Transmittance Measurements Research Articles

Characterization of the “Ultra Small Unilamellar Carrier System (USUC)” Nanodispersion Optimal Formula from the Active Compound Quercetin

Quercetin is a flavonoid compound with strong antioxidant activity found in various plants. The permeability of quercetin into the skin is very low due to its poor water solubility which makes its transdermal delivery inefficient. As a drug delivery system, USUC can increase the effectiveness of drug therapy by reducing the particle size to the nanometer range. The results of the evaluation of the nanodispersion preparation base obtained were stable in the form of a clear, yellow, distinctive aroma resulting from the addition of lecithin and homogeneous, the average pH was 6.8, the turbidity measurement was 0.050%, freeze and thaw testing, namely the stable preparation was stored at room temperature. as well as extreme temperatures, 52 cp viscosity and 1.073 g/ml specific gravity. The results of the evaluation of the quercetin nanodispersion preparation obtained were stable in the form of a clear solution, yellow in color, characteristically flavored resulting from the addition of lecithin and homogeneous, the average pH was 6.4, the transmittance measurement was 94.519%, freeze and thaw testing, namely the stable preparation was stored at room temperature. as well as extreme temperatures, viscosity 52 cp, specific gravity 1.062 g/ml, irritation test which was negative for all parameters observed, the maximum wavelength of quercetin was 371.50, the regression equation for quercetin was linear and the encapsulation efficiency value obtained was 96.22%. The results of characterization using PSA obtained a particle size of 11.0 nm , polydispersity index 0.243, and a zeta potential value of -11.4 mV.

Optical absorption enhancement in ultrathin chalcopyrite solar cells with Ag reflective back contact

The optical performance of ultrathin solar cells based on chalcopyrite CuInS2 absorber has been studied, simulating the total absorption as a function of the absorber thickness with and without Ag reflective back contact. The structure chosen is ZnO:Al/SnS2/CuInS2/Ag/Mo/glass, using for the simulation the experimental data extracted from the layers prepared in our laboratory by evaporation (CuInS2 and SnS2) and sputtering (ZnO:Al, Ag and Mo). The main purpose has been to apply realistic input parameters (refractive index and extinction coefficient extracted from transmittance and reflectance measurements for each layer) to simulate and analyze the optical behavior of the entire device. It is found that the overall absorption of the cell with 0.2 μm-thick CuInS2 and 60 nm-thick Ag is the same as that obtained for 0.4 μm-thick CuInS2 without Ag layer. Thus, the incorporation of Ag reflective contact allows reducing the absorber layer thickness and therefore the time and cost of manufacturing chalcopyrite cells, being especially relevant for absorber thicknesses below 0.4 μm.

From gradient-index to step-index filters: A switch between the two types of photonic crystals induced by the amplitude and period of sinusoidal function applied during high-temperature anodisation of aluminium

Porous anodic alumina (PAA) holds promise for the realisation of high-quality optical filters with first-order photonic stop-bands (PSBλ1) located in the infrared spectral region, thereby expanding the possibility of its application in photonics and light-based industries. High-temperature (30 °C) sinusoidal pulse anodisation (SPA) of aluminium was applied to fabricate PAA with PSBλ1 in the range of 800–2500 nm. The systematic increase in the anodisation period (tp) and amplitude (A) caused a significant change in the optical properties of the PAAs, which were monitored by both transmittance and reflectance measurements. A switch from gradient-index to step-index optical filters was observed when A and tp were increased from the lowest (5 V and 100 s, respectively) to the highest (15 V and 300 s, respectively) values. The switch was ascribed to the transition between different self-ordering regimes. The finest filtering properties (PSBλ1 reflectance close to 100 %) were achieved when the SPA proceeded between diffusion and kinetic regimes, providing a better porosity/refractive index contrast within the periodic structure. The analysis under polarised light confirmed both the excellent filtering properties of the PAAs and the asymmetrical light reflectance produced through the robust and cost-effective SPA process.

