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Cubic ZrV 2 O 7 thin films have been synthesized by sol-gel spin-coating method. The influences of annealing temperatures on the phase composition and morphology of ZrV 2 O 7 thin films were investigated using XRD, SEM, and EDX. Negative thermal expansion (NTE) and optical performances of cubic ZrV 2 O 7 thin films were analyzed using variable temperature XRD and UV–Vis spectroscopy. Results indicate that as-deposited ZrV 2 O 7 thin films have an amorphous structure with smooth and dense surface. Cubic ZrV 2 O 7 thin films were prepared after heat treatment at 720 °C for 1 h. It was found that the thin films contained V 2 O 5 impurity with the Zr: V = 1:2 precursor solution. Pure cubic ZrV 2 O 7 thin films were fabricated with the Zr: V = 1.75:2 precursor solution. Cubic ZrV 2 O 7 thin films show isotropic NTE in the temperature range of 100–700 °C. The coefficients of thermal expansion (CTEs) of ZrV 2 O 7 films along the a , b , and c axes are −6.88 × 10−6 °C−1, and the volumetric and linear CTEs are −20.56 × 10−6 °C−1 and -6.85 × 10−6 °C−1, respectively. The transmittance of cubic ZrV 2 O 7 thin film is approximately 80 %. [ABSTRACT FROM AUTHOR]

Herein, we report significant microstructure-induced dynamic visible–infrared transmittance regulation on a novel fluoroaluminate glass (AlF 3) via femtosecond-laser-customized fabrication technology. Fluoroaluminate glass, which has excellent optical transmittance in the visible–infrared wavelength range (400–5000 nm), is a candidate for visible and infrared optical devices. Based on its performance, three types of microstructures or material transitions (Snow-Layer Microstructure (SLS), Surface-Ablation Microstructure (SAS), and Interior-Modified Microstructure (IMS)) were successfully achieved using a femtosecond-laser-customized microstructure, including surface and interior fabrication routes with cylindrical lens focusing. Dynamic and reversible structural transition features were observed between the snow-layer and surface-ablation microstructures. These types of structures showed different transmittance regulation trends at visible and infrared wavelengths. The transmittance is decreased for IMS, SAS, and SLS in the visible region, while in the infrared region the transmittance increased for IMS and decreased for SAS and SLS. Based on Raman spectroscopy analyses, the chemical structures of the SAS before and after femtosecond-laser ablation appeared to remain constant, whereas the SLS showed a significant difference, giving rise to different transmittance regulations. This study provides a novel fabrication method and strategy for regulating visible and infrared transmission and promotes smart application of glass materials. [ABSTRACT FROM AUTHOR]

Glass ceramic (GC) is a promising optical gain material for fiber laser applications. However, the greatest challenge for GC is the conflict between high crystallinity and significant optical loss produced by crystals scattering. Herein, we propose a simple method based on crystal engineering of glass to enhance the crystallinity and transmittance. On the basis of this approach, the crystallinity, transparency and luminescence efficiency of the GC samples are all enhanced dramatically. In addition, owing to the depletion of Y3+ ions in the glass matrix during the precipitation of KYF 4 crystals, the refractive index differences between the glass matrix and the crystals are significantly diminished, which results in suppressed light scattering towards higher crystallinity (∼72%) and transmittance (∼88% at 900 nm). These excellent performances of GC show that crystal engineering of glass not only presents a way to overcome the conflict between crystallinity and transmittance, but also offers significant potential for the fabrication of optical composites with multiple functions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Convolutional Variational Autoencoder was built for better feature extraction. • The base classifiers of Deep Forest were upgraded to improve the detection ability. • The performance of the hybrid deep learning method was superior to baselines. • The proposed method can initially detect unfertilized duck eggs before hatching. • The spectral differences of fertilized and unfertilized duck eggs were interpreted. Unfertilized duck eggs not removed prior to incubation will deteriorate quickly, posing a risk of contaminating the normally fertilized duck eggs. Thus, detecting the fertilization status of breeding duck eggs as early as possible is a meaningful and challenging task. Most existing work usually focus on the characteristics of chicken eggs during mid-term hatching. However, little attention has been paid to the detection for duck eggs prior to incubation. In this paper, we present a novel hybrid deep learning detection framework for the fertilization status of pre-incubation duck eggs, termed CVAE-DF, based on visible/near-infrared (VIS/NIR) transmittance spectroscopy. The framework comprises the encoder of a convolutional variational autoencoder (CVAE) and an improved deep forest (DF) model. More specifically, we first collected transmittance spectral data (400–1000 nm) of 255 duck eggs before hatching. The multiplicative scatter correction (MSC) method was then used to eliminate noise and extraneous information of the raw spectral data. Two efficient data augmentation methods were adopted to provide sufficient data. After that, CVAE was applied to extract representative features and reduce the feature dimension for the detection task. Finally, an improved DF model was employed to build the classification model on the enhanced feature set. The CVAE-DF model achieved an overall accuracy of 95.94 % on the test dataset. These experimental results in terms of four metrics demonstrate that our CVAE-DF method outperforms the traditional methods by a significant margin. Furthermore, the results also indicate that CVAE holds great promise as a novel feature extraction method for the VIS/NIR spectral analysis of other agricultural products. It is extremely beneficial to practical engineering. [ABSTRACT FROM AUTHOR]

In this study, Zinc (Zn)- doped nickel oxide (NiO) thin films were fabricated via the electrodeposition method. The synthesized films were created with different concentrations of Zn (2 %, 4 %, 6 %, and 8 %) after that annealed at two different temperatures (300 °C and 500 °C). The prepared samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy (RAM), UV–vis spectrophotometry, photocurrent (PC), photoluminescence (PL), electrochemical impedance spectroscopy (EIS), Energy-Dispersive X-ray spectroscopy (EDX), photocurrent (PC), and Mott-Schottky (MS) analysis. XRD patterns indicate that Zn: NiO thin films have a cubic phase, with the (111) direction as the preferred orientation. Various structural parameters such as dislocation density, stacking fault, lattice strain, and crystallite size have been determined. The presence of Zn doping in NiO has been confirmed by EDX analysis. The EDX mapping of elements revealed the uniform distribution of Ni, Zn, and O in the sample. The optical transmittance and absorbance were analyzed using a UV–vis spectrophotometer. The lowest transmittance values were found for 8 % Zn: NiO thin films annealed at 300 °C and 500 °C. The absorption edge corresponding to pure NiO-300 °C and NiO-500 °C has been observed at 300 and 320 nm, respectively. The band gap energy (Eg) decreased to 3.88 eV for 8 %Zn: NiO (300 °C) and 3.71 eV for 8 %Zn: NiO (500 °C). The Raman analysis showed three distinct peaks at 590 cm−1, 705 cm−1, and 1172 cm−1, which correspond to the vibration of Ni—O bonds. The SEM results indicated that increasing the doping concentration and annealing temperature resulted in larger grain sizes in the manufactured samples. Furthermore, the PL spectra analysis of the synthesized films revealed two distinct emission peaks at around 400 and 490 nm. PC analysis confirmed the p-type conductivity of manufactured arrays. From MS measurements, the highest carrier concentration (NA) values of 8.81×1018 cm−3 and 9.41×1019 cm−3 were obtained for 8 %Zn: NiO (300 °C) and 8 %Zn: NiO (500 °C), respectively. EIS analysis confirmed the highest conductivity and enhanced electrochemical activity for 6 % Zn: NiO (500 °C) and 8 % Zn: NiO (300 °C). These results suggest that Zn-doped NiO is suitable for optoelectronic applications. • Low-cost electrodeposition technique to grow Zinc (Zn) -doped nickel oxide (NiO) thin films on FTO substrates at room temperature using varying ratios of Zn (2 %, 4 %, 6 %, and 8 %). • Subsequently annealed at two different temperatures (300 °C and 500 °C). • XRD patterns have shown that all samples possess the cubic phase, with the (111) direction being the preferred orientation. • RAM analysis showed the presence of three distinctive peaks associated with the vibration of Ni—O bonds. • The presence of Zn doping in NiO has been confirmed by EDX analysis. [ABSTRACT FROM AUTHOR]

An orthogonal composite approach is proposed to study the multielement synergistic modified TiO 2 photocatalytic films. The relationship between different preparation factors and photocatalytic evaluation indexes including photo-degradation activities, antibacterial properties, light transmittance and hydrophilicity, is revealed by the correlation and difference analysis. The increase of F content improves the photocatalytic and antibacterial activities. While the increase of Fe content and calcination temperature are not conducive to the transmittance. Additionally, reduced graphene oxide (rGO) is beneficial to improve the antibacterial properties, but it is not conducive to the self-cleaning performance. The interaction between different factors cannot be ignored in the design of multifunctional TiO 2 films from Pareto analysis. The optimal state shows that the glass coated with multifunctional F (9%) -N (1%) -TiO 2 /rGO (0.5%) -300 ℃ film exhibits the highest photo-degradation (59.8%) and antibacterial activities (87.1%) with superior transmittance (84.1%) and hydrophilicity (7.0°) under visible-light irradiation condition. [Display omitted] • An orthogonal composite approach was proposed for the preparation process. • The interaction between factors influenced the design of multifunctional TiO 2. • The increase of F content improved the hydrophilicity and photo-degradation. • GO content was beneficial to improve the antibacterial properties. • F (9%) -N (1%) -TiO 2 /rGO (0.5%) -300 ℃ film showed excellent multifunctional properties. [ABSTRACT FROM AUTHOR]

