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- 2019
- 2018
- infrared image
- target detection
- lucas–kanade method (LK)
- local contrast method (LCM)
- facet model
- target detection
- zero-crossing point
- Image processing
- Infrared camera
- Eye movement
- Optoelectronic Information Science and Engineering
- Chinese Academy of Sciences
- Gunma University
- University of Chinese Academy of Science
- Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Science
- University of Science and Technology of China
- Space Star Technology Co. LTD
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A Novel Near-infrared Hyperspectral Absorption/Scattering Imaging Method using Multiple Ground Plates for Evaluating Polymer Composites
摘要： This paper proposes a nondestructive method of evaluating polymer composites using near-infrared (NIR) diffuse reflection spectroscopy with multiple ground plates. Wavelength-dependent absorption and reduced scattering coefficients were acquired to evaluate the chemical structure and the concentration of the substances from absorption and to determine the size and the dispersity of filler in the polymer domain from scattering. NIR spectra of the sample were measured on multiple ground plates, namely, “ground-plate-dependent” diffuse reflection spectra. The effects of the external reflection on the ground-plate-dependent diffuse reflection spectra were subsequently removed. The internal reflection coefficient was calculated based on the difference between the diffuse reflectances of the neat resin and ground plates without prior information of the incident angle of light and the refractive index of sample. The external reflection coefficient was evaluated by the gap of diffuse reflectances between the sample and a white ground plate. After the corrections of reflections, the spectra were fitted by a physical model of light propagation based on the two-flex theory to acquire the absorption and the reduced scattering coefficients. The calculated absorption coefficients indicated a good linear relationship with particle concentration. The calculated reduced scattering coefficients agreed with the theoretical values by Mie scattering theory. It was demonstrated that the proposed method achieved to the simultaneous evaluation of particulate-filler concentrations and sizes in polymer composites.
关键词： Near-infrared,Hyperspectral imaging,Absorption,Scattering,Polymer composites
更新于2025-09-04 15:30:14
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A novel experimental approach for liver analysis in rats exposed to Bisphenol A by means of LC-mass spectrometry and infrared spectroscopy
摘要： An innovative complementary approach using a liquid chromatographic-mass spectrometer method and infrared spectroscopy is proposed for measuring internal biological exposure to dangerous chemical contaminants and for monitoring biochemical changes in target organs. The proposed methodologies were validated and applied in the case of rats exposed to low-doses of Bisphenol A (BPA). A liquid chromatographic method coupled to a tandem mass spectrometer was used in order to measure BPA concentration in rat livers. BPA was detected at different levels in all liver samples from BPA-treated rats, although the exposure dose was the same in all treated animals, and also from control rats, highlighting the difficulties in eliminating external uncontrolled exposure and the need for internal biological monitoring. Fourier Transform Infrared analysis was applied to detect structural changes occurring in several molecules (lipids, proteins, carbohydrates and nucleic acids) as well as the presence of specific metabolic processes. The spectroscopic analyses clearly demonstrated a different lipid composition more than an evident lipid accumulation and a glycogen accumulation decrease, revealing a metabolic disturbance in livers with a normal histological aspect. These results demonstrated the potential of an integrated approach based on mass spectrometry and infrared spectroscopy to evaluate at an early stage the hepatotoxic effect of BPA exposure in an animal model. This approach can be usefully exploited in all the investigations aimed to provide better information concerning the interrelationships between contaminant exposure, dose, and health effects.
关键词： Bisphenol A exposure,Metabolic disturbance,Rat liver,Mass spectrometry,Infrared spectroscopy
更新于2025-09-04 15:30:14
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Structure and Properties of Gallium-Rich Sodium Germano-Gallate Glasses
摘要： Glass compositions in the gallium-rich region of the ternary GaO3/2-GeO2-NaO1/2 vitreous system are studied as a function of the Na/Ga cationic ratio (ranging from 1.30 to 1.61) for a fixed GeO2 content. Glass structures are investigated by 71Ga MAS-NMR, infrared and Raman spectroscopies, and the thermal, optical and physical properties are characterized. Vibrational spectra are interpreted with the help of density functional theory (DFT) calculations. Gallium oxide generally enters the germania network in four-fold coordination, however for Na/Ga ratio below unity, gallium cations tend to charge balance with the formation of 5- or 6-fold coordination units. When the amount of sodium is greater than gallium, non-bridging oxygens (NBOs) are formed preferably on germanate tetrahedral units. These structural descriptions are used to understand the evolution of glass properties such as glass transition temperature, density and refractive index.
关键词： germano-gallate glasses,infrared,vibrational spectroscopy,glass structure,71Ga NMR spectroscopy
更新于2025-09-04 15:30:14
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Er3+-to-Yb3+ and Pr3+-to-Yb3+ energy transfer for highly efficient near-infrared cryogenic optical temperature sensing
摘要： Here, the very high thermal sensing capability of Er3+,Yb3+ doped LaF3 nanoparticles, where Er3+-to-Yb3+ energy transfer is used, are reported. Also Pr3+,Yb3+ doped LaF3 nanoparticles, with Pr3+-to-Yb3+ energy transfer, showed temperature sensing in the same temperature regime, but with lower performance. The investigated Er3+,Yb3+ doped LaF3 nanoparticles show a remarkably high relative sensitivity Sr up to 6.6092 %K-1 (at 15K) in the near-infrared (NIR), in the cryogenic (15 – 105K) temperature region opening a whole new thermometric system suitable for advanced applications in the very low temperature ranges. Up to date reports on NIR cryogenic sensors are very scarce.
