68,375 Works

Gradient index lens based combined two-photon microscopy and optical coherence tomography

Taejun Wang, Qingyun Li, Peng Xiao, Jinhyo Ahn, Young Eun Kim, Youngrong Park, Minjun Kim, Miyeoun Song, Euiheon Chung, Wan Kyun Chung, G-One Ahn, Sungjee Kim, Pilhan Kim, Seung-Jae Myung & Ki Hean Kim
We report a miniaturized probe-based combined two-photon microscopy (TPM) and optical coherence tomography (OCT) system. This system is to study the colorectal cancer in mouse models by visualizing both cellular and structural information of the colon in 3D with TPM and OCT respectively. The probe consisted of gradient index (GRIN) lenses and a 90° reflecting prism at its distal end for side-viewing, and it was added onto an objective lens-based TPM and OCT system. The...

Gradient index lens based combined two-photon microscopy and optical coherence tomography

Taejun Wang, Qingyun Li, Peng Xiao, Jinhyo Ahn, Young Eun Kim, Youngrong Park, Minjun Kim, Miyeoun Song, Euiheon Chung, Wan Kyun Chung, G-One Ahn, Sungjee Kim, Pilhan Kim, Seung-Jae Myung & Ki Hean Kim
We report a miniaturized probe-based combined two-photon microscopy (TPM) and optical coherence tomography (OCT) system. This system is to study the colorectal cancer in mouse models by visualizing both cellular and structural information of the colon in 3D with TPM and OCT respectively. The probe consisted of gradient index (GRIN) lenses and a 90° reflecting prism at its distal end for side-viewing, and it was added onto an objective lens-based TPM and OCT system. The...

Three-dimensional structured illumination microscopy using Lukosz bound apodization reduces pixel negativity at no resolution cost

Christiaan H. Righolt, Sabine Mai, Lucas J. Van Vliet & Sjoerd Stallinga
The quality of the reconstructed image in structured illumination microscopy (SIM) depends on various aspects of the image filtering process. To optimize the trade-off between resolution and ringing artifacts, which lead to negative intensities, we extend Lukosz-bound filtering to 3D SIM and derive the parametrization of the 3D SIM cut-off. We compare the use of the Lukosz-bound as apodization filter to triangular apodization and find a tenfold reduction in the most negative pixel value with...

Three-dimensional structured illumination microscopy using Lukosz bound apodization reduces pixel negativity at no resolution cost

Christiaan H. Righolt, Sabine Mai, Lucas J. Van Vliet & Sjoerd Stallinga
The quality of the reconstructed image in structured illumination microscopy (SIM) depends on various aspects of the image filtering process. To optimize the trade-off between resolution and ringing artifacts, which lead to negative intensities, we extend Lukosz-bound filtering to 3D SIM and derive the parametrization of the 3D SIM cut-off. We compare the use of the Lukosz-bound as apodization filter to triangular apodization and find a tenfold reduction in the most negative pixel value with...

Numerical method for an analysis of nonlinear light propagation in photorefractive media - time nonlocal approach

Andrzej Ziółkowski
Nonlinear light propagation in photorefractive media can be analyzed by numerical methods. The presented numerical approach has regard to the effects of time nonlocality. Two algorithms are presented, and compared in terms of physical results and computing times. The possibility to address the issue of time nonlocality in two ways is attributed to the fact that, it is possible to completely separate carrier dynamics evaluation and wave equation calculation. This in turn, allows to choose...

Numerical method for an analysis of nonlinear light propagation in photorefractive media - time nonlocal approach

Andrzej Ziółkowski
Nonlinear light propagation in photorefractive media can be analyzed by numerical methods. The presented numerical approach has regard to the effects of time nonlocality. Two algorithms are presented, and compared in terms of physical results and computing times. The possibility to address the issue of time nonlocality in two ways is attributed to the fact that, it is possible to completely separate carrier dynamics evaluation and wave equation calculation. This in turn, allows to choose...

