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- Front Matter: Volume 10711
- OMC and BISC Joint Session I
- OMC and BISC Joint Session II
- Advanced Optical Microscopy
- Optical Coherence Tomography
- Optical Imaging of Multimodal and Biomedical Information
- Multimodal Imaging and Devices
- Digital Holographic Microscopy
- Optical Diagnosis and Treatment
- Poster Session
Front Matter: Volume 10711
Front Matter: Volume 10711
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This PDF file contains the front matter associated with SPIE Proceedings Volume 10711, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.
OMC and BISC Joint Session I
High temporal and spatial pattern stimulation to manipulate brain function
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In the central nervous system (CNS), glial cells, originally termed “nervenkitt,” recently focused because of the understanding of their physiological functions. Here, we focused how glial cell regulates the function of neuronal circuits using in vivo two photon microscope. In this research, we visualized neural activity in the motor cortex during motor learning using in vivo two photon microscope to understand the abnormality of neural activity associated with impaired behavior output with myelin dysregulation. We further demonstrate the optogenetic stimulation to compensate the abnormal activity of neural activity to rescue the learning disability.
Monitoring ruffling cells by lattice light-sheet microscopy
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Membrane ruffling is an essential process at the leading edge of the migrating cells, which contains protrusion and retraction of plasma membrane. The extension membrane determines the direction of migration. The dynamic of membrane ruffling depends on the interaction between filament actin and motor proteins. Upon the activation of motor proteins by calcium ions, the migration process starts. Therefore, it is important to study the correlation between local calcium concentration and the membrane dynamics. To study the dynamics of the membrane ruffling, we established several stable cell lines, which contain chemical and optogenetic inducible dimerization . In addition, the proteins of interest such as actin, myosin, membrane anchors and calcium indicators were labeled with fluorescence proteins. The dynamics of membrane ruffling was investigated by lattice light-sheet microscope (LLSM), which is capable of high spatial and temporal recording over three-dimensions.
OMC and BISC Joint Session II
Computational imaging and reconstruction in digital holographic microscopy
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Imaging systems are foundational to our observation and understanding of the world around us, and biological microscopy is our window to the microscopic world of living things. Ideally, we wish to capture all the spatial, directional, spectral, even statistical information about a specimen with infinite precision; practically, the optics and detector impose significant constraints, forcing us to choose among accepting various tradeoffs depending on the specific applications. In recent years, computational algorithms are effective in pushing these limitations. Specifically, our focus is on holographic microscopy, where the axial information is encoded in the digital holograms. By recording the interferometric patterns created by the interaction of a reference light source and an object, we can achieve volumetric imaging; equivalently, we can reconstruct individual sections of the 3D object computationally. In this work, we will overview two types of computational advances for digital holographic microscopy. First is the development of computational techniques that aim to reduce data capture and increase spatial resolution. This is possible often with appropriate image model, such as sparsity, which becomes part of the constraints in the image reconstruction process. Second relates to the recent popularity of machine learning techniques in many applications of computer vision. We will discuss how such data-driven approach to digital holography is possible, and can be effective tools among different holographic image reconstruction algorithms.
Advanced Optical Microscopy
Coherent brightfield (COBRI) microscopy for ultrahigh-speed single-particle tracking on lipid bilayer membranes
Yi-Hung Liao,
Chia-Lung Hsieh
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Following the journey of a single molecule is a powerful tool for studying the structures and functions of biological membranes. To resolve the interplays between individual membrane molecules and their nano-associations, membrane dynamics needs to be measured at the nanoscale with high temporal resolution. Here, we demonstrate ultrahigh-speed coherent brightfield (COBRI) microscopy for capturing diffusive motion of single lipid molecules in model membranes labeled by single 40 nm gold nanoparticles with a spatial precision of 3.6 nm and a temporal resolution of 2.56 microseconds (corresponding to a frame rate of 390 kHz) under an illumination intensity of 15 μW/μm2. Our method is readily applicable to the future study of plasma membrane of live cells where the transient confinements in membrane nanodomains could be investigated with unprecedented clarity.
Visualizing a beating zebrafish heart with improved line-scan microscopy
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We have developed a high-speed line-scan optical microscope that is capable of acquiring high-resolution, high-contrast fluorescence images at more than 100 fps. This advanced imaging technique has been applied to multi-dimensional imaging of zebrafish heart.
Fast, long-term super-resolution imaging with Hessian structured illumination microscopy
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To increase the temporal resolution and maximal imaging time of super-resolution (SR) microscopy, we have developed a deconvolution algorithm for structured illumination microscopy based on Hessian matrixes (Hessian-SIM). It uses the continuity of biological structures in multiple dimensions as a priori knowledge to guide image reconstruction and attains artifact-minimized SR images with less than 10% of the photon dose used by conventional SIM. Hessian-SIM enables spatiotemporal resolution of 88 nm and 188 Hz, and hour-long time-lapse SR imaging of actin filaments in live cells. Finally, we observed the structural dynamics of mitochondrial cristae and structures that, to our knowledge, have not been observed previously, such as enlarged fusion pores during vesicle exocytosis.
Multi-focal holographic slit confocal fluorescence microscopy
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Confocal microscopy has been widely used to acquire optical sectioning fluorescent image. However, traditional confocal technique requires point-by-point scanning which is time consuming. Alternative techniques to confocal microscopy, such as structured illumination, exist for fast sectioning images, but they require multiple axial planes to be imaged individually. Here, a non-axial line-scanning multifocal confocal microscopy is presented. The proposed system incorporates multiplex volume holographic grating (MVHG) in illumination and combination of multifocal image system. The detailed explanation for resolution on depth axial and simulation results are compared. Also both XY resolution is verified through resolution target. The ability of the proposed system to optical sectioning and multi-depth resolve image of fluorescently labeled microsphere and cornea is experimentally demonstrated.
Lateral spatial resolution improvement in laser scanning fluorescence microscopy using a subdiffraction limit optical spot
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This paper presents lateral spatial resolution improvement by scanning a focused spot array pattern. To enhance the effective point spread function (PSF), we employed a phase-only computer generated hologram (CGH) that can reduce the spot size comparing to the single diffraction limited spot. A CGH was designed based on the Gerchberg-Saxton algorithm with a specific constraint to control the dispersion of light energy and the phase of generated spots. As a design example, we obtained a CGH for generating 3x3 optical spots whose sizes were reduced to 78.5% of the single diffraction limited spot. We also confirmed by simulation that the effective PSF was improved from 208 nm to 183 nm when using the subdiffraction limit spots for excitation.
Optical Coherence Tomography
Endoscopic optical coherence tomography and angiography for gastroenterology applications
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Endoscopic optical coherence tomography (OCT) angiography enables volumetric coregistered architectural and microvasculature imaging of the human gastrointestinal tract in vivo. In this talk, we will discuss technical advances and clinical gastroenterology applications with the endoscopic OCT angiography technique.