The extent to which hue, saturation, and transmittance of thin light-transmitting layers are perceived as constant when the illumination changes (transparent layer constancy , TLC) has previously been investigated with simple stimuli in asymmetric matching tasks. In this task, a target filter is presented under one illumination and a second filter is matched under a second illumination. Although two different illuminations are applied in the stimulus generation, there is no guarantee that the stimulus will be interpreted appropriately by the visual system. In previous work, we found a higher degree of TLC when both illuminations were presented alternately than when they were presented simultaneously, which could be explained, for example, by an increased plausibility of an illumination change. In this work, we test whether TLC can also be increased in simultaneous presentation when the filter's belonging to a particular illumination context is made more likely by additional cues. To this end, we presented filters in differently lit areas of complex, naturalistically rendered 3D scenes containing different types of cues to the prevailing illumination, such as scene geometry, object shading, and cast shadows. We found higher degrees of TLC in such complex scenes than in colorimetrically similar simple 2D color mosaics, which is consistent with the results of similar studies in the area of color constancy. To test which of the illumination cues available in the scenes are actually used, the different types of cues were successively removed from the naturalistically rendered complex scene. A total of eight levels of scene complexity were examined. As expected, TLC decreased the more cues were removed. Object shading and illumination gradients due to shadow cast were both found to have a positive effect on TLC. A second filter had a small positive effect on TLC when added in strongly reduced scenes, but not in the complex scenes that already provide many cues about the illumination context of the filter. [ABSTRACT FROM AUTHOR]

• A SLM-assisted ns-laser processing technique is proposed for fabricating large-area, uniform, and well-arranged periodic structures on Cr films. • 2. For 1000-nm thick Cr films, the processed surface exhibits hybrid periodic microstructures comprised by modulated grating (MG) and laser induced periodic surface structures (LIPSS), that is, MG-LIPSS, which displays vivid anisotropic structural colors. • 3. For 200-nm thick Cr films, the processed hybrid structures are a combination of MG and cracks, that is, MGC, which can be utilized as a transmission grating with diffraction effects. An effective technique for preparing different hybrid periodic structures on chromium (Cr) films of different thicknesses using a 1064-nm nanosecond laser assisted by spatial light modulator (SLM) is proposed. For 1000-nm Cr films, by combining periodic modulated grating (MG) patterned by SLM with laser-induced periodic surface structures (LIPSS), regular dual-scale MG-LIPSS can be fabricated, with the morphological characteristics controlled by laser fluence, effective pulse number, and MG period. Due to diffraction effects of MG and LIPSS, MG-LIPSS patterned surfaces exhibit vivid anisotropic structural colors. In contract to MG-LIPSS, complex periodic structures consisting of MG and cracks (MGC) are fabricated on 200-nm Cr films due to the more significant thermal stress of a thinner film. Although the cracks of MGC distributed randomly, MGC show a long-range order characteristic with a certain transmittance, which can be utilized as a transmission grating with diffraction effects. These results demonstrate that optical field modulated laser machining based on SLM offers an efficient, cost-effective, and controllable method for fabricating large-area periodic structures on Cr films. Moreover, variations in film thickness can be employed to explore hybrid microstructures with specific properties, and thus utilized in diverse applications, such as optical components and anti-counterfeiting measures. [ABSTRACT FROM AUTHOR]

• Method of Defect Compensation was proposed to reduce the content of ODC, E' center and NBOHC. • The glass has high transmittance with internal transmittance of 99.9%@ 193nm, low stress birefringence with 0.9nm/cm @632.8nm and good optical homogeneity with 0.78ppm @ 632.8nm. Synthetic quartz materials with high ultraviolet transmittance are widely used in lenses and other optical devices. However, the relatively insufficient transmittance limits the application. In this paper, method of Defect Compensation is proposed to reduce the content of ODC, E'center and NBOHC and synthetic quartz glass with UV high transmittance was prepared successfully. The glass has high transmittance with internal transmittance of 99.9%@193nm, low stress birefringence with 0.9nm/cm @632.8nm and good optical homogeneity with 0.78ppm @ 632.8nm. [ABSTRACT FROM AUTHOR]

This study systematically investigated the structural, optical, and morphological evolution of Gallium oxide (Ga 2 O 3) films deposited at different substrate temperatures on Al 2 O 3 (0001) using pulsed laser deposition (PLD). The thickness of the Ga 2 O 3 films was standardized in order to eliminate its effect on the film properties. The effect of substrate temperature from room temperature to 600 °C on the film's transmittance, crystalline structure, chemical composition and surface morphology, was explored. The plasma species generated during the deposition of the PLD process were monitored and analyzed employing in situ optical emission spectroscopy. The deposition rate of the films decreased with increasing substrate temperature. X-ray photoelectron spectroscopy was used to detect both Ga3+ and Ga + oxidation states in all prepared films, which indicated substoichiometric Ga 2 O 3 films deficient in oxygen. The percentage of non-lattice oxygen decreased with increasing substrate temperature. At optimal condition, mono-crystaline β-Ga 2 O 3 was produced with a high visible and near-infrared transmittance, large grain size and smooth surface, which is suitable for the application in high-performance power electric devices and photoelectronic devices. [ABSTRACT FROM AUTHOR]

Zinc tin oxide (ZTO) thin films can be deposited by atomic layer deposition (ALD) with adjustable electrical, optical and structural properties. However, the ternary ALD processes usually suffer from low growth rate and difficulty in controlling film thickness and elemental composition, due to the interaction of ZnO and SnO 2 processes. In this work, ZTO thin films with different Sn levels are prepared by ALD super cycles using diethylzinc, tetrakis(dimethylamido)tin, and water. It is observed that both the film growth rate and atom composition show nonlinear variation versus [Sn]/([Sn]+[Zn]) cycle ratio. The experimental thickness measured by spectroscopic ellipsometry and X-ray reflectivity are much lower than the expected thickness linearly interpolated from pure ZnO and SnO x films. The [Sn]/([Sn]+[Zn]) atom ratios estimated by X-ray photoelectron spectroscopy have higher values than that expected from the cycle ratios. Hence, to characterize the film growth behavior versus cycle ratio, a numerical method is proposed by simulating the effect of reduced density and reactivity of surface hydroxyls and surface etching reactions. The structure, electrical and optical properties of ZTO with different Sn levels are also examined by X-ray diffraction, atomic force microscope, Hall measurements and ultraviolet–visible–infrared transmittance spectroscopy. The ZTO turns out to be transparent nanocrystalline or amorphous films with smooth surface. With more Sn contents, the film resistivity gets higher (>1 Ω cm) and the optical bandgap rises from 3.47 to 3.83 eV. [ABSTRACT FROM AUTHOR]

The Cu 2 O thin films were prepared from copper (II) acetylacetonate (Cu(acac) 2) by the mist chemical vapor deposition (mist-CVD) method, depending on the pH value of the prepared solution. It was confirmed that the well-oriented Cu 2 O thin films were grown at a dominant (111) peak according to X-ray diffraction (XRD) measurement using an alkaline precursor solution. The pH of the prepared solution drastically affected the surface morphology of the Cu 2 O thin films, and the lowest Root Means Square (RMS) was found for pH-10 of the precursor solution. The confocal Raman spectrum confirmed the formation of the cubic Cu 2 O crystal structures for each pH value of the precursor solution. The very transparent Cu 2 O thin films that were grown. The highest transmittance, 70%, was obtained at 1100 nm from the absorption spectrum for Sample B. The optical energy band gaps of Cu 2 O thin films were determined using Tauc's method and found to vary within a range of 2.53 to 2.49 eV, indicating a change in the material's electronic structure. The study demonstrated the crucial role of the pH level of the prepared solution in the growth of the Cu 2 O thin film. Specifically, it was found that a higher pH level resulted in a greater concentration of hydroxide ions (OH−), which was a crucial factor in the growth process. These findings can be significant in using p-type Cu 2 O thin films prepared based on mist-CVD for optoelectronic applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Using numerical calculations, we present the design of terahertz transmission modulators based on transmissive metal–insulator–metal metasurfaces, which consist of two planar arrays of parallel metallic ribbons while the deeply-subwavelength space between them is infiltrated with nematic liquid crystals (LCs). We demonstrate that only metasurfaces with narrow lateral gaps between adjacent metallic ribbons have a single transmission peak and low background transmission. Spectral shifting of the transmission peak is then provided by the electrical control of the LC refractive index. The proposed modulators operate either as spectrally-tunable passband filters in a certain frequency range or as amplitude (transmission) modulators at a single specified frequency. Optimal modulators have the following properties: maximal relative spectral shift of around 10%, transmittance change of around 0.6, modulation depth of around 90%, insertion loss of 40%, and switching time of around 100 ms. The modulators have a very simple geometry, which provides a straightforward design procedure and selection of geometrical parameters for specified operating frequency. • Terahertz transmission modulators based on metal–insulator–metal metasurfaces. • Electrical tunability by nematic liquid crystals between two metallic layers. • Operation as spectrally-tunable passband filters in a certain frequency range. • Operation as amplitude (transmission) modulators at a single specified frequency. [ABSTRACT FROM AUTHOR]

