Changes In Spectral Response Research Articles

Reducing non-effective pixel rate and nonuniformity in AlGaN solar-blind UV focal plane detectors by controlled curvature

A 1600 × 1280 small pixel photodetector was successfully fabricated to verify the controlled curvature of the focal plane array improving the non-effective pixel rate and non-uniformity of the detector. The stress strain generated during epitaxial growth was reduced by growing a 2 μm thick AlN stress correction layer on the backside of the AlGaN/sapphire system substrate. Compared with the material without an AlN stress correction layer on the backside, material curvature reduced from 7.252 μm to 2.740 μm over a length of 0.5 cm. The non-effective pixel rate and the non-uniformity of a focal plane array have been reduced. A process was proposed to reduce the impact of misalignment generated by the flip-chip interconnection process. A solar-blind UV focal plane array was hybridized with a readout integrated circuit using an unsymmetrical flip-chip interconnection process. There is no significant change in peak spectral response, nonuniformity, non-effective pixel rate, or responsivity.

Tolerância à salinidade e respostas espectrais foliares em mudas de quatro espécies ornamentais herbáceas

ABSTRACT Studies on using brackish water for the irrigation of ornamental species are still scarce, mainly considering qualitative aspects of the plants. Therefore, the present study aimed to identify salt tolerance and characterize leaf spectral responses of herbaceous ornamental species at the stage of commercial seedling production. The research was carried out from December 2020 to February 2021, under greenhouse conditions, in Fortaleza - Ceará, Brazil. The experiment was conducted in a randomized block design with split plots, with main plots consisting of irrigation-water salinity levels (0.5, 2.0, 4.0, 6.0, and 8.0 dS m-1), and subplots by the species Catharanthus roseus, Celosia cristata, Celosia plumosa, and Chrysanthemum coronarium, with four replications. The evaluation parameters were dry mass production, visual sensory analysis, salt tolerance, and leaf spectral responses. Plant visual quality was maintained up to 2.0 dS m-1 for Chrysanthemum coronarium and 4.0 dS m-1 for Celosia cristata, Celosia plumosa, and Catharanthus roseus, which were classified as moderately tolerant at those respective salinity levels. Salinity caused noticeable changes in leaf spectral responses, especially in the visible region.

Ultrafast optical properties of stoichiometric and non-stoichiometric refractory metal nitrides TiNx, ZrNx, and HfNx.

Refractory metal nitrides have recently gained attention in various fields of modern photonics due to their cheap and robust production technology, silicon-technology compatibility, high thermal and mechanical resistance, and competitive optical characteristics in comparison to typical plasmonic materials like gold and silver. In this work, we demonstrate that by varying the stoichiometry of sputtered nitride films, both static and ultrafast optical responses of refractory metal nitrides can efficiently be controlled. We further prove that the spectral changes in ultrafast transient response are directly related to the position of the epsilon-near-zero region. At the same time, the analysis of the temporal dynamics allows us to identify three time components: the "fast" femtosecond one, the "moderate" picosecond one, and the "slow" at the nanosecond time scale. We also find out that the non-stoichiometry does not significantly decrease the recovery time of the reflectance value. Our results show the strong electron-phonon coupling and reveal the importance of both the electron and lattice temperature-induced changes in the permittivity near the ENZ region and the thermal origin of the long tail in the transient optical response of refractory nitrides.

Magnetic Field Sensing Using Tapered Small-Core Optical Fibre Surrounded by Different Concentrations of Magnetic Fluid.

In this paper, a high-sensitivity magnetic field sensor based on a single-mode-tapered small-core-single-mode (STSCS) optical fibre structure is investigated. The tapered small-core section of STSCS is surrounded by magnetic fluid (MF) containing ferromagnetic particles (FMPs) of different concentrations. The FMPs align themselves along the magnetic field, depending on the strength of the magnetic field. This alignment of FMPs changes the refractive index around the tapered small-core section, which in turn changes the output spectral response of the STSCS optical fibre structure. The change in spectral response is then calibrated for sensing the magnetic field strength. This paper also investigates the effect of both the taper waist diameter of the STSCS optical fibre structure and the concentration of MF surrounding it on the magnetic field sensitivity. The maximum sensitivity demonstrated in this paper is 0.46 nm/mT for a taper waist diameter of 10 μm surrounded by 1.22% FMPs in the MF. The magnetic sensor demonstrates reversible results, and its effects on the orientation of the magnetic field along the X-Y, X-Z and Y-Z axes are also investigated, which suggest that the sensor is capable of vector magnetic field measurement.