关键词： near-infrared,Pr3+-to-Yb3+ energy transfer,Er3+-to-Yb3+ energy transfer,LaF3 nanoparticles,cryogenic temperature sensing
更新于2025-09-04 15:30:14
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Towards a nanophotonic nose: a compressive sensing-enhanced, optoelectronic mid-infrared spectrometer
摘要： Infrared (IR) spectroscopy has been a central tool for chemical analysis for decades, useful in a wide range of fields for the detection and quantification of molecules based on their unique vibrational resonances. Conventional IR spectroscopy relies on bulky, dispersive optics, however, making portability and miniaturization a substantial challenge. Here we demonstrate a micron-scale IR spectrometer where spectrally selective detection is performed optoelectronically, based on the wavelength-dependent mid-IR photocurrent responses of an array of Al grating-based detectors fabricated on a doped Si substrate. Compressive sensing techniques extend our resolution, enabling spectral features to be identified with a remarkably small number of detectors. This work demonstrates a CMOS-compatible, readily scalable approach for the fabrication of compact, room-temperature IR spectrometers capable of use in fieldable applications.
关键词： miniature,aluminum,infrared,super-resolution,compressive sensing,Spectroscopy
更新于2025-09-04 15:30:14
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Benchmarking the calculation of stochastic heating and emissivity of dust grains in the context of radiative transfer simulations
摘要： Context. Thermal emission by stochastically heated dust grains (SHGs) plays an important role in the radiative transfer (RT) problem for a dusty medium. It is therefore essential to verify that RT codes properly calculate the dust emission before studying the effects of spatial distribution and other model parameters on the simulated observables. Aims. We define an appropriate problem for benchmarking dust emissivity calculations in the context of RT simulations, specifically including the emission from SHGs. Our aim is to provide a self-contained guide for implementors of such functionality and to offer insight into the effects of the various approximations and heuristics implemented by the participating codes to accelerate the calculations. Methods. The benchmark problem definition includes the optical and calorimetric material properties and the grain size distributions for a typical astronomical dust mixture with silicate, graphite, and PAH components. It also includes a series of analytically defined radiation fields to which the dust population is to be exposed and instructions for the desired output. We processed this problem using six RT codes participating in this benchmark effort and compared the results to a reference solution computed with the publicly available dust emission code DustEM. Results. The participating codes implement different heuristics to keep the calculation time at an acceptable level. We study the effects of these mechanisms on the calculated solutions and report on the level of (dis)agreement between the participating codes. For all but the most extreme input fields, we find agreement within 10% across the important wavelength range 3 μm ≤ λ ≤ 1000 μm. Conclusions. We conclude that the relevant modules in RT codes can and do produce fairly consistent results for the emissivity spectra of SHGs. This work can serve as a reference for implementors of dust RT codes, and it will pave the way for a more extensive benchmark effort focusing on the RT aspects of the various codes.
关键词： dust, extinction,radiative transfer,infrared: ISM,methods: numerical,radiation mechanisms: thermal
更新于2025-09-04 15:30:14
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CRIRES-POP: a library of high resolution spectra in the near-infrared
摘要： Context. High resolution stellar spectral atlases are valuable resources to astronomy. They are rare in the 1?5 μm region for historical reasons, but once available, high resolution atlases in this part of the spectrum will aid the study of a wide range of astrophysical phenomena. Aims. The aim of the CRIRES-POP project is to produce a high resolution near-infrared spectral library of stars across the H-R diagram. The aim of this paper is to present the fully reduced spectrum of the K giant 10 Leo that will form the basis of the first atlas within the CRIRES-POP library, to provide a full description of the data reduction processes involved, and to provide an update on the CRIRES-POP project. Methods. All CRIRES-POP targets were observed with almost 200 different observational settings of CRIRES on the ESO Very Large Telescope, resulting in a basically complete coverage of its spectral range as accessible from the ground. We reduced the spectra of 10 Leo with the CRIRES pipeline, corrected the wavelength solution and removed telluric absorption with Molecfit, then resampled the spectra to a common wavelength scale, shifted them to rest wavelengths, flux normalised, and median combined them into one final data product. Results. We present the fully reduced, high resolution, near-infrared spectrum of 10 Leo. This is also the first complete spectrum from the CRIRES instrument. The spectrum is available online. Conclusions. The first CRIRES-POP spectrum has exceeded our quality expectations and will form the centre of a state-of-the-art stellar atlas. This first CRIRES-POP atlas will soon be available, and further atlases will follow. All CRIRES-POP data products will be freely and publicly available online.