CdS thin films are commonly utilized as a buffer layer in chalcopyrite thin-film solar cells. However, due to the toxic nature of Cadmium (Cd), ongoing efforts are being directed towards exploring alternative options. In this contribution, doped graphene film with remarkable optical and electrical properties has been introduced for the first time as an alternative buffer layer, replacing CdS in CZTS thin-film solar cell application. In this study, nitrogen-doped graphene (N-doped graphene) film was utilized as a substitute buffer layer in the CZTS thin-film solar cell structure, replacing the conventional CdS thin film. For comparative analysis, CZTS/N-doped graphene and CZTS/CdS traditional solar cell structures were fabricated and separately characterized. The CZTS thin films produced were examined through EDX, XRD, SEM, Raman, optical transmission and PL spectroscopy measurements. According to performed analyses, the Cu-poor and Zn-rich kesterite CZTS thin films exhibited a uniform and dense polycrystalline microstructure as observed in surface and cross-sectional SEM images. XRD spectra of the kesterite CZTS thin film displayed predominant peaks corresponding to the (112), (220/204), and (312/116) diffraction planes of the kesterite CZTS phase. Raman spectra showed a dominant peak at ∼336 cm−1 associated with the kesterite CZTS phase. PL emission spectra indicated transitions from the conduction band to defect levels. The CVD-grown doped graphene film exhibited a 3.43 I 2D /I G ratio and a 25 cm−1 FWHM of the 2D peak, indicating a single-layer graphene according to Raman analysis. Permanent nitrogen doping with a 2% atomic concentration was confirmed by XPS measurement. The optical transmission measurement of the single layer doped graphene film showed a 95% transmittance value. Nitrogen doping was contributed to decrease the sheet resistance of the graphene film. The Glass/Mo/CZTS/N-doped graphene/i-ZnO/ITO/Al solar cell displayed a V OC of 0.267 V, J SC of 24.6 mA/cm2, FF of 36.46, and η of 2.37%, showing higher FF and Jsc values but lower conversion efficiency compared to the Glass/Mo/CZTS/CdS/i-ZnO/ITO/Al traditional solar cell structure. Hence, the superior working function and transparency properties position the N-doped graphene film as a competitive buffer layer for use in CZTS-based thin-film solar cells. [Display omitted] • CZTS thin films were fabricated employing sputtering and RTA techniques. • CVD grown nitrogen-doped graphene film was employed as a buffer layer. • The sheet resistance of the graphene film decreased via nitrogen doping. • Glass/Mo/CZTS/N-doped graphene/i-ZnO/ITO/Al showed higher FF and J sc values. • It was seen that N-doped graphene can be used as an alternative to CdS thin film. [ABSTRACT FROM AUTHOR]

• HfO 2 –SiO 2 mixture coatings with different proportions were investigated. • Admixing 10% or higher SiO 2 in the mixture coatings suppresses inhomogeneity of HfO 2. • Short-wave pass dichroic laser mirror coatings were prepared using mixture layers. • Using HfO 2 –SiO 2 mixture layers fundamentally solves the half-wave hole effect. • Using different mixture layers gets further optical improvement in the pass band. Hafnia/silica (HfO 2 /SiO 2) short-wavelength pass dichroic laser mirror (DLM) coatings are widely utilized in high-power laser systems. However, the half-wave hole effect resulting from the refractive index inhomogeneity of HfO 2 severely restricts the spectra and potential applications of these coatings. To address this issue, an investigation was conducted on HfO 2 –SiO 2 mixture coatings with different proportions, which were produced by electron beam co-evaporation. Compared to the inhomogeneous growth characteristics observed in pure HfO 2 coatings, the introduction of 10 % or higher SiO 2 admixing in HfO 2 –SiO 2 mixture coatings results in an amorphous structure characterized by excellent refractive index homogeneity and improved surface smoothness. Leveraging this, different DLM coatings with the objective of achieving high transmittance across the 400 to 900 nm range were designed and prepared, while ensuring high reflectance at 1064 nm. The incorporation of HfO 2 –SiO 2 mixture layers instead of pure HfO 2 layers in the mirror coatings led to a fundamental inhibition of the half-wave hole effect throughout the entire broad transmission band, resulting in a substantial improvement in the optical performance of the coatings. Moreover, by incorporating several types of HfO 2 –SiO 2 mixture layers with different proportions in the coating stacks, the transmittance of DLM coatings in the pass band can be further increased, and the transmission fluctuations at different wavelengths can be further compressed. Additionally, compared to traditional DLM coatings with HfO 2 layers, DLM coatings incorporating HfO 2 –SiO 2 mixture layers exhibit lower roughness, higher laser-induced damage threshold (LIDT) at 532 nm, and similar LIDT at 1064 nm. These results indicate a promising strategy for fabricating DLM coatings tailored for high-power laser systems. [ABSTRACT FROM AUTHOR]

Mn-dopant concentrations ranging from 0.05 mM to 10 mM were utilized for producing Mn-doped CdO thin films on glass substrates employing spray pyrolysis technique. The structural, morphological, topological, optical, and vapour sensing properties of CdO thin films are acknowledged to be impacted by Mn doping. According to the XRD analysis, the generated thin film displays polycrystalline nature with a cubic structure and Mn doping also contributes to a substantial reduction in the crystallinity of CdO thin films. SEM images show homogenous grains, and as the concentration of dopants rises, so does the size of the aggregated grains. The absorbance and transmittance spectra of the produced thin films captured in the UV visible spectra demonstrate that the transmittance of the CdO thin film has decreased substantially with an increase in Mn dopant concentration along with a significant red shift with respect to molar concentration which may facilitate a good sensing behaviour of the test sample. The findings indicate that the band gap energy decreases with doping concentration, ranging from 2.85 to 2.59 eV. The intensity of the SAED pattern has significantly decreased, implying that the doped samples' degree of crystalline nature has decreased. According to the photoluminescence spectra, the emission band near 485 nm is produced by both the pure and doped CdO nanoparticles. The ethanol sensing behaviour of the prepared thin film was examined using the chemiresistive method at room temperature. The film's responsiveness to vapour drastically increased with an increase in Mn dopant concentration, leading to the development of a thin film that is incredibly selective for ethanol vapour. Based on the findings of this study, room temperature ethanol sensors can be developed by making use of Mn-doped CdO thin films. • Structure-property relationships of Mn-doped CdO thin films have been reported. • By increasing the doping percentage of Mn, the band gap energy is reduced. • On increasing the doping concentration of Mn in CdO thin film, the sensor response is enhanced. [ABSTRACT FROM AUTHOR]

In this study, the structural and optical properties as well as the radiation shielding capabilities of Holmium Dolomite Glass (HDG) 30CaMgC 2 O 6 –34P 2 O 5 -(36-x)CdO-(xHo 2 O 3), (x = 0, 1, 2, 3, and 5 wt%), were investigated. The HDG samples were prepared using a melt-quenching method, and X-ray diffraction (XRD) analysis revealed that they had an amorphous structure with no prominent peaks. The FTIR spectra over a range from 4000 to 400 cm⁻1 and a deconvoluted view of the spectra within the 1600-400 cm⁻1 range were recorded. The optical properties were characterized through transmission and reflectance spectra across a wide wavelength range. HDG exhibited high optical transmission, with over 90 % average transmittance in the visible spectrum. The refractive index was found to be in the range of 2.1–2.3, while the absorption coefficient exhibited values between 0.01 and 0.1 across the studied wavelengths. The calculated direct energy gap E g O p t value for HDG is 4.43 eV which decreased to 3.91 eV upon increasing Holmium concentrations in HDG. Beyond optical properties, we delved into the radiation shielding capabilities of the HDG samples by meticulously measuring linear attenuation coefficients (μ) at multiple energy levels. The mass attenuation coefficient (μm), half value layer (T 0.5), and mean free path (λ) values were then extracted from the μ measurements. Strikingly, our results showcased that the 5-H/C glass sample, showed outstanding performance, exhibiting a linear attenuation coefficient of around 0.025 cm−1 at 662 keV. This resulted in a remarkable mass attenuation coefficient of about 0.050 cm2/g, with a half-value layer of approximately 27 cm and a mean free path of 40 cm. These findings position the 5-H/C glass as an environmentally friendly and highly promising material for diverse radiation shielding applications, supported by robust numerical evidence. • HDG samples exhibit a distinct amorphous halo in XRD analysis. • FTIR spectra confirms PO 4 , CO 3 , and Mg–O bond presence in HDG. • Homogeneity across HDG samples shown by consistent FTIR patterns. • Minor band shifts in FTIR indicate subtle structural variations. • HDG series displays uniform amorphous structure with varying Ho content. [ABSTRACT FROM AUTHOR]