Evaluation of photodamage with polarization-sensitive optical coherence tomography
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Polarization sensitive optical coherence tomography (PS-OCT) is an extension of conventional optical coherence tomography (OCT) which enable the function to investigate birefringence characteristic of materials of biological tissue. In this research, we utilized PS-OCT for evaluation of photodamage on skin and several parameters were developed to investigate the photodamage including birefringence, diattenuation and depolarization properties of mouse skin. Additionally, the recovering progress of mouse skin was observed. The results indicate that the birefringence of skin is changed by laser irradiation.
A 2.8-mm beam diameter system for retinal imaging with OCT and adaptive optics
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A less-complex 2.8-mm beam diameter spectral domain optical coherence tomography system with an adaptive optics module presented. In this system a Shack-Hartmann wavefront sensor used for aberration sensing and the Deformable mirror used for aberration correction. We demonstrated the diffraction-limited resolution performance of this system on model retina. On the model, measured speckle size with present system is 2.2 times smaller than a 1.2-mm beam diameter OCT system. Further, on the model eye SNR gain of 6.7 dB was quantified with the present system over a 1.2-mm beam diameter OCT system. Relatively small size of 25 cm by 50 cm, less complexity, large field of view of the present system as compared to the conventional AO-OCT systems, would make it suitable for ophthalmic clinical applications.
Motion artifacts in endoscopic catheter-based images: simulation and motion correction method
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A model for motion artifacts for 3D/2D rotational catheter data and a motion correction method called azimuthal en face image registration is presented. Qualitative and quantitative evaluations of the method are analysed on optical coherence tomography (OCT) and AFI images.
Assessment of micro-optical coherence tomography (μOCT) as an imaging tool for pancreatic disease diagnosis
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As an emerging technique capable of providing cellular/subcellular-level tissue microstructure images, optical coherence tomography (OCT) is regarded to be a viable tool for early disease diagnosis, yet few studies on pancreatic imaging have ever been reported in literature. In this paper, we utilized a lab-built micro-OCT (μOCT) for cellular/subcellular pancreatic imaging for both normal tissues and those specimens with edema, and evaluate the feasibility of OCT as an imaging tool for early pancreatic disease diagnosis. Results show that the cellular/subcellular-level pancreatic microstructures of normal tissues could be clearly identified, and is quite different from those in tissues with edema. Such results demonstrate the great potential of μOCT as a viable tool for pancreatic tissue imaging in clinical practice.
Optical Imaging of Multimodal and Biomedical Information
Spatial resolution enhancement in laser scanning microscopy using vector beams
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We report the superior properties of cylindrical vector beams such as radially and azimuthally polarized beams realized under tight focusing condition. A higher-order radially polarized Laguerre-Gaussian beam has a capability of producing a much smaller focal spot compared to a conventional linearly or circularly polarized beam. On the other hand, a higherorder azimuthally polarized mode beam can produce a smaller dark spot at the focus. We utilize these features to significantly enhance the spatial resolution in laser scanning microscopy.
Computational imaging utilizing volume hologram
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Volume hologram, which has unique characteristics such as wavelength and angular selectivity, is a powerful tool for enabling computational imaging. For example, light-field three-dimensional imaging can be realized with a thin, flat, and transparent material by utilizing the volume hologram. This report mainly introduces the light-field imaging system utilizing volume hologram with describing a calibration method and an experimental result. The talk corresponding to this report also addresses other imaging applications of the volume hologram.
Multimodal digital holographic microscopy for simultaneous phase and fluorescence imaging
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This paper introduces a new type of multimodal digital holographic microscopy for biological applications. Off-axis digital holography is applied both in 3D phase imaging and 3D fluorescence imaging. In addition, image recovery by iterative method to obtain focused fluorescence images are introduced.
Fluorescent molecular force probes for rheology and mechanobiology
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Fluorescent molecular force probes have been developed for rheology and mechanobiology. Single covalent bond is generally cleaved by nano-Newton force, which has been confirmed by the analyses of AFM and optical tweezers. To quantitatively evaluate stress concentration in stretched polymeric materials or biological systems before they break, pico- Newton force must be detected at molecular scale, and therefore molecular force probes based on a bond-breaking mechanism cannot be used for this purpose. Here we have explored flexible force probes that show fluorescence response by a conformational change of flapping π-conjugated molecules (FLAP), which have the potential to realize fluorescence response to pico-Newton forces. In this presentation, a series of FLAPs synthesized in our laboratory will be introduced in connection with the force mapping technology.
Illuminating gene expression dynamics by optogenetics
Akihiro Isomura
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Cells receive diverse signaling cues from their environment that trigger cascades of biochemical reactions in a dynamic manner. Live-cell imaging technologies have revealed dynamic patterns of gene activities; however it has been challenging to clarify how such dynamic information is delivered and decoded in complex networks of inter-cellular and inter-molecular interactions. The recent development of optogenetic technology with photo-sensitive proteins has changed this situation. In this talk, we introduce our recent efforts to visualize the flows of dynamic patterns in gene expression dynamics, which utilize methods combining single-cell imaging and optogenetics.
Multimodal Imaging and Devices
Non-scanning in-vivo three-dimensional hybrid structured illumination microscopy
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Imaging a volumetric sample in real time is required to directly observe biological anatomy and mechanisms. There are a variety of microscopic imaging systems, developed to achieve optical sectioning, such as confocal microscopy. However, the drawbacks of existing systems are long scanning time or strong laser power. To overcome such problems and to obtain high-speed optical sectioning images, we demonstrate HiLo structured illumination microscopy by the use of digital micro-mirror device (DMD) and the focal tunable lens (FTL). The proposed system is configured such that hybrid uniform and non-uniform pattern are projected onto DMD to reconstruct optical sectioning images. In addition, FTL is utilized to digitally change observation plane with constant magnification and resolution; thus, mechanical movement is eliminated. Furthermore, in vivo three-dimensional (3D) images of biological samples, including a live Canenorhabditis elegans, are experimentally demonstrated.
Shape based pharmacokinetic fluorescence optical tomography
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Pharmacokinetic analysis of optical fluorophore provides physiological information of the abnormalities in tissue. Compartment modeling of the fluorophore pharmacokinetics quantify the physiological changes in the tissue. We propose a shape based tomographic reconstruction of pharmacokinetic rates, concentrations and volume fractions of the fluorophore using the time varying near infra-red measurements. Radial basis function based parametric levelsets are used to represent the boundary of the spatially varying parameters of interest. A regularized Gauss-Newton filter based scheme is used reconstruct shape, pharmacokinetic rates, volume fractions and concentration parameters. Reconstruction results for tumor mimicking numerical phantom validate our proposed approach.
