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Biomedical Optics Express

Miguel García García, Arne Ohlendorf, Frank Schaeffel, Siegfried Wahl
One of the factors proposed to regulate the eye growth is the error signal derived from the defocus in the retina and actually, this might arise from defocus not only in the fovea but the whole visual field. Therefore, myopia could be better predicted by spatio-temporally mapping the 'environmental defocus' over the visual field. At present, no devices are available that could provide this information. A 'Kinect sensor v1' camera (Microsoft Corp.) and a portable eye tracker were used for developing a system for quantifying 'indoor defocus error signals' across the central 58° of the visual field...
January 1, 2018: Biomedical Optics Express
G Scrofani, J Sola-Pikabea, A Llavador, E Sanchez-Ortiga, J C Barreiro, G Saavedra, J Garcia-Sucerquia, M Martínez-Corral
In this work, Fourier integral microscope (FIMic), an ultimate design of 3D-integral microscopy, is presented. By placing a multiplexing microlens array at the aperture stop of the microscope objective of the host microscope, FIMic shows extended depth of field and enhanced lateral resolution in comparison with regular integral microscopy. As FIMic directly produces a set of orthographic views of the 3D-micrometer-sized sample, it is suitable for real-time imaging. Following regular integral-imaging reconstruction algorithms, a 2...
January 1, 2018: Biomedical Optics Express
Tanja Dragojević, Joseph L Hollmann, Davide Tamborini, Davide Portaluppi, Mauro Buttafava, Joseph P Culver, Federica Villa, Turgut Durduran
Speckle contrast optical spectroscopy (SCOS) measures absolute blood flow in deep tissue, by taking advantage of multi-distance (previously reported in the literature) or multi-exposure (reported here) approach. This method promises to use inexpensive detectors to obtain good signal-to-noise ratio, but it has not yet been implemented in a suitable manner for a mass production. Here we present a new, compact, low power consumption, 32 by 2 single photon avalanche diode (SPAD) array that has no readout noise, low dead time and has high sensitivity in low light conditions, such as in vivo measurements...
January 1, 2018: Biomedical Optics Express
Leonel Malacrida, Per Niklas Hedde, Suman Ranjit, Francesco Cardarelli, Enrico Gratton
Despite recent advances in optical super-resolution, we lack a method that can visualize the path followed by diffusing molecules in the cytoplasm or in the nucleus of cells. Fluorescence correlation spectroscopy (FCS) provides molecular dynamics at the single molecule level by averaging the behavior of many molecules over time at a single spot, thus achieving very good statistics but at only one point in the cell. Earlier image-based methods including raster-scan and spatiotemporal image correlation need spatial averaging over relatively large areas, thus compromising spatial resolution...
January 1, 2018: Biomedical Optics Express
Ryosuke Kasahara, Saiko Kino, Shunsuke Soyama, Yuji Matsuura
A method for performing noninvasive blood glucose measurements was developed. The method is based on mid-infrared absorption spectroscopy and uses only a few wavenumbers to measure blood glucose levels in vivo unconditionally. We found that the regression of blood glucose levels using only three wavenumbers, which were selected using a series cross-validation technique, realized accuracies comparable to those of cases in which a greater number of wavenumbers are used. In addition, we demonstrated the performance of this model through correlations among different types of data...
January 1, 2018: Biomedical Optics Express
Takashi Buma, Nicole C Conley, Sang Won Choi
We demonstrate optical resolution photoacoustic microscopy (OR-PAM) of lipid-rich tissue between 1050-1714 nm using a pulsed supercontinuum laser based on a large-mode-area photonic crystal fiber. OR-PAM experiments of lipid-rich samples show the expected optical absorption peaks near 1210 and 1720 nm. These results show that pulsed supercontinuum lasers are promising for OR-PAM applications such as label-free histology of lipid-rich tissue and imaging small animal models of disease.
January 1, 2018: Biomedical Optics Express
Kaikai Guo, Zibang Zhang, Shaowei Jiang, Jun Liao, Jingang Zhong, Yonina C Eldar, Guoan Zheng
Fluorescence imaging through a turbid layer holds great promise for various biophotonics applications. Conventional wavefront shaping techniques aim to create and scan a focus spot through the turbid layer. Finding the correct input wavefront without direct access to the target plane remains a critical challenge. In this paper, we explore a new strategy for imaging through turbid layer with a large field of view. In our setup, a fluorescence sample is sandwiched between two turbid layers. Instead of generating one focus spot via wavefront shaping, we use an unshaped beam to illuminate the turbid layer and generate an unknown speckle pattern at the target plane over a wide field of view...