Detailed dynamic modeling of a solar sail requires recording of solar radiation pressure influence. A photon-solar sail is determined by the thrust value and the direction. We define the solar sail's reflectivity depending on the film materials, the sail design and temperature, the thickness of multiple layers, and degradation factor, with a reasonable degree of accuracy. Thus, this work is devoted to the identification of optical characteristics of thin multilayer films in space flight conditions, i.e. to finding its reflectance, absorbance, and transmittance. In particular, the paper asks whether the solar sail simulates by a mathematical model of the optical characteristics of a multilayer epitaxial thin film. The temperature change effect and optical properties of solar sail degradation are considered as well. Solar sail flight from Earth to Mercury is designed as a simulation of the flight change in optical parameters. [ABSTRACT FROM AUTHOR]

• Transparent a-Si:H solar cells are developed using very thin back OMO electrodes. • Thin OMO electrode composed of Al-doped ZnO and Ag is 110 nm thick. • Cell efficiency and transmittance are experimentally and numerically studied. • Laser-patterning optimization is presented for thin OMO electrodes. • Transparent modules are optimally designed using equivalent-circuit model. Transparent hydrogenated amorphous silicon thin-film solar modules are fabricated using oxide-metal-oxide (OMO) electrodes as the back electrode for building-integrated photovoltaic applications. The outer aluminum-doped zinc oxide and inner silver layers constitute a thin OMO electrode (~110 nm thick), exhibiting a sheet resistance of 6.8 Ω/□ and an average transmittance of ~88% in the visible range of 400–800 nm. The external quantum efficiency and average transmittance of the cell were investigated for the absorber-layer thickness using the finite-difference time-domain method, and it was found that the optical loss in the cell was mainly due to the absorption of the front electrode in the ultra-violet region and free-carrier absorption of the OMO in the infrared region. Fabrication issues are introduced for a 532 nm short-pulse high-power laser patterning process for transparent modules with thin OMO electrodes. Optimization of the laser power for the P2 and P3 laser processes is demonstrated by observing the profiles and measuring the shunt resistance of the laser-patterned edges. Furthermore, the cell width is optimized based on an equivalent circuit model using PSpice simulation. The highest module efficiency and average transparency achieved in the range of 500–800 nm were 5.6% and 15.2%, respectively. The short-circuit current density, fill factor, and open-circuit voltage per cell of the module were found to be 10.8 mA/cm2, 62.7%, and 0.830 V, respectively. [ABSTRACT FROM AUTHOR]

The concentration, microscopic characterization and transmittance of a P(A)SiO 2 smoke product with different SiO 2 ratios were measured by using particle collector, scanning electron microscopy and infrared spectrometer. The micro-Characterization of the product and the effect of the product on the transmittance were analyzed. The results show that the proportion of SiO 2 has no linear effect on smoke concentration, and there is an optimal proportion; the size of particulate matter of smoke products is about 10-20 μm, and the structure is irregular; The transmittance of smoke is affected by concentration in the early stage of smoke release. The higher the concentration, the lower the transmittance. The later stage of smoke release is mainly affected by particulate deposition. The higher the settling speed, the faster the transmittance increases. [ABSTRACT FROM AUTHOR]

Undoped and boron- (B) doped VO 2 thin films were successfully deposited by pulsed laser deposition. Boron doping enables to drastically reduce the metal–insulator transition (MIT) temperature (T MIT) at a rate as large as 31.5 °C/at.%B. As boron doping is interstitial, B atoms can be incorporated in the VO 2 matrix without affecting its stoichiometry as demonstrated by the invariability of the valence state of vanadium ions. Therefore, boron doping stands as an efficient strategy to reduce T MIT toward room temperature, while maintaining the contrast of both electrical resistivity and infrared transmittance across the MIT suitable for applications such as smart radiators. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• The energy performance of a D/M/D film in hot weather is elucidated. • The long-wave regulation of a D/M/D film proved to be important. • Suitable application mode of a D/M/D film is demonstrated. • A clear relationship between the Ag thickness and optical properties is presented. • Samples with highest T vis and T vis + R si are prepared for energy-efficient windows. A dielectric/metal/dielectric (D/M/D) film with a high visible (0.38–0.78 μm) transmittance and a high solar infrared (0.78–2.5 μm) reflectance can be applied on the outdoor surface of a window for energy saving in hot weather. However, in this kind of application with a D/M/D film, the regulation of long-wave (>3 μm) radiation is often neglected but proved to be significant in energy saving according to our previous work. For a ZnO/Ag/ZnO structure on flexible PET applied as a visible transparent solar infrared reflecting film with a low long-wave emittance, based on matrix formulation and a ray-tracing method, the influence of Ag layer thickness on visible transmittance (T vis), solar infrared reflectance (R si) and long-wave emittance (ε lw) are investigated. Two samples with the highest T vis and T vis + R si are prepared, respectively, with high visible transmittance, high solar infrared reflectance and low long-wave emittance, simultaneously. In hot weather, compared with a traditional silica glass, the exterior applied film consumes more energy, while the interior applied film saves 9.6% energy consumption for cooling. [ABSTRACT FROM AUTHOR]

• Method for room temperature magnetron sputtered indium tin oxide films developed. • Control of oxygen concentration during sputtering resulted in optimized properties. • Transparent conductive oxide properties optimized for low temperature substrates. Indium Tin Oxide (ITO) thin films are commonly used as transparent conductive layers in the production of solar cells. ITO films are typically heat-treated at temperatures exceeding 200 °C after magnetron sputtering to optimize the physical, optical, and electrical characteristics for photovoltaic devices. This high temperature heating procedure greatly limits the use of potential substrates, particularly those comprised of low-temperature-rated polymers. Herein, we examine the physical, optical, and electrical transport effects of oxygen:argon plasmas during radio frequency magnetron sputtering of ITO on glass and flexible polymer surfaces without subsequent heat treatment. ITO thin films were characterized via sheet resistance testing, UV–Vis spectroscopy, X-ray diffraction, and scanning electron microscopy imaging. Sheet resistance measurements revealed an increase in surface resistance with increasing oxygen concentration during sputtering. UV–Vis optical transmittance measurements demonstrated an improvement in optical transmittance with an increase in oxygen concentration reaching a maximum transmittance at an oxygen concentration of 1-2%. Most importantly, it was discovered that producing bilayers of ITO with pure argon sputtered plasmas followed by oxygen:argon plasmas produced ITO thin films with suitable resistance and transmittance without the need for high temperature post annealing. These results highlight a methodology for the deposition of ITO thin films on temperature sensitive substrates for flexible photovoltaics and low-cost module production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface texture in materials jetting is strongly influenced by the build orientation. • Texture variation affects gloss and scattering more than color. • Transmittance varies the most at 75° build orientation. • The largest variation in reflectance was observed for 60°. • Results of gloss nuances vary with measurement direction. Material jetting (MJT) is a promising additive manufacturing (AM) technique that offers high-quality appearance reproduction. Considering the limited selection of aesthetic materials available for MJT technology, a thorough optical analysis is required to determine their optimal application. This study focuses on the prominent appearance attributes in MJT and the role of texture variation due to different build orientations (BOs). For this purpose, tilted surfaces were manufactured in a direction ranging from 0° to 90° degrees at 15° intervals. The spectral reflectance, absorbance, transmittance, color difference, gloss, haze, scattering, and texture of MJT objects with varying BOs were investigated. To illustrate the variation in visual appearance and texture of the studied surfaces, the optical properties were rendered to three-dimensional (3D) spherical models. Further, the interaction of the appearance of 3D printing interacts with the quality improvement of AM surfaces is discussed. The results indicated that BO significantly affected the surface texture and layer orientation, leading to variation in surface quality by impacting all studied appearance attributes. Furthermore, tilted MJT surfaces exhibited more variation in reflectance than transmittance. As a result of the Kendall rank correlation coefficient and principal component analysis (PCA), light transmittance through parts manufactured at BO 75° showed the largest variation compared to 0°. Regarding light reflectance, 60° showed more variation among studied angles. The results of gloss, haze, and scattering studies revealed the significance of the measurement direction due to the role of microsurface normals in the surface texture. [ABSTRACT FROM AUTHOR]

• An innovative black Si with enhanced transmittance was fabricated via the femtosecond laser. • The low-cost black Si was used as the substrate for HgCdTe infrared remote sensing detector. • 20 % transmittance enhancement was achieved via the Si substrate ablated under appropriate processing parameters. • The enhancement in transmittance was attribute to the synergistic effect of surface roughness and oxidation effect. An innovative black silicon (Si) with enhanced transmittance in the infrared spectral band is directly processed by femtosecond (fs) laser irradiation in ambient air. Interestingly, this black Si can provide a low-cost, alternative substrate for infrared detector replacing the expensive CdZnTe, also offering an effective improvement of the detector performance. An enhancement in transmittance of up to 20 % is achieved in the case of black Si processed with laser fluence and scanning speed of 0.68 J∙cm−2 and 1 mm∙s−1, respectively. The microscopic characterization and the elemental analyses of the black Si indicate a direct link between the enhanced transmittance and the features of the processed surface. The transmittance improvement can be mainly ascribed to the surface microstructures and surface oxidation induced by the laser irradiation process. The microstructures may effectively extend the incident light path, whereas the oxidized black Si can result in a graded refractive index surface layer avoiding a sudden change of the refractive index from air to Si. The observed increase in infrared transmittance can eventually be explained by contribution of both these effects. [ABSTRACT FROM AUTHOR]