Fast spatial domain reconstruction for structured illumination microscopy
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As a wide-field super-resolution (SR) technique, structured illumination microscopy (SIM) features the merits of fast imaging speed, low excitation intensity and a large field of view. However, it is hard for SIM to realize real-time imaging as the SR-image restoration always time-consuming. The basic workflow for conventional SIM reconstruction is based on the frequency domain reconstruction (FDR), which inevitably brings some computational errors and slows down the image reconstruction speed. In this letter, we introduce a fast SIM reconstruction scheme named spatial domain reconstruction (SDR) algorithm, which allow for obtaining a much faster reconstruction than FDR, making it suitable for real-time SR imaging. Meanwhile, the validity of the SDR algorithm is verified by real experiment.
Visible resonance Raman spectroscopy detect key molecular biomarker vibrations to characterize for human brain gliomas
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Visible resonant Raman (VRR) spectroscopy provides an effective way to enhance Raman signal from particular
bonds associated with key molecules due to changes on molecular level. This paper reports on the VRR use for
detection of human brain the control and gliomas of three grades. From the RR spectra additional two molecular
vibrational biomarkers at 1129cm-1 and 1338cm-1, for the four types of brain tissues are significantly different in
intensity. The new RR spectral peaks can be used as molecular biomarkers to evaluate glioma grades and identify
the margin of gliomas from the controls. The metabolic process of glioma cells based on the RR spectral changes
may reveal the Warburg hypothesis.
Long-life plastic optical fiber probes for scanning near-field optical microscope
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Nowadays, sharpened glass fiber – made probes attached to a quartz tuning fork (TF) and exploiting the shear force – based feedback are by far the most popular in the field of SNOM. These probes are expensive, very fragile and their fabrication is difficult, hard to control and in many cases a hazardous process. Here we are presenting the first SNOM probes made from plastic optical fibers with a small, submicron size, core diameter. The sharp tips were prepared by chemical etching of the fibers in dichloromethane - ethyl acetate solution, and the probes were prepared by proper gluing of sharpened fibers onto the TF. These probes demonstrate excellent performance in both topographical and optical channels after intense use.
Effect of speckle pattern illumination on holographic recording and reconstruction
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We present an experimental technique to investigate the effect of speckle pattern illumination on holographic recording and reconstruction. In this work, we apply speckle field illumination for digital holography and present our preliminary experimental results. The technique is applied for recording and reconstruction of the complete wavefronts and compare with conventional holographic approach. This technique is expected to play an important role in studying the polarization sensitive materials and opens up a new approach for holographic imaging with high field of view for polarization objects.
Isotropic quantitative differential phase contrast microscopic imaging
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Differential phase contrast microscopic (DPCM) imaging is a popular methodology to recover quantitative phase image of thin transparent sample under multi-axis intensity measurements. To improve the accuracy and stability of phase recovery in conventional DPCM imaging effectively, we propose a new illumination method to achieve isotropic differential phase contrast microscopic (iDPCM) imaging efficiently. Our iDPCM imaging is implemented with a partially coherent microscopy, and a programmable thin-film transistor panel to modulate the illumination pattern. We demonstrate our theoretical approach for iDPCM imaging and experimental results of quantitative phase image of a microlens array and unstained live human cells.
Digital Holographic Microscopy
Incoherent digital holography for biomedical imaging
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Incoherent self-interference digital holography can be used for several applications, among which are high resolution fluorescence microscopy and imaging through a scattering medium. Systems in which both interfering beams originate from the same observed objects are considered as self-interference hologram recorders. Furthermore, the hologram recorders reviewed in this presentation are configured in a setup of a single channel optical system. In this presentation we describe the evolution of a well-known method of incoherent digital holography, the Fresnel incoherent correlation holography (FINCH). Following the review of FINCH, other recently developed self-reference single-channel incoherent hologram recorders, branched out from FINCH, are discussed and several biomedical-related applications are described.
Investigations of wavelength resolution and adoptable phase shifts in phase-shifting color digital holography with 2pi ambiguity and wavelength-multiplexed images
Tatsuki Tahara,
Shotaro Maruo,
Takuya Gotohda,
et al.
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We investigate wavelength resolution and adoptable phase shifts in phase-shifting color digital holography with 2π ambiguity and wavelength-multiplexed images. This digital holography requires six wavelength-multiplexed phaseshifted holograms and performs color holographic three-dimensional (3D) imaging with high light use efficiency and compact optical setup. However, wavelength resolution of the technique has not been clarified yet. Furthermore, there have not been investigated in adoptable phase shifts under the condition using 2π ambiguity of the phase. In this proceeding, we conducted investigations to evaluate the two factors. The results show that, the wavelength resolution is 1 nm when using a monochrome image sensor with 12 bit-resolution and a guideline for adoptable shifts can be confirmed.
Single-shot incoherent digital holography using parallel phase-shifting radial shearing interferometry
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We propose single-shot incoherent digital holography using parallel-phase shifting radial shearing interferometry. The object wave from an incoherently illuminated or self-luminous object is Fourier transformed, and enters a parallel phase-shifting radial shearing interferometer. Then, the radially sheared two object waves combines and the hologram whose phases are relatively shifted in every 2x2 pixels of the image sensor are generated. By applying parallel phaseshifting interferometry to the hologram, we obtain the amplitude and the phase of the complex spatial coherence function of the object wave. Then, the complex amplitude distribution of the object wave at arbitrary depth is calculated from the function. We applied the proposed technique to the three-dimensional imaging of two LEDs and experimentally demonstrated the proposed technique.
Optical Diagnosis and Treatment
Quantitative evaluation of healing degree in injured tendons based on orientation analysis of collagen fibers by using Fourier-transform second-harmonic-generation microscopy and its relationship to mechanical property
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We used Fourier-transform second-harmonic generation (FT-SHG) microscopy to analyze the orientation of collagen fibers in healing rabbit tendons recovered from an artificial transection. The histological difference between normal and healing tendons can be observed from normal SHG images, whereas the percentage of anisotropic (preferred orientation) regions obtained from the orientation analysis was well correlated (R2 = 0.63) with Young’s modulus obtained from tensile testing of the same sample. Since Young’s modulus reflects the degree of mechanical healing, our results indicate that FT-SHG microscopy have a unique potential as a non-destructive and non-invasive modality for a simultaneous assessment of the histological and mechanical healing degree in injured tendons.
Noninvasive estimation of light scattering and hemoglobin concentration in mice cutaneous carcinogenesis through multispectral imaging
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Skin cancer is the most common cancer, predominantly found in people with light-skin color. With a view to diagnosing at early stage, we evaluated a new optical method to investigate the alterations in skin morphology and hemodynamics during skin cancer in mice by multispectral imaging system as traditional measures based on gross lesions that appear at the advanced stage when the prognosis is terrible. Here, the use of isosbestic wavelengths of hemoglobin makes it possible to measure hemoglobin concentration irrespective of oxygenation status of hemoglobin. Results illustrate that while there scattering power decreased, hemoglobin concentration increased in the carcinogenic mice. It demonstrated that the proposed system is competent to monitor pathophysiological changes specially scattering power and hemoglobin concentration during cutaneous two-stage chemical carcinogenesis.
