Broad band optical band-reject filters in near-infrared regime utilizing bilayer Ag metasurface

2017 ◽  
Vol 121 (15) ◽  
pp. 153105 ◽  
Author(s):  
X. L. Hu ◽  
L. B. Sun ◽  
Q. J. Wu ◽  
L. S. Wang ◽  
S. A. Bai ◽  
...  
Keyword(s):  
Near Infrared ◽  
Broad Band

Ab Initio Two-sites Occupancy and Broadband Near-Infrared Emission of Cr3+ in Li2MgZrO4

2021 ◽  
Author(s):  
Xue Zhou ◽  
Jinmeng Xiang ◽  
Jiming Zheng ◽  
Xiaoqi Zhao ◽  
Hao Suo ◽  
...  
Keyword(s):  
Plant Growth ◽  
Ab Initio ◽  
Light Source ◽  
Near Infrared ◽  
Broad Band ◽  
Infrared Emission ◽  
Night Vision ◽  
Light Emitting ◽  
Non Destructive ◽  
Near Infrared Emission

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) light source have great potential in non-destructive detection, promoting plant growth and night vision applications, while the discovery of a broad-band NIR phosphor still...

scholarly journals Final design and on-sky testing of the iLocater SX acquisition camera: broad-band single-mode fibre coupling

2020 ◽  
Vol 501 (2) ◽  
pp. 2250-2267
Author(s):  
J Crass ◽  
A Bechter ◽  
B Sands ◽  
D King ◽  
R Ketterer ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
Broad Band ◽  
Single Mode ◽  
Injection System ◽  
Single Mode Fibre ◽  
Astronomical Instruments ◽  
Final Design ◽  
Camera Design ◽  
And Performance

ABSTRACT Enabling efficient injection of light into single-mode fibres (SMFs) is a key requirement in realizing diffraction-limited astronomical spectroscopy on ground-based telescopes. SMF-fed spectrographs, facilitated by the use of adaptive optics (AO), offer distinct advantages over comparable seeing-limited designs, including higher spectral resolution within a compact and stable instrument volume, and a telescope independent spectrograph design. iLocater is an extremely precise radial velocity (EPRV) spectrograph being built for the Large Binocular Telescope (LBT). We have designed and built the front-end fibre injection system, or acquisition camera, for the SX (left) primary mirror of the LBT. The instrument was installed in 2019 and underwent on-sky commissioning and performance assessment. In this paper, we present the instrument requirements, acquisition camera design, as well as results from first-light measurements. Broad-band SMF coupling in excess of 35 per cent (absolute) in the near-infrared (0.97–1.31 ${\mu {\rm m}}$) was achieved across a range of target magnitudes, spectral types, and observing conditions. Successful demonstration of on-sky performance represents both a major milestone in the development of iLocater and in making efficient ground-based SMF-fed astronomical instruments a reality.

Reflectance characteristics of cumulative defoliation of balsam fir

1988 ◽  
Vol 18 (8) ◽  
pp. 1008-1016 ◽  
Author(s):  
D. G. Leckie ◽  
P. M. Teillet ◽  
G. Fedosejevs ◽  
D. P. Ostaff
Keyword(s):  
Near Infrared ◽  
Spectral Characteristics ◽  
Broad Band ◽  
Integrating Sphere ◽  
Simple Relationship ◽  
Spectral Bands ◽  
Infrared Wavelengths ◽  
Remote Sensing Techniques ◽  
Middle Infrared ◽  
Airborne Sensors

Knowledge of the spectral characteristics of trees with varying degrees of needle loss is essential for developing remote sensing techniques for assessing defoliation. Spectra covering the range 400–2400 nm were acquired for single tree crowns suffering varying degrees of cumulative defoliation due to the spruce budworm (Choristoneurafumiferana (Clem.)), using a spectrometer mounted in the bucket of a boom truck. Spectra over the range 360–1100 nm were also obtained for the components of defoliated trees (i.e., needles, bare branches, and lichen), using a separate spectrometer and integrating sphere. Estimates of defoliation symptoms of each tree were made from the ground and above the tree. Changes in reflectance had a close and simple relationship with the defoliation symptoms measured. The spectral differences due to cumulative defoliation that were observed were broad-band features. The best spectral regions for differentiating levels of cumulative defoliation symptoms were the blue, red, shorter near-infrared wavelengths, and middle-infrared. Although currently available satellite and airborne sensors operate in these spectral regions, defoliation assessment may be improved by the use of optimized spectral bands.

