Search results for "resolution"
showing 10 items of 1928 documents
Elemental distribution and structural characterization of GaN/InGaN core-shell single nanowires by Hard X-ray synchrotron nanoprobes
2019
Improvements in the spatial resolution of synchrotron-based X-ray probes have reached the nano-scale and they, nowadays, constitute a powerful platform for the study of semiconductor nanostructures and nanodevices that provides high sensitivity without destroying the material. Three complementary hard X-ray synchrotron techniques at the nanoscale have been applied to the study of individual nanowires (NWs) containing non-polar GaN/InGaN multi-quantum-wells. The trace elemental sensitivity of X-ray fluorescence allows one to determine the In concentration of the quantum wells and their inhomogeneities along the NW. It is also possible to rule out any contamination from the gold nanoparticle …
Study of spatial lateral resolution in off-axis digital holographic microscopy
2015
The lateral resolution in digital holographic microscopy (DHM) has been widely studied in terms of both recording and reconstruction parameters. Although it is understood that once the digital hologram is recorded the physical resolution is fixed according to the diffraction theory and the pixel density, still some researches link the resolution of the reconstructed wavefield with the recording distance as well as with the zero-padding technique. Aiming to help avoiding these misconceptions, in this paper we analyze the lateral resolution of DHM through the variation of those two parameters. To support our outcomes, we have designed numerical simulations and experimental verifications. Both…
Non-Homogeneity of Lateral Resolution in Integral Imaging
2013
We evaluate the lateral resolution in reconstructed integral images. Our analysis takes into account both the diffraction effects in the image capture stage and the lack of homogeneity and isotropy in the reconstruction stage. We have used Monte Carlo simulation in order to assign a value for the resolution limit to any reconstruction plane. We have modelled the resolution behavior. Although in general the resolution limit increases proportionally to the distance to the lens array, there are some periodically distributed singularity planes. The phenomenon is supported by experiments.
Speckle random coding for 2D super resolving fluorescent microscopic imaging.
2006
In this manuscript we present a novel super resolving approach based upon projection of a random speckle pattern onto samples observed through a microscope. The projection of the speckle pattern is created by coherent illumination of the inspected pattern through a diffuser. Due to local interference of the coherent wave front with itself, a random speckle pattern is superimposed on the sample. This speckle pattern can be scanned over the object. A super-resolved image can be extracted from a temporal sequence of images by appropriate digital processing of the image stream. The resulting resolution is significantly higher than the diffraction limitation of the microscope objective. The new …
High-resolution hard-x-ray photoelectron diffraction in a momentum microscope—the model case of graphite
2019
New journal of physics 21(11), 113031 - (2019). doi:10.1088/1367-2630/ab51fe
Geometrical super resolved lensless imaging
2011
In the field of super resolution researchers are trying to overcome both the diffraction as well as the geometrical bounds of an imaging system. In this paper we present a recently developed approach that aims to overcome the geometrical bounds while using a unified spatial light modulator (SLM) based lensless configuration.
Super resolved optical system for objects with finite sizes using circular gratings
2015
We present a real time all optical super resolution method for exceeding the diffraction limit of an imaging system which has a circular aperture. The resolution improvement is obtained using two fixed circular gratings which are placed in predetermined positions. The circular gratings generate synthetic circular duplications of the aperture, thus they are the proper choice for a circular aperture optical system. The method is applicable for both spatially coherent and incoherent illuminations, as well as for white light illumination. The resolution improvement is achieved by limiting the object field of view. The proposed method is presented analytically, demonstrated via numerical simulat…
Diffraction-managed superlensing using metallodielectric heterostructures
2012
We show that subwavelength diffracted wave fields may be managed inside multilayered plasmonic devices to achieve ultra-resolving lensing. For that purpose we first transform both homogeneous waves and a broad band of evanescent waves into propagating Bloch modes by means of a metal/dielectric (MD) superlattice. Beam spreading is subsequently compensated by means of negative refraction in a plasmon-induced anisotropic effective-medium that is cemented behind. A precise design of the superlens doublet may lead to nearly aberration-free images with subwavelength resolution in spite of using optical paths longer than a wavelength. This research was funded by the Spanish Ministry of Economy and…
Electromagnetic Singularities and Resonances in Near-Field Optical Probes
2007
Over the last two decades scanning near-field optical microscopy (SNOM) has demonstrated its ability to provide optical resolution significantly better than the diffraction limit (<20 nm). The general principle of SNOM relies on the approach of a nanometer-sized object in the optical near-field of a sample to be studied. This nano-object (NO) is usually the extremity of a probe. Regardless of the nature of the observed SNOM signal (inelastic scattering, fluorescence, etc.), the detection of the light is achieved in the far-field regime where the NO acts as a mediator between the optical near-field and the detector. Figure 1 is a schematic illustration of the SNOM principle.
IMAGING OF DICHROISM IN PHOTOEMISSION ELECTRON MICROSCOPY AT NONMAGNETIC MATERIALS USING CIRCULARLY POLARIZED SOFT X-RAYS
2002
A new approach for investigations of circular dichroism in the angular distribution of photoelectrons (CDAD) is presented. The image contrast using a photoemission line of a certain material is combined with imaging of the angular distribution pattern using a photoemission electron microscope (PEEM). CDAD can be used to investigate pure scattering information by means of the same instrument in microscopically selected regions on a surface. The experiment combines angle-resolved XPS imaging with the indirect mapping of the local environment of atoms by means of CDAD holography. In a conventional photoelectron diffraction or photoelectron holography experiment, it is necessary to move the sa…