Characterization of cancer metastasis in model mice by multiphoton microscopy and Raman spectroscopy
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Raman spectroscopy provides a wealth of diagnostic information to the surgeon with in situ cancer detection and labelfree histopathology in clinical practice. However, to identify cancer diagnostic biomarkers in vivo is still challenging, because malignancy can be characterized not only by the cancer cells but also by the environmental factors. Here we investigate molecular dynamics in both cancer cells and their environment in xenograft models and spontaneous metastasis models using Raman spectroscopy and nonlinear optical imaging. We are constructing a custom-designed Raman spectral imaging system to reveal the metastasis process and to evaluate therapeutics toward the clinical application of the technique.
Glucose sensing in the presence of scattering particles using decomposition of partial Mueller matrix
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A Partial Mueller matrix polarimeter retrieves a subset of sample polarization properties that can be useful for specific measurement. A partial Mueller matrix decomposition method is proposed to retrieve the optical rotation and depolarization simultaneously for measuring glucose concentration in the presence of scattering. A dual-photoelasticmodulator based Mueller matrix polarimeter is designed for this purpose. We verify the proposed decomposition method by measuring different glucose concentrations mixed with scattering particles.
Quantitative in situ time-series evaluation of osteoblastic collagen synthesis under cyclic strain using second-harmonic-generation microscopy
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The aim of this study is to provide an in situ method to non-invasively monitor osteoblastic collagen synthesis under mechanical stimulation. We applied second-harmonic-generation (SHG) microscopy to monitor the collagen fibers produced by osteoblast-like cells. To evaluate the influence of mechanical stimulation on collagen synthesis and maturation, we compared SHG images of osteoblast-produced collagen fibers with and without a cyclic stretch stimulus. Image analysis of the average SHG intensity indicated that the amount of osteoblastic collagen synthesis was significantly enhanced by the cyclic stretch. Furthermore, the maturity of the collagen fibers was not affected in the early stage of bone formation by the mechanical stimulus.
Fluid dynamic modeling and comparison of the intraocular pressure changes in eyes with SMILE and LASIK
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We developed an intraocular pressure (IOP) analytic model utilizing fluid dynamics (simulating air-puff), solid mechanics (simulating cornea structure deformation), and ray-tracing technique (simulating applanation detection) to simulate the air-puff noncontact tonometry (NCT) for post-SMILE and post-LASIK IOP measurement. This novel model is validated by a retrospective review of a database with 174,666 eyes undergoing LASIK surgery1,2. Our novel analytic model is able to comprehensively analyze the components of IOP changes after SMILE and LASIK in addition to the corneal thickness. Based on our study, the factors affecting the IOP changes after SMILE and LASIK surgeries in order include the Young’s modulus of corneal stroma, geometric shape of ablated stroma, diameter of ablated zone, corneal thickness, and corneal curvature.
Enhanced therapeutic effect of an antitumor agent on malignant glioma in rats by photomechanical wave-based transvascular drug delivery
Yumiko Koshi,
Yasuyuki Tsunoi,
Arata Tomiyama,
et al.
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Malignant glioma is one of the most deadly malignancies due to the blood-brain barrier (BBB), which limits the delivery of an antitumor drug to the tumor. In this study, we used a nanosecond pulsed laser-induced photomechanical wave (PMW) to enhance the delivery efficiency of an antitumor drug, temozolomide (TMZ) through the blood-brain barrier (BBB) in a F98 rat glioma model. Seven days after glioma cell injection into the brain, rats were divided into four groups: control without any treatment (group 1); PMW application alone (group 2); TMZ application alone (group 3); and combined application of PMW and TMZ (group 4). Seven days after these treatments, rats were sacrificed and tumor sizes were evaluated. The tumor size of group 4 was significantly smaller than that of group 1, while there was no significant difference in the tumor size between group1 and group 3. This shows that the therapeutic effect of TMZ can be enhanced by PMW application.
Poster Session
Non-invasive glucose monitoring based on optical coherence tomography
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A novel technique based on optical coherence tomography (OCT) for noninvasive glucose monitoring is proposed. The feasibility of the proposed technique is demonstrated by detecting the glucose concentration of aqueous solution ranging from 0-4000 mg/dL with 0.02% lipofundin. The practical applicability of the proposed technique is demonstrated by detecting the glucose concentration of the human fingertip tissue based on the oral glucose tolerance test (OGTT).
Monitoring protein-related degeneration of Drosophila eyes with optical coherence tomography
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Drosophila melanogaster has become an invertebrate genetic model for studies of genes-related diseases and developmental biology. Neurodegenerative diseases such Alzheimer and Parkinson’s diseases are health problem and get worse with age. However, the causes and progress of neurodegenerative diseases are still poorly understood. The compound eye of Drosophila demonstrates a heterologous system to investigate neurodegenerative diseases. In this study, we propose to use optical coherence tomography (OCT) for the study of protein-related degeneration of Drosophila eyes. With OCT, the bristles of Drosophila eye can be identified and different mutant Drosophila were scanned with OCT for investigation of progress of protein-related degeneration. From the results, it can be noted that OCT could be a powerful and noninvasive inspection tool for protein-related degenerative diseases.
Parallel phase-shifting radial shearing interferometry and its numerical verification
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We propose parallel phase-shifting radial shearing interferometry and apply this technique to single-shot wavefront measurement. This technique records a single interference image consisting of the combination of radially sheared two object waves. By applying parallel phase-shifting interferometry and a wavefront reconstruction algorithm to the recorded single interference image, the phase image of the measuring object wave is obtained. We numerically simulated single-shot wavefront measurement by using the proposed technique. It was assumed that the object was two particles. The amplitude and phase images of the particles were assumed as Gaussian distribution. The cross-correlation coefficient between the original phase image and the phase image reconstructed by using the proposed technique was 0.984.
Motion-picture phase imaging by an integrated optical system of a parallel phase-shifting digital holographic microscope
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A parallel phase-shifting digital holographic microscope achieves motion-picture phase imaging of a dynamic minute specimen. However, much time and skill are required to construct the optical system of the microscope. The authors designed and constructed an optical system of a parallel phase-shifting digital holographic microscope in which the optical components of the microscope were integrated on a breadboard standing perpendicular to an optical table. The lateral and longitudinal magnifications of the microscope are 10 and 100, respectively. The authors experimentally demonstrated the motion-picture phase imaging of a dynamic minute specimen by the microscope. The holograms were recorded at 1,000 fps and the shutter speed was 0.5 ms.
Digital holographic microscopy using speckle illuminations and two-wavelength method
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In this study, we propose digital holographic microscopy using speckle illuminations and two-wavelength method. In this method, the spatial resolution is enhanced by speckle illuminations, and the measurement range in depth direction is extended by two-wavelength method. We demonstrate the proposed method experimentally.
