincidence-rate expressions share permutational symmetries with the input state. Our results are obtained by employing representation theory of the symmetric group to analyze systems of an arbitrary number of photons in arbitrarily sized interferometers.

High Resolution Depth-Resolved Imaging From Multi-Focal Images for Medical Ultrasound

DEFF Research Database (Denmark)

Diamantis, Konstantinos; Dalgarno, Paul A.; Greenaway, Alan H.

2015-01-01

An ultrasound imaging technique providing subdiffraction limit axial resolution for point sources is proposed. It is based on simultaneously acquired multi-focal images of the same object, and on the image metric of sharpness. The sharpness is extracted by image data and presents higher values...... calibration curves combined with the use of a maximum-likelihood algorithm is then able to estimate, with high precision, the depth location of any emitter fron each single image. Estimated values are compared with the ground truth demonstrating that an accuracy of 28.6 µm (0.13λ) is achieved for a 4 mm depth...

Rapid Spontaneously Resolving Acute Subdural Hematoma

Science.gov (United States)

Gan, Qi; Zhao, Hexiang; Zhang, Hanmei; You, Chao

2017-01-01

Introduction: This study reports a rare patient of a rapid spontaneously resolving acute subdural hematoma. In addition, an analysis of potential clues for the phenomenon is presented with a review of the literature. Patient Presentation: A 1-year-and-2-month-old boy fell from a height of approximately 2 m. The patient was in a superficial coma with a Glasgow Coma Scale of 8 when he was transferred to the authors’ hospital. Computed tomography revealed the presence of an acute subdural hematoma with a midline shift beyond 1 cm. His guardians refused invasive interventions and chose conservative treatment. Repeat imaging after 15 hours showed the evident resolution of the hematoma and midline reversion. Progressive magnetic resonance imaging demonstrated the complete resolution of the hematoma, without redistribution to a remote site. Conclusions: Even though this phenomenon has a low incidence, the probability of a rapid spontaneously resolving acute subdural hematoma should be considered when patients present with the following characteristics: children or elderly individuals suffering from mild to moderate head trauma; stable or rapidly recovered consciousness; and simple acute subdural hematoma with a moderate thickness and a particularly low-density band in computed tomography scans. PMID:28468224

Multi-frame pyramid correlation for time-resolved PIV

NARCIS (Netherlands)

Sciacchitano, A.; Scarano, F.; Wieneke, B.

2012-01-01

A novel technique is introduced to increase the precision and robustness of time-resolved particle image velocimetry (TR-PIV) measurements. The innovative element of the technique is the linear combination of the correlation signal computed at different separation time intervals. The domain of the

Examination of wound healing after curettage by multiphoton tomography of human skin in vivo.

Science.gov (United States)

Springer, S; Zieger, M; Böttcher, A; Lademann, J; Kaatz, M

2017-11-01

The multiphoton tomography (MPT) has evolved into a useful tool for the non-invasive investigation of morphological and biophysical characteristics of human skin in vivo. Until now, changes of the skin have been evaluated mainly by using clinical and histological techniques. In this study, the progress of wound healing was investigated by MPT over 3 weeks with a final examination after 24 months. Especially, the collagen degradation, reepithelization and tissue formation were examined. As specific parameter for wound healing and its course the second-harmonic generation-to-autofluorescence aging index of dermis (SAAID) was used. About 10 volunteers aged between 25 and 58 years were examined. Acute wounds were scanned with three Z-stacks taken per visit. The stacks were taken up to a depth of 225 μm at increments of 5 μm and a scan time for 3 seconds per scan. Subsequently, the SAAID was evaluated as an indicator for wound healing. Furthermore, single scans were taken for morphological investigations. The evaluation revealed a distinct difference in the SAAID behavior between the Z-stacks taken at each visit. Furthermore, the degradation of collagen and cells and their reappearance could be shown in the course of the visits. Clear differences in the curve behavior of the SAAID at every visit were shown in this study. The SAAID curves and morphological images could be correlated with findings of the clinical examination of different wound healing phases. Therefore, SAAID curves and morphological MPT imaging could provide a non-invasive tool for the determination of wound healing phases in patients in vivo. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A compressed sensing approach for resolution improvement in fiber-bundle based endomicroscopy

Science.gov (United States)

Dumas, John P.; Lodhi, Muhammad A.; Bajwa, Waheed U.; Pierce, Mark C.

2018-02-01

Endomicroscopy techniques such as confocal, multi-photon, and wide-field imaging have all been demonstrated using coherent fiber-optic imaging bundles. While the narrow diameter and flexibility of fiber bundles is clinically advantageous, the number of resolvable points in an image is conventionally limited to the number of individual fibers within the bundle. We are introducing concepts from the compressed sensing (CS) field to fiber bundle based endomicroscopy, to allow images to be recovered with more resolvable points than fibers in the bundle. The distal face of the fiber bundle is treated as a low-resolution sensor with circular pixels (fibers) arranged in a hexagonal lattice. A spatial light modulator is located conjugate to the object and distal face, applying multiple high resolution masks to the intermediate image prior to propagation through the bundle. We acquire images of the proximal end of the bundle for each (known) mask pattern and then apply CS inversion algorithms to recover a single high-resolution image. We first developed a theoretical forward model describing image formation through the mask and fiber bundle. We then imaged objects through a rigid fiber bundle and demonstrate that our CS endomicroscopy architecture can recover intra-fiber details while filling inter-fiber regions with interpolation. Finally, we examine the relationship between reconstruction quality and the ratio of the number of mask elements to the number of fiber cores, finding that images could be generated with approximately 28,900 resolvable points for a 1,000 fiber region in our platform.