January 1, 2018: Biomedical Optics Express
Kayvan Forouhesh Tehrani, Emily G Pendleton, William M Southern, Jarrod A Call, Luke J Mortensen
Cell metabolism and viability are directly reflected in their mitochondria. Imaging-based analysis of mitochondrial morphological structure, size and dynamic characteristics can therefore provide critical insight into cell function. However, mitochondria are often very abundant, and due to their close to diffraction-limit size, it is often non-trivial to distinguish a tubular or large mitochondrion from an ensemble of punctate mitochondria. In this paper, we use membrane potential dependent fluorescence fluctuations of individual mitochondria to resolve them using an approach similar to single molecule localization microscopy...
January 1, 2018: Biomedical Optics Express
Erwan Capitaine, Nawel Ould Moussa, Christophe Louot, Sylvia M Bardet, Hideaki Kano, Ludovic Duponchel, Philippe Lévêque, Vincent Couderc, Philippe Leproux
We present a bimodal imaging system able to obtain epi-detected mutiplex coherent anti-Stokes Raman scattering (M-CARS) and second harmonic generation (SHG) signals coming from biological samples. We studied a fragment of mouse parietal bone and could detect broadband anti-Stokes and SHG responses originating from bone cells and collagen respectively. In addition we compared two post-processing methods to retrieve the imaginary part of the third-order nonlinear susceptibility related to the spontaneous Raman scattering...
January 1, 2018: Biomedical Optics Express
Xiao Chen, Xiaoyu Zhang, Qiuyuan Zhong, Qingtao Sun, Jie Peng, Hui Gong, Jing Yuan
Acquiring an accurate orientation reference is a prerequisite for precisely analysing the morphological features of Golgi-stained neurons in the whole brain. However, the same reflective imaging contrast of Golgi staining for morphology and Nissl staining for cytoarchitecture leads to the failure of distinguishing soma morphology and simultaneously co-locate cytoarchitecture. Here, we developed the dual-mode micro-optical sectioning tomography (dMOST) method to simultaneously image the reflective and fluorescent signals in three dimensions...
January 1, 2018: Biomedical Optics Express
David M Small, Jason S Jones, Irwin I Tendler, Paul E Miller, Andre Ghetti, Nozomi Nishimura
Multiphoton microscopy using laser sources in the mid-infrared range (MIR, 1,300 nm and 1,700 nm) was used to image atherosclerotic plaques from murine and human samples. Third harmonic generation (THG) from atherosclerotic plaques revealed morphological details of cellular and extracellular lipid deposits. Simultaneous nonlinear optical signals from the same laser source, including second harmonic generation and endogenous fluorescence, resulted in label-free images of various layers within the diseased vessel wall...
January 1, 2018: Biomedical Optics Express
Atsushi Doi, Ryosuke Oketani, Yasunori Nawa, Katsumasa Fujita
We present a technique for improving the spatial resolution of two-photon excitation microscopy; our technique combines annular illumination with an in situ estimation of the point spread function (PSF) used for deconvolution. For the in situ estimation of the PSF, we developed a technique called autocorrelation scanning, in which a sample is imaged by the scanning of two excitation foci that are overlapped over various distances. The image series obtained with the variation of the distance between the two foci provides the autocorrelation function of the PSF, which can be used to estimate the PSF at specific positions within a sample...
January 1, 2018: Biomedical Optics Express
Daisuke Sakota, Tatsuki Fujiwara, Katsuhiro Ohuchi, Katsuyuki Kuwana, Hiroyuki Yamazaki, Ryo Kosaka, Masahiro Nishida, Tomohiro Mizuno, Hirokuni Arai, Osamu Maruyama
We developed an optical thrombus sensor for a monopivot extracorporeal centrifugal blood pump. In this study, we investigated its quantitative performance for thrombus detection in acute animal experiments of left ventricular assist using the pump on pathogen-free pigs. Optical fibers were set in the driver unit of the pump. The incident light at the near-infrared wavelength of 810 nm was aimed at the pivot bearing, and the resulting scattered light was guided to the optical fibers. The detected signal was analyzed to obtain the thrombus formation level...
January 1, 2018: Biomedical Optics Express
James A Germann, Eduardo Martinez-Enriquez, Susana Marcos
Many optical and biomechanical properties of the cornea, specifically the transparency of the stroma and its stiffness, can be traced to the degree of order and direction of the constituent collagen fibers. To measure the degree of order inside the cornea, a new metric, the order coefficient, was introduced to quantify the organization of the collagen fibers from images of the stroma produced with a custom-developed second harmonic generation microscope. The order coefficient method gave a quantitative assessment of the differences in stromal collagen arrangement across the cornea depths and between untreated stroma and cross-linked stroma...