Tomographic phase imaging of RBCs in blood coagulation structures using digital holographic microscopy
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Blood coagulation is an important role in hemostasis process. In microscopic observation, an aggregation structure of red blood cells (RBCs) indicates the degree of blood coagulation. In this study, we demonstrate a tomographic imaging of phase distributions of aggregation structures of RBCs in blood coagulation using digital holographic microscopy.
Reconstruction of complex amplitude by lensless phase-shift digital holography through an opaque glass plate
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Optical imaging through diffusive or scattering media has attracted much attention. Digital holographic microscopy provides quantitative phase imaging thorough diffusive media. We experimentally reconstruct intensity and phase images of an object through an opaque ground glass screen by means of digital holography. A clear image of the object is acquired by wavefield back propagation algorithm for the object with an information of a quantitative phase distribution of the diffusive screen measured in advance with the principle of the lensless digital holography.
Digital holographic size measurement of Daphnia pulex
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Toxicity of chemical substances should be determined for protecting biological environment. A Daphnia pulex is one of the indicator organisms for searching the toxicity, because the shape is changed depending on the toxicity. Conventional method for its observation has been performed under suppression of its movement in a small thin room with an ordinary optical microscope. There had been concern of the stress for the Daphnia pulex. The digital holography having the postfocusing ability was applied to it for a freely-moving Daphnia pulex. The digital holography was given a low-coherence light source and an in-line structure toward a practical on-site use with not-clean environment and vibration disturbances.
Incoherent holographic imaging of subsurface structures with volume holographic gratings
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Under broadband illumination, a multiplane microscopy incorporating volume holographic gratings (VHGs) to observe three-dimensional structures of biological samples with different depth simultaneously is presented. VHGs formed in thick recording materials, including PQ-PMMA, provide strong angular and wavelength transmittance filtering properties, which enable acquiring spatial–spectral images of fine structures within biological samples. Here, we experimentally demonstrate this microscopic imaging capability to obtain multiple depth-resolved mixed pollen grains images of fine structures from eight depths in one shot.
In vivo time-series monitoring of dermal collagen fiber during skin burn healing using second-harmonic-generation microscopy
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Burn healing is a process to repair thermally damaged tissues. Although burn healing has many aspects, it is common for dynamics of collagen fiber to be closely related with burn healing. If such healing process can be visualized from the viewpoint of the collagen dynamics, one may obtain new findings regarding biological repairing mechanisms in the healing process. In this paper, we applied second-harmonic-generation microscopy for in vivo imaging of the healing process in animal skin burn and successfully visualized the decomposition, production, and growth of renewal collagen fibers as a series of time-lapse images in the same subject.
In vivo visualization of dermal collagen fibers in human skin using a photonic-crystal-fiber-coupled, hand-held second-harmonic-generation microscope
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Second-harmonic-generation (SHG) microscopy is a powerful tool for in vivo monitoring of collagen fibers in human skin. However, its practical use in the dermatological field is still limited due to the bulky and complicated setup. In this paper, we constructed a photonic-crystal-fiber-coupled, hand-held SHG microscope for in vivo monitoring of collagen fibers in human skin. Fiber delivery of ultrashort pulse light was achieved by a large-mode-area photonic-crystal-fiber whereas the SHG microscopy setup was enclosed into a hand-held probe head. The combination of PCF with the hand-held probe head largely enhances the flexibility of measurement sites in the human skin.
Analysis of collagen fiber orientation in biological tissues using polarization-resolved second-harmonic-generation microscopy
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Collagen plays an important role as a structural protein to determine the morphology and the mechanical property of tissues. Collagen orientation is one important parameter closely related with the mechanical property because collagen possesses fiber structure in tissues. However, it is difficult to evaluate the collagen fiber orientation quantitatively without invasiveness. In this article, we constructed continuously-polarization-resolved second-harmonic-generation (SHG) microscopy based on rapid polarization rotation every 15 degrees with electric-optic modulator, and applied it for the quantitative analysis of collagen fiber orientation. The orientation angle and degree of collagen fiber in different biological tissues were extracted from the curve fitting with a model function to a series of polarization-resolved
In situ monitoring of incised wound healing in animal model using second-harmonic-generation and third-harmonic-generation microscopy
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Precise assessment of wound healing degree is important to avoid infection and achieve good prognosis without remaining of keloid or hypertrophic scars. In this paper, we apply the combination of second-harmonic-generation (SHG) microscopy with third-harmonic-generation (THG) microscopy for incised wound animal model, and visualize collagen dynamics during the wound healing process in time series in situ. Due to the difference of contrast mechanism, SHG image visualizes distribution of dermal collagen fibers whereas THG image visualizes surface of the epidermis. SHG/THG microscopy enable us to track the phase of wound healing for the same subject from the viewpoint of the temporal and spatial dynamic of collagen fibers and the epidermis surface.
Resonance Raman and fluorescence spectroscopy to evaluate increased brain kynurenine pathway activity in samples from patients with neurodegenerative disease
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Resonance Raman and fluorescence spectroscopy were used to assess increased kynurenine pathway activity in brain samples from Alzheimer’s patients and age-matched controls. Increased activity was seen in areas of the brain involved in Alzheimer’s disease.
Development of dual-wavelength microscopic laser speckle contrast imaging system
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Laser Speckle Contrast Imaging (LSCI), which used coherent light, has fully been used for observing blood flow due to its non-invasive, non-contact acquisition method. Generally, LSCI system uses just a single wavelength for measurement. In this research, first, considering the biological characteristics of different reflection rates and absorption, we use two lasers at 633nm and 855 nm and two CCD cameras to build a microscopic LSCI system. Second, by using Spatial, Temporal Speckle Contrast Analysis methods and analysis with Beer–Lambert law, the microcirculation can be in vivo visualized and oxygenation can be observed. Such developed system can be further used for in vivo animal studies.
Polarization-resolved second-harmonic-generation imaging of dermal collagen fiber in pre-wrinkled skin of ultraviolet-B-exposed mouse
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Wrinkling is a typical symptom of cutaneous photoaging in skin; however, mechanism of such wrinkling is still not clear. In this paper, we investigated orientation change of dermal collagen fiber in pre-wrinkled skin of ultraviolet-B-exposed (UVB-exposed) skin using polarization-resolved second-harmonic-generation (SHG) microscopy. A polarization anisotropic image of the SHG light indicated that change of collagen fiber orientation started in the pre-wrinkled skin of ultraviolet-B-exposed (UVB-exposed) mouse. Furthermore, the dominant direction of collagen fiber orientation was significantly parallel to the wrinkle direction in post-wrinkled skin of UVB-exposed mouse. This result implies that change of collagen fiber orientation is a trigger of wrinkling in photo-aged skin.
