Search results for "Microscope"

Angular spreading measurements using MeV ion microscopes

2013

Abstract The sharpness of MeV ion microscope images is governed by small-angle scattering and associated lateral spreading of the ion beam in the sample. We have investigated measurement of the half-angle of the angular spreading distribution by characterising the image blurring in direct-Scanning Transmission Ion Microscopy (direct-STIM). In these tests Mylar™ foils of 0.5–6 μm were used to induce angular spreading. Images were taken of an electron microscope grid using 2 MeV protons with, and without, the foils in the beam path. The blurring was measured by fitting the width of a circular Gaussian point spread function to the images with and without the foil in position. The results show …

Enhancing spatial resolution in digital holographic microscopy by biprism structured illumination.

2014

A novel and efficient architecture of a structured-illumination digital holographic microscope (DHM) is presented. As the DHM operates at the diffraction limit, its spatial resolution on label-free imaging of transparent samples is improved by illuminating the sample with a structured illumination produced by a Fresnel's biprism. The theoretical analysis of the method forecasts a twofold improvement of the spatial resolution. The proposed method requires only two images to improve the spatial resolution, which eases the process of unmixing the high-resolution components by means of an unknown phase-shift procedure. Numerical modeling and experimental results validate the theoretical finding…

Axial apodization in 4Pi-confocal microscopy by annular binary filters

2002

We present a novel technique for considerably decreasing the sidelobe height of the axial point-spread function of one-photon 4Pi-confocal microscopes. By means of a numerical example, in which the ratio between the excitation and the fluorescence wavelengths was set to epsilon = lambdaexc/lambdadet = 0.8, we show that simply inserting a pair of properly designed two-ring binary masks in the illumination set allows the height of the axial sidelobes to be reduced from 20% to 5% of the height of the central peak. This allows one to receive the full benefit of the strong narrowness of the central lobe provided by the 4Pi-confocal technique.

Magneto-optical linear dichroism in threshold photoemission electron microscopy of polycrystalline Fe films.

2000

Magnetic linear dichroism in threshold photoemission has been exploited to obtain magnetic contrast in a photoemission electron microscope using a mercury arc lamp. The dichroism at threshold can be described similar to the magneto-optical Kerr effect in the region of visible light. The asymmetry of electron intensity observed for a 100 nm polycrystalline Fe film on silicon is A=(0.37+/-0.05)%. The asymmetry occurs for the geometry of the transverse Kerr effect. For unpolarized light the asymmetry was about half the value observed for linearly polarized light. Threshold photoemission microscopy has a large potential for high resolution magnetic domain imaging with fast data acquisition.

Morphological patterns of circumpulpal dentin affected by radiation-related caries

2020

Background The aim of this work was to evaluate the microscopic characteristics through polarized light microscopy, scanning electron microscopy and the mineral content of circumpulpal dentin of irradiated (IT) and non-irradiated teeth (NIT), with deep caries that reached the root canal. Material and methods A total of 25 IT were analyzed macroscopically, and radiographed. 5 NIT were used as controls. Two 100-μm-thick sections, per specimen, were evaluated in a polarized light microscopy and a scanning electron microscope. Demographics and clinical data were collected. Results The results did not demonstrate distinct morphology of the IT compared with NIT. Mineral content values by weight p…

Book review

2008

Plasma Polymer Membranes for Immobilising Metalloporphyrins

2013

Atmospheric pressure dielectric barrier discharge formation of organosilicon thin films loaded with zinc 5,10,15,20-tetraphenylporphyrin (Zn(TPP)) was investigated for different deposition conditions. UV–visible spectroscopy and scanning electron microscopy revealed the effects of the metalloporpyhrins injection parameters and the plasma polymerisation conditions can affect the dispersion of the metalloporphyrins and the morphology of the coatings. The stability of the embedded Zn(TPP) molecules was investigated by orbitrap mass spectrometry.

Aroma behaviour during steam cooking within a potato starch-based model matrix.

2012

To help understand the organoleptic qualities of steam cooked foods, the kinetics of aroma release during cooking in a potato starch based model matrix was studied. Behaviour of components having a major impact in potato flavour were studied using solid phase micro extraction-gas chromatography (SPME-GC). Evolution of microstructure of potato starch model-matrix during steam cooking process was analyzed using environmental scanning electron microscopy (ESEM). Both aroma compounds that are naturally present in starch matrix and those that were added were analyzed. Both the aroma compounds naturally presented and those added had different behaviour depending on their physico-chemical properti…

Diffusion in concentrated colloidal suspensions and glasses

1998

The well established analogy between colloidal suspensions and atomic fluids has been extended to the glass transition problem in the past few years. Colloids have become the ideal test case for checking glass transition theories; this was due to the possibility of modeling hard spheres with colloidal dispersions. Significant progress has also been made in instrumentation, especially in the development of light-scattering techniques allowing moderately turbid and nonergodic samples to be analyzed. Mode coupling theory has become a paradigm not only for the glass transition, but also for the understanding of dynamics in highly concentrated colloidal dispersions where crystallization is suppr…

Surface-relief gratings in halogen-bonded polymer-azobenzene complexes A concentration-dependence study

2017

In recent years, supramolecular complexes comprising a poly(4-vinylpyridine) backbone and azobenzene-based halogen bond donors have emerged as a promising class of materials for the inscription of light-induced surface-relief gratings (SRGs). The studies up to date have focused on building supramolecular hierarchies, i.e., optimizing the polymer–azobenzene noncovalent interaction for efficient surface patterning. They have been conducted using systems with relatively low azobenzene content, and little is known about the concentration dependence of SRG formation in halogen-bonded polymer–azobenzene complexes. Herein, we bridge this gap, and study the concentration dependence of SRG formation…