Near-infrared Visibilities Research Articles

Pixelated NIR–VIS Spectral Routers Based on 2D Mie‐Type Metagratings

AbstractThe out‐of‐band energy loss caused by in‐built color filters significantly degrades the signal‐to‐noise ratio and the dynamic range of conventional image sensors, which has restricted the attempt to develop ultrahigh‐density imaging devices by merely shrinking the pixel size. This issue will be more serious for security cameras, which need to collect both visible (VIS) and near‐infrared (NIR) light. The existing solutions mostly explore complex photonic nanostructures, which are often too complicated for production. In this work, a pixelated spectral router is demonstrated utilizing a 2D Si3N4 Mie‐type metagrating that can spatially divide NIR (850 nm) and VIS (400–700 nm) light to different pixels at high efficiencies. It has a minimum feature size larger than 360 nm, highly promising for massive production. Compared with the traditional filter design, this router can gain ≈42% and ≈30% signal enhancement for NIR and VIS bands, respectively. It is shown that it also has good polarization insensitivity and incident angle tolerance. The NIR–VIS simultaneous imaging is inspected without any complex reconstruction algorithm. Mode analysis indicates that the periodic interference of multipolar scattered fields caused by this metagrating provides the necessary degrees of freedom to spatially optimize the routing functions for broadband photons.

A Self-Assembly ICG Nanoparticle Potentiating Targeted Photothermal and Photodynamic Therapy in NSCLC.

In nonsmall cell lung cancers (NSCLC), near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) has proven to be an efficient approach for locating pulmonary nodules and pulmonary sentinel lymph nodes. However, due to a lack of tumor selectivity, ICG's use as a photosensitizer for photothermal therapy (PTT) and photodynamic therapy (PDT) is restricted. In the current study, we aimed to develop a type of high-performance NIR nanoparticle formulated with ICG to enhance its targeted efficacy and tumor specificity on NSCLC. An ICG-osimertinib nanoparticle (ICG-Osi) was self-assembled through π-π stacking, with a size of 276 nm and a surface charge of -7.4 mV. The NIR visibility and epidermal growth factor receptor (EGFR) targetability of the ICG-Osi was confirmed by its binding efficiency to EGFR-expressing NSCLC cells in vitro and in vivo, regardless of EGFR mutation status. The targeted effect was further confirmed in mouse xenograft models and showed an extended tumor retention time (>96 h). We demonstrated a significantly enhanced hyperthermia effect and a retained reactive oxygen species (ROS) generating ability of ICG-Osi, resulting in a 2-fold higher cell death rate than ICG alone. The ICG-Osi down-regulated GPX4 and p62 expression while up-regulating caspase-3 and beclin1 expression in NSCLC cells, indicating a complex network of cell death-related proteins. Considering the merits of simple assembly, EGFR binding efficacy, improved hyperthermia effect, and efficient cancer cell suppression, the ICG-Osi exhibits great potential for clinical application in EGFR-expressing NSCLC therapy.

CDP-GAN: Near-Infrared and Visible Image Fusion Via Color Distribution Preserved GAN

Dear Editor, This letter is concerned with dealing with the great discrepancy between near-infrared (NIR) and visible (VS) image fusion via color distribution preserved generative adversarial network (CDP-GAN). Different from the global discriminator in prior GAN, conflict of preserving NIR details and VS color is resolved by introducing an attention guidance mechanism into the discriminator. Moreover, perceptual loss with adaptive weights increases quality of high-frequency features and helps to eliminate noise appeared in VS image. Finally, experiments are given to validate the proposed method.

Cross-sensor periocular biometrics in a global pandemic: Comparative benchmark and novel multialgorithmic approach

