Search results for "resolution"
showing 10 items of 1928 documents
Realization and drive tests of active thin glass x-ray mirrors
2016
A technique to obtain lightweight and high-resolution focusing mirror segments for large aperture X-ray telescopes is the hot slumping of thin glass foils. In this approach, already successfully experimented to manufacture the optics of the NuSTAR X-ray telescope, thin glasses are formed at high temperature onto a precisely figured mould. The formed glass foils are subsequently stacked onto a stiff backplane with a common axis and focus to form an XOU (X-ray Optical Unit), to be later integrated in the telescope optic structure. In this process, the low thickness of the glass foils guarantees a low specific mass and a very low obstruction of the effective area. However, thin glasses are sub…
Single molecule imaging using a highly confined optical field at a triangular aperture
2005
We demonstrate that scanning near-field optical microscopy based on a probe with a triangular aperture is capable of imaging single fluorescent molecules with an optical resolution of 30 nm. Numerical simulations agree well with experiment.
Detection of defects buried in metallic samples by scanning microwave microscopy
2011
This paper reports the local detection of buried calibrated metal defects in metal samples by a new experimental technique, scanning microwave microscopy. This technique combines the electromagnetic measurement capabilities of a microwave vector network analyzer with the subnanometer-resolution capabilities of an atomic force microscope. The network analyzer authorizes the use of several frequencies in the range 1--6 GHz, allowing three-dimensional tomographical investigation, which is useful for the detection of bulk defects in metal materials.
Long axial crystals for PET applications: The AX-PET demonstrator and beyond
2013
The usage of long, axially oriented scintillator crystals in a PET scanner has been shown by the AX-PET Demonstrator as a possible solution for a high resolution and high sensitivity PET detector. In the AX-PET implementation, arrays of wavelength shifting (WLS) strips, placed orthogonally behind every crystal layer, are used to define the axial coordinate. After extensive characterization measurements, the AX-PET Demonstrator has been successfully used for the reconstruction of several phantoms and a few rodents. Possible extensions of the AX-PET concept towards Time Of Flight capabilities have been investigated, using Philips digital SiPMs as alternative photodetector. Promising CRT value…
Usage of moving nanoparticles for improved holographic recording
2013
Metal nanoparticles are used for different applications in holographic configurations. The metal nanoparticles are placed close to an object and encode it by a time varying random mask. A decoding mask is computed and used to obtain super-resolution digital hologram and eliminate the twin image and DC from a digital hologram. The method is also shown to be applicable for other optical methods.
Magnetic Field Gradiometer with Sub-Micron Spatial Resolution Based on Caesium Vapour in an Extremely Thin Cell
2015
Abstract In this paper we present a device for measuring the magnetic field and its gradient with a spatial resolution of several hundred nanometres. This device is based on caesium metal vapour confined to an extremely thin cell (ETC). To measure magnetic signals, we use absorption and very low laser powers, which might be appealing for modern fabrication techniques. A portable, fully automated device was constructed.
Simultaneous dual mode imaging platform in lensless holographic microscopy
2019
We present a novel layout capable of dual mode imaging in real time with different magnifications and resolution capabilities in lensless microscopy based on wavelength multiplexing. Experiments using static and dynamic samples are included.
Photoemission Electron Microscopy as a tool for the investigation of optical near fields
2005
Photoemission electron microscopy was used to image the electrons photoemitted from specially tailored Ag nanoparticles deposited on a Si substrate (with its native oxide SiO$_{x}$). Photoemission was induced by illumination with a Hg UV-lamp (photon energy cutoff $\hbar\omega_{UV}=5.0$ eV, wavelength $\lambda_{UV}=250$ nm) and with a Ti:Sapphire femtosecond laser ($\hbar\omega_{l}=3.1$ eV, $\lambda_{l}=400$ nm, pulse width below 200 fs), respectively. While homogeneous photoelectron emission from the metal is observed upon illumination at energies above the silver plasmon frequency, at lower photon energies the emission is localized at tips of the structure. This is interpreted as a signat…
Resolution enhancement and orders separation in on-axis nanoparticles based digital holography
2013
A method for eliminating the unwanted terms in an on axis hologram is presented. Free randomly distributed nanoparticles are used to encode and later on to decode/separate the desired term from the unwanted aberrations.
Femtosecond time-resolved photoemission electron microscopy operated at sample illumination from the rear side
2019
We present an advanced experimental setup for time-resolved photoemission electron microscopy (PEEM) with sub-20 fs resolution, which allows for normal incidence and highly local sample excitation with ultrashort laser pulses. The scheme makes use of a sample rear side illumination geometry that enables us to confine the sample illumination spot to a diameter as small as 6 μm. We demonstrate an operation mode in which the spatiotemporal dynamics following a highly local excitation of the sample is globally probed with a laser pulse illuminating the sample from the front side. Furthermore, we show that the scheme can also be operated in a time-resolved normal incidence two-photon PEEM mode w…