Design and fabrication of 0.6-1.55 μm visible/near infrared ultra-broad band antireflection coatings

2012 ◽  
Vol 5 (3) ◽  
pp. 270-287
Author(s):  
杨道奇 YANG Dao-qi ◽  
付秀华 FU Xiu-hua ◽  
耿似玉 GENG Si-yu ◽  
杨永亮 YANG Yong-liang ◽  
潘永刚 PAN Yong-gang
Keyword(s):  
Near Infrared ◽  
Broad Band ◽  
Antireflection Coatings

scholarly journals The Star Formation Region Associated with the Cometary Nebula GM24

1987 ◽  
Vol 115 ◽  
pp. 188-188
Author(s):  
M. Tapia ◽  
M. Roth ◽  
L.F. Rodríguez ◽  
J. Cantó ◽  
P. Persi ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Near Infrared ◽  
Broad Band ◽  
Large Temperature ◽  
Stellar Objects ◽  
Star Formation Region ◽  
The Past ◽  
Visible Part ◽  
H Ii Region

GM24 is a small visible nebulosity in the vicinity of a molecular cloud. In this contribution we present the results of continuum (6-cm) and CO line (J = 1 → 0) radio observations, infrared maps, broad-band photometry and low-resolution spectroscopy as well as long-slit Echelle Ha spectroscopy. We found evidence that the GM24 = PP85 nebula is part of a larger region where star formation occurred in the past 104 years; the region is embedded in a typical molecular cloud with a dimension of ∼ 10 pc and mass of ∼104 M⊙. A compact radio H II region seems to be associated with GM24 and with one of the mid-infrared peaks detected. The nebula is most probably the visible part of an embedded H II region that is starting to emerge from the cloud. The other infrared peaks found in its vicinity (∼ 1 pc) are probably associated with less evolved stellar objects. The complex also shows an extended near-infrared flux which we believe to arise in a reflection nebula. From energy arguments, we found that the luminosity required to power the H II region and keep the cloud at the observed large temperature (TK ≅33 K), is ∼105 L⊙ which is consistent with the infrared total flux from the present measurements and those from IRAS of 4x104 L⊙; this corresponds to the flux of ∼3 BO ZAMS stars. The details of the present work have appeared in the Revista Mexicana de Astronomía y Astrofísica, Volume 11, 83, 1985.

scholarly journals Orientation effects on the near-infrared broad-band emission of quasars

2019 ◽  
Vol 485 (1) ◽  
pp. 1405-1411 ◽  
Author(s):  
Susanna Bisogni ◽  
Elisabeta Lusso ◽  
Alessandro Marconi ◽  
Guido Risaliti
Keyword(s):  
Near Infrared ◽  
Broad Band ◽  
Broad Band Emission ◽  
Band Emission ◽  
Orientation Effects

scholarly journals The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy PKS J1222+0413

2019 ◽  
Vol 487 (1) ◽  
pp. 181-197 ◽  
Author(s):  
Daniel Kynoch ◽  
Hermine Landt ◽  
Martin J Ward ◽  
Chris Done ◽  
Catherine Boisson ◽  
...  
Keyword(s):  
Near Infrared ◽  
Uv Spectroscopy ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Physical Models ◽  
Spectral Energy ◽  
Narrow Line ◽  
Relativistic Jet ◽  
Γ Ray ◽  
Apply Physical

ABSTRACT We present a multifrequency study of PKS J1222+0413 (4C +04.42), currently the highest redshift γ-ray emitting narrow-line Seyfert 1 (γ-NLS1). We assemble a broad spectral energy distribution (SED) including previously unpublished datasets: X-ray data obtained with the NuSTAR and Neil Gehrels Swift observatories; near-infrared, optical, and UV spectroscopy obtained with VLT X-shooter; and multiband radio data from the Effelsberg telescope. These new observations are supplemented by archival data from the literature. We apply physical models to the broad-band SED, parametrizing the accretion flow and jet emission to investigate the disc–jet connection. PKS J1222+0413 has a much greater black hole mass than most other NLS1s, MBH ≈ 2 × 108 M$\odot$, similar to those found in flat spectrum radio quasars (FSRQs). Therefore this source provides insight into how the jets of γ-NLS1s relate to those of FSRQs.

scholarly journals Surrogate modelling the Baryonic Universe – I. The colour of star formation

2020 ◽  
Vol 495 (2) ◽  
pp. 2088-2104
Author(s):  
Jonás Chaves-Montero ◽  
Andrew Hearin
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Principal Component ◽  
Major Axis ◽  
Sloan Digital Sky Survey ◽  
Star Formation History ◽  
Spectral Energy ◽  
Colour Space