The massive availability of cameras and personal devices results in a wide variability between imaging conditions, producing large intra-class variations and a significant performance drop if images from heterogeneous environments are compared for person recognition purposes. However, as biometric solutions are extensively deployed, it will be common to replace acquisition hardware as it is damaged or newer designs appear or to exchange information between agencies or applications operating in different environments. Furthermore, variations in imaging spectral bands can also occur. For example, face images are typically acquired in the visible (VIS) spectrum, while iris images are usually captured in the near-infrared (NIR) spectrum. However, cross-spectrum comparison may be needed if, for example, a face image obtained from a surveillance camera needs to be compared against a legacy database of iris imagery. Here, we propose a multialgorithmic approach to cope with periocular images captured with different sensors. With face masks in the front line to fight against the COVID-19 pandemic, periocular recognition is regaining popularity since it is the only region of the face that remains visible. As a solution to the mentioned cross-sensor issues, we integrate different biometric comparators using a score fusion scheme based on linear logistic regression This approach is trained to improve the discriminating ability and, at the same time, to encourage that fused scores are represented by log-likelihood ratios. This allows easy interpretation of output scores and the use of Bayes thresholds for optimal decision-making since scores from different comparators are in the same probabilistic range. We evaluate our approach in the context of the 1st Cross-Spectral Iris/Periocular Competition, whose aim was to compare person recognition approaches when periocular data from visible and near-infrared images is matched. The proposed fusion approach achieves reductions in the error rates of up to 30%–40% in cross-spectral NIR–VIS comparisons with respect to the best individual system, leading to an EER of 0.2% and a FRR of just 0.47% at FAR = 0.01%. It also represents the best overall approach of the mentioned competition. Experiments are also reported with a database of VIS images from two different smartphones as well, achieving even bigger relative improvements and similar performance numbers. We also discuss the proposed approach from the point of view of template size and computation times, with the most computationally heavy comparator playing an important role in the results. Lastly, the proposed method is shown to outperform other popular fusion approaches in multibiometrics, such as the average of scores, Support Vector Machines, or Random Forest.

LAMP-HQ: A Large-Scale Multi-pose High-Quality Database and Benchmark for NIR-VIS Face Recognition

Near-infrared-visible (NIR-VIS) heterogeneous face recognition matches NIR to corresponding VIS face images. However, due to the sensing gap, NIR images often lose some identity information so that the NIR-VIS recognition issue is more difficult than conventional VIS face recognition. Recently, NIR-VIS heterogeneous face recognition has attracted considerable attention in the computer vision community because of its convenience and adaptability in practical applications. Various deep learning-based methods have been proposed and substantially increased the recognition performance, but the lack of NIR-VIS training samples leads to the difficulty of the model training process. In this paper, we propose a new $$\mathbf{L} {} \mathbf{a} $$ rge-Scale $$\mathbf{M} $$ ulti- $$\mathbf{P} $$ ose $$\mathbf{H} $$ igh- $$\mathbf{Q} $$ uality NIR-VIS database ‘ $$\mathbf{LAMP}-HQ $$ ’ containing 56,788 NIR and 16,828 VIS images of 573 subjects with large diversities in pose, illumination, attribute, scene and accessory. We furnish a benchmark along with the protocol for NIR-VIS face recognition via generation on LAMP-HQ, including Pixel2-Pixel, CycleGAN, ADFL, PCFH, and PACH. Furthermore, we propose a novel exemplar-based variational spectral attention network to produce high-fidelity VIS images from NIR data. A spectral conditional attention module is introduced to reduce the domain gap between NIR and VIS data and then improve the performance of NIR-VIS heterogeneous face recognition on various databases including the LAMP-HQ.

Interferometric study on the temporal variability of the brightness distributions of protoplanetary disks

Context. Optical and infrared spatially unresolved multi-epoch observations have revealed the variability of pre-main sequence stars and/or their environment. Moreover, structures in orbital motion around the central star, resulting from planet-disk interaction, are predicted to cause temporal variations in the brightness distributions of protoplanetary disks. Through repeated observations of pre-main sequence stars with the Very Large Telescope Interferometer (VLTI) over nearly two decades, the ESO Archive has become a treasure chest containing unprecedented high-resolution multi-epoch near- and mid-infrared observations of the potential planet-forming regions in protoplanetary disks. Aims. We aim to investigate whether the existing multi-epoch observations provide evidence for the variability of the brightness distributions of the innermost few astronomical units of protoplanetary disks and to quantify any variations detected. Methods. We present different approaches to search for evidence of temporal variations based on multi-epoch observations obtained with the VLTI instruments PIONIER, AMBER, and MIDI for 68 pre-main sequence stars. Results. For nine objects in our sample, multi-epoch data obtained using equal baselines are available that allow us to directly detect variations in the visibilities due to temporally variable brightness distributions. Significant variations of the near-infrared visibilities obtained in different epochs with PIONIER and/or AMBER for HD 50138, DX Cha, HD 142527, V856 Sco, HD 163296, and R CrA were found. HD 37806, TW Hya, and CPD-36 6759 show no significant variations. By estimating the impact of a small variation of the baseline on the measured squared visibilities, we are able to compare the data of another 12 pre-main sequence stars. Thereby, we find evidence for temporal variations of the brightness distribution of one additional object, AK Sco. Besides the two binaries DX Cha and AK Sco, HD 50138 and V856 Sco also show signs of variability caused by variations of asymmetric structures in the brightness distribution.

