Variations In Reflectance Research Articles

Spectral Response at Different Water Depth Standing in the Field

Water availability and irrigation management can be estimated in agricultural fields through observation of field water storage. In order to calculate runoff and recharge through these fields, the water depth stored in the haveli fields must meet certain requirements. Remote Sensing data obtain through Satellite in all visible and NIR region might be helpful for such requirements. An experimental study is made to assess the utility of different bands for depicting depth of storage in field. Spectral reflectance was recorded on different depth from 0 to 100 cm of water. Ground Truth Radiometer (GTR) was used to conduct the experiment. Experimental observation shows the variation in reflectance with different depth of water stored in 1 m3 ponding water. It has been observed that spectral response shows variation under different storage level and different time of observation. To minimize error on observation the readings were taken under uniform sunshine condition and wind velocity. The Radiation under wavelength 0.4 and 1.1 µm was used to collect response in reflectance from experimental fields. The increase in reflectance with was observed with decrease in water level. This could be due to visibility of bottom soil in lower depths. A comparison between experimental response data and satellite image data of indicate that there is variation on band 4 and similar trend on band 1, 2. Mixed tread was observed in band 3. A clear decrease in reflectance up to 50 percent was observed when water storage depth increase up to 90 cm but then it started increasing. Similar variation was observed for observation with a depth of more than 1 m. Satellite data is more stable as compared to GTR data.

Intensity Dependent Photoluminescence Imaging for In‐Line Quality Control of Perovskite Thin Film Processing

AbstractLarge area fabrication of high‐quality polycrystalline perovskite thin films remains one of the key challenges for the commercial readiness of perovskite photovoltaic (PV). To enable high‐throughput and high‐yield processing, reliable and fast in‐line characterization methods are required. The present work reports on a non‐invasive characterization technique based on intensity‐dependent photoluminescence (PL) imaging. The change in PL intensity as a function of excitation power density can be approximated by a power‐law with exponent k, which is a useful quality indicator for the perovskite layer, providing information about the relative magnitudes of radiative and non‐radiative recombination. By evaluating k‐parameter maps instead of more established PL intensity images, 2D information is obtained that is robust to optically induced artifacts such as intensity variations in excitation and reflection. Application to various half stacks of a perovskite solar cell showcase its ability to determine the importance of the interface between the charge transporting and perovskite layers. In addition, the k‐parameter correlates to the bulk passivation concentration, enabling rapid assessment of open‐circuit voltage variations in the range of 20 mV. Considering expected improvements in data acquisition speed, the presented k‐imaging method will possibly be obtained in real‐time, providing large‐area quality control in industrial‐scale perovskite PV production.

Latitudinal Variations in Methane Abundance, Aerosol Opacity and Aerosol Scattering Efficiency in Neptune's Atmosphere Determined From VLT/MUSE

AbstractSpectral observations of Neptune made in 2019 with the Multi Unit Spectroscopic Explorer (MUSE) instrument at the Very Large Telescope (VLT) in Chile have been analyzed to determine the spatial variation of aerosol scattering properties and methane abundance in Neptune's atmosphere. The darkening of the South Polar Wave at ∼60°S, and dark spots such as the Voyager 2 Great Dark Spot is concluded to be due to a spectrally dependent darkening (λ < 650 nm) of particles in a deep aerosol layer at ∼5 bar and presumed to be composed of a mixture of photochemically generated haze and H2S ice. We also note a regular latitudinal variation of reflectivity at wavelengths of very low methane absorption longer than ∼650 nm, with bright zones latitudinally separated by ∼25°. This feature, which has similar spectral characteristics to a discrete deep bright spot DBS‐2019 found in our data, is found to be consistent with a brightening of the particles in the same ∼5‐bar aerosol layer at λ > 650 nm. We find the properties of an overlying methane/haze aerosol layer at ∼2 bar are, to first‐order, invariant with latitude, while variations in the opacity of an upper tropospheric haze layer reproduce the observed reflectivity at methane‐absorbing wavelengths, with higher abundances found at the equator and also in a narrow “zone” at 80°S. Finally, we find the mean abundance of methane below its condensation level to be 6%–7% at the equator reducing to ∼3% south of ∼25°S, although the absolute abundances are model dependent.

