Search results for "Image resolution"
showing 10 items of 377 documents
Performance evaluation of a very high resolution small animal PET imager using silicon scatter detectors
2007
A very high resolution positron emission tomography (PET) scanner for small animal imaging based on the idea of inserting a ring of high-granularity solid-state detectors into a conventional PET scanner is under investigation. A particularly interesting configuration of this concept, which takes the form of a degenerate Compton camera, is shown capable of providing sub-millimeter resolution with good sensitivity. We present a Compton PET system and estimate its performance using a proof-of-concept prototype. A prototype single-slice imaging instrument was constructed with two silicon detectors 1 mm thick, each having 512 1.4 mm x 1.4 mm pads arranged in a 32 x 16 array. The silicon detector…
Measurements with a hybrid detector prototype composed of a MOS CCD and a CZT spectrometer
2008
The scientific objectives of the future X-ray astronomy instruments require new type of focusing telescopes able to extend the observational range starting from 0.1 keV at least up to 100 keV to solve crucial question concerning the nature of the high energy emission. A challenging technology to extend the classical grazing incidence range to higher energy is today offered by the development of multilayer optics that are effective as X-ray concentrators between few keV up to 100 keV. A useful arrangement for this type of mission concept can foresee the soft (e.g. 0.1-10 keV) X-ray optics nested and coaxial with the hard-X mirrors. The focal plane of the telescope shall operate on a very wid…
Wavelength-multiplexed computational temporal ghost imaging
2017
Ghost imaging is a novel imaging technique based on correlation measurements between a structured illumination pattern (the reference) and the total intensity transmitted or reflected by an object [1]. The reference illumination patterns may be either randomly generated by a spatially incoherent light source, or pre-programmed e.g. with a spatial light modulator. Light transmitted (or reflected) by the object is measured by a single-pixel “bucket” detector with null spatial resolution. A unique feature associated with ghost imaging is that (i) neither the bucket detector nor the reference measurement caries enough information to retrieve the object shape and (ii) it is insensitive to distor…
VLTI-PIONIER imaging of the red supergiant V602 Carinae
2020
Context. Red supergiant stars possess surface features and extended molecular atmospheres. Photospheric convection may be a crucial factor of the levitation of the outer atmospheric layers. However, the mechanism responsible is still poorly understood. Aims. We image the stellar surface of V602 Carinae (V602 Car) to constrain the morphology and contrast of the surface features and of the extended atmospheric layers. Methods. We observed V602 Car with the Very Large Telescope Interferometer (VLTI) PIONIER instrument (1.53-1.78 $\mathrm{\mu}$m) between May and July 2016, and April and July 2019 with different telescope configurations. We compared the image reconstructions with 81 temporal sna…
Calibration of the XRT-SOLARB flight filters at the XACT facility of INAF-OAPA
2004
The X-Ray Telescope (XRT) experiment on-board the Japanese satellite SOLAR-B (launch in 2006) aimed at providing full Sun field of view at ~ 1.5" angular resolution, will be equipped with two wheels of focal-plane filters to select spectral features of X-ray emission from the Solar corona, and a front-end filter to significantly reduce the visible light contamination. We present the results of the X-ray calibrations of the XRT flight filters performed at the X-ray Astronomy Calibration and Testing (XACT) facility of INAF-OAPA. We describe the instrumental set-up, the adopted measurement technique, and present the transmission vs. energy and position measurements.
Calibration of the XRT-SOLARB flat mirror samples at the XACT Facility of INAF-OAPA
2004
The X-Ray Telescope (XRT) experiment on-board the Japanese satellite SOLAR-B (launch in 2006) is equipped with a modified Wolter I grazing incidence X-ray telescope (focal length 2700 mm) to image the full Sun at ~ 1.5" angular resolution onto a 2048 x 2048 back illuminated CCD focal plane detector. The X-ray telescope consisting of one single reflecting shell is coated with ion beam sputtered Iridium over a binding layer of Chromium to provide nearly 5 square centimetres effective area at 60 A. We present preliminary results of X-ray calibrations of the XRT flat mirror samples performed at the X-ray Astronomy Calibration and Testing (XACT) facility of INAF-OAPA. We describe the instrumenta…
Development of the wide field imager for Athena
2015
The WFI (Wide Field Imager) instrument is planned to be one of two complementary focal plane cameras on ESA's next X-ray observatory Athena. It combines unprecedented survey power through its large field of view of 40 arcmin x 40 arcmin together with excellent count-rate capability (>= 1 Crab). The energy resolution of the silicon sensor is state-of-the-art in the energy band of interest from 0.2 keV to 15 keV, e.g. the full width at half maximum of a line at 6 keV will be <= 150 eV until the end of the nominal mission phase. This performance is accomplished by using DEPFET active pixel sensors with a pixel size of 130 μm x 130 μm well suited to the on-axis angular resolution of 5 arcsec of…
Resolution and field of view improvement in digital holography using a VCSEL source array
2011
We describe a new implementation capable to produce superresolution (SR) and object field of view (FOV) improvement in digital lensless Fourier holography. The method provides synthetic aperture (SA) generation using angular multiplexing incoming from a Vertical Cavity Surface Emitting Laser (VCSEL) source array. SR imaging in a single exposure is obtained after proper digital processing of a multiplexed hologram coming from the incoherent addition of multiple sub-holograms, each one corresponding with a different source of the VCSEL array. FOV improvement in addition with SR imaging is achieved by recording a set of individual holograms obtained by sequential activation of the VCSEL source…
Parallel Phase-Shifting Digital Holography Based on the Fractional Talbot Effect
2010
Digital holography allows us to record and process digitally the complex amplitude distribution associated to diffracted light beams and therefore has offered new possibilities for a variety of applications such as 3D microscopy, interferometry, or information security (see, for example, review [1]). In principle, phase-shifting techniques are the most efficient in terms of spatial resolution to record digital holograms [2]. However, a sequential acquisition of several interference patterns with different phase retardations of the reference beam is necessary, preventing dynamic measurements. Different techniques for time-resolved dynamic interferometry have been developed allowing one-shot …
Full field of view super-resolution imaging based on two static gratings and white light illumination.
2008
The usage of two static gratings for obtaining super-resolved imaging dates back to the work by Bachl and Lukosz in 1967. However, in their approach a severe reduction in the field of view was the necessary condition for improving the resolution. We present an approach based on two static gratings without sacrificing the field of view. The key idea for not paying with the field of view is to use white light illumination to average the ghost images obtained outside the region of interest since the positions of those images are wavelength dependent. Moreover, large magnification is achieved by using a commercial microscope objective instead of a test system with a unity magnification as prese…