Cu(In,Ga)Se2 absorbers prepared by electrodeposition for low-cost thin-film solar cells

Reducing the manufacturing cost of solar cells is necessary to their industrial production. Electrodepositing is an effective, non-vacuum method which is very suitable for cutting the manufacturing cost of thin films as well as developing its large-scale industrial production. In this study, about 1-μm-thick Cu(In,Ga)Se2 (CIGS) precursors were electrodeposited on Mo/glass substrates in aqueous solution utilizing a three-electrode potentiostatic system. Triethanolamine was used as complexing agent, and all parameters of electrodeposition were precisely controlled. After that, the electrodeposited precursors were selenized in a Se atmosphere with different heating ramp rates (60 and 600 °C·min−1). High-quality CIGS films were obtained, and their characteristics were investigated by X-ray fluorescence, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, Raman spectra and near-infrared–visible (NIR-Vis) spectra. The results reveal that there are many differences between the properties of the films under different heating rates. Finally, CIGS solar cells were fabricated using a fast and a slow heating rate. The maximum efficiencies achieved for the films selenized at 60 and 600 °C·min−1 are 3.15% and 0.71%, respectively.

Heterogeneous face matching using geometric edge-texture feature (GETF) and multiple fuzzy-classifier system

A novel and accurate method for matching of heterogeneous faces, such as sketch and near-infrared (NIR) images, with the visible (VIS) photo gallery and vice a versa has been presented here. A new geometric edge-texture feature (GETF) is proposed, which is not only able to capture the edge information but also the texture information. GETF is constructed from the combined information of edge and texture image of same individual. For texture information local binary pattern (LBP) is used, while for edge information canny edge detection is chosen. Edges are sensitive to illumination, so before applying canny edge operation, we convert the image into illumination invariant gradient domain. For each pixel of the edge image, the nearest edge pixel is found. Finally, the total hamming distance between any pixel and its nearest edge pixel of the corresponding texture image gives GETFDist and the angle between them gives the GETFAng feature. To classify the heterogeneous faces we proposed a multiple fuzzy-classifier system, which is a combination of fuzzy partial least square (FPLS) and fuzzy local feature-based discriminant analysis (FLFDA). We have tested statistically that, the proposed classifier performs better than the individual classifiers. In sketch-photo matching, a rank-1 accuracy of 99.66% is achieved in a gallery of 606 photos consisting of CUHK student dataset, AR face dataset, and XM2VTS dataset. In NIR–VIS image matching, a rank-1 accuracy of 99.50% is achieved in a gallery of 400 VIS images from CASIA-HFB dataset.

Online Determination of Ergosterol in Naturally Contaminated Grape Mashes Under Industrial Conditions at Wineries