Here, the solution-processed heterojunction structure Ta doped ZnSnO/InSnO (TaZTO/ITO) semiconductor thin film and TFTs have been fabricated on atomic layer deposition deposited Al 2 O 3. The effects of Ta doping on the structure, thickness, thermal decomposition, contact angle, surface morphology, transmittance, chemical bond states and electrical characteristics of ZTO back-channel layer have been investigated by glancing angle incidence X-ray diffraction (GIXRD), cross sectional transmission electron microscopy (TEM), thermogravimetric analysis (TGA), contact angle meter, atomic force microscopy spectrometer (AFM), spectrometer, X-ray photoelectron spectroscopy (XPS) and semiconductor characterization system, respectively. Moreover, the influence of Ta doping in the electrical property and stability of heterojunction structure TaZTO/ITO TFTs has been also analyzed. A proper Ta concentration in the TaZTO back-channel layer can realize stable, dense film and good electrical and stable heterojunction structure TFTs due to inhibiting the generation of defects originated from oxygen vacancies. The heterojunction structure TaZTO/ITO TFTs with 1%mol Ta doping shows the best electrical property with the mobility (μ) of 4.72 cm2/Vs and the best stability with the threshold voltage shift of 0.95 V under positive bias stress. The strategy has coordinated the relationship between μ and stability effectively, and provide a new way for the development of oxide TFTs technology in the future. • Heterojunction structure TaZTO/ITO semiconductor thin film. • Ta doping. • Application for high stable and electrical associated TFTs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn and Ce co-doped ZnS quantum dots prepared using co-precipitation technique. • ∼ 2 nm –sized crystallites confirmed its cubic phase and purity through XRD and HR-TEM results. • Optical band gap and transmittance was increased due to the addition of Ce3+ ions. • Yellow and Red emission were received during Photoluminescence study. Quantum dots (QDs) are semiconductors whose size falls in a range between 1 and 10 nm; they are generally known as zero-dimension materials. It finds various applications in optical industries including light-emitting diodes, display technology, imaging, and labelling. ZnS is one of the excellent QDs in its class of II-VI semiconductors. In this paper, It is reported that the preparation of Mn-doped ZnS and Mn, Ce co-doped ZnS QDs using facile co-precipitation technique. XRD and HR-TEM results confirmed the cubic structure, particle size, and phase of the synthesized particles, and the crystallite is measured as ∼ 2 nm. The surface morphology, elemental analysis, and FT-IR spectra revealed the purity of the samples and confirmed the presence of dopants as expected. Cyclic voltammetry studies expressed the electrochemical behaviour of the samples, which increased as a function of Ce3+ doping concentration. UV–visible absorbance and transmittance spectra disclosed the optical characteristics of the samples. A wide band gap (4.02 eV) was received for 2% Ce-doped Zn: MnS QDs. Week Blue and strong yellow emissions were received for 4% Ce-doped Zn:MnS QDs. Whereas, high intensity red-emission was received for 2% Ce-doped Zn:MnS QDs. The different colour emissions are discussed in terms of defects produced. [ABSTRACT FROM AUTHOR]

Over the last few decades, a large number of research papers on the optical properties of thin films have been published, and significant efforts have been made to supply a mathematical formulation that can describe the transmittance (T(λ)) and reflectance (R(λ)) of various optical systems. Swanepoel suggested a straightforward analysis using the upper (T M) and lower (T m) envelopes of measured transmittance. He suggested a good correlation between the index of refraction (n), T m , and absorbance (x) in the form of ( T m = 16 n 2 s x / (A + B x + C x 2 ) where s, A, B, and C parameters are given in the text). He solved this equation to determine the value of the refractive index (see eq. (9) in Ref.1). Here comes the question why we do not resolve the equation to determine the value of the absorption coefficient? In this investigation the author tries to estimate both the film refractive index (n), absorbance (x) based only on the values of T m and without any dependence on the film thickness (t). Also, a new analysis to find the film thickness precisely is based on the interference fringes main equation (2 nt = mλ). [Display omitted] • The optical constants have been accurately determined using only the lower envelope (T m) of the transmittance spectra. • Without dependence of the film thickness, the complex index (real (n) and imaginary (k)) of refraction has been estimated. • New relationship has been suggested to estimate film absorbance (x). • New analysis to estimate the film thickness based on the interference fringes main equation. [ABSTRACT FROM AUTHOR]

Near-infrared spectroscopy (NIRS) has been widely used to determine various composition traits of many dairy products in the industry. In the last few years, near-infrared (NIR) instruments have become more and more accessible, and now, portable devices can be easily used in the field, allowing the direct measurement of important quality traits. However, the comparison of the predictive performances of different NIR instruments is not simple, and the literature is lacking. These instruments may use different wavelength intervals and calibration procedures, making it difficult to establish whether differences are due to the spectral interval, the chemometric approach, or the instrument's technology. Hence, the aims of this study were (1) to evaluate the prediction accuracy of chemical contents (5 traits), pH, texture (2 traits), and color (5 traits) of 37 categories of cheese; (2) to compare 3 instruments [2 benchtop, working in reflectance (R) and transmittance (T) mode (NIRS-R and NIRS-T, respectively) and 1 portable device (VisNIRS-R)], using their entire spectral ranges (1100–2498, 850–1048, and 350–1830 nm, respectively, for NIRS-R, NIRS-T and VisNIRS-R); (3) to examine different wavelength intervals of the spectrum within instrument, comparing also the common intervals among the 3 instruments; and (4) to determine the presence of bias in predicted traits for specific cheese categories. A Bayesian approach was used to develop 8 calibration models for each of 13 traits. This study confirmed that NIR spectroscopy can be used to predict the chemical composition of a large number of different cheeses, whereas pH and texture traits were poorly predicted. Color showed variable predictability, according to the trait considered, the instrument used, and, within instrument, according to the wavelength intervals. The predictive performance of the VisNIRS-R portable device was generally better than the 2 laboratory NIRS instruments, whether with the entire spectrum or selected intervals. The VisNIRS-R was found suitable for analyzing chemical composition in real time, without the need for sample uptake and processing. Our results also indicated that instrument technology is much more important than the NIR spectral range for accurate prediction equations, but the visible range is useful when predicting color traits, other than lightness. Specifically for certain categories (i.e., caprine, moldy, and fresh cheeses), dedicated calibrations seem to be needed to obtain unbiased and more accurate results. [ABSTRACT FROM AUTHOR]

Multilayered inorganic transparent materials have been widely used as laser materials, scintillators and phosphors due to their excellent combined properties or functions. However, owing to the limitation of the current preparation technology, only the ceramics with cubic crystal structure could be fabricated into multilayered transparent materials, which has greatly obstructed the diversity of multilayered transparent materials. Here we report a novel non-cubic multilayered transparent phosphor with a ceramic/glass/ceramic sandwich-like structure prepared by controlling crystallization from Eu 2 O 3 -SrO-Al 2 O 3 -SiO 2 bulk glass. The ceramic thicknesses, total transmittances, emission colors and the fluorescence quantum yields of the samples can be adjusted continuously within a certain range. The multilayered transparent phosphor could be used as a potential candidate for the white LEDs with high color rendering index. It can be anticipated that the controlled crystallization from bulk glass method is a simple, fast, cost-effective and promising synthesis approach to prepare non-cubic transparent materials with ceramic/glass/ceramic structures. [ABSTRACT FROM AUTHOR]

ThO 2 films were obtained by photochemical metal–organic deposition method using the hinokitiolate thorium (IV) complex as the precursor. The influence of annealing temperature on the structural, morphological and optical properties of ThO 2 thin films was studied by X-ray diffraction, UV–Vis transmittance spectroscopy, spectroscopic ellipsometry (SE) and atomic force microscopy (AFM). The SE and AFM results suggest that ThO 2 films annealed at 750 °C might be used as a transparent reflector material for short wavelengths. In this work, we report the influence of annealing temperature on the structural, morphological and optical properties of ThO 2 thin films deposited on fused quartz and (100) silicon substrates by photochemical metal–organic deposition (PMOD) using hinokitiolate thorium (IV) complex as the precursor. X-ray photoelectron spectroscopy (XPS) confirmed the deposition of the ThO 2 films. The effect of thermal annealing (from 300 °C to 1100 °C) on the structural properties of the ThO 2 films was evaluated with X-ray diffraction (XRD), UV–Vis transmittance spectroscopy, spectroscopic ellipsometry and atomic force microscopy (AFM). XRD patterns of the films annealed above 300 °C revealed that all diffraction peaks belong to a cubic ThO 2 structure without preferential orientation. The average crystallite size increased from 2.3 nm to 3.7 nm as the annealing temperature increased from 300 °C to 750 °C. Annealing at 1100 °C promoted the formation of huttonite (β-ThSiO 4) in the ThO 2 layer. Films deposited on fused quartz showed 80% transmittance in the visible range, and the annealing temperature did not impact the band gap energy. The AFM studies revealed that as the annealing temperature increased, the film surface roughness decreased. Between 750 °C and 950 °C, the film surface was relatively smooth with an of RMS surface roughness in the range 2.3–5.0 nm. The values of the refractive index of the films were in the range of n = 1.6 for the as-deposited film to n = 2.1 for the films annealed at 750 °C. This result suggests the potential use of ThO 2 films as a transparent reflector material for short wavelengths. [ABSTRACT FROM AUTHOR]