Photoelectrochemical hydrogen generation with linear gradient Al composition dodecagon faceted AlGaN/n-GaN electrode

W. C. Lai, M. H. Ma, B. K. Lin, B. H. Hsieh, Y. R. Wu & J. K. Sheu
We demonstrated photoelectrochemical cells (PECs) with dodecagon faceted AlGaN/n-GaN heterostructure electrode for H2 generation, where the AlGaN/n-GaN heterostructure has a linear gradient Al composition (LGAC). The separation efficiency of the photo-generated electron–hole pairs in the electrode performs a key function in the H2 generation efficiency of PEC cells. The linear gradient Al composition, AlGaN, could create more internal field and light absorption because of the linear graded band gap. Therefore, the zero-bias photocurrent density of...

Photoelectrochemical hydrogen generation with linear gradient Al composition dodecagon faceted AlGaN/n-GaN electrode

W. C. Lai, M. H. Ma, B. K. Lin, B. H. Hsieh, Y. R. Wu & J. K. Sheu
We demonstrated photoelectrochemical cells (PECs) with dodecagon faceted AlGaN/n-GaN heterostructure electrode for H2 generation, where the AlGaN/n-GaN heterostructure has a linear gradient Al composition (LGAC). The separation efficiency of the photo-generated electron–hole pairs in the electrode performs a key function in the H2 generation efficiency of PEC cells. The linear gradient Al composition, AlGaN, could create more internal field and light absorption because of the linear graded band gap. Therefore, the zero-bias photocurrent density of...

Enhancing photovoltaic output power by 3-band spectrum-splitting and concentration using a diffractive micro-optic

Nabil Mohammad, Peng Wang, Daniel J. Friedman & Rajesh Menon
We report the enhancement of photovoltaic output power by separating the incident spectrum into 3 bands, and concentrating these bands onto 3 different photovoltaic cells. The spectrum-splitting and concentration is achieved via a thin, planar micro-optical element that demonstrates high optical efficiency over the entire spectrum of interest. The optic (which we call a polychromat) was designed using a modified version of the direct-binary-search algorithm. The polychromat was fabricated using grayscale lithography. Rigorous optical characterization...

Enhancing photovoltaic output power by 3-band spectrum-splitting and concentration using a diffractive micro-optic

Nabil Mohammad, Peng Wang, Daniel J. Friedman & Rajesh Menon
We report the enhancement of photovoltaic output power by separating the incident spectrum into 3 bands, and concentrating these bands onto 3 different photovoltaic cells. The spectrum-splitting and concentration is achieved via a thin, planar micro-optical element that demonstrates high optical efficiency over the entire spectrum of interest. The optic (which we call a polychromat) was designed using a modified version of the direct-binary-search algorithm. The polychromat was fabricated using grayscale lithography. Rigorous optical characterization...

Proof of principle demonstration of a self-tracking concentrator

Volker Zagolla, Eric Tremblay & Christophe Moser
We present to the best of our knowledge the first successful demonstration of a planar, self-tracking solar concentrator system capable of a 2-dimensional angular acceptance of over 40°. The light responsive mechanism allows for efficient waveguide coupling and light concentration independently of the angle of incidence within the angular range. A coupling feature is created at the focal spot of the optical system by locally melting a phase change material which acts as an actuator...

Proof of principle demonstration of a self-tracking concentrator

Volker Zagolla, Eric Tremblay & Christophe Moser
We present to the best of our knowledge the first successful demonstration of a planar, self-tracking solar concentrator system capable of a 2-dimensional angular acceptance of over 40°. The light responsive mechanism allows for efficient waveguide coupling and light concentration independently of the angle of incidence within the angular range. A coupling feature is created at the focal spot of the optical system by locally melting a phase change material which acts as an actuator...

Multi-meter fiber-delivery and pulse self-compression of milli-Joule femtosecond laser and fiber-aided laser-micromachining

B. Debord, M. Alharbi, L. Vincetti, A. Husakou, C. Fourcade-Dutin, C. Hoenninger, E. Mottay, F. Gérôme & F. Benabid
We report on damage-free fiber-guidance of milli-Joule energy-level and 600-femtosecond laser pulses into hypocycloid core-contour Kagome hollow-core photonic crystal fibers. Up to 10 meter-long fibers were used to successfully deliver Yb-laser pulses in robustly single-mode fashion. Different pulse propagation regimes were demonstrated by simply changing the fiber dispersion and gas. Self-compression to ~50 fs, and intensity-level nearing petawatt/cm2 were achieved. Finally, free focusing-optics laser-micromachining was also demonstrated on different materials.