In general, vinification of sound grapes is an essential requirement for the production of high-quality wines. Grape rot, mainly caused by filamentous fungi, commonly impairs perceptual quality of wine; food safety may be affected due to the formation of biogenic amines and mycotoxins. Grape rot assessment by visual examination, taste or smell remains subjective. Other methods for grape rot quantification frequently lack specify, sensitivity or reproducibility. In contrast, ergosterol represents an objective and specific marker for filamentous fungal grape rot. In our study, we approved the suitability of ergosterol as a marker for grape rot of commercially harvested grapes, delivered to wineries under normal operating conditions. A total of 177 grape samples from five grape varieties was analysed by HPLC-UV for ergosterol content. Pinot Meunier showed the highest ergosterol contents up to 11.4 mg/kg. Mean ergosterol content for all varieties amounted to 2.3 mg/kg. About 20 % of the samples exceeded the limit of 3.0 mg/kg for sound grapes, and about 3.4 % were above the limit of 6.2 mg/kg indicating rotten grapes. Moreover, near-infrared/visible (NIR/VIS) spectroscopy has been applied as a rapid tool for online determination of ergosterol under industrial conditions. Calibration models were established and validated. Validation statistics for a dependent test set were coefficient of determination of the validation (R 2 val) of 0.726, root mean square error of prediction (RMSEP) of 0.84 mg/kg and ratio of prediction to deviation (RPD) of 2.0. At least semi-quantitative measurements of ergosterol in grape mashes upon delivery at wineries appeared feasible, thus enabling the objective detection of grape rot. Thereby, fair and incentive quality-based payment may be enabled; quality management and food safety may be improved.

Strong near-infrared emission in the sub-AU disk of the Herbig Ae star HD 163296: evidence of refractory dust?

We present new long-baseline spectro-interferometric observations of the HerbigAe star HD163296 obtained in the H and K bands with the AMBER instrument at VLTI. The observations cover a range of spatial resolutions between 3 and 12 milli-arcseconds, with a spectral resolution of ~30. With a total of 1481 visibilities and 432 closure phases, they result in the best (u,v) coverage achieved on a young star so far. The circumstellar material is resolved at the sub-AU spatial scale and closure phase measurements indicate a small but significant deviation from point-symmetry. We discuss the results assuming that the near-infrared excess in HD163296 is dominated by the emission of a circumstellar disk. A successful fit to the spectral energy distribution, near-infrared visibilities and closure phases is found with a model where a dominant contribution to the H and K band emissions arises from an optically thin, smooth and point-symmetric region extending from about 0.1 to 0.45 AU. At the latter distance from the star, silicates condense, the disk becomes optically thick and develops a puffed-up rim, whose skewed emission can account for the non-zero closure phases. We discuss the nature of the inner disk emission and tentatively rule out dense molecular gas as well as optically thin atomic or ionized gas as its possible origin. We propose instead that the inner emission traces the presence of very refractory grains in a partially cleared region, extending at least to 0.5 AU. If so, we may be observing the disk of HD163296 just before it reaches the transition disk phase. However, we note that the nature of the refractory grains or even the possibility for any grain to survive at the very high temperatures we require (~2100-2300 K at 0.1 AU from the star) is unclear and should be investigated further.

Collinear Generation of Ultrashort UV and XUV Pulses for Pump/probe Spectroscopy

AbstractThe collinear generation of sub-4 fs ultraviolet (UV) and attosecond extreme ultraviolet (XUV) pulses via subsequent third-harmonic and high harmonic generation in noble gases is demonstrated. The ultrashort coherent light bursts are produced by focusing a sub-1.5 cycle near-infrared/visible (NIR) laser pulse in two subsequent quasi-static noble gas targets. With this simple approach, inherently synchronized UV pulsed radiation with a photon energy of ˜5 eV and a pulse energy of ˜1 μJ, and XUV pulses with a cut-off photon energy of more than 120 eV and up to ˜107 XUV photons can be generated. This source represents a novel tool for future UV pump/XUV probe experiments with unprecedented time-resolution.

ModelingSpitzerObservations of VV Ser. I. The Circumstellar Disk of a UX Orionis Star

We present mid-infrared Spitzer-IRS spectra of the well-known UX Orionis star VV Ser. We combine the Spitzer data with interferometric and spectroscopic data from the literature covering UV to submillimeter wavelengths. The full set of data are modeled by a two-dimensional axisymmetric Monte Carlo radiative transfer code. The model is used to test the prediction of (Dullemond et al. 2003) that disks around UX Orionis stars must have a self-shadowed shape, and that these disks are seen nearly edge-on, looking just over the edge of a puffed-up inner rim, formed roughly at the dust sublimation radius. We find that a single, relatively simple model is consistent with all the available observational constraints spanning 4 orders of magnitude in wavelength and spatial scales, providing strong support for this interpretation of UX Orionis stars. The grains in the upper layers of the puffed-up inner rim must be small (0.01-0.4 micron) to reproduce the colors (R_V ~ 3.6) of the extinction events, while the shape and strength of the mid-infrared silicate emission features indicate that grains in the outer disk (> 1-2 AU) are somewhat larger (0.3-3.0 micron). From the model fit, the location of the puffed-up inner rim is estimated to be at a dust temperature of 1500 K or at 0.7-0.8 AU for small grains. This is almost twice the rim radius estimated from near-infrared interferometry. A best fitting model for the inner rim in which large grains in the disk mid-plane reach to within 0.25 AU of the star, while small grains in the disk surface create a puffed-up inner rim at ~0.7-0.8 AU, is able to reproduce all the data, including the near-infrared visibilities. [Abstract abridged]