Nowadays, flexible substrates, as a part of flexible electronics, receive great attention by its wide application. Particularly, organic light emitting diodes and photovoltaics place high demands on the optical transmittance of flexible substrates. In this paper, direct fluorination is selected to treat commercial poly(ethylene terephthalate) (PET) and polyimide (PI) films. A suitable gradient distribution of fluorine atoms in the fluorinated layer were obtained in the vertical direction of the PET film by optimizing the conditions of direct fluorination. In this way, the refractive index was reduced by the introduction of the fluorine atoms, and the fluorine atoms with gradient distribution on the film's vertical direction led to the gradient decrease of the refractive index. Given this gradient-refractive index, a high broadband and omnidirectional transmittance of >93.0% was achieved by such a non-nanostructured surface over the entire optical wavelength (380–2200 nm), while the transmittance still remains relatively high (>85.0%) when the incident angle is increased from 0° to 60°. Moreover, this cost-effective and easy method presents its universality with the treatment of PI film, which also achieves high broadband and omnidirectional transmittance by direct fluorination. Unlabelled Image • High transmittance of PET and PI films can be achieved by direct fluorination, the transmittance of fluorinated PET can reach 97.5% at 850nm. • The transmittance of the fluorinated flexible substrates is broadband (380-2200nm) and omnidirectional, the transmittance still remains relatively high (> 85.0%) when the incident angle is increased from 0° to 60°. • The gradient-refractive index of fluorinated flexible substrate is non-nanostructured and achieved by fluorine diffusion. [ABSTRACT FROM AUTHOR]

In 0.024 Cd 0.976 O thin films were inserted between two layers of Ga 0.04 Zn 0.96 O films, in an effort to improve the electrical properties of the oxide film. The multilayer structure with an optimum InCdO layer thickness of ∼30 nm showed significantly improved electrical properties without seriously deteriorating the optical properties, with an average optical transmittance of ∼90% over the visible and the NIR range and a resistivity of 7.5 × 10−5 Ω cm. It was also observed that efficiency of the CuInGaSe solar cell devices using the Ga 0.04 Zn 0.96 O (50 nm)/In 0.024 Cd 0.976 O (30 nm)/Ga 0.04 Zn 0.96 O (50 nm) structure as the front electrode shows much higher efficiency (8.5%) than that (4.7%) of the devices with 100 nm Ga 0.04 Zn 0.96 O front electrode. This result indicates that the proposed multilayer structure would be a strong candidate for the transparent conducting electrode for the high performance optoelectronic devices. • In this work, InCdO films with very high-mobility were used as the conducting layer to constitute the ZnGaO/InCdO/GaZnO structure. • The ZnGaO/InCdO/GaZnO TCO films show a very low resistivity (ρ ∼ 7.5 × 10−5 Ω cm) and an average optical transmittance of ∼90% over the visible and the NIR range. • Efficiency of CIGS solar cell devices using the GaZnO(50 nm)/InCdO(30 nm)/GaZnO(50 nm) structure as the front electrode shows much higher efficiency (8.5%) than that (4.7%) of the devices with 100 nm GaZnO electrode. [ABSTRACT FROM AUTHOR]

Next-generation hybrid optics will provide superior performances over traditional optics by combining the advantages of refractive, reflective, and diffractive optics and metasurfaces. Hybrid optics have been realized by integrating diffractive optical structures to the top surface of traditional bulk refractive or reflective optics. However, high-resolution manufacturing requirement of diffractive patterns on top of free-form refractive or reflective optical surfaces have hindered the wide-spread dissemination of hybrid optics. In this paper, we demonstrate a transferable ultra-thin micro-optics having multi-level transmittance and phase profiles which are arbitrarily patterned by tunable photoreduction and photoablation of graphene oxides (GO) using femtosecond (fs) direct laser writing. A 5 × 5 array of multi-level ultra-thin micro diffractive lens having a focal length of 15 mm was exemplarily patterned with real-time laser power control; the resulting spot size was smaller than 14 μm with the suppression of diffractive side peaks by 14.9% at the first order and 10.8% at the second order ones. This laser-patterned diffractive lens array was successfully transferred to the surface of a refractive cylindrical lens via polydimethylsiloxane (PDMS) as the flexible/stretchable substrate; the resulting optical performance agrees well with the theoretical simulation result. This new fabrication method will pave a way to novel hybrid optical systems. Image 1 [ABSTRACT FROM AUTHOR]

Experimental identification method is a fundamental means of determining the spectral properties of semitransparent materials. A series of distinctly different and independent experimental data is usually required so as to provide multiple constraints to feed the retrieval model. However, for high-transparency and low-absorption materials, directional transmittance measurements may encounter unpredictable temperature gradients due to too many outlets on the heating compartment. And the transmittance measurements in a certain direction may confront the problem of low recognition that the transmittances of samples with different acceptable and reasonable thicknesses are undistinguished. To resolve these problems, a rotating-interface method coupling with an identifying procedure was proposed in this study. The rotating-interface method can provide a means of measuring various directional transmittances without additional outlets in the heating cell. There is barely any influence on the temperature field of the sample. Applied on multilayered specimens with various layers, this method could provide more independent and distinctly different transmittances by using as few specimens as possible. And thus the enough transmittance data was used as constraints to feed the retrieval model, guaranteeing the uniqueness and stability of the result. To verify this method, a C-cut sapphire was measured for the low absorption wavelengths throughout 0.35 to 1.1 μm at temperatures ranging from 300 to 1500 K. And then an experimental identification procedure was performed to retrieve the indexes of refraction and absorption. Considering the incident and detecting solid angles, a Monte-Carlo ray-tracing (MCRT) method was used to predict the experimental transmittances. A genetic algorithm was adopted to search and to optimize the association of refractive index and absorption index, which was brought in the retrieval model of least-square to minimize the difference between the transmittances, measured and predicted. Finally, temperature and wavelength dependence of transmission properties of the C-cut sapphire up to 1500 K were obtained. • A rotating-interface method was proposed to measure directional transmittances without additional outlets on the heating cell. • The method can provide many distinctly different transmittances by using as few samples as possible. • Spectral properties of C-cut sapphire were determined at the high-transparency range of 0.35-1.1 microns. [ABSTRACT FROM AUTHOR]

Recently, demand for authentication technology is growing rapidly in an attempt to overcome counterfeiting of high-value agricultural products, such as patchouli oil. Fingerprinting methods based on spectroscopy are one such technology being used for authentication. However, the spectral datasets obtained are multivariate in nature; containing thousands of data points for a single sample, making data acquisition and processing time-consuming. Therefore, reduction and simplification in the number of variables used required is needed to provide a more rapid and applicable method. Color cameras, which can capture image in the visible region light, could be such an alternative spectral data acquisition approach. In this research, a simplified spectroscopy method was developed for origin authentication of patchouli oil. The system consists of front ultraviolet light induced (365 nm) fluorescence and a white LED-based backlighting imaging system that consecutively captures the fluorescence and transmittance characteristics of the oil in the visible region. From the captured images, features were extracted and analyzed using Principle Component Analysis (PCA) to identify important image features for discrimination of origin. From the samples measured, the samples clustered around three islands of origin in the PCA space. A classification model based on fluorescence and transmittance image features (color values) could discriminate origin classes with a total accuracy of 88.46%. A lower accuracy was found for the Java class due to low sample numbers. This result demonstrates that the proposed system has the potential to be a rapid authentication tool for determining the geographical origin of patchouli oils. Unlabelled Image • Fluorescence-transmittance imaging for patchouli oil authentication • Principal component analysis used to identify important variables • Samples successfully classified based on a simple decision tree model [ABSTRACT FROM AUTHOR]