Effects of nitric oxide on cortical hemodynamic responses in the rat brain exposed to a shock wave
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The pathophysiology and mechanism of primary blast-induced traumatic brain injury (bTBI) have not yet been elucidated. We previously observed the occurrence of spreading depolarization (SD) and transient hyperemia/hyperoxemia followed by persistent oligemia/hypoxemia in the cortex of the rat brain exposed to a laserinduced shock wave (LISW). However, the mechanism of such hemodynamic abnormalities is not clear. In this study, we investigated the involvement of nitric oxide (NO), which is known as an endothelium-derived relaxing factor (EDRF) and also as a substance associated with vasoconstriction. By the inhibition of NO synthesis, we found that the transient hyperemia/hyperoxemia immediately after LISW application was diminished and the level of persistent oligemia/hypoxemia was mitigated even when SD occurred. The results suggest that hemodynamic abnormalities caused by an LISW in the rat cortex was associated with an increased NO production and its vasodilatory/vasoconstrictory effects.
Partial optical path length in the scalp in subject-specific head models for multi-distance probe configuration of near infrared spectroscopy
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In the brain function measurement by near infrared spectroscopy using a multi-distance probe configuration, the ratio of the partial optical path length in the scalp for the long spacing probe pair to that for the short spacing probe pair is important for the calculation to eliminate the scalp component in the signal. Light propagation in the subject specific head models of 45 volunteers was calculated to predict the dependence of the partial optical path length in the scalp and the weighting factor for the multi-distance probe configuration. The weighting factor ranges from 1.0 to 2.3 and increases with the scalp thickness when the scalp thickness is less than 15 mm.
Measurement of head phantom by functional near infrared imaging using multi-distance probe configuration
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The contamination of the signal corresponding to the blood volume change in the scalp is one of the serious problems in functional near infrared imaging and the multi-distance probe configuration has been used to reduce the contamination of the scalp signal. The head phantom mimicking the local absorption change in the gray matter and global absorption change in the scalp was measured by a functional near infrared spectroscopy system using the multi-distance probe configuration to obtain the topographic image of the absorption change in the phantom. The measurement using the multi-distance probe configuration can effectively reduce the contamination of the scalp signal during the functional near infrared imaging.
Diffuse light reflectometry for measuring scattering and absorption coefficients of a biological tissue
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The optical properties, a scattering and an absorption coefficients, of biological tissues will be used to estimate quantitatively change in bioactivity. Diffuse light reflectometry has been investigated to measure the optical properties of biological tissues from the viewpoints of applicability and practicality. Experimental results obtained from the scattering and the absorption coefficients of the phantom confirm the exactness in measurement by comparing the theoretical values based on the Mie scattering theory. It is also confirmed by changing the roughness of the surface that the performance is effective for the rough surface as a skin tissue.
Adjoint based Hessian evaluation for SPN modeled optical tomography
Nishigandha Patil,
Naren Naik
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Hessian matrices are important in inversion algorithms due to their potential of use in full Newton schemes, analysis of reconstruction results, and in experimental design. We present for the first time an adjoint based evaluation of the Hessian matrix for the SPN-approximation modeled forward operator in optical tomography. The Hessians so calculated are numerically validated with respect to finite difference calculations. We present comparisons between computational requirements of the present scheme with a mixed scheme which evaluates the Hessian as the first difference of the adjoint based Jacobians.
Three-dimensional beam focusing control for lensless vascular endoscopes using local wavefront control
Masaki Hisaka
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In this study, the focusing beam generated by an optical fiber bundle having locally optical delay has been investigated to simplify the structure of vascular endoscopes. The wavefront propagating within each fiber core is delayed locally by an optical delay system. Each diffraction beam emitted from the fiber core forms a superimposed convergent wave. The optical delays make arbitrary beam focusing after the light exits the bundle. We have demonstrated the beam focusing and three-dimensional scanning of the beam using a liquid lens. In this experiment, six points of unnecessary convergent light, which depended on the hexagonal lattice structures of the bundle, were also formed at the same time.
Application of scan-less two-dimensional confocal microscopy achieved by a combination of confocal slit with wavelength/space conversion
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Confocal laser microscope (CLM) has been widely used in the fields of the non-contact surface topography, biomedical imaging, and other applications, because the confocality gives two-dimensional (2D) optical-sectioning or threedimensional (3D) imaging capability and the stray light elimination. One potential method for scan-less 2D CLM is a combination of the line-focused CLM with the 1D spectral encoding CLM. In this paper, we constructed such scan-less 2D CLM with the image acquisition time of 0.23 ms, the lateral resolution of 1.2 μm, the depth resolution of 2.4 μm, and apply it for in situ imaging of plant leaf to investigate a potential for plant health monitoring.
Multi-focal imaging system by using a programmable spatial light modulator
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The multi-focal imaging system is implemented with a spatial light modulator (SLM) placed at the Fourier plane of the system. The multiplexed grating pattern displayed on the SLM can modify the wavefront of the incoming light and compensate aberrations existing in the system. We demonstrate the multiplexed grating pattern displayed on the SLM can acquire 25 images in a short time sequence by acquiring 9 images at different depths simultaneously in each exposure. We compare and discuss the advantages and disadvantages between the digital micro-mirror device (DMD) with the liquid crystal spatial light modulator (LC-SLM) based on the theory and experimental results.
Underwater image enhancement algorithm based on granular computing
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Due to the light scattering and absorption, underwater images were blurred such as fog, uneven illumination, overexposure or lack of light. We proposed an image enhancement algorithm based on granular computing to enhance underwater optical image in this paper. First, the illumination information of underwater image was extracted. Then, we dividing the illumination information into granularity of different sizes from wide to thin by calculated the effectiveness indicators. Finally, by calculating their value and compensation for each granularity, we obtained the adaptive enhancement image. The simulation and experiment results verify the effectiveness of the algorithm.
An edge detection method based artificial bee colony for underwater dam crack image
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In this paper, an edge extraction model based on artificial bee colony algorithm has been proposed to overcome the problems of concrete defect detection in complex underwater environment specialized to dam cracks detection. To enhance weak-object edge gray contrast under different brightness, the adaptive enhancement method is presented in which a concept of two-dimensional lateral inhibitory network is introduced and a border highlighting rule is designed. Furthermore, to increase the edge extraction effective, the improved artificial bee colony algorithm is used in which an optimization strategy is based on edge direction information. Some experiments are carried out on underwater dam crack images in different environments and the experimental results show the efficiency and effectiveness of the algorithm.
Practical image quality evaluation for whole slide imaging scanner
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Whole slide imaging (WSI) scanner scans pathological specimens to produce digital slides to use in pathology practice, research and computational pathology which enables monitor-based diagnosis and image analysis. However, the scanned image is sometimes insufficient in quality such as focusing-error and noise. Therefore, a quality evaluation method is obligatory for practical use of WSI system. In previous work, referenceless quality evaluation technique was proposed for this purpose but some artefacts (i.e. tissue-fold, air-bubble) in slide would also be detected as false positives, while they are useless. In this paper, we proposed a method for the practical system to assess WSI quality with eliminating false detection due to the artefacts. Firstly, support vector machine (SVM) was utilized for detecting ROIs with artefacts and then the image quality was evaluated excluding detected ROIs. Through the experiments, the effectiveness of proposed system has been demonstrated.