Spectrophotometric Evaluation of Translucency of Various Commercially Available Zirconium Oxide Ceramic Systems: An In Vitro Study

To evaluate and compare the translucency of various commercially available zirconium oxide ceramic systems, i.e., Ceramill® Zolid Classic, Ceramill® Zi, and DD Bio ZX²71 by using a dual beam UV-visible spectrophotometer. The present study comprised of 21 disk-shaped samples of zirconia for every group, i.e., group I-Ceramill® Zolid Classic, group II-Ceramill Zi®, and group III-DD Bio ZX²71. Furthermore, each group was split into three subgroups and every subgroup had seven samples each one of 0.7, 0.8, and 0.9 mm thickness. The samples were prepared by computer-aided design/computer-aided manufacturing (CAD/CAM) system devised by Amann Girrbach AG in accord with the steps provided by the manufacturer. The entire sample was designed having 10 mm in diameter with 0.7, 0.8, and 0.9 mm thickness for every group. The UV-visible dual beam spectrophotometer equipped with D2 lamp and W lamp was used for the measurement of absorbance and transmittance in order to assess the translucency of the fabricated zirconia samples. The mean value of transmittance % for Ceramill® Zi at 0.8 mm came out to be 0.849 ± 0.024, i.e., the least among all, whereas the mean value of Ceramill® Zolid Classic was 1.408 ± 0.033, being the highest for the same thickness. DD Bio ZX²71 had an intermediate value of 1.274 ± 0.012. The mean value of absorbance for Ceramill® Zi at 0.8 mm came out to be 2.086 ± 0.013, i.e., the maximum among all, whereas the mean value of Ceramill® Zolid Classic was, being the lowest for the same thickness. DD Bio ZX²71 had an intermediate value of 1.902 ± 0.004. The present study data suggest that all the materials subjected to evaluation exhibited a substantial translucency. We attempted to study few of the desirable properties, these materials should possess when used for prosthetic rehabilitation with esthetic contentment a clinical setup. There has been an ambiguous distinction that Ceramill® Zi Zirconia supersedes the Ceramill® Zolid Classic and DD Bio ZX²71. Furthermore, 0.8 mm thickness substantiates to be the most ideal among 0.7, 0.8, and 0.9 mm. The desired outcome of the procedure becomes dependent solely on the clinician's judgment to opt for the material whose properties are most fitting as per the demands of the esthetics. While a clinician should always be ambitious, but a good clinician should also bear in mind that the success of any treatment procedure not only depends on the assortment of properties of these materials but also the host response and satisfaction evoked by these materials.

UV light blocking and conversion by porous europium-doped titanium dioxide (TiO2-Eu) thin films for potential protection of photovoltaic devices

In recent years, transparent thin films capable of screening and converting ultraviolet (UV) photons into visible spectrum gained significant interest in the protection of photovoltaic devices. We investigated the optical properties and UV screening capability of europium-doped titanium oxide (TiO2−Eu) thin films deposited by the spin-coating method from a solution precursor for the first time in this study. We showed that TiO2-Eu thin films demonstrate europium concentration-dependent optical properties, and the quantum yield of the optimized sample was found to be ∼10.2%. Transmittance and photoluminescence measurements suggested that TiO2−Eu thin film can effectively block UV photons (∼30.5% at 320 nm) at glass substrate and convert them to the red emission thanks to 5D0 →7Fj (j = 0, 1, 2, 3, and 4) Eu (III) electronic transitions. Photodegradation experiments with methylene blue dye revealed that TiO2−Eu thin films offer better UV protection compared to uncoated samples. We strongly believe that porous TiO2−Eu thin films can be effectively utilized as a UV blocking and light conversion coating.

Robust unbalanced Gires-Tournois mirror for group delay dispersion measurement evaluation by white light interferometer

A robust unbalanced Gires-Tournois interferometer (GTI) mirror for evaluating group delay dispersion (GDD) measurement by scanning white light interferometer is presented, and a novel processing algorithm based on scanning white light interferometer (WLI) is proposed to extract group delay and group delay dispersion characteristics with improved accuracy and low level of noise. The GDD measurement evaluation method is based on error analysis of manufacturing errors and spectral measurement. Spectral measurement is carried out to determine the resonance wavelength of GTI mirror. The sample was prepared by ion beam sputtering deposition. The relative errors of refractive index and layer thickness for the sample are estimated through reverse engineering based on multi-angle transmittance measurements. A novel processing algorithm the extrema searching method (ESM) is proposed that search the positions of multi-order extrema from reconstructed interferogram intensity to exact the GDD characteristics of the sample. GDD measurements performed by WLI with different processing methods are added to comparison including windowed Fourier transform, wavelet transform and time-domain scanning method. The results show that our method is reliable and effective for GDD measurement with a good accuracy and low level of noise.