PVD Black Coating for Decorative Applications

PVD coatings have gained considerable attention as decorative coatings because they combine decorative with protective properties. Within the frame of this work, a black PVD coating based on chromium, carbon and oxygen was developed in a semi-industrial coating machine with four magnetrons and continuous substrate rotation. Based on the optical properties of CrxCyOz, the optical properties of the coating can be used in the design of the coating. EDX measurements point to an average composition of Cr0.35O0.53C0.12 for coatings with the most interesting optical properties. XPS measurements show that the chemical state of the constituting elements changes throughout the coating thickness. CrxCyOz shows a strong columnar growth which may give origin to a rough surface structure. This effect, depending on the coating thickness, allows the deposition of black coatings with a variation of strong specular reflection (“piano black”) and diffuse reflection (“matt”) for a coating thickness variation between 1 and 5 μm. The diffusive reflection increased from almost 2% to 6% for the thicker samples whereby the specular reflection decreased from about 20% to almost 0 of the samples with a thin coating and samples with a coating thickness close to 5 μm. Within the frame of this work, we also determined the functional properties of adherence and surface energy, which show that the coating can be used in demanding applications without an additional protective topcoat.

The impact of aerosols on stratiform clouds over southern West Africa: a large-eddy-simulation study

Abstract. Low-level stratiform clouds (LLSCs) covering a large area appear frequently during the wet monsoon season in southern West Africa. This region is also a place where different types of aerosols coexist, including biomass burning aerosols coming from central and southern Africa and aerosols emitted by local anthropogenic activities. We investigate the indirect and semi-direct effects of these aerosols on the life cycle of LLSCs by conducting a case study based on airborne and ground-based observations from the field campaign of Dynamic-Aerosol-Chemistry-Cloud-Interaction in West Africa (DACCIWA). This case is modeled using a large-eddy-simulation (LES) model with fine resolution and in situ aerosol measurements, including size distribution and chemical composition. The model has successfully reproduced the observed life cycle of the LLSC, from stratus formation to stabilization during the night and to upward development after sunrise until break-up of the cloud deck in the late afternoon. Additional sensitivity simulations using different measured aerosol profiles also suggest that aerosols can affect the cloud life cycle through both the indirect and semi-direct effects. As expected, modeled cloud microphysical features, including cloud droplet number concentration, mean radius, and thus cloud reflectivity, are all controlled by aerosol concentration. However, it is found that the variation in cloud reflectivity induced by different aerosol profiles is not always the only factor in determining the incoming solar radiation at the ground and thus for the cloud life cycle after sunrise. Instead, the difference in cloud fraction brought by dry-air entrainment from above and thus the speed of consequent evaporation – also influenced by aerosol concentration – is another important factor to consider. Clouds influenced by higher aerosol concentrations and thus with a higher number concentration and smaller sizes of cloud droplets are found to evaporate more easily and thus impose a lower cloud fraction. In addition, our sensitivity runs including versus excluding aerosol direct radiative effects have also demonstrated the impacts specifically of solar absorption by black carbon on the cloud life cycle. The semi-direct effect resulting from an excessive atmospheric heating of up to 12 K d−1 by black carbon in our modeled cases is found to lower the cloud top as well as the liquid water path, reducing surface incoming solar radiation and dry entrainment and increasing the cloud fraction.

Quality Control of Thermally Modified Western Hemlock Wood Using Near-Infrared Spectroscopy and Explainable Machine Learning.

The quality control of thermally modified wood and identifying heat treatment intensity using nondestructive testing methods are critical tasks. This study used near-infrared (NIR) spectroscopy and machine learning modeling to classify thermally modified wood. NIR spectra were collected from the surfaces of untreated and thermally treated (at 170 °C, 212 °C, and 230 °C) western hemlock samples. An explainable machine learning approach was practiced using a TreeNet gradient boosting machine. No dimensionality reduction was performed to better explain the feature ranking results obtained from the model and provide insight into the critical wavelengths contributing to the performance of classification models. NIR spectra in the ranges of 1100-2500 nm, 1400-2500 nm, and 1700-2500 nm were fed into the TreeNet model, which resulted in classification accuracy values (test data) of 94.35%, 89.29%, and 84.52%, respectively. Feature ranking analysis revealed that when using the range of 1100-2500 nm, the changes in wood color resulted in the highest variation in NIR reflectance amongst treatments. As a result, associated features were given higher importance by TreeNet. Limiting the wavelength range increased the significance of features related to water or wood chemistry; however, these predictive models were not as accurate as the one benefiting from the impact of wood color change on the NIR spectra. The developed framework could be applied to different applications in which NIR spectra are used for wood characterization and quality control to provide improved insights into selected NIR wavelengths when developing a machine learning model.