Warm water vapor envelope in Mira variables and its effects on the apparent size from the near-infrared to the mid-infrared

We present a possible interpretation for the increase of the angular diameter of the Mira variables o Cet, R Leo, and χ Cyg from the K band to the 11 µm region revealed by the recent interferometric observations using narrow bandpasses where no salient spectral feature is present (Weiner et al. 2003a,b). A simple two-layer model consisting of hot and cool H2O layers for the warm water vapor envelope, whose presence in Mira variables was revealed by previous spectroscopic observations, can reproduce the angular diameters observed with Infrared Spatial Interferometer as well as the high-resolution TEXES spectra obtained in the 11 µm region. The warm water vapor layers are optically thick in the lines, and therefore, strong absorption due to H2O can be expected from such a dense water vapor envelope. However, the absorption lines are filled in by emission from the extended part of the envelope, and this results in the high-resolution 11 µm spectra which exhibit only weak, fine spectral features, masking the spectroscopic evidences of the dense, warm water vapor envelope. On the other hand, the presence of the warm water vapor envelope manifests itself as the larger angular diameters in the 11 µm region as compared to those measured in the near-infrared. Furthermore, comparison of the visibilities predicted in the near-infrared (1.5-3.8 µm) with observational results available in the literature demonstrates that our two-layer model for the warm water vapor envelope can also reproduce the observed near-infrared visibilities and angular diameters, and suggests that the wavelength dependence of the angular size of Mira variables in the infrared largely reflects the H2O opacity. The radii of the hot H2O layers in the three Mira variables are derived to be 1.5-1.7 Rwith temperatures of 1800-2000 K and H2O column densities of (1−5) × 10 21 cm −2 , while the radii of the cool H2O layers are derived to be 2.2-2.5 Rwith temperatures of 1200-1400 K and H2O column densities of (1−7) × 10 21 cm −2 .

Fractional Extraction of Paprika using Supercritical Carbon Dioxide and On‐line Determination of Carotenoids

ABSTRACT: Fractionation of pigments occurs over time during supercritical extraction of oil from natural matrices containing carotenoids. Paprika powder and paprika oleoresin were extracted using CO2 at temperatures of up to 80°C and pressures up to 50 MPa. The pigment concentration in the supercritical phase was monitored with an on‐line near infrared visible (NIR‐VIS) detector. Concentrations of 90 to 200 g/kg total carotenoids were achieved in oleoresin extracted from starting material containing only 1.2 g/kg total carotenoids. The ratio of ß‐carotene + free xanthophylls to total carotenoids in the recovered oleoresin diminished from nearly 50% (w/w) at the beginning down to 10% at the end of the extraction. Increased pressure improved kinetics of carotenoid extraction.

A multi-wavelength study of the oxygen-rich AGB star CIT 3: Bispectrum speckle interferometry and dust-shell modelling