Evaluation of chitosan/xanthan gum polyelectrolyte complexes potential for pH-dependent oral delivery of escin

Escin is an amphiphilic and weakly acidic drug that oral administration may lead to the irritation of gastric mucosa. The entrapment of escin into chitosan (CH)/xanthan gum (XG)-based polyelectrolyte complexes (PECs) can facilitate controlled drug release which may be beneficial for the reduction of its side effects. This study aimed to investigate the influence of escin content and drying method on the formation, physicochemical, and controlled, pH-dependent drug release properties of CH/XG-based PECs. Measurements of transmittance, conductivity, and rheological characterization confirmed the formation of CH/XG-based PECs with escin entrapped at escin-to-polymers mass ratios 1:1, 1:2, and 1:4. Ambient-dried PECs had higher yield, entrapment efficiency, and escin content in comparison with spray-dried ones. FT-IR spectra confirmed the interactions between CH, XG, and escin, which were stronger in ambient-dried PECs. PXRD and DSC analyses showed the amorphous escin character in all dry PECs, regardless of the drying method. The most promising controlled and pH-dependent in vitro escin release was from the ambient-dried PEC at the escin-to-polymers mass ratio of 1:1. For that reason and due to the highest yield and entrapment efficiency, this carrier has the potential to prevent the irritation of gastric mucosa after oral administration of escin.

Glycerol methacrylate-based copolymers: Reactivity ratios, physicochemical characterization and cytotoxicity

Understanding the chemical composition of biocompatible copolymers is crucial for diverse biomedical applications such as the conjugation of polymers to drugs, peptides or proteins. Here, we report the Reversible Addition-Fragmentation Chain Transfer (RAFT) copolymerizations and reactivity ratios (r) of the less explored biocompatible copolymer systems based on glycerol mono-methacrylate (GMMA) monomer. Hence, we investigated the copolymerization of GMMA with the comonomers N-hydroxy succinimide methacrylate (NHSMA), N-isopropylacrylamide (NIPAM) and butyl acrylate (BuA). The estimated r values and sequence length distributions suggest that a chain radical of GMMA monomer prefers cross propagation in the system GMMA/NHSMA (rGMMA = 0.32 rNHSMA = 1.01). In the case of GMMA/NIPAM (rGMMA = 2.55 rNIPAM = 0.11) and GMMA/BuA (rGMMA = 3.31 rBuA = 0.66) systems, as shown by the relatively high rGMMA values in both copolymerizations, the formation of gradient copolymers might be favored. To understand the role of the comonomer composition in the thermal and solution properties of the final materials, the glass transition temperature (Tg) values of the copolymers, as determined by differential scanning calorimetry (DSC), were compared to build Tgvs. composition plots generated with the Fox, Brostow and Kwei equations. DSC investigations also revealed an interesting effect of molecular interactions between the polymer chains possibly formed via hydrogen bonding conveyed by the GMMA groups in the copolymers. Furthermore, light transmittance measurements of the poly(GMMA-stat-NIPAM) copolymer system in aqueous solutions revealed that the cloud point temperature (Tcp) of the solutions increases with the content of GMMA groups in the copolymer; however, this behavior was limited by the NIPAM composition (>0.74 mol fraction). Interestingly, a copolymer material with a GMMA/NIPAM composition (FGMMA/FNIPAM) of 26/74 exhibited a TCP = 38 °C, which is close to the human body temperature. Finally, cytotoxicity assays indicated the excellent biocompatibility of the obtained copolymers, which suggests that these copolymer systems might be suitable alternatives for bioconjugated systems in biomedical applications.

Studies of the Structure and Optical Properties of BaSrMgWO6 Thin Films Deposited by a Spin-Coating Method.