Abstract The temperature of a surface that is exposed to sunlight is influenced by the solar reflectance and the infrared emittance of the surface. A coating that reduces the surface temperature is often referred to as a cool coating. Cool coatings on building surfaces have several potential benefits, such as reduction of energy needed for cooling, improved thermal comfort, and mitigation of the urban heat island effect. In addition to low weight, aluminium is a metal that is known for its excellent reflectance properties. Recycled aluminium is now increasingly requested by the building market, both due to reduced cost as well as for environmental considerations. For building applications, surface treatments and coatings that completely hide the aluminium substrate are needed in order to obtain an attractive appearance, good corrosion properties and overall protection against outdoor environments. We see a need for a low-cost approach that can be used to obtain a cool coating on aluminium sheet. For this we have developed several different one-layer coating systems that can be applied in a coil-coating process. A total of 8 different coloured pigments with low absorption in the near infrared have been investigated with the goal to make cool coatings with various desirable colours. The coated surfaces achieved high solar reflectance by utilizing the excellent reflectance properties of the aluminium substrate. Good hiding of the substrate in the visible range and high infrared emittance has also been obtained. The colours include black and different shades of red, orange and yellow. Solar reflectance spectra and infrared reflectance spectra have been measured. From these spectra, optical properties of the coated surface such as total solar reflectance (TSR), infrared emittance and solar reflectance index (SRI) have been calculated. In addition, we also present results from weathering testing of the coated materials. The results show that the one-layer approach can be used to obtain cool coatings with high near infrared transmittance that are feasible to apply in a coil coating process. Highlights • Cool coating systems for coil coating of aluminium sheet have been investigated. • Eight cool coatings of different colours have been prepared and tested. • NIR transmitting pigments take advantage of the solar reflectance of aluminium. • All eight coatings obtain NIR reflectance >0.6 and IR emittance >0.68 • The cool coatings demonstrate good visual homogeneity and sufficient visual hiding. [ABSTRACT FROM AUTHOR]

• A normal distribution model for diffuse radiation is proposed. • The normal distribution is related to the incident angle of direct radiation. • Weather and season do not influence the normal distribution. • Weather only influences the value of diffuse radiation. • The normal distribution has higher accuracy than other models. Solar radiation is an important factor in the design and simulation of transparent systems. The angle-dependent optical properties of transparent systems are hard to predict because it is difficult to obtain the incidence angle of diffuse irradiance. In this paper, a normal distribution model is proposed for diffuse radiation. It is assumed that diffuse irradiance follows normal distribution. The expectation of the distribution is the incidence angle of direct radiation, while the variance is expressed as the isotropy index. Through the experimental results for a transparent double-glazing (DG) system, it is found that the values of isotropy index are related to the incidence angle of direct radiation. The normal distribution model is evaluated with the diffuse irradiance map given by the researchers in SRRL. And then the indoor diffuse irradiance through the DG system is calculated by the normal distribution model and other distribution models. The calculated results are compared with the experimental results. It is assumed that the outdoor diffuse irradiance incident on a DG system follows normal distribution. The diffuse irradiance and transmittance through a DG system are predicted by the interface energy-balance method. The predicted diffuse irradiance and transmittance by the model are compared with measured values and those predicted by other distribution models. The predicted indoor irradiance or transmittance for the proposed normal distribution model has better accuracies than the Perez and isotropic model. [ABSTRACT FROM AUTHOR]

• Highly transparent and conductive MGZO films are prepared for CZTSSe solar cells. • Correlation between transmittance and resistivity of TCO on the solar cells is studied. • A deviation of transmittance was caused by the thickness of MGZO in NIR-IR region. • Efficiency of the CZTSSe solar cell is up to 7.54% with the MGZO of 600 nm. The doping of Mg and Ga into ZnO is a method for obtaining excellent optical and electrical properties for a window layer in an inorganic solar cell. Because a tradeoff exists between the electrical and optical properties in the window layer, balancing them is important for enhancing the performance of the solar cells. From this viewpoint, the thickness change of the window layer affects the transmittance and the conductivity. In particular, it affects the transmittance in the NIR-IR region significantly, which can enhance the current collection but lead to poor conductivity when the transmittance of the window layer is increased. We examine the thickness effect of MGZO films for CZTSSe solar cells in order to determine the optimal conversion efficiency. The enhanced transmittance in the NIR-IR region with a thin MGZO layer contributed to a high current density, although the electrical resistivity was relatively high. An enhanced conversion efficiency of 7.54% was eventually recorded for an optimal thickness of the MGZO layer with an improved current density over 7 mA/cm2. [ABSTRACT FROM AUTHOR]

Abstract Semitransparent (ST) organic photovoltaics (OPVs) are demonstrating great potential for building integration applications, especially in windows. For that purpose, ST-OPVs should achieve adequate transparency and performance stability. In this regard, the present research deals with the experimental performance of three different building-integrated ST-OPV technologies (technology A: developed in the frame of the present study; technologies B and C: commercial modules). More specifically, spectral transmittance and electrical measurements have been conducted in order to determine the characteristics of the modules for building integration and electricity generation purposes. Results regarding the transmittance reveal that technology A outperforms technologies B and C. The stability analysis of the modules verifies that module C is the most stable one with almost no decrease (3.6%) in the power conversion efficiency (PCE). Furthermore, the PCE of technology B is slightly higher than in the case of technology C, which experiences a PCE degradation of about 10–15% over the whole time period. Finally, technology A presents a 20% reduction in PCE at around 500 h. [ABSTRACT FROM AUTHOR]

Highlights • Proposed an alternative low-e film installation approach—elevating it from window-pane to reduce thermal transmittance of window. • Experimentally and theoretically studied the thermal insulating performance of the elevated low-e assembly. • The optical and mechanical properties of this assembly were proved to be desirable. Abstract To minimize the heat loss through single-pane windows, we investigate the effects of elevating low-emissivity (low-e) film from glass pane. With an insulating air gap, not only heat conduction but also radiative thermal transfer can be suppressed. The thermal transmittance is reduced from 5~7 W/(m2K) to less than 2.8 W/(m2K). The water condensation resistance is enhanced. The visual transmittance and haze are satisfactory. The structural resilience of the hollow structure is excellent. [ABSTRACT FROM AUTHOR]

• Algae-photobioreactors were installed as shading system in a real kindergarten. • The visible transmittance of the algae was determined through a 21 days monitoring. • The room daylighting and energy demand for lighting were simulated with Daysim. • Further simulations were run changing the site and the orientation of the room. • Performances with the algae shading system were compared to a venetian blind. • The lighting performances of algae and venetian blinds are comparable. A study on a novel photo-bio screen (PBS) used as a shading system in a real building is presented. The green microalgal culture (Scenedesmus obliquus) of the PBS allows a screening of the direct sunlight and a production of biomass containing bioactive compounds. The PBS was tested in a kindergarten classroom at Saint Marcel (Aosta Valley, north-west of Italy) and monitored for 3 weeks (June-July 2016). The visible transmittance T v of PBS was determined through in situ illuminance measurements, while the daylight amount in the room and the energy demand for lighting ED l were calculated through Diva-for-Rhino simulations (using the median measured T v as input). The analysis was split in two phases: (i) the real room (with south-facing windows and external obstructions); (ii) the same room without obstructions, analyzed parametrically by changing the site (Turin, Östersund, Athens, and Abu Dhabi) and the orientation (south, west, north, and east). For both phases, the results for PBSs were compared to what obtained applying a traditional venetian blind VB of comparable light transmission to the window. From the monitoring campaign, the T v of the PBS was found to have a quite high variation as a function of the dynamic boundary conditions, so an median value of 0.75 was identified as the reference T v. From simulations, it was found that the daylight amount and the ED l for PBS and the VB were comparable, with slightly better results for the PBS in Turin and Athens and slightly better results for the VB in Östersund and Abu Dhabi. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Investigation for thermochromic properties of VO 2 thin films with different pattern size was done. • Pattern size was varied as a diameter of polystyrene spheres with 550, 900, and 1230 nm. • It was found that pattern size strongly effect on transmittance curves in certain wavelength. • With increasing pattern size, a changing point of transmittance curve were shifted to long wavelength. • This phenomena are good agree with Bragg condition presented in manuscript. Abstract This paper presents the optical characteristics of 2D honeycomb structured vanadium dioxide (VO 2) thermochromic thin films with different pattern size prepared by sol-gel method with adopting colloidal lithography. Pattern sizes of films were varied as a diameter of polystyrene spheres and size of obtained films are 550, 900, and 1230 nm, respectively. Crystal structure of prepared films is monoclinic phase of VO 2 (M) and there are no impurities or other oxides. The transmittance curve change was observed for all patterned VO 2 thin films and it is strongly correlated with pattern sizes and shapes which can make difference in photonic band gap. In addition, it is found that such transmittance curve change are originated from reflection at certain wavelength section which confirmed by reflectance spectra. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A concept depositing high LIDT, low stress coating is presented. • A stress model based on intermolecular force is presented. • An anti-reflection coating is prepared for certification. Abstract Both low stress and high laser induced damage threshold are required in the development of high power large laser facilities. IBS and ALD films have potential in such applications in aspects of film thickness control and high LIDT, but their severe stresses cause an obstacle towards the widely application. The origin of compressive stress of IBS coating and tensile stress of ALD coating is analyzed with a model based on intermolecular potential. An anti-reflection coating having compensated stress is designed and fabricated with ALD Al 2 O 3 and IBS SiO 2. The LIDT of the anti-reflection coating as well as the single layers are tested at wavelength 532 nm. A transmittance of 96.5% at single surface and a stress as low as 38 MPa are achieved. The LIDT of the anti-reflection coating is limited by the additional defects introduced at the film interfaces. This design takes advantage of the power resistance of IBS/ALD coatings and their contrary stresses, providing a concept towards the application in high power laser systems. [ABSTRACT FROM AUTHOR]

