Perturbative Fourier ptychographic microscopy for fast quantitative phase imaging

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Objectives: We are interested in the numerical simulation of the anastomotic region comprised between outflow canula of LVAD and the aorta. Segmentation, geometry reconstruction and grid generation from patient specific data remain an issue because of the variable quality of DICOM images, in particular CT-scan (e.g. metallic noise of the device, non-aortic contrast phase). We propose a general framework to overcome this problem and create suitable grids for numerical simulations. Methods: Preliminary treatm

In vivo fetal magnetic resonance imaging provides a unique approach for the study of early human brain development [1]. In utero cerebral morphometry could potentially be used as a marker of the cerebral maturation and help to distinguish between normal and abnormal development in ambiguous situations. However, this quantitative approach is a major challenge because of the movement of the fetus inside the amniotic cavity, the poor spatial resolution provided by very fast MRI sequences and the partial volume

Many biological objects are mainly transparent and weakly scattering, thus a promising (and already widely used) way of imaging them consists in considering optical refractive index variations. The method proposed here permits 3D imaging of the refractive index distribution with a tomographic approach. Usually, the classical Radon transform does not sufficiently take into account the physical interaction between light and biological cells, therefore diffraction has to be considered.

We present a novel Fourier domain method for microscopic imaging - so- called k-microscopy - with lateral resolution independent of the detection numerical aperture. The concept is based on sample illumination by a lateral fringe- pattern of varying spatial frequency, which probes the lateral spatial frequency or k- spectrum of the sample structure. The illumination pattern is realized by interference of two collimated coherent beams. Wavelength tuning is employed for modulation of the fringe spacing. The u

With the use of a Bessel-like illumination beam produced by an axicon lens an extended depth of field can be achieved. The resulting illumination pattern exhibits a strong central lobe extending over 300um along the optical axis without diffraction. Here we present a fast digital focusing algorithm to correct for remaining out of focus artifacts, manifest in sidelobes for out of focus scatterers, due to the decoupled Gaussian detection. The waist of the detection in the focal plane is 2.1um, with a Rayleigh

Digital holographic microscopy (DHM) is a technique that allows obtaining, from a single recorded hologram, quantitative phase image of living cell with interferometric accuracy. Specifically, the optical phase shift induced by the specimen on the transmitted wave front can be regarded as a powerful endogenous contrast agent, depending on both the thickness and the refractive index of the sample. We discuss some approaches allowing to directly obtain separate measurements of the thickness and the refractive

Coherent x-rays from synchrotron sources are increasingly used in non-conventional radiological techniques ('phase-contrast' radiology). Our experiments demonstrate that by using white (unmonochromatic) radiation and a time-resolving system, it is possible to image microscopic details of moving blood vessels in different live animals without using any contrast agent. The images have excellent contrast plus unprecedented spatial resolution for microangiography (< 10 mum). This result is likely to impact many

In this thesis, we describe new approaches and methods for reconstructing complex-valued wave fields from digital holograms. We focus on Fresnel holograms recorded in an off-axis geometry, for which operational real-time acquisition setups readily exist. The three main research directions presented are the following. First, we derive the necessary tools to port methods and concepts of wavelet-based approaches to the field of digital holography. This is motivated by the flexibility, the robustness, and the u

An optically-active multi-layer dielectric structure comprises an optically active zone between two mirrors forming a Fabry-Perot microcavity. The optically active zone comprises an optically active material of wavelength lambda centred in a layer of high refractory index medium of optical thickness less than lambda/2 surrounded by two layers of low refractory index medium each of optical thickness less than &lambda/4,the combined optical thickness of said three layers making up the optically active zone be

In this paper, we present a simple method to almost quadruple the spatial resolution of aliased images. From a set of four low resolution, undersampled and shifted images, a new image is constructed with almost twice the resolution in each dimension. The resulting image is aliasing-free. A small aliasing-free part of the frequency domain of the images is used to compute the exact subpixel shifts. When the relative image positions are known, a higher resolution image can be constructed using the Papoulis-Ger

Purpose: To improve the quantification of myocardial perfusion by registering the time series of magnetic resonance (MR) images with injection of gadolinium. Materials and Methods: Eight patients underwent MR scans to perform myocardial perfusion exam. Two short axis views of the left ventricle (LV) were acquired in free breathing. Two masks for performing the spatial registration of the images were evaluated. The registration was based on pixel intensity in a multi-resolution scheme. The efficiency of this

The present work investigates the possibility of selective electrochemical metal deposition on ion implanted p-Si. The idea is that defects introduced into the substrate by ion implantation make it more susceptible to electrochemical reactions compared to intact Si; this increased sensitivity is to be used for selective reactions at the defect sites. It is believed that the increased reactivity is due to a lowering of the Schottky barrier breakdown potential, Ubd, of the semiconductor-electrolyte interface

Perturbative Fourier ptychographic microscopy for fast quantitative phase imaging

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Segmentation and Grid Generation for Numerical Simulations of VAD Connections with Patientspecific Data

Quantitative morphometry analysis of the fetal brain using clinical MR imaging

Diffraction tomography for biological cells imaging using digital holographic microscopy

k-Microscopy: resolution beyond the diffraction limit

Enhancement of extended depth of field by digital focusing

Analysis of cellular structure and dynamics with digital holographic microscopy

Synchrotron microangiography with no contrast agent

On Fresnelets, interference fringes, and digital holography

Phase shifted microcavities

Superresolution images reconstructed from aliased images

Improvement in the Quantification of Myocardial Perfusion Using an Automatic Spline-Based Registration Algorithm

Electrochemical investigation of ion implanted p-Si