Highly transparent thin films with the chemical formula BaSrMgWO6 were deposited by spin coating using a solution of nitrates of Ba, Sr, and Mg and ammonium paratungstate in dimethylformamide with a Ba:Sr:Mg:W ratio = 1:1:1:1. XRD, SEM, EDX, and XPS investigations evidenced that annealing at 800 °C for 1 h results in an amorphous structure having a precipitate on its surface, and that supplementary annealing at 850 °C for 45 min forms a nanocrystalline structure and dissolves a portion of the precipitates. A textured double perovskite cubic structure (61.9%) was found, decorated with tetragonal and cubic impurity phases (12.7%), such as BaO2, SrO2, and MgO, and an under-stoichiometric phase (24.4%) with the chemical formula Ba2−(x+y) SrxMgyWO5. From transmittance measurements, the values of the optical band gap were estimated for the amorphous (Egdir = 5.21 eV, Egind = 3.85 eV) and nanocrystalline (Egdir = 4.69 eV, Egind = 3.77 eV) phases. The presence of a lattice disorder was indicated by the high Urbach energy values and weak absorption tail energies. A decrease in their values was observed and attributed to the crystallization process, lattice strain diminution, and cation redistribution.

New pyridyl and aniline-functionalized carbamoylcarboxylic acids for removal of metal ions from water by coagulation-flocculation process

In this work, a library of new aniline and pyridyl functionalized carbamoylcarboxylic acids were synthesized, physicochemically analyzed and evaluated as ligands for the simultaneous removal of environmental interest cations. The effect of the structural characteristics of these functionalized ligands over the simultaneous removal performance of metal ions (Cr3+, Pb2+, Cd2+, Cu2+, Ni2+, Zn2+ and Ca2+) was established. The metal ion-ligand association constants calculated from zeta potential (102 to 104 M−1) and UV–vis (103 to 107 M−1) demonstrate a strong affinity of these ligands towards metal ions. The micro-Jar test for cation removal shows these new functionalized carbamoylcarboxylic acids L1-L12 show average removal efficiencies of 100 % Cr3+, 73 % Pb2+, 42 % Zn2+, 50 % Ni2+, 42 % Cd2+, 39 % Cu2+ and 30 % Ca2+. The quantification of destabilization phenomena through transmittance and backscattering measurements allowed to evaluate the mechanisms of colloidal instability to all ligands. Among the twelve ligands, L9 showed the best removal performance at pH = 4.0 with an overall removal capacity (19.28 mg Mn+ removed/mg of L9), clarification kinetics (55.99 T%/h) and sedimentation ratio (117.6 mm/h). The flocs recovered from the coagulation-flocculation tests were analyzed by scanning electron microscopy and dispersive energy spectroscopy with mapping finding the dispersion patterns of metals on the surface. A BOD5/COD = 0.44 indicates that L9 is a biodegradable compound. Based on the results, aniline and pyridyl functionalized carbamoylbenzoic acids have great potential to be applied in the wastewater treatment industry containing multiple cations.

Impact of Se and Te addition on optical characteristics of ternary GeInSb chalcogenide films as promising materials for optoelectronic applications

The present study investigates the linear and non-linear optical characteristics of non-crystalline quaternary Ge15In5Sb5Se75 (GIS-Se) and Ge15In5Sb5Te75 (GIS-Te) chalcogenide thin films. The amorphous nature of the studied compositions was confirmed by x-ray diffraction (XRD). The values of transformation temperatures determined by differential thermal analysis (DTA), such as glass transition and crystallization temperatures, are 524.3 and 639.6 K for GIS-Se and 503.6 and 542.0 K for GIS-Te. The calculated values of glass forming ability () and thermal stability () for GIS-Se are higher than those for GIS-Te. The transmittance and reflectance spectrophotometric measurements in the UV–vis. wavelength range (400–2500 nm) are used to estimate the index of refraction and extinction coefficient The obtained values of and are found to be thickness independent in the investigated range. Tauc’s extrapolation model was used to determine both Urbach tail () and optical band gap () energies. The values of () are 0.416, 0.526 eV and () are 1.83, 1.31 eV with indirect allowed transitions for GIS-Se and GIS-Te, respectively. The optical conductivity increased as photon energy () increased, and it was enhanced in the presence of Te than Se addition. The analysis of the index of refraction () is used to evaluate the dispersion energy the high frequency dielectric constant the oscillator strength the lattice dielectric constant the ratio and the optical electronegativity which were found to be higher in GIS-Te than those in GIS-Se composition. The volume () and surface () energy loss functions were found to be increased with increasing () and the presence of Te. Furthermore, the calculated values of nonlinear optical susceptibility and nonlinear index of refraction for GIS-Se and GIS-Te are 0.195 × 10−12, 2.44 × 10−11 esu and 0.868 × 10−12, 10.19 × 10−11 esu, respectively. The detailed outcomes show that the studied film samples are suitable for various optical applications such as phase-change optical rewritable disks, optical sensors, optoelectronic devices and high-speed optical fibers.