Accurate measurement of high-reflective surface based on adaptive fringe projection technique

Fringe projection profilometry (FPP) is one of the most effective methods to obtain three-dimensional surface topography information about an object. However, for objects with large variations in surface reflectance, it is difficult to measure the saturated regions with conventional FPP. In this paper, a new adaptive fringe projection (AFP) method is proposed to solve this problem. Compared with existing methods, the proposed method can automatically generate low-intensity projected fringe patterns instead of requiring manual adjustment. First, we built a projection intensity model for the captured pixels and defined the surface reflection factor and environmental factor for saturated pixels. Then, a small number of uniform grayscale pattern sequences were projected to mark the saturated areas, while the surface reflection factor and the environment factor of individual pixels were calculated and a surface coefficient look-up table (SCLUT) was created. The low-intensity projected fringe patterns were automatically calculated and generated based on the captured uniform grayscale sequences of images to establish the mapping relationship between the camera image plane and the projector image plane. Finally, the optimal projection intensities of pixels in the saturated regions were calculated according to the SCLUT, and adaptive fringe patterns were generated. Experiments show that using the adaptive fringe patterns generated by the proposed method to measure objects can accurately adjust the projection intensity and substantially improve the measurement accuracy of high-reflective surface.

Upper-plate conduits linked to plate boundary that hosts slow earthquakes

In shallow subduction zones, fluid behavior impacts various geodynamic processes capable of regulating slip behaviors and forming mud volcanoes. However, evidence of structures that control the fluid transfer within an overriding plate is limited and the physical properties at the source faults of slow earthquakes are poorly understood. Here we present high-resolution seismic velocity models and reflection images of the Hyuga-nada area, Japan, where the Kyushu-Palau ridge subducts. We image distinct kilometer-wide columns in the upper plate with reduced velocities that extend vertically from the seafloor down to 10–13 km depth. We interpret the low-velocity columns as damaged zones caused by seamount subduction and suggest that they serve as conduits, facilitating vertical fluid migration from the plate boundary. The lateral variation in upper-plate velocity and seismic reflectivity along the plate boundary correlates with the distribution of slow earthquakes, indicating that the upper-plate drainage system controls the complex pattern of seismic slip at subduction faults.

Optical properties of tilted surfaces in material jetting

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.

Over-coupled resonator for broadband surface enhanced infrared absorption (SEIRA)

Detection of molecules is a key issue for many applications. Surface enhanced infrared absorption (SEIRA) uses arrays of resonant nanoantennas with good quality factors which can be used to locally enhance the illumination of molecules. The technique has proved to be an effective tool to detect small amount of material. However, nanoresonators can detect molecules on a narrow bandwidth so that a set of resonators is necessary to identify a molecule fingerprint. Here, we introduce an alternative paradigm and use low quality factor resonators with large radiative losses (over-coupled resonators). The bandwidth enables to detect all absorption lines between 5 and 10 μm, reproducing the molecular absorption spectrum. Counterintuitively, despite a lower quality factor, the system sensitivity is improved and we report a reflectivity variation as large as one percent per nanometer of molecular layer of PMMA. This paves the way to specific identification of molecules. We illustrate the potential of the technique with the detection of the explosive precursor 2,4-dinitrotoluene (DNT). There is a fair agreement with electromagnetic simulations and we also introduce an analytic model of the SEIRA signal obtained in the over-coupling regime.

Non-contact measurement of neck pulses achieved by imaging micro-motions in the neck skin.

We report a method and system of micro-motion imaging (µMI) to realize non-contact measurement of neck pulses. The system employs a 16-bit camera to acquire videos of the neck skin, containing reflectance variation caused by the neck pulses. Regional amplitudes and phases of pulse-induced reflection variation are then obtained by applying a lock-in amplification algorithm to the acquired videos. Composite masks are then generated using the raw frame, amplitude and phase maps, which are then used to guide the extraction of carotid pulse (CP) and jugular vein pulse (JVP) waveforms. Experimental results sufficiently demonstrate the feasibility of our method to extract CP and JVP waves. Compared with conventional methods, the proposed strategy works in a non-contact, non-invasive and self-guidance manner without a need for manual identification to operate, which is important for patient compliance and measurement objectivity. Considering the close relationship between neck pulses and cardiovascular diseases, for example, CA stenosis, the proposed µMI system and method may be useful in the development of early screening tools for potential cardiovascular diseases.