Multi-meter fiber-delivery and pulse self-compression of milli-Joule femtosecond laser and fiber-aided laser-micromachining

B. Debord, M. Alharbi, L. Vincetti, A. Husakou, C. Fourcade-Dutin, C. Hoenninger, E. Mottay, F. Gérôme & F. Benabid
We report on damage-free fiber-guidance of milli-Joule energy-level and 600-femtosecond laser pulses into hypocycloid core-contour Kagome hollow-core photonic crystal fibers. Up to 10 meter-long fibers were used to successfully deliver Yb-laser pulses in robustly single-mode fashion. Different pulse propagation regimes were demonstrated by simply changing the fiber dispersion and gas. Self-compression to ~50 fs, and intensity-level nearing petawatt/cm2 were achieved. Finally, free focusing-optics laser-micromachining was also demonstrated on different materials.

Terahertz phase contrast imaging of sorption kinetics in porous coordination polymer nanocrystals using differential optical resonator

F. Blanchard, K. Sumida, C. Wolpert, M. Tsotsalas, T. Tanaka, A. Doi, S. Kitagawa, D. G. Cooke, S. Furukawa & K. Tanaka
The enhancement of light-matter coupling when light is confined to wavelength scale volumes is useful both for studying small sample volumes and increasing the overall sensing ability. At these length scales, nonradiative interactions are of key interest to which near-field optical techniques may reveal new phenomena facilitating next-generation material functionalities and applications. Efforts to develop novel chemical or biological sensors using metamaterials have yielded innovative ideas in the optical and terahertz frequency range whereby the...

Terahertz phase contrast imaging of sorption kinetics in porous coordination polymer nanocrystals using differential optical resonator

F. Blanchard, K. Sumida, C. Wolpert, M. Tsotsalas, T. Tanaka, A. Doi, S. Kitagawa, D. G. Cooke, S. Furukawa & K. Tanaka
The enhancement of light-matter coupling when light is confined to wavelength scale volumes is useful both for studying small sample volumes and increasing the overall sensing ability. At these length scales, nonradiative interactions are of key interest to which near-field optical techniques may reveal new phenomena facilitating next-generation material functionalities and applications. Efforts to develop novel chemical or biological sensors using metamaterials have yielded innovative ideas in the optical and terahertz frequency range whereby the...

Axial standing-wave illumination frequency-domain imaging (SWIF)

Benjamin Judkewitz & Changhuei Yang
Despite their tremendous contribution to biomedical research and diagnosis, conventional spatial sampling techniques such as wide-field, point scanning or selective plane illumination microscopy face inherent limiting trade-offs between spatial resolution, field-of-view, phototoxicity and recording speed. Several of these trade-offs are the result of spatial sampling with diffracting beams. Here, we introduce a new strategy for fluorescence imaging, SWIF, which instead encodes the axial profile of a sample in the Fourier domain. We demonstrate how this...

Axial standing-wave illumination frequency-domain imaging (SWIF)

Benjamin Judkewitz & Changhuei Yang
Despite their tremendous contribution to biomedical research and diagnosis, conventional spatial sampling techniques such as wide-field, point scanning or selective plane illumination microscopy face inherent limiting trade-offs between spatial resolution, field-of-view, phototoxicity and recording speed. Several of these trade-offs are the result of spatial sampling with diffracting beams. Here, we introduce a new strategy for fluorescence imaging, SWIF, which instead encodes the axial profile of a sample in the Fourier domain. We demonstrate how this...