Transmittance Characteristics of Dimethacrylate Resin Based Dental Composites

Background: The transmission of light through dental composites is a major factor responsible for photo activation polymerisation and optical properties of these materials. The extent of the light transmission depends on their formulations.Objectives: The purpose of this study was to determine the transmittance of dental resin-composites and investigate the effect of material thickness and light wavelength.Methods: Four photo-cured disc samples (Φ20mm) with different material thicknesses (ranging from x=0.11mm to x=1.46mm) of three different nanohybrid dental resin–composites (Regular, Flowable and Sealant) of the same shade, A3 and matrix but different filler loading were prepared. Transmittance measurements (n=3) were made using an Ocean Optics USB 4000 fibre optic Spectrometer operated by a Spectra Suite software. Data were analysed by One-way analysis of variance (ANOVA) combined with Tukey multiple test.Results: Differences were found in transmittance values as both material thickness and light wavelength increases. Transmittance (T) increase significantly (P<0.05) with increasing wavelength and decrease with increasing thickness. Linear regression analysis of In (T)with material thickness for light wavelength, gave R2 values ranging from 0.81 to 0.99. Correlation of attenuation coefficient with light wavelength for the materials indicated significant correlation (p<0.05, r =0.94) with Grandio Seal but not with Grandio (p>0.05, r=0.77) and Grandio Flow (p>0.05, r =0.79).Conclusions: The significant differences in the transmittance with increasing light wavelength and material thickness of the materials may affect their clinical appearance.

Integration of biocompatible Coomassie Brilliant Blue dye on silicon in organic/Inorganic heterojunction for photodetection applications

Here, we introduce systematic investigations of structural, morphological, and optical properties of solution-processed coomassie brilliant blue, CBB, thin films for photodetection applications. First, the structural and morphological features of the spin-coated CBB thin films are investigated using XRD and FESEM microscopy and yielded a polycrystalline, nanostructured, and porous CBB film of crystallite size and RMS roughness ∼31.95 nm and 10.65 nm, respectively. The UV–Vis–NIR spectrophotometric measurements of transmittance and reflectance elucidated the efficient absorption and light-harvesting of the UV and visible light range with estimated indirect energy gap and Urbach energy ∼1.54 eV and 22.3 meV, respectively. Next, the dispersion behavior of the fabricated thin films is analyzed in the light of the single-oscillator model estimating the detail dispersion parameters. Furthermore, the dielectric function, as well as the nonlinear optical parameters, is accurately estimated. Subsequently, the microelectronic parameters of the engineered rectifying Ag/CBB/p-Si/Al heterojunction such as ideality factor, barrier height, series, and shunt resistances are estimated at different temperatures. The charges dynamical mechanism and the interface states density profile are analyzed, and the thermionic emission model is confirmed to fit the low bias region with a modified Richardson constant of about 34.8A/cm2K2.After that, the photoresponse of the implemented organic/inorganic heterojunction is checked at different illumination intensities and showed a significant stable sensitivity with fast On-Off switching behavior. The fabricated heterojunction achieved good figures of merit such as responsivity, specific detectivity, linear dynamic range, and rise/fall time of about 4.289 mA/W, 2.07 × 109 Jones, 30.36 dB, and 61.6/82.5 ms, respectively. The good and stable responsive performance of the current Ag/CBB/p-Si/Al architecture may make it a potential candidate for photodetection applications.