关键词： infrared: stars,atlases,atmospheric effects,stars: atmospheres,techniques: spectroscopic,stars: late-type
更新于2025-09-04 15:30:14
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Optical spectroscopy of the microquasar GRS 1758?258: a possible intermediate mass system?
摘要： Context. GRS 1758?258 is one of two prototypical microquasars towards the Galactic center direction discovered almost a quarter of a century ago. The system remains poorly studied in the optical domain due to its counterpart being a very faint and absorbed target in a crowded region of the sky. Aims. Our aim is to investigate GRS 1758?258 in order to shed light on the nature of the stellar binary components. In particular, the main physical parameters of the donor star, such as the mass or the spectral type, are not yet well constrained. Methods. GRS 1758?258 has remained so far elusive to optical spectroscopy owing to its observational di?culties. Here, we use this traditional tool of stellar astronomy at low spectral resolution with a 10 m class telescope and a long slit spectrograph. Results. An improved spectrum is obtained as compared to previous work. The quality of the data does not allow the detection of emission or absorption features but, nevertheless, we manage to partially achieve our aims comparing the de-reddened continuum with the spectral energy distribution expected from an irradiated disc model and di?erent donor star templates. Conclusions. We tentatively propose that GRS 1758?258 does not host a giant star companion. Instead, a main sequence star with mid-A spectral type appears to better agree with our data. The main impacts of this ?nding are the possibility that we are dealing with an intermediate mass system and, in this case, the prediction of an orbital period signi?cantly shorter than previously proposed.
关键词： X-rays: binaries,stars: individual: GRS 1758-258,infrared: stars
更新于2025-09-04 15:30:14
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Towards a census of high-redshift dusty galaxies with Herschel
摘要： Context. Over the last decade a large number of dusty star-forming galaxies has been discovered up to redshift z = 2 ? 3 and recent studies have attempted to push the highly confused Herschel SPIRE surveys beyond that distance. To search for z ≥ 4 galaxies they often consider the sources with ?uxes rising from 250 μm to 500 μm (so-called “500 μm-risers”). Herschel surveys offer a unique opportunity to ef?ciently select a large number of these rare objects, and thus gain insight into the prodigious star-forming activity that takes place in the very distant Universe. Aims. We aim to implement a novel method to obtain a statistical sample of 500 μm-risers and fully evaluate our selection inspecting different models of galaxy evolution. Methods. We consider one of the largest and deepest Herschel surveys, the Herschel Virgo Cluster Survey. We develop a novel selection algorithm which links the source extraction and spectral energy distribution ?tting. To fully quantify selection biases we make end-to-end simulations including clustering and lensing. Results. We select 133 500 μm-risers over 55 deg2, imposing the criteria: S 500 > S 350 > S 250, S 250 > 13.2 mJy and S 500 > 30 mJy. Differential number counts are in fairly good agreement with models, displaying a better match than other existing samples. The estimated fraction of strongly lensed sources is 24+6 Conclusions. We present the faintest sample of 500 μm-risers down to S 250 = 13.2 mJy. We show that noise and strong lensing have an important impact on measured counts and redshift distribution of selected sources. We estimate the ?ux-corrected star formation rate density at 4 < z < 5 with the 500 μm-risers and ?nd it to be close to the total value measured in far-infrared. This indicates that colour selection is not a limiting effect to search for the most massive, dusty z > 4 sources.
关键词： galaxies: photometry,galaxies: evolution,galaxies: statistics,galaxies: high-redshift,infrared: galaxies,galaxies: star formation
更新于2025-09-04 15:30:14
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Rembrandt's <i>An Old Man in Military Costume</i> : Combining hyperspectral and MA-XRF imaging to understand how two paintings were painted on a single panel
摘要： Over the past several decades the painting An Old Man in Military Costume by Rembrandt Harmensz van Rijn (ca. 1630–31; J. Paul Getty Museum, 78.PB.246) has been the subject of a number of investigations carried out in order to better visualize a second painting beneath the surface figure. The underlying image – the head and shoulders of a man wearing a cloak – is oriented 180 degrees from the upper image and appears to be fairly complete. Scanning macro x-ray fluorescence (XRF) spectroscopy reveals the face is painted with lead white and a mercury-(likely vermilion), and the cloak is painted with a copper-containing pigment. Following the revelation and digital color reconstruction of the underlying figure, a number of questions still remained. Here, through the use of infrared reflectance imaging spectroscopy (i.e., hyperspectral imaging) and macro-XRF imaging spectroscopy, together with cross-sections taken from targeted areas, the sequence of painting in both compositions was explored. Of particular interest was the discovery of evidence of multiple attempts to situate the lower figure, and the subsequent application of a blocking-out layer over the lower figure before the artist rotated the panel and executed the upper figure. In addition, examination of the placement of the two images on the panel adds to our understanding of the subtle complexities of Rembrandt’s working process.
关键词： re-use of painting supports,Early Rembrandt,infrared reflectance imaging spectroscopy,X-ray fluorescence imaging spectroscopy
更新于2025-09-04 15:30:14