CIT 3 is an oxygen-rich long-period variable evolving along the Asymptotic Giant Branch and is one of the most extreme infrared AGB objects. Due to substantial mass loss it is surrounded by an optically thick dust shell which absorbs almost all visible light radiated by the star and nally re-emits it in the infrared regime. We present the rst near infrared bispectrum speckle-interferometry observations of CIT 3 in the J-, H-, and K 0 -band. The J-, H-, and K 0 -band resolution is 48 mas, 56 mas, and 73 mas, resp. The interferograms were obtained with the Russian 6 m telescope at the Special Astrophysical Observatory. While CIT 3 appears almost spherically symmetric in the H -a ndK 0 -band it is clearly elongated in the J-band along a symmetry axis of position angle 28. Two structures can be identied: a compact elliptical core and a fainter north-western fan- like structure. The eccentricity of the elliptical core, given by the ratio of minor to major axis, is approximately = 123 mas/154 mas = 0.8. The full opening angle of the fan amounts to approximately 40 .E xtensive radiative transfer calculations have been carried out and confronted with the observations taking into account the spectral energy distribution ranging from 1 m to 1 mm, our near-infrared visibility functions at 1.24 m, 1.65 ma nd 2.12 m, as well as 11 m ISI interferometry. The best model found to match the observations refers to a cool central star with Te = 2250 K which is surrounded by an optically thick dust shell with (0:55 m) = 30. The models give a central-star diameter of = 10:9 mas and an inner dust shell diameter of 1 =7 1: 9m as being in line with lunar occultation observations. The inner rim of the dust-shell is located at r1 =6 :6 R and has a temperature of T1 = 900 K. The grain sizes were found to comply with a grain-size distribution according to Mathis et al. (1977) with n(a) a 3:5 , and 0.005 m a 0:25 m. Uniform outflow models, i.e. density distributions with 1=r 2 , turned out to underestimate the flux beyond 20 m. A two-component model existing of an inner uniform-outflow shell region ( 1=r 2 ) and an outer region where the density declines more shallow as 1=r 1:5 proved to remove this flux deciency and to give the best overall match of the observations. The transition between both density distributions is at r2 =2 0:5 r1 = 135:7 R where the dust-shell temperature has dropped to T2 = 163 K. Provided the outflow velocity kept constant, the more shallow density distribution in the outer shell indicates that mass-loss has decreased with time in the past of CIT 3. Adopting vexp =2 0 km s 1 , the termination of that mass-loss decrease and the begin of the uniform-outflow phase took place 87 yr ago. The present-day mass-loss rate can be determined to be _ M =( 1:3 2:1) 10 5 M/yr for d = 500 800 pc.

Assessing seed-coat color in a wheat breeding program with a NIR/VIS instrument

Red seed-coat can be distinguished from white seed-coat of unground wheat (Triticum spp.) by measurement of the first-derivative of the reflectance spectra at approximately 516 nm. Values around 450 nm distinguish durum (T. turgidum L. var. durum) from common (T. aestivum) white types. Classification accuracy is sufficient for screening purposes to reduce the number of samples requiring further examination. For breeding programs currently using combination near-infrared/visible (NIR/VIS) instruments, the additional time and costs to process the seed-coat information are minimal. Key words: Red, white, wheat, pigment, near-infrared, visible, breeding program

Near-infrared speckle interferometry of evolved stars and bipolar nebulae

view Abstract Citations (116) References (46) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Near-infrared speckle interferometry of evolved stars and bipolar nebulae. Dyck, H. M. ; Zuckerman, B. ; Leinert, Ch. ; Beckwith, S. Abstract Near-infrared visibility functions are presented for 16 late-type giants and supergiants and bipolar nebulae. The observational sample consists primarily of OH/IR stars and carbon stars with millimeter wave CO emission. The results are discussed in terms of currently available circumstellar envelope models and in relationship to radio observations. It is found that many infrared-bright stars with dense circumstellar dust envelopes are at least partially resolvable from the ground by speckle interferometry. If the near-infrared diameters are interpreted as the inner boundary for dust in the envelope, this boundary has a radius of order 10 to the 15th cm. The envelope diameters show a systematic increase with wavelength, carbon stars appearing to have a shallower increase than oxygen stars. There is a systematic increase of the apparent angular diameter of the dust envelope with increasing mass loss rate. Publication: The Astrophysical Journal Pub Date: December 1984 DOI: 10.1086/162739 Bibcode: 1984ApJ...287..801D Keywords: Infrared Stars; Interferometry; Late Stars; Near Infrared Radiation; Nebulae; Stellar Evolution; Giant Stars; Infrared Interferometers; Speckle Patterns; Spectral Resolution; Stellar Mass Ejection; Supergiant Stars; Visibility; Astrophysics full text sources ADS | data products SIMBAD (11)