Machine Learning in the Analysis of Multispectral Reads in Maize Canopies Responding to Increased Temperatures and Water Deficit

Real-time monitoring of crop responses to environmental deviations represents a new avenue for applications of remote and proximal sensing. Combining the high-throughput devices with novel machine learning (ML) approaches shows promise in the monitoring of agricultural production. The 3 × 2 multispectral arrays with responses at 610 and 680 nm (red), 730 and 760 nm (red-edge) and 810 and 860 nm (infrared) spectra were used to assess the occurrence of leaf rolling (LR) in 545 experimental maize plots measured four times for calibration dataset (n = 2180) and 145 plots measured once for external validation. Multispectral reads were used to calculate 15 simple normalized vegetation indices. Four ML algorithms were assessed: single and multilayer perceptron (SLP and MLP), convolutional neural network (CNN) and support vector machines (SVM) in three validation procedures, which were stratified cross-validation, random subset validation and validation with external dataset. Leaf rolling occurrence caused visible changes in spectral responses and calculated vegetation indexes. All algorithms showed good performance metrics in stratified cross-validation (accuracy >80%). SLP was the least efficient in predictions with external datasets, while MLP, CNN and SVM showed comparable performance. Combining ML with multispectral sensing shows promise in transition towards agriculture based on data-driven decisions especially considering the novel Internet of Things (IoT) avenues.

Improving neural network classification of indigenous forest in New Zealand with phenological features

Accurate and up-to-date land cover maps inform and support effective management and policy decisions. Describing phenological changes in spectral response using time-series data may help to distinguish vegetation types, thereby allowing for more specificity within vegetation classification. In this research, we test this by classifying indigenous forest vegetation in New Zealand, using PlanetScope (PS) and Sentinel-2 (S-2) satellite time-series data.The study was undertaken in a podocarp forest in New Zealand's central north island, which was classified into nine land cover classes. Phenological features, based on S-2 imagery, were extracted, including the enhanced vegetation index (EVI), enhanced vegetation index 2 (EVI2) and normalised difference vegetation index (NDVI). Google Earth Engine (GEE) harmonic analysis and TIMESAT double logistic fitting function were used to extract phenological features. Pixel-based classifications were performed using a Neural Network on six different scenarios. The accuracy of the classification scenarios was determined and the importance score for each feature was evaluated.Using only the fused PS and S-2 bands, the land cover in the study area was classified with 90.1% accuracy. Adding phenological features increased the classification accuracy to 93.1%. When combined with VIs, texture features, and a digital terrain model, the addition of phenological features increased the classification accuracy to 96.6%. Including GEE-generated phenological features resulted in better classification accuracies than TIMESAT features. In terms of feature importance evaluation, EVI2- and NDVI-generated phenological features all had high scores; the effectiveness of EVI features could potentially have been limited by the quality of the blue band. The results demonstrate that it is possible to produce a more accurate classification of New Zealand's native vegetation by using phenological features. This method offers important cost-savings as the platforms for phenological analysis are free to use.

High-energy per-pixel calibration of timepix pixel detector with laboratory alpha source

The spectral response of the pixel detector Timepix at the high per-pixel proportional range is examined and calibrated using a simple technique and alpha particles from a standard laboratory source in air. For the detector used, a Timepix ASIC chip equipped with a 300 μ m thick silicon sensor, the spectral range is newly extended up to about 1750 keV per-pixel. This expands and covers the region above 850 keV per pixel which is described and covered by the existing low-energy calibration. The low-energy calibration uses discrete low-energy gamma rays in the range 5–60 keV and is extrapolated over the linear range up to 850 keV/px. Above this level, the per-pixel spectral response changes. At higher energies it undergoes distortion and saturation. The proportional and monotonic response is observed with regions of varying dependence up to nearly 2 MeV. This high-energy region is covered and described by the newly developed calibration method which Uses an alpha source of common low activity (kBq level). Data are collected within one day of total measuring time. Measurements are performed in air at various source-to-distance positions and several sensor bias settings. The developed method together with suitable setting of the sensor bias, which determines the extent of charge sharing, expands the spectral response of Timepix to high energy-loss particles such as alpha particles and light ions in wide energy range. Results are demonstrated on alpha particles, protons and 12C ions. Resulting spectra of deposited energy and cluster pixel height are correctly calibrated and they reproduce expected values.