Efficiency enhancement of solar cell by using methylammonium lead tribromide/polymethyl methacrylate hybrid film as luminescent down shifting layer

Luminescent down-shifting (LDS) layer was introduced to tackle the issue of poor short-wavelength response of solar cell. Besides LDS effect, coating a LDS layer on the surface of a solar cell leads to a change in surface reflectance. LDS and antireflection (AR) effect are coupled and usually reported as a single effect. For those solar cell with optimized AR, it is difficult to enhance power conversion efficiency (PCE) with the LDS layer due to the variation of reflectance. In this work, we report an obvious PCE enhancement of two mainstream commercial silicon (Si) solar cells with the optimized AR by using methylammonium lead tribromide (MAPbBr3)/polymethyl methacrylate (PMMA) hybrid film as a LDS layer. The used MAPbBr3/PMMA nanoplatelets solutions for LDS layer have an absolute photoluminescent quantum yield of ∼85 % (excited by 350 nm) in air atmosphere for more than 30 days, laying a foundation for the realization of effective LDS effect. Theoretical analysis has separated the AR and LDS effect. It has demonstrated that AR effect has a positive influence on LDS effect, and PMMA plays the key role in the improvement of AR. Experimental studies further elucidated the LDS and AR effect provided by MAPbBr3/PMMA hybrid film. Thanks to this combined effect, the application of MAPbBr3/PMMA hybrid film as a LDS layer on Si heterojunction solar cell yields a PCE gain of 0.3 % absolute and that on passivated emitter and rear cell produces an absolute PCE enhancement of about 0.7 %.

Ce doped LaAlO3 pigments with high NIR reflectance and modification of thermal aging properties of polyvinyl chloride

Based on the modified weather resistance of PVC plastics, a series of La1-xCexAlO3 inorganic pigments were synthesized in this study. A single La1-xCexAlO3 (x varies from 0.00 to 0.20) phase replacement solid solution of rhombohedral crystal structure with the addition of more Ce3+ doping. The sample pigments demonstrated a curved rod to spherical particle morphology change as Ce doping amount increased. The analysis by X-ray photoelectron spectroscopy (XPS) demonstrated that the cerium ion chemical valence states in the synthesized samples were + 3 and + 4. The carrier concentration and electron trap theory can be used to understand the variation in near-infrared reflectance of La1-xCexAlO3 pigment powder from 72.55% to 83.35%. Electric charge transfer (La 3d ↔ Ce 3d) can be used to describe how the La1-xCexAlO3 pigment shifts from white to orange to yellow. When PVC plastic is modified with pigment, the near-infrared reflectance varies from 52.87% to 61.63%. Inner surface temperature of La1-xCexAlO3/PVC composite plastics can be lowered by 8.5–13.7 °C, and the weather resistance of the modified PVC plastic is greatly increased. In conclusion, the modification of PVC plastics with La1-xCexAlO3 inorganic pigments can significantly reduce the surface temperature of plastics and prolong their service life.

Multi-scale feature retention and aggregation for colorectal cancer diagnosis using gastrointestinal images

