304,666 research outputs found
Near-Infrared Super Resolution Imaging with Metallic Nanoshell Particle Chain Array
We propose a near-infrared super resolution imaging system without a lens or
a mirror but with an array of metallic nanoshell particle chain. The imaging
array can plasmonically transfer the near-field components of dipole sources in
the incoherent and coherent manners and the super resolution images can be
reconstructed in the output plane. By tunning the parameters of the metallic
nanoshell particle, the plasmon resonance band of the isolate nanoshell
particle red-shifts to the near-infrared region. The near-infrared super
resolution images are obtained subsequently. We calculate the field intensity
distribution at the different planes of imaging process using the finite
element method and find that the array has super resolution imaging capability
at near-infrared wavelengths. We also show that the image formation highly
depends on the coherence of the dipole sources and the image-array distance.Comment: 15 pages, 6 figure
Near-infrared and Mid-infrared Spectroscopy with the Infrared Camera (IRC) for AKARI
The Infrared Camera (IRC) is one of the two instruments on board the AKARI
satellite. In addition to deep imaging from 1.8-26.5um for the pointed
observation mode of the AKARI, it has a spectroscopic capability in its
spectral range. By replacing the imaging filters by transmission-type
dispersers on the filter wheels, it provides low-resolution (lambda/d_lambda ~
20-120) spectroscopy with slits or in a wide imaging field-of-view
(approximately 10'X10'). The IRC spectroscopic mode is unique in space infrared
missions in that it has the capability to perform sensitive wide-field
spectroscopic surveys in the near- and mid-infrared wavelength ranges. This
paper describes specifications of the IRC spectrograph and its in-orbit
performance.Comment: 13 pages, 7 figures, accepted for publication on PAS
Spitzer Mid-Infrared Imaging of Nearby Ultraluminous Infrared Galaxies
We have observed 14 nearby (z<0.16) Ultraluminous Infrared Galaxies (ULIRGs)
with Spitzer at 3.6-24 microns. The underlying host galaxies are well-detected,
in addition to the luminous nuclear cores. While the spatial resolution of
Spitzer is poor, the great sensitivity of the data reveals the underlying
galaxy merger remnant, and provides the first look at off-nuclear mid-infrared
activity.Comment: To appear in the conference proceedings for Spitzer New Views of the
Universe, held Nov. 2004 in Pasadena, C
High Resolution Mid-Infrared Imaging of Ultraluminous Infrared Galaxies
Observations of ultraluminous infrared galaxies (ULIRGs) with an achieved
resolution approaching the diffraction limit in the mid-infrared from 8 - 25
m using the Keck Telescopes are reported. We find extremely compact
structures, with spatial scales of (diameter) in six of the seven
ULIRGs observed. These compact sources emit between 30% and 100% of the
mid-infrared energy from these galaxies. We have utilized the compact
mid-infrared structures as a diagnostic of whether an AGN or a compact (100 --
300 pc) starburst is the primary power source in these ULIRGs. In Markarian
231, the upper limit on the diameter of the 12.5 m source, 0.13, shows
that the size of the infrared source must increase with increasing wavelength,
consistent with AGN models. In IRAS 05189-2524 and IRAS 08572+3915 there is
strong evidence that the source size increases with increasing wavelength. This
suggests heating by a central source rather than an extended luminosity source,
consistent with the optical classification as an AGN. The compact mid-infrared
sources seen in the other galaxies cannot be used to distinguish the ultimate
luminosity source. If these ULIRGs are powered by compact starbursts, the star
formation rates seen in the central few hundred parsecs far exceed the global
rates seen in nearby starburst galaxies, and approach the surface brightness of
individual clusters in nearby starburst galaxies.Comment: 33pages, 6 tables, 5 figures, Accepted for publication in A
Evaluation of time-series registration methods in dynamic area telethermometry for breast cancer detection
Automated motion reduction in 3D dynamic infrared imaging is on demand in many applications. Few methods for registering time-series dynamic infrared frames have been proposed. Almost all such methods are feature based algorithms requiring manual intervention. We apply different automated registration methods based on spatial displacement to 11 datasets of Breast Dynamic Infrared Imaging (DIRI) and evaluate the results in terms of both the image similarity and anatomical consistency of the transformation. The aim is to optimize the registration strategy for breast DIRI in order to improve the spectral analysis of temperature modulation; thus facilitating the acquisition procedure in a Dynamic Area Telethermometry framework. The results show that symmetric diffeomorphic demons registration outperforms both warped frames similarity and smoothness of deformation fields; hence proving effective for time-series dynamic infrared registratio
Probing the Nuclear and Circumnuclear Activity of NGC1365 in the Infrared
We present new far-infrared (70-500micron) Herschel PACS and SPIRE imaging
observations as well as new mid-IR Gemini/T-ReCS imaging (8.7 and 18.3micron)
and spectroscopy of the inner Lindblad resonance (ILR) region (R<2.5kpc) of the
spiral galaxy NGC1365. We complemented these observations with archival Spitzer
imaging and spectral mapping observations. The ILR region of NGC1365 contains a
Seyfert 1.5 nucleus and a ring of star formation with an approximate diameter
of 2kpc. The strong star formation activity in the ring is resolved by the
Herschel/PACS imaging data, as well as by the Spitzer 24micron continuum
emission, [NeII]12.81micron line emission, and 6.2 and 11.3micron PAH emission.
The AGN is the brightest source in the central regions up to lambda~24micron,
but it becomes increasingly fainter in the far-infrared when compared to the
emission originating in the infrared clusters (or groups of them) located in
the ring. We modeled the AGN unresolved infrared emission with the CLUMPY torus
models and estimated that the AGN contributes only to a small fraction (~5%) of
the infrared emission produced in the inner ~5kpc. We fitted the non-AGN
24-500micron spectral energy distribution of the ILR region and found that the
dust temperatures and mass are similar to those of other nuclear and
circumnuclear starburst regions. Finally we showed that within the ILR region
of NGC1365 most of the on-going star formation activity is taking place in
dusty regions as probed by the 24micron emission.Comment: Accepted for publication in MNRA
Infrared Space Observatory Polarimetric Imaging of the Egg Nebula (RAFGL 2688)
We present polarimetric imaging of the protoplanetary nebula RAFGL 2688
obtained at 4.5 microns with the Infrared Space Observatory (ISO). We have
deconvolved the images to remove the signature of the point spread function of
the ISO telescope, to the extent possible. The deconvolved 4.5 micron image and
polarimetric map reveal a bright point source with faint, surrounding
reflection nebulosity. The reflection nebula is brightest to the
north-northeast, in agreement with previous ground- and space-based infrared
imaging. Comparison with previous near-infrared polarimetric imaging suggests
that the polarization of starlight induced by the dust grains in RAFGL 2688 is
more or less independent of wavelength between 2 microns and 4.5 microns. This,
in turn, indicates that scattering dominates over thermal emission at
wavelengths as long as ~5 microns, and that the dust grains have characteristic
radii < 1 micron.Comment: 27 pages, 9 figures; to appear in the Astronomical Journal, May 2002
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