Search results for " Resolution"

The mirror module design for the cryogenic x-ray imaging spectrometer on-board ORIGIN

2011

ORIGIN is a medium size high-energy mission concept submitted to ESA in response to the Cosmic Vision call issued on July 2010. The mission will investigate the evolution of the Universe by performing soft X-ray high resolution spectroscopic measurements of metals formed in different astrophysical environments, from the first population III stars at z > 7 to the present large scale structures. The main instrument on-board ORIGIN will be a large format array of TES X-ray micro-calorimeters covering a FOV of 30' at the focal plane of a grazing incidence optical module with a focal length of 2.5 m and an angular resolution of 30'' HEW at 1 keV. We present the optical module design which is bas…

Strong Exciton-Coherent Phonon Coupling in Single-Layer MoS2

2020

Broadband transient absorption with sub-20fs temporal resolution, supported by ab-initio calculations, quantitatively provides the strength of exciton-coherent phonon coupling in 1L-MoS2, showing a resonant profile around the C exciton.

Impact of crystal quality, geometry and surface finish for 3D impact position measurements in gamma ray detection systems

2007

We have studied several ways of optimizing the 3D impact position measurements for gamma ray imaging detectors based on continuous monolithic large sized and thick scintillation crystals. The readout of such detectors is performed with position sensitive photo multipliers and with a depth of interaction (DOI) enhanced charge division readout. We have studied the effect of the crystal truncation angle, the reflective covering and the absorption and scattering mean free paths of the crystal. In particular, we have simulated and measured the impact on the energy resolution and the 3D spatial resolution. The results show that by optimization of the accessible crystal parameters we can enhance t…

Enhanced depth of field integral imaging with sensor resolution constraints.

2009

One of the main challenges in integral imaging is to overcome the limited depth of field. Although it is widely assumed that such limitation is mainly imposed by diffraction due to lenslet imaging, we show that the most restricting factor is the pixelated structure of the sensor (CCD). In this context, we demonstrate that by proper reduction of the fill factor of pickup microlenses, the depth of field can be substantially improved with no deterioration of lateral resolution.

Far-field light imaging in the presence of atmospheric turbulence with rotating anti-phase apertures: Theoretical investigation

2017

We investigated the diffraction of far-field light objects in the presence of turbulence formed by an optical system with a rotating anti-phase mask. This mask facilitates to detect the position of faint companion in every direction around the bright companion. In the presence of atmospheric turbulence, diffraction images of distant objects are beyond the diffraction limits, the proposed phase shift mask has a merit to compensate the turbulence results high contrast astronomical imaging under partially coherent light illumination and it is proficient to increase the resolution limits in a Sparrow criterion sense. In this approach, we demonstrated the mask fabrication in laboratory condition…

Resolution enhancement in quantitative phase microscopy

2019

Quantitative phase microscopy (QPM), a technique combining phase imaging and microscopy, enables visualization of the 3D topography in reflective samples, as well as the inner structure or refractive index distribution of transparent and translucent samples. Similar to other imaging modalities, QPM is constrained by the conflict between numerical aperture (NA) and field of view (FOV): an imaging system with a low NA has to be employed to maintain a large FOV. This fact severely limits the resolution in QPM up to 0.82λ/NA, λ being the illumination wavelength. Consequently, finer structures of samples cannot be resolved by using modest NA objectives in QPM. Aimed to that, many approaches, suc…

2011

Expansion of SN 1993J: New λλ6 and 13 cm images

1997

Abstract Radio supernovae are rare events among supernovae, usually taking place in distant galaxies. In recent years, great progress has been made in the study of radio supernovae with high angular resolution, due to advances in the VLBI technique and to the lucky occurrence of the powerful supernova SN 1993J in M81 only 3.6 Mpc distant. Its spatial structure has been unveiled and its expansion rate determined at 3.6 cm. Here we present new preliminary VLBI results on the expansion of this supernova at 6 and 13 cm. We resolve the shell at both wavelengths. The size estimates at 6 cm indicate a lower expansion rate than previously estimated. This may be the first evidence of deceleration.

All-optical super resolved and extended depth of focus imaging with random pinhole array aperture

2008

In this paper, we present a novel approach which allows combining super resolved imaging with extended depth of focus while the result is obtained by all-optical means and no digital processing is required. The presented approach for the super resolved imaging includes attaching a random pinhole array plate to the aperture plane of the imaging system. The energetic efficiency of the system is high and it is much larger than an imaging through a single pinhole which also has extended depth of focus. The super resolving result is obtained by mechanic scanning of the aperture plane with the random plate.

HINODE /EIS SPECTROSCOPIC VALIDATION OF VERY HOT PLASMA IMAGED WITH THE SOLAR DYNAMICS OBSERVATORY IN NON-FLARING ACTIVE REGION CORES

2012

We use coronal imaging observations with SDO/AIA, and Hinode/EIS spectral data, to explore the potential of narrow band EUV imaging data for diagnosing the presence of hot (T >~5MK) coronal plasma in active regions. We analyze observations of two active regions (AR 11281, AR 11289) with simultaneous AIA imaging, and EIS spectral data, including the CaXVII line (at 192.8A) which is one of the few lines in the EIS spectral bands sensitive to hot coronal plasma even outside flares. After careful coalignment of the imaging and spectral data, we compare the morphology in a 3 color image combining the 171, 335, and 94A AIA spectral bands, with the image obtained for CaXVII emission from the an…