Colonoscopy is considered the gold standard for colorectal cancer diagnosis and prognosis. However, existing methods are less accurate and prone to overlooking lesions during gastrointestinal endoscopic examinations. Computer-assisted diagnosis combined with robot-assisted minimally invasive surgery (RMIS) can significantly help medical practitioners detect and treat lesions. Therefore, two novel architectures are developed for polyp and surgical instrument segmentation to aid colorectal cancer diagnosis, assessment, and treatment. Colorectal cancer segmentation network (CCS-Net) is the base network used in this study. It uses the maximum convolutional layers near the input image for effective feature extraction from low-level information. In addition, CCS-Net uses an efficient feature upsampling unit to efficiently increase the input spatial features’ map size. Hence, CCS-Net is capable of providing a fair performance with satisfactory computational efficiency The multi-scale feature retention and aggregation network (MFRA-Net) is the final network in this study. MFRA-Net is developed to improve the segmentation accuracy of the CCS-Net further as it uses multi-scale feature retention to retain low-level spatial features and transfers them to deep stages of the network. MFRA-Net also combines multi-scale high-strided low-level information with high-level information to boost network segmentation performance. Finally, all the transferred multi-scale features from the early stages of the network are aggregated with high-level features in the deep levels of the network. This multi-scale feature retention and aggregation mechanism enables the network to maintain a better segmentation performance compared with other methods even with challenging blur, specular reflection, low contrast, and high variation cases. We evaluated both architectures on four challenging datasets: Kvasir-SEG, CVC-ClinicDB, Kvasir-Instrument, and the UW-Sinus-Surgery-Live dataset. The proposed method achieves dice similarity coefficients of 95.98%, 94.19%, 92.81%, and 88.57% for the CVC-ClinicDB, Kvasir-SEG, Kvasir-Instrument, and UW-Sinus-Surgery-Live datasets. The proposed method achieves superior segmentation performance compared with state-of-the-art methods and requires only 4.9 million trainable parameters for complete training. Therefore, the proposed networks can effectively assist health professionals in surgical procedures and colorectal cancer diagnosis through surgical instruments and polyp segmentation, respectively.

A novel approach to the design of multi section ultra-wideband Jaumann absorber

A novel ultra-wideband Jaumann absorber design and analytical procedure that greatly enhance the absorption bandwidth and absorptivity level using few dielectric layers are described. The absorptivity bandwidth of the proposed structure is much better than the traditional absorbers. In Jaumann absorbers, determining resistivity of resistive sheets is a complex task and optimization techniques are generally utilized for the solution. The new contribution given in this paper is that the reflected waves from each boundary inside the dielectric layers are eliminated. Therefore, input reflection coefficient is obtained analytically using Binomial expansion without any approximation. Then a binomial matching procedure is applied to obtain the ultra-wideband absorption. Absorption enhancement is achieved by quarter wavelength dielectric slabs, resistive sheets with critical resistivities and a metallic ground plane backed final dielectric layer with high permittivity. Proposed structure is designed for normal illumination. Parallel and perpendicular polarizations are also studied for oblique incidences. Absorptivity and reflectivity variations are presented versus frequency in 0–40 GHz band for the 20 GHz design frequency for several structures. It is shown that choosing three layers backed with a final layer (εrb=20) structure gives absorptivity greater than 90% in a 6.8–33.2 GHz band region with a fractional bandwidth of 132%. CST Microwave Studio and AWR programs are used to prove the correctness of the proposed method. Great consistency is observed and demonstrated in the numerical results section.

Reflectance spectroscopy as a promising tool for ‘sensing’ metals in hyperaccumulator plants

Main conclusionThe VNIR reflectance spectra of nickel hyperaccumulator plant leaves have spectral variations due to high nickel concentrations and this property could potentially be used for discovery of these plants. Hyperaccumulator plants accumulate high concentrations of certain metals, including manganese, cobalt, or nickel. Of these metals, the divalent ions of nickel have three absorption bands in the visible to near-infrared region which may cause variations in the spectral reflectance of nickel hyperaccumulator plant leaves, but this has not been investigated previously. In this shortproof-of-concept study, the spectral reflectance of eight different nickel hyperaccumulator plant species leaves were subjected to visible and near-infrared and shortwave infrared (VNIR-SWIR) reflectance spectrum measurements in dehydrated state, and for one species, it was also assessed in hydrated state. Nickel concentrations in the plant leaves were determined with other methods and then correlated to the spectral reflectance data. Spectral variations centred at 1000 ± 150 nm were observed and had R-values varying from 0.46 to 0.96 with nickel concentrations. The extremely high nickel concentrations in nickel hyperaccumulator leaves reshape their spectral reflectance features, and the electronic transition of nickel-ions directly contributes to absorption at ~ 1000 nm. Given that spectral variations are correlated with nickel concentrations it make VNIR-SWIR reflectance spectrometry a potential promising technique for discovery of hyperaccumulator plants, not only in the laboratory or herbarium, but also in the field using drone-based platforms. This is a preliminary study which we hope will instigate further detailed research on this topic to validate the findings and to explore possible applications.

High Variation in Inner Retinal Reflectivity Predicts Poor Visual Outcome in Patients With Central Retinal Vein Occlusion: SCORE2 Report 21.