Speckle reconstruction based on oversampling smoothness algorithm
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Target object image would deteriorate into unrecognizable speckle pattern when encountering with scattering media. It’s necessary to reconstruct the target object image from captured speckle. In this paper, a method combining correlation method and oversampling smoothness is proposed. It is used for target object reconstruction from scattered speckle pattern. The reconstruction is based on the Fourier transform of the target object. The Fourier amplitude of the target object can be calculated through an inverse Fourier transform of the autocorrelation of captured speckle pattern. The Fourier phase can be recovered with oversampling smoothness method. Experiments were used to comparing the proposed C-OSS method with the C-ERHIO method. The results indicate that the proposed method improves the reconstruction with lower background components than the other. The proposed method can also be applied to optical image encryption et al.
Speckle reconstruction method based on machine learning
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Scattering media would deteriorate an object image into unrecognizable speckle pattern. Machine learning is introduced to reconstruct the object image from speckle pattern. In the proposed method, a database containing two groups (i.e., face image-and-speckle-pattern pairs, non-face image-and-speckle-pattern pairs) is firstly established. Then support vector classification (SVC) is introduced to classify a given unknown speckle pattern into which group it belongs to. Taking advantage of support vector regression (SVR), the object image corresponding to the unknown speckle pattern can be reconstructed. Experiments are conducted to verify the effectiveness of the proposed method, as well as the necessity of the introduction of SVC.
Fractality of biospeckle pattern observed in blood coagulation process
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It has been known that speckle images observed for living bodies illuminated by laser light sometimes show fractal appearances. This has been utilized, for example, for tomographic imaging of the porcine arterial tissue. Fractality can also be seen in speckle images generated by the blood in the process of coagulation. A fractal dimension (FD) of the speckle image is, thus, expected to be a global marker of haemostasis, arteriosclerosis, and so on. In the present study, we experimentally investigate fractality of biospeckle pattern observed in coagulation process of horse blood.
Computational ghost imaging by using complementary illumination patterns
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Computational ghost imaging (CGI) is a single-pixel imaging technique by illuminating the object with structuredlight. The image of the object can be retrieved by the correlation of numerous power measurements and the corresponding illumination patterns. Although CGI owns many unique merits, its shortcoming is apparent. The demand of numerous measurements is time-consuming, and the reconstructed image always suffers from speckle-like noise. In this paper we proposed to use complementary illumination patterns to perform CGI. In addition, we applied Gerchberg-Saxton-like algorithm to optimize the reconstructed image. By this way, the time of reconstruction is reduced. In addition, the signalto-noise ratio (SNR) significantly increases in comparison with that by using complete random illumination patterns.
Preliminary study on x-ray phase-contrast imaging with tilted-grid
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We present preliminary experimental results of X-ray phase-contrast imaging with a tilted-grid to measure the twodimensional phase gradient. The direction of the grid line is rotated 10 degrees relative to the horizontal axis. To obtain the differential phase-contrast image, we employ the spatial harmonic method based on the Fourier transform phase retrieval. The two-dimensional phase gradient of a PMMA sample is well defined in the phase-contrast image acquired with the tilted-grid setup.
Implementation of a Raspberry-Pi-based LED array microscope for multi-contrast images
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The light emitting diode (LED) array microscope enables various multi-contrast imaging such as bright-field, darkfield and differential phase-contrast by various illumination patterns without any expensive optical components. We build an LED array microscopic system operated with Raspberry Pi. Illumination patterns are controlled with Raspberry Pi and images are obtained with a Raspberry Pi camera module. We demonstrate acquisition of bright-field, dark-field, and differential phase-contrast of cells.
Image acquisition with smartphone-based LED array microscope
Kazuko Koda,
Shu Uenoyama,
Ryo Sugimoto,
et al.
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The light emitting diode (LED) array microscope enables various multi-contrast imaging such as bright-field, dark- field and differential phase-contrast (DPC) by various illumination patterns without any expensive optical components. We built LED array microscopic system that enables us to obtain multi-contrast images with a smartphone camera. We demonstrate that a smartphone-based LED array microscope can acquire bright field, dark field, and DPC of cell by changing the numerical apertures of objective lenses.
Scan-less, line-filed, confocal phase imaging with dual-comb microscopy
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We introduce an optical frequency comb (OFC) to microscopy to coherently link the confocal microscopy and phase microscopy. One-dimensional (1D) image pixels of a sample were encoded onto OFC modes via 1D spectral encoding, in which OFC acted as an optical carrier with a vast number of discrete frequency channels. Then, a scan-less line-field confocal image with a depth resolution of 50 μm was decoded from a mode-resolved OFC amplitude spectrum obtained by dual-comb spectroscopy. Furthermore, a phase image with a depth resolution of sub-λ was decoded from a moderesolved OFC phase spectrum under the above confocality. The proposed hybrid microscopy approach will be a powerful tool for a variety of applications.
Visual search efficiency depending on spatial layout of stimuli in volumetric image
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In medical imaging, large sets of two-dimensional images are used for evaluating anatomical structures. Observers experience high cognitive load due to necessity of memorizing information and data is not seen in a real volume. A volumetric multi-planar display is a promising technology that can eliminate above mentioned issues by producing images in a real three-dimensional space. Therefore, the goal of our study was to investigate how well individuals perceived a difference in spatial localization of visual stimuli and describe its impact on visual search performance in three-dimensional digital space. Participants searched for a target stimulus which was located closer to the observer comparing to other stimuli in different depth segments of a display and provided subjective evaluation of the task difficulty. The results revealed that on average visual attention could be deployed without significant differences on all four depths segments in terms of response time and quality. But at the same time, eccentricity of stimuli influenced considerably the performance which can be related to higher cognitive load due to limitation of visual acuity and attention in the peripheral visual field. To be added, subjective evaluation of perceived task difficulty matched well response time and accuracy in visual search. The obtained results leaded to the conclusion that spatial layout of stimuli in horizontal and vertical dimension had a bigger impact on visual search performance comparing to the third dimension on a volumetric multi-planar display.
Real-time detection of 192Ir gamma-ray source positon using organic scintillator array sensor in HDR brachytherapy
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In this study, we fabricated an organic scintillator array sensor (OSAS) based the array of organic scintillators. The scintillator array of OSAS for detecting positions of 192Ir gamma-ray source was fabricated using four types of organic scintillators, which emit the scintillating lights of different wavelength, respectively. To evaluate the performance of the OSAS, 192Ir gamma-ray source employed in a HDR brachytherapy was used. In this research, the spectra were measured with positions of 192Ir gamma-ray source which was moved at intervals of 5 mm and 10 mm using the OSAS. The experimental results show that the proposed OSAS can measure and discriminate the wavelength of scintillating lights generated in the OSAS according to the positions of 192Ir gamma-ray source. It is expected that the OSAS can used to detect positions of 192Ir gamma-ray source during a HDR brachytherapy. Further studies are planned to fabricate the OSAS with the different intervals of movements and the small size of organic scintillators.