Abstract Transparent ceramics are a kind of optical materials which have a wide range of applications in various engineering sectors, including the medical devices (implants, anti-wear coatings), cars, smartphones (anti-wear and shockproof plates), watches (anti-wear and anti-shock lenses with high strength), optical lenses, etc. Control of various parameters like the volume fraction of secondary phase, the grain size of the main and secondary phase, and the number of pores in unit volume, which affect the absorption, reflection and finally the transparency of ceramics, is a vital issue. Studying the physical aspects besides applying the principles of simulation is a very efficient way to achieve this aim. Simulation of the behavior of ceramics helps to attain optimized parameters. Therefore, to accomplish an optical ceramic with prominent transparency and admissible transmittance in selective wavelengths, the appropriate simulation theory should be used. In this paper, first, the physical basis of optical ceramics including band gaps, absorption, reflection, diffraction, refractive index, refraction, dispersion, etc., are briefly presented. Additionally, different simulation theories are reviewed and discussed. Highlights • Critical reviewing of basic requirements for optically transparent ceramics. • Introducing the most important factors, which affect the transparency of ceramics. • Comparing the scattering theories presented to investigate the transparency of the ceramics. [ABSTRACT FROM AUTHOR]

Abstract We present the analysis of optical spectroscopy fingerprints of three different varieties of Sardinian red wine, Carignano, Cannonau and Monica, belonging to Italian DOC (Controlled Origin Designation) red wines family. We selected 15 commercial wines (five for each variety), produced in the middle and south regions of Sardinia form monovarietal grapes. Despite different grapes, farming and tasting, all the samples share common absorption and fluorescence features. A two steps analysis is applied to achieve good classification of the wines. We recorded typical absorbance spectra with a large absorption below 300 nm and a visible absorption band at about 520 nm. Colour attributes according to chromaticity coordinates were evaluated by means of transmittance data and coupled to wine aging data to achieve classification. Despite similar values of lightness (L*), chroma (C* ab), and hue angle (h° ab) for the three varieties, good clustering was gathered for Carignano and Cannonau wines, whilst Monica variety has wide spread chromatic coordinates. UV excited fluorescence spectra display large and composite emission bands from the near UV down to the whole visible range. We performed multivariate analysis in the framework of the principal component analysis of fluorescence spectra coupled with absorption ones being able to achieve good clustering between the three varieties. One anomaly among Cannonau wines is discussed. Graphical abstract Unlabelled Image Highlights • Classification of monovarietal Sardinian red wines by means of a new chemometric tool • Analysis of absorption spectra in the chromatic coordinates framework • Multivariate analysis of front face fluorescence spectra • Exploiting combined absorption and front face fluorescence spectroscopy [ABSTRACT FROM AUTHOR]

• The U-values of double/triple evacuated glazing with tempered glass were simulated. • Compared with the U-values of double/triple vacuum glazing with annealed glass. • the U-value of double evacuated glazing with tempered glass is reduced by 47.4%. • the U-value of triple evacuated glazing with tempered glass is reduced by 60.7%. • as tempered glass is 4 times stronger than annealed glass, less pillars are used. The application of tempered glass has made it possible to significantly reduce the support pillar number within evacuated glazing (EG) since tempered glass (T-glass) is four to ten times mechanically stronger than annealed glass (A-glass). The thermal transmittance (U-value) of 0.4 m by 0.4 m double evacuated glazing (DEG) with 4 mm thick T-glass and A-glass panes with emittance of 0.03 were determined to be 0.3 Wm−2K−1 and 0.57 Wm−2K−1, respectively (47.4% improvement) using previously experimentally validated finite volume model. The thermal transmittance (U-value) of 0.4 m by 0.4 m triple evacuated glazing (TEG) with 4 mm thick T-glass and A-glass panes with emittance of 0.03 were determined to be 0.11 Wm−2K−1 and 0.28 Wm−2K−1, respectively (60.7% improvement). The improvement in the U-value of EG with T-glass is due to a reduction in support pillar number, leading to reduction in heat conduction through pillar array. The impact of tempered glass on the thermal transmittance for TEG is greater than that of DEG since radiative heat transfer in TEG is much lower than that in DEG, thus the reduction in heat conduction resulted from the reduction of support pillar number in TEG is much larger than that in DEG. [ABSTRACT FROM AUTHOR]

Abstract Hermeticity of vacuum edge-sealing materials are one of the paramount requirements, specifically, to the evolution of energy-efficient smart windows and solar thermal evacuated flat plate collectors. This study reports the design, construction and performance of high-vacuum glazing fabrication system and vacuum insulated glazing (VIG). Experimental and theoretical investigations for the development of vacuum edgeseal made of Sn-Pb-Zn-Sb-AlTiSiCu composite in the proportion ratio of 56:39:3:1:1 by % (CS-186) are presented. Experimental investigations of the seven constructed VIG samples, each of size 300 mm·300 mm·4 mm, showed that increasing the hot-plate surface temperatures improved the cavity vacuum pressure whilst expediting the pump-out hole sealing process but also increases temperature induced stresses. Successful pump-out hole sealing process of VIG attained at the hot-plate set point temperature of 50 °C and the approximate cavity pressure of 0.042 Pa was achieved. An experimentally and theoretically validated finite volume model (FVM) was utilised. The centre-of-pane and total thermal transmittance values are calculated to be 0.91 Wm−2K−1 and 1.05 Wm−2K−1, respectively for the VIG. FVM results predicted that by reducing the width of vacuum edge seal and emissivity of coatings the thermal performance of the VIG is improved. Graphical abstract Image 1 Highlights • Novel design and construction of vacuum insulated glazing (VIG) were discussed. • A vacuum edge-seal made of composite (Sn 56 Pb 39 Zn 3 Sb 1 - AlTiSiCu 1 wt%) was analysed. • Influences of temperatures on evacuation and pump-out sealing of VIG were studied. • A high-vacuum pressure of 0.042 Pa at 50 °C surface temperature was achieved with VIG. • Thermal performance of VIG with surface-coatings and vacuum-edge seal was analysed. [ABSTRACT FROM AUTHOR]

In this study photon distribution and their correlation with measured diffuse reflectance and transmittance from UHMWPE were investigated from 200 nm to 800 nm. The values of scattering coefficients μ s , absorption coefficients μ a in cm−1 for UHMWPE were extracted by using Kubelka Munk Model (KMM) from diffuse reflectance and transmittance measurements. It was found that both absorption and scattering coefficients has higher values in shorter wavelength regions. The void space in UHMWPE matrix, C=C poly-unsaturation and high values of refractive index mismatch, respectively were considered responsible for this behavior. In addition, the penetration depth δ was found higher in near IR region i.e. from 680 to 780 nm and it has peak value 75 ± 1.5 mm at 700 nm. The lowest values of μ a i.e. 0.042 cm−1, forward directed scattering behavior of UHMWPE and almost constant values of μ s in this region were the major responsible factors for larger penetration of incident photons. Furthermore, the accuracy of results was validated theoretically using Monte Carlo method while using extracted optical parameters as input for Monte Carlo code. It was found that experimental results were in good agreement with theoretical one. Also, distribution of photons for 300 nm and 800 nm were simulated and plotted as a function of their radial and depth positions which revealed the higher penetration depth for low energy photons i.e. up to 0.05 cm for 800 nm. • KMM was used to extract UHMWPE optical properties experimentally. • Extracted properties were theoretically validated using Monte Carlo Model. • Photon distribution was done with Monte Carlo Model. • These results will be useful for UHMWPE modification with lasers. [ABSTRACT FROM AUTHOR]

Highlights • Time-resolved pump-probe system is used to monitoring the femtosecond laser annealing of indium tin oxide. • The transmittance variation detected by the probe beam gradually increases with increasing machining power. • The 400-nm probe beam is more sensitive than the 800-nm probe beam in measuring curve variation. Abstract In this study, a set of time-resolved pump-probe systems for the real-time monitoring of femtosecond (fs) laser annealing of ITO substrates is established. A pump beam is used as the light source for thermal annealing, and a probe beam is used to monitor the transmittance variation of ITO in real time. Measurement results show that with increasing machining energy, the transmittance variation detected by the probe beam gradually increases. When the laser energy is small, the transmittance changes arithmetically. When the laser energy is sufficient to complete the modification of ITO, the transmittance variation rises suddenly and sharply, indicating that the thermal annealing modification has been completed in the irradiated area. Then, the laser source is shut down to achieve real-time monitoring. Degenerate and non-degenerate pump-probe experimental results indicate that the 400-nm probe beam is more sensitive than the 800-nm probe beam in measuring curve variation because the variation in the ITO transmission spectrum in the 400-nm wave band is greater than that in the 800-nm wave band. Electron backscatter diffraction analysis indicates that the crystallographic directions of ITO after laser annealing are consistent. This shows that the ITO changed from non-crystallized to crystallized after being irradiated by the pump beam, confirming the thermal annealing modification. [ABSTRACT FROM AUTHOR]