To assess the association of a novel spectral domain optical coherence tomography biomarker with 6-month visual acuity in in the Study of COmparative Treatments for REtinal Vein Occlusion 2. Spectral domain optical coherence tomography volume scans were evaluated for inner retinal hyperreflectivity, quantified by optical intensity ratio (OIR) and OIR variation. Baseline visual acuity letter score (VALS), baseline OCT biomarkers, and month 1 OIR were correlated with VALS at month 6. Regression trees, a machine learning technique yielding readily interpretable models, were used to assess for variable interaction. Only baseline VALS correlated positively with month 6 VALS in multivariate regression. Regression trees detected a novel functional and anatomical interaction in a subgroup. Among patients with a baseline VALS worse than 43, those with an OIR variation at month 1 of more than 0.09 had a mean of 13 fewer letters of vision at 6 months compared with patients with an OIR variation of 0.09 or less. Baseline VALS was the strongest predictor of month 6 VALS. Regression tree analysis detected an interaction effect, in which higher OIR variation at month 1 predicted worse 6-month VALS in patients with low VALS at baseline. OIR variation may serve as a predictor for poor visual outcome despite treatment of macular edema secondary to retinal vein occlusion in patients with poor vision at baseline. Pixel heterogeneity in three-dimensional OCT data may serve as measure of disruption of the retinal laminations, and this factor may carry visually prognostic value.

Temporal variation of surface reflectance and cloud fraction used to identify background aerosol retrieval information over East Asia

Temporal variation in cloud cover and surface conditions greatly affects estimation errors associated with reference surface reflectance and atmospheric composition retrievals. In this study, to determine an optimal temporal window for clear-sky composition methods that are used to identify surface reflectance for the retrieval of atmospheric properties, we analyzed temporal variation in surface reflectance and cloud fractions using long-term daily observations from the Moderate Resolution Imaing Spectroradiometer (MODIS) satellite. For the temporal variation in surface reflectance, gridded pixels with a standard deviation less than 0.025 represented 87.0%, 84.5%, 80.5%, and 77.3% of the total pixels for periods of 15, 20, 30, and 40 days, respectively. The temporal variability of surface reflectance was lowest in summer and highest in winter due to vegetation and snow cover changes over land surface in East Asia. For the temporal variation in cloud fractions, pixels with a cloud fraction <10% ranged from 91.2% (15-day) to 98.1% (40-day). Only temporal windows of 30 and 40 days satisfied the criterion of 95% cumulative distribution in the 10% cloud fraction range. Thus, and appropriate temporal window for clear-sky composition methods must be selected in consideration of the seasonal dependency of surface types and cloud cover variation. The temporal window for the clear-sky composition must be longer than 30 days considering the temporal variability of cloud cover, and shorter than 30 days considering that of surface reflectance. However, seasonal dependencies of surface reflectance and cloud fraction are also additionally considered to select the appropriated temporal window for the clear-sky composition.

Quantitative phase-amplitude surface determination in reflection differential interference contrast profilometry.

An approach for measuring the surface profile of the samples with reflection variations using the Nomarski differential interference method is presented. The system is analyzed with Jones's matrices tool, and polarization effects of a non-polarizing beam splitter are taken into account. Equations are also developed to allow the determination of the surface profile from interference intensity when the sample reflectively is not uniform. The validity and accuracy of the measurement are verified by measuring the adhered silicon cantilever on a substrate with high reflectivity. This method is expected to be a valuable tool to inspect elements of micromechanics and microsystems.

Plasmonic grating H2S sensor based on a chitosan-polyaniline-nano-composite

In this study, a plasmonic sensor was designed based on the grating coupling to detect the low concentration of H2S as a toxic chemical. The polyaniline nanostructure was prepared using the laser ablation technique in a chitosan solution and the final products were tested using analytical methods. The chitosan-polyaniline nanocomposite layer was used as a sensing layer and coated on the surface of 1D polydimethylsiloxane grating. The variation of reflectivity with different concentrations of H2S was registered from the surface of the grating for evaluating the sensor’s response. Finally, it was explained using the Langmuir isotherm absorption model. The limit of detection and the sensitivity of chitosan-polyaniline-nanocomposite were about 1 ppm and 0.10767 for the detection of H2S, respectively.