In vivo imaging of middle-ear and inner-ear microstructures of a mouse guided by SD-OCT combined with a surgical microscope

Nam Hyun Cho, Jeong Hun Jang, Woonggyu Jung & Jeehyun Kim
We developed an augmented-reality system that combines optical coherence tomography (OCT) with a surgical microscope. By sharing the common optical path in the microscope and OCT, we could simultaneously acquire OCT and microscope views. The system was tested to identify the middle-ear and inner-ear microstructures of a mouse. Considering the probability of clinical application including otorhinolaryngology, diseases such as middle-ear effusion were visualized using in vivo mouse and OCT images simultaneously acquired through the eyepiece...

In vivo imaging of middle-ear and inner-ear microstructures of a mouse guided by SD-OCT combined with a surgical microscope

Nam Hyun Cho, Jeong Hun Jang, Woonggyu Jung & Jeehyun Kim
We developed an augmented-reality system that combines optical coherence tomography (OCT) with a surgical microscope. By sharing the common optical path in the microscope and OCT, we could simultaneously acquire OCT and microscope views. The system was tested to identify the middle-ear and inner-ear microstructures of a mouse. Considering the probability of clinical application including otorhinolaryngology, diseases such as middle-ear effusion were visualized using in vivo mouse and OCT images simultaneously acquired through the eyepiece...

Real-time integral imaging system for light field microscopy

Jonghyun Kim, Jae-Hyun Jung, Youngmo Jeong, Keehoon Hong & Byoungho Lee
We propose a real-time integral imaging system for light field microscopy systems. To implement a 3D live in-vivo experimental environment for multiple experimentalists, we generate elemental images for an integral imaging system from the captured light field with a light field microscope in real-time. We apply the f-number matching method to generate an elemental image to reconstruct an undistorted 3D image. Our implemented system produces real and orthoscopic 3D images of micro objects in 16...

Real-time integral imaging system for light field microscopy

Jonghyun Kim, Jae-Hyun Jung, Youngmo Jeong, Keehoon Hong & Byoungho Lee
We propose a real-time integral imaging system for light field microscopy systems. To implement a 3D live in-vivo experimental environment for multiple experimentalists, we generate elemental images for an integral imaging system from the captured light field with a light field microscope in real-time. We apply the f-number matching method to generate an elemental image to reconstruct an undistorted 3D image. Our implemented system produces real and orthoscopic 3D images of micro objects in 16...

Parallel excitation-emission multiplexed fluorescence lifetime confocal microscopy for live cell imaging

Ming Zhao, Yu Li & Leilei Peng
We present a novel excitation-emission multiplexed fluorescence lifetime microscopy (FLIM) method that surpasses current FLIM techniques in multiplexing capability. The method employs Fourier multiplexing to simultaneously acquire confocal fluorescence lifetime images of multiple excitation wavelength and emission color combinations at 44,000 pixels/sec. The system is built with low-cost CW laser sources and standard PMTs with versatile spectral configuration, which can be implemented as an add-on to commercial confocal microscopes. The Fourier lifetime confocal method allows...

Parallel excitation-emission multiplexed fluorescence lifetime confocal microscopy for live cell imaging

Ming Zhao, Yu Li & Leilei Peng
We present a novel excitation-emission multiplexed fluorescence lifetime microscopy (FLIM) method that surpasses current FLIM techniques in multiplexing capability. The method employs Fourier multiplexing to simultaneously acquire confocal fluorescence lifetime images of multiple excitation wavelength and emission color combinations at 44,000 pixels/sec. The system is built with low-cost CW laser sources and standard PMTs with versatile spectral configuration, which can be implemented as an add-on to commercial confocal microscopes. The Fourier lifetime confocal method allows...

Design constraints of optical parametric chirped pulse amplification based on chirped quasi-phase-matching gratings

C. R. Phillips, B. W. Mayer, L. Gallmann, M. M. Fejer & U. Keller
Chirped quasi-phase-matching (QPM) gratings offer efficient, ultra-broadband optical parametric chirped pulse amplification (OPCPA) in the mid-infrared as well as other spectral regions. Only recently, however, has this potential begun to be realized [1]. In this paper, we study the design of chirped QPM-based OPCPA in detail, revealing several important constraints which must be accounted for in order to obtain broad-band, high-quality amplification. We determine these constraints in terms of the underlying saturated nonlinear processes, and...

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