ABSTRACT The spectral energy distribution of a galaxy emerges from the complex interplay of many physical ingredients, including its star formation history (SFH), metallicity evolution, and dust properties. Using galaxpy, a new galaxy spectral prediction tool, and SFHs predicted by the empirical model universemachine and the cosmological hydrodynamical simulation IllustrisTNG, we isolate the influence of SFH on optical and near-infrared colours from 320 to 1080 Å at z = 0. By carrying out a principal component analysis, we show that physically motivated SFH variations modify galaxy colours along a single direction in colour space: the SFH-direction. We find that the projection of a galaxy’s present-day colours on to the SFH-direction is almost completely regulated by the fraction of stellar mass that the galaxy formed over the last billion years. Together with cosmic downsizing, this results in galaxies becoming redder as their host halo mass increases. We additionally study the change in galaxy colours due to variations in metallicity, dust attenuation, and nebular emission lines, finding that these properties vary broad-band colours along distinct directions in colour space relative to the SFH-direction. Finally, we show that the colours of low-redshift Sloan Digital Sky Survey galaxies span an ellipsoid with significant extent along two independent dimensions, and that the SFH-direction is well-aligned with the major axis of this ellipsoid. Our analysis supports the conclusion that variations in SFH are the dominant influence on present-day galaxy colours, and that the nature of this influence is strikingly simple.

scholarly journals The surface albedo of the Greenland ice sheet: satellite-derived and in situ measurements in the Søndre Strømfjord area during the 1991 melt season

1996 ◽  
Vol 42 (141) ◽  
pp. 364-374 ◽  
Author(s):  
Wouter H. Knap ◽  
Johannes Oerlemans
Keyword(s):  
Surface Albedo ◽  
Near Infrared ◽  
Broad Band ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Zone Ii ◽  
High Degree ◽  
Pixel Scale ◽  
Very High

AbstractThe temporal and spatial variation in the surface albedo of the Greenland ice sheet during the ablation season of 1991 is investigated. The study focuses on an area east of Søndre Strømfjord measuring 200 km by 200 km and centred at 67°5′ N, 48° 13′W. The analysis is based on satellite radiance measurements carried out by the Advanced Very High Resolution Radiometer (AVHRR). The broad-band albedo is estimated from the albedos in channel 1 (visible) and channel 2 (near-infrared). The results are calibrated with the surface albedo of sea and dry snow.Satellite-derived albedos are compared with GIMEX ground measurements at three stations. There is a high degree of consistency in temporal variation at two of the three stations. Large systematic differences are attributed to albedo variations on sub-pixel scale.In the course of the ablation season four zones appear, each parallel to the ice edge. It is proposed that these are, in order of increasing altitude: (I) clean and dry ice, (II) ice with surface water, (III) superimposed ice, and (IV) snow. An extensive description of these zones is given on the basis of the situation on 25 July 1991. Zones I, III and IV reveal fairly constant albedos (0.46, 0.65 and 0.75 on average), whereas zone II is characterised by an albedo minimum (0.34). Survey of the western margin of the Greenland ice sheet (up to 71° N) shows that the zonation occurs between 66° and 70° N.

Visual and Near-Infrared Photometry of Nearby Dwarf Spheroidals

1999 ◽  
Vol 192 ◽  
pp. 455-458 ◽  
Author(s):  
F. Kerschbaum ◽  
W. Nowotny ◽  
J. Hron ◽  
M. Schultheis
Keyword(s):  
Near Infrared ◽  
Broad Band ◽  
Feasibility Studies ◽  
Asymptotic Giant Branch ◽  
Agb Stars ◽  
Faint Object ◽  
Nearby Galaxies ◽  
Dwarf Spheroidals ◽  
Faint Object Spectrograph ◽  
Infrared Survey

This paper is based on photometry from two different observational approaches. Both are of an explorative character and act as feasibility studies. For the future we plan to use these methods to study Asymptotic Giant Branch (AGB) stars in nearby galaxies.First, we present results on broad-band photometry in Bessell V and I, as well as narrow-band measurements in the Wing 778 nm and 812 nm filters of a galactic globular cluster using the new Austrian Oe-FOSC (Oesterreich Faint Object Spectrograph and Camera), a copy of the ESO Instrument EFOSC mounted on our 1.5 m-telescope.The second part of the contribution deals with the possibilities of using Gunn I, J and KS measurements originating from the DENIS (DEep Near Infrared Survey of the Southern Sky) project on similar objects. A few southern dwarf spheroidals already observed within DENIS (covering now some 40% of the southern hemisphere) are selected.

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