January 1, 2018: Biomedical Optics Express
Niklas Domdei, Lennart Domdei, Jenny L Reiniger, Michael Linden, Frank G Holz, Austin Roorda, Wolf M Harmening
Due to the enormous dynamic range of human photoreceptors in response to light, studying their visual function in the intact retina challenges the stimulation hardware, specifically with regard to the displayable luminance contrast. The adaptive optics scanning laser ophthalmoscope (AOSLO) is an optical platform that focuses light to extremely small retinal extents, approaching the size of single photoreceptor cells. However, the current light modulation techniques produce spurious visible backgrounds which fundamentally limit experimental options...
January 1, 2018: Biomedical Optics Express
C H Hage, P Leclerc, J Brevier, M Fabert, C Le Nézet, A Kudlinski, L Héliot, F Louradour
In situ fluorescence lifetime imaging microscopy (FLIM) in an endoscopic configuration of the endogenous biomarker nicotinamide adenine dinucleotide (NADH) has a great potential for malignant tissue diagnosis. Moreover, two-photon nonlinear excitation provides intrinsic optical sectioning along with enhanced imaging depth. We demonstrate, for the first time to our knowledge, nonlinear endogenous FLIM in a fibered microscope with proximal detection, applied to NADH in cultured cells, as a first step to a nonlinear endomicroscope, using a double-clad microstructured fiber with convenient fiber length (> 3 m) and excitation pulse duration (≈50 fs)...
January 1, 2018: Biomedical Optics Express
Chandan-Ganesh Bangalore-Yogananda, Ryan Rosenberry, Sagar Soni, Hanli Liu, Michael D Nelson, Fenghua Tian
Noninvasive, direct measurement of local muscle blood flow in humans remains limited. Diffuse correlation spectroscopy (DCS) is an emerging technique to measure regional blood flow at the microvascular level. In order to better understand the strengths and limitations of this novel technique, we performed a validation study by comparing muscle blood flow changes measured with DCS and Doppler ultrasound during exercise. Nine subjects were measured (all males, 27.4 ± 2.9 years of age) for a rhythmic handgrip exercise at 20% and 50% of individual maximum voluntary contraction (MVC), followed by a post-exercise recovery...
January 1, 2018: Biomedical Optics Express
Jan Philip Kolb, Tom Pfeiffer, Matthias Eibl, Hubertus Hakert, Robert Huber
We present a new 1060 nm Fourier domain mode locked laser (FDML laser) with a record 143 nm sweep bandwidth at 2∙ 417 kHz  =  834 kHz and 120 nm at 1.67 MHz, respectively. We show that not only the bandwidth alone, but also the shape of the spectrum is critical for the resulting axial resolution, because of the specific wavelength-dependent absorption of the vitreous. The theoretical limit of our setup lies at 5.9 µm axial resolution. In vivo MHz-OCT imaging of human retina is performed and the image quality is compared to the previous results acquired with 70 nm sweep range, as well as to existing spectral domain OCT data with 2...
January 1, 2018: Biomedical Optics Express
Mark Van Gastel, Sander Stuijk, Gerard De Haan
Camera-based pulse-oximetry has recently shown to be feasible, even when the signal is corrupted by noise and motion artifacts. Earlier work showed that using three instead of the common two wavelengths improves robustness of the measurement, however without a thorough investigation on the optimal wavelength selection. We therefore performed a search to identify these wavelengths to further improve the robustness of the measurement. Besides motion, it is empirically known that there are several other factors that influence the measurement leading to falsely-low or falsely-high SpO2 readings...
January 1, 2018: Biomedical Optics Express
S Kleiser, D Ostojic, B Andresen, N Nasseri, H Isler, F Scholkmann, T Karen, G Greisen, M Wolf
Cerebral near-infrared spectroscopy (NIRS) oximetry may help clinicians to improve patient treatment. However, the application of NIRS oximeters is increasingly causing confusion to the users due to the inconsistency of tissue oxygen haemoglobin saturation (StO2) readings provided by different oximeters. To establish a comparability of oximeters, in our study we performed simultaneous measurements on the liquid phantom mimicking properties of neonatal heads and compared the tested device to a reference NIRS oximeter (OxiplexTS)...
January 1, 2018: Biomedical Optics Express
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