Electron beam addressable potentiometric sensor for ion distribution imaging with high resolution
Wataru Inami,
Kiyohisa Nii,
Satoru Shibano,
et al.
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We have developed an electron beam addressable potentiometric sensor to improve the spatial resolution. Ion sensors are widely used in the fields of medical and life science, food and material development, environmental protection and so on. However, the spatial resolution of the ion distribution imaging sensor is limited by the diffraction limit of light or microfabrication technology. So, we proposed an addressable potentiometric sensor using a focused electron beam instead of light. The electron beam can be easily focused to a spot of several nanometer, and the spatial resolution of the addressable potentiometric sensor improved. We showed that ion concentration can be measured by irradiating the ion sensor substrate (SiN/SiO2/Si) with a focused electron beam.
Design of add-on optics for optimization of COT endoscope camera for epiduroscopic surgery
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This paper presents a method for designing an add-on lens assembly to optimize the performance of Chip-on-the-Tip (COT) endoscope. In particular, an add-on lens assembly is designed here attributes to a commercially available COT camera, NanEye, in such a way that overall optical performances such as field-of-view (FOV) and depth-of-field (DOF) are optimized for the particular microsurgery at hand: Epiduroscopic surgery. The add-on lens assembly is designed with four lenses compactly assembled into 1.3 mm length and 1.52 mm diameter. It provides a FOV of 110° and DOF of 1.5 mm to 8 mm under the refractive index of water, greatly increasing the native 62° FOV of NanEye in the air (90° in the air) to 110° while decreasing the minimum DOF from 3 mm to 1.5 mm.
Disturbance location algorithm of the single-core fiber optic sensor based on frequency domain
Haiyan Xu,
Lijuan Zhao,
Yingjuan Xie,
et al.
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A novel distributed fiber-optic sensor based on Wavelength Division Multiplex (WDM) for determining the position of disturbances is presented. The configuration and operating principle of the system is illustrated. The location principle and the method for the detection system are analyzed. Based on the initial method in the frequency domain, the system realizes the disturbances location using the WDM technology to compare the signals which are the same vibration corresponding to different light sources and light paths. Theory analysis and experiment results show that the proposed algorithm can realize the detection and location of the multipoint disturb signals rapidly and effectively, this method is simply and can be obtained easily, it could increase the length of fiber-optic sensors which has high measurement sensitivity and location precision.
Design optimization of a single-mode microring resonator for label-free detection of biomarkers within a tunable spectral range of 2 nm
Prabodh Panindre,
N.S. Susan Mousavi,
Sunil Kumar
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This computational parametric study analyzes the effect of geometrical design parameters of a microring resonator on its optical characteristics with the goal to optimize its performance for label-free detection of biomarkers. Electromagnetic frequency domain analysis was performed using finite element numerical technique for the microring resonator. Effect of the width of feed and pickup waveguides, the coupling gap between the waveguide and microring, and the outer radius of microring on the quality factor were analyzed and quantified for a narrow operational range of wavelength between 1309-1311 nm. The computational simulation showed that these parameters play an important role in avoiding the loss of electromagnetic field, while increasing the effective circulation of energy in the resonator, the ability to achieve multiple single-mode resonances within certain wavelength bandwidth, and the quality of output signal for detection. As a result, the quality factor was enhanced by an order of magnitude with the obtained optimum values of waveguide width, coupling gap, and microring radius without changing the material of resonator or waveguide, and the medium surrounding the resonator. The ability to optically detect a nanoparticle representing a cell vesicle was demonstrated. This enhanced quality factor of the resonator will allow highly sensitive and rapid detection of biomarkers and measurement of their size.
Low dose of narrow-band ultraviolet B lamp for improving vitamin D synthesis with minimum skin damage
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The Vitamin D synthesis mainly takes place in skin after solar exposure of UVB, but usually the solar exposure dose is not adequate with modern daily activity. Thus, it is a novel solution to develop home-use UV health lamp to compensate the vitamin-D deficient. In this study, a low dose and narrow band UV-B lamps was developed for animal study. The lamp design was based on arrangement of UV-B light bulbs, band pass filters and electric-mechanical devices. The vitamin D synthesis of mice under various irradiation conditions was observed and analyzed. The experimental results show that the UV light with a wavelength of 310-320 nm can effectively improve the vitamin D synthesis and minimize the skin damage.
Photostability study of CdTe quantum dots using laser induced fluorescence
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Semiconductor quantum dots (QDs) having high quantum yields and unique photostability. This research studies the optical properties of the synthesized CdTe QDs with two different sizes using Laser induced fluorescence for investigating their photostability. TEM images illustrate that the two prepared QDs sizes are 2.4 and 3.5 nm. FTIR analysis revealed that the prepared QD capped with oleic acid. LIF technique showed that there is a red shift of the fluorescence emission of the bigger size QDs compared to the smaller one. The small size QD has a lower photostability when compared to the big size 2.4 nm. This study introduces guidance adapting CdTe photophysical properties for generalized applications especially biological laser imaging and solar cell applications.
Edge contrast enhancement at multiple planes using forked shaped defocus grating
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We report on the implementation of spiral phase contrast imaging at multiple planes using forked-shaped defocus grating. The dual function of grating helps in simultaneous generation of multiple edge enhanced images corresponding to different depths. Present method is simple, direct and is applicable to coherent and incoherent imaging system.
Orthogonal functional system for finite Fresnel transform
Tomohiro Aoyagi,
Kouichi Ohtsubo M.D.,
Nobuo Aoyagi
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The Fresnel transform has been studied mathematically and revealed the topological properties in Hilbert space. Main aim is to reveal the property of band-limited function. We seek the function that its total power is maximized in finite Fresnel transform plane, on condition that an input signal is zero outside the bounded region. This problem is a variational one with an accessory condition. This leads to the eigenvalue problems of Fredholm integral equation of the first kind. The kernel of the integral equation is Hermitian conjugate and positive definite. Therefore, eigenvalues are real non-negative numbers. We prove that the eigenfunctions corresponding to distinct eigenvalues are orthogonal.
Nanoscale three-dimensional imaging of biological tissue with x-ray holographic tomography
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Enabling exploration of biological tissue in three-dimensions at sub-cellular scale is instrumental for advancing our understanding of biological systems and for finding better ways to cope with diseases. Over the last few years, remarkable advances in microscopy facilitated probing cells and tissues at the nanometer scale but many limitations are yet to be overcome. Here we present a novel technique which enables label-free volume imaging of biological tissue with pixel sizes down to 25 nm while maintaining extensive sample coverage. X-ray holographic nanotomography is a full-field 3D imaging technique which benefits from the deep penetration of X-rays and the powerful mechanism of phase contrast. By using cryogenic sample preservation, the tissue can be investigated close to the native state. The unprecedented data created by this technique opens new avenues in life sciences research.