Infrared optical properties modulation of VO2 thin film fabricated by ultrafast pulsed laser deposition for thermochromic smart window applications

Over the years, vanadium dioxide, (VO2(M1)), has been extensively utilised to fabricate thermochromic thin films with the focus on using external stimuli, such as heat, to modulate the visible through near-infrared transmittance for energy efficiency of buildings and indoor comfort. It is thus valuable to extend the study of thermochromic materials into the mid-infrared (MIR) wavelengths for applications such as smart radiative devices. On top of this, there are numerous challenges with synthesising pure VO2 (M1) thin films, as most fabrication techniques require the post-annealing of a deposited thin film to convert amorphous VO2 into a crystalline phase. Here, we present a direct method to fabricate thicker VO2(M1) thin films onto hot silica substrates (at substrate temperatures of 400 °C and 700 °C) from vanadium pentoxide (V2O5) precursor material. A high repetition rate (10 kHz) femtosecond laser is used to deposit the V2O5 leading to the formation of VO2 (M1) without any post-annealing steps. Surface morphology, structural properties, and UV–visible optical properties, including optical band gap and complex refractive index, as a function of the substrate temperature, were studied and reported below. The transmission electron microscopic (TEM) and X-ray diffraction studies confirm that VO2 (M1) thin films deposited at 700 °C are dominated by a highly texturized polycrystalline monoclinic crystalline structure. The thermochromic characteristics in the mid-infrared (MIR) at a wavelength range of 2.5–5.0 μm are presented using temperature-dependent transmittance measurements. The first-order phase transition from metal-to-semiconductor and the hysteresis bandwidth of the transition were confirmed to be 64.4 °C and 12.6 °C respectively, for a sample fabricated at 700 °C. Thermo-optical emissivity properties indicate that these VO2 (M1) thin films fabricated with femtosecond laser deposition have strong potential for both radiative thermal management or control via active energy-saving windows for buildings, and satellites and spacecraft.

Indoor validation of a multiwavelength measurement approach to estimate soiling losses in photovoltaic modules

Soiling is a factor that impacts the performance of photovoltaic (PV) modules. Nowadays, the research related to PV soiling monitoring is focused on optical sensors, which estimate the soiling loss through a monochromatic transmittance or reflectance measurement. However, these typically neglect the spectral profile of soiling transmittance, which tends to absorb shorter wavelengths more than the longer ones. This leads to a spectral red shift of the light that is transmitted to the PV cells of a module. Therefore, if the spectral component of soiling is not considered, the estimated soiling losses are not fully representative of those occurring in the real PV modules. This investigation aims to address this issue by modeling the full soiling transmittance spectrum using several monochromatic light sources in a new version of a previously presented optical soiling sensor, called “DUSST”. Four different combinations of mono-wavelength light-emitting diodes have been used to model the full spectral transmittance profile of artificially soiled PV glass coupons and to estimate the electrical losses of distinct PV technologies. The results show that the errors in soiling estimation can be minimized by using an appropriate wavelength combination. The difference between the measured and the estimated soiling losses can be lower than 3% if the most convenient wavelength combination is utilized. In the case of m-Si, which is the prevalent PV technology nowadays, the application of the optimum wavelength combination is found to reduce the maximum measurement error to 2.6%, from the initial 7.7% returned when a single wavelength was employed.

Development of the spectrum transmittance measurement system for large-size optical elements of Cherenkov telescope

The Cherenkov and fluorescence telescopes are used to detect cosmic rays in many large-scale experiments. Certain large-size optical elements, such as quartz glasses with window and filters, are installed in front of cameras as the window to seal the cameras and minimize the impact of the night sky background light. The transmittance of those optical elements in Cherenkov and fluorescence telescopes is therefore vital for the measurement of the number of photons reaching the camera. The uniformity is an important parameter of transmittance at different wavelength over the whole window surface. It is difficult to ensure the uniformity of the window material when it is produced, especially for the size as large as 1 m2. The measurement of the uniformity of the transmittance of filters at different positions on the window, and over a large optical spectrum, is not a trivial task and therefore a dedicated system has been developed. The large-size filter transmittance measurement system can measure the spectrum range from 250 nm to 900 nm. A two dimensional motorized device is used to carry the system and the accuracy of the system is up to 0.01 mm. In addition, the measuring system can measure the transmittance at an incident angle ranging from 0° to 44°. The relative standard deviation can be reduced to less than 1% by alternately measuring with and without samples. The transmittance spectra of the neodymium glass standard sheets and quartz glass JGS2, of size 876 mm × 862 mm × 4 mm have been measured with this system and compared. The result of neodymium glass indicates that the system can measure the transmittance spectrum precisely, up to 1% uncertainty. The results of the JGS2 quartz glass demonstrate that our system is capable of measuring the optical parameters of very large sample with a precision at the level of 1% over a wide spectrum range.

Development of new transmissive light materials by "control of randomness"

Biometrics combines principles from engineering, physics, chemistry, biology and informatics and applies them to create materials, systems and machines that mimic biological processes. The idea is to mimic things that exist naturally in order to develop artificial things with novel properties. Dr Akira Saito, Department of Precision Engineering, Osaka University, Japan, is working to develop new transmissive light materials inspired by butterflies. The blue Morpho butterfly has brilliant blue wings and scientists have discovered that the colour is attributed to a specific nanostructure that has both order and disorder. Saito and the team have been working to artificially reproduce this coloration and have proven the optical principles of the Morpho butterfly's reflection, progressed various application technologies and, more recently, found a new direction - the transfer from reflection to transmission which has applications in window technologies. The researchers have developed a daylight window that satisfies at once all conditions of high transmittance, wide angular spread, low colour dispersion, and spread-shape controllability and have also realised the diffuser that will enable the light source to 'see the object correctly' in terms of the colour rendering. This has potential to be used in fields that rely on different forms of lighting, including fine arts, surgery and various types of photography. The important methods that Saito and the team have used in their research are nanofabrication (including lithography, etching and nanoimprinting), structural and optical evaluation (SEM and AFM, measurement of reflectivity and transmittance versus angle with spectroscopy), and numerical simulation.

Comparison of Hyperspectral Imaging and Fiber-Optic Reflectance Spectroscopy for Reflectance and Transmittance Measurements of Colored Glass

The work presented in this paper is part of a wider research project, which aims at documenting and analyzing stained glass windows by means of hyperspectral imaging. This technique shares some similarities with UV-VIS-IR spectroscopy, as they both provide spectral information; however, spectral imaging has the additional advantage of providing spatial information, since a spectrum can be collected in each pixel of the image. Compared to UV-VIS-IR spectroscopy, spectral imaging has rarely been used for the investigation of stained glass windows. One of the objectives of this paper is, thus, to compare the performance of these two instruments to validate the results of hyperspectral imaging. The second objective is to evaluate the potential of analyzing colored-glass pieces in reflectance modality and compare the results with those obtained in transmittance, in order to highlight the differences and similarities between the two approaches. The geometry of the systems and the backing material for the glass, as well as the characteristics of the glass pieces, are discussed. L*a*b* values obtained from the spectra, as well as the calculated color difference ΔE00, are provided, to show the degree of agreement between the instruments and the two measurement modalities.

Total transmittance measurement using an integrating sphere calibrated by a screen image synthesis system

The measurement of bidirectional scattering distribution function (BSDF) and total transmittance (TT) is a complicated issue. We have proposed a screen image synthesis (SIS) BSDF meter that provides high-speed and precise measurement. However, the measurement of TT using integrating sphere cannot offer a precise measurement. Therefore, we propose a calibration method that uses SIS BSDF meter and responsivity of the integrating sphere. It brings us not only precise BSDF function but precise TT measurement.

Nanocrystalline embedded In2Se3 amorphous thin film investigation and optical enhancement characterization for photo-sensing application

In this investigation, highly adherent and unique advantageous properties of In2Se3 films were prepared for different studies and applications using a thermal evaporation technique under a high vacuum on different substrates (including glass, quartz, and a p-Si single crystal). X-ray diffraction results show that the prepared In2Se3 powder has a polycrystalline nature with α-phase. The average size of the crystallite, microstrain, and dislocation density was measured and found to be 273.6 nm, 4.9 × 10–3, and 1.34 × 10–5 nm−2, respectively. Due to the long-range array, the deposited In2Se3 films have an amorphous nature. SEM images of the film surface were measured to examine the RMS roughness features and grain-boundary effect. Spectrophotometer measurements of transmittance and reflectance were used to estimate the optical constants of In2Se3 films. The relationship between absorption coefficient and photon energy was tested, and the results revealed that the optical transition is directly allowed with an energy gap of 2.25 eV. The dispersion and oscillator energies were measured using the single oscillator model employing a relation of Wemple–DiDomenico and found to be 3.8 and 1.7 eV. The characteristics of the In2Se3-based junction showed promising candidates for photosensor applications under illumination.Graphical abstract