Phenanthridine based rapid “turn-on” fluorescent sensor for selective detection of Th4+ ion and its real-time application

A new and highly sensitive and selective phenanthridine based sensor, 9-(7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)benzo[h]quinolin-10-ol (PHBQ), was developed for the fluorescent ‘‘turn-on’’ detection of Th4+ ion in acetonitrile: water (8:2) medium. The fluorescence intensity of PHBQ diminished in the region of pH 1 to 3 and could be recovered by adjusting the pH to above 4. The sensor PHBQ showed distinct spectral changes in response to Th4+ ion over other competitive metal ions. The fluorescence displayed good linearity with the Th4+ concentration in the equivalence of 0–0.5 equivalents. The detection limit was calculated to be as low as 99 nM, which was less than that of previously reported sensors. The recognizing mechanism of PHBQ towards Th4+ was investigated in detail using HR-MS, NMR, and IR spectroscopy. The economically viable Whatman filter paper was fabricated with PHBQ to develop a paper-based fluorescence kit to detect the Th4+ in an aqueous medium efficiently. Furthermore, the application of sensor ligand in fluorescence imaging was studied in E-coli cells due to its minimal cytotoxicity and good optical properties. The obtained data suggest that the ligand PHBQ can be used as a fluorescent sensor for tracking Th4+ in multiple applications.

Spectral and mineralogical alteration process of naturally-heated CM and CY chondrites

Spectral and mineralogical analyses were performed using nine naturally hydrated and dehydrated carbonaceous chondrite samples which were classified into heating stages (HS) from I to IV based on previous X-ray diffraction results. In-situ heating of samples at 120–400 °C was performed during spectral measurements and successfully removed absorbed water and part of rehydrated water from chondrite samples. Reflectance spectra of HS-I samples show the positive slope in visible (Vis)-infrared (IR) range and the significant 0.7- and 3-μm absorption bands. The 0.7-μm band appears in only HS-I sample spectra. With increasing temperature of heating, (1) Vis-IR slope decreases, (2) the 3-μm band becomes shallower, and (3) Christiansen feature (CF) and Reststrahlen bands (RB) shift toward longer wavelength. TEM-EDX analyses showed that the matrix of strongly-heated chondrites consists of tiny olivine, low-Ca pyroxene, and FeNi metallic particles mostly smaller than 100 nm in diameter, instead of Fe-rich serpentines and tochilinite observed in the HS-I chondrite. Therefore, in proportion to the heating degree, amorphization and dehydration of serpentine and tochilinite from HS-I to HS-II may cause the 0.7- and 3-μm band weakening, spectral bluing and darkening of chondrite spectra. In addition, formation of secondary anhydrous silicates and FeNi-rich metal grains at HS-IV would be responsible for the 3-μm band depth decrease, spectral reddening and brightening, CF peak shift, and RB changes of chondrite spectra. Those spectral changes in response to mineralogical alteration processes will be useful to interpret planetary surface composition by remote-sensing observations using ground-based or airborne/space telescopes or spacecraft missions.

Colon Cancer Detection by Designing and Analytical Evaluation of a Water-Based THz Metamaterial Perfect Absorber

Colon Cancer is the fourth most common form of cancer and the second-leading cause of cancer related deaths in the United States. A large part of the reason the number of fatalities is so high is late detection as when detected in the early stages of development 9 out of 10 cases of colon cancer are non-fatal 5 years after detection. Currently the main method of colon cancer detection are colonoscopies which are highly invasive and time intensive procedures. In this work we propose a new diagnostic technique for colon cancer using an InSb based device that works by a change in the spectral response of the metamaterial when exposed to electromagnetic waves in the terahertz regime and combined with cancerous colon tissue as compared to the response when combined with healthy colon tissue. We attribute this change in spectral response is due to the differing optical properties of the healthy and cancerous colon tissue as well as the creation of surface plasmon polaritons within our device.

Molecular docking analysis and spectroscopic investigations of zinc(II), nickel(II) N-phthaloyl-β-alanine complexes for DNA binding: Evaluation of antibacterial and antitumor activities

Herein, computational molecular docking, UV/visible and fluorescence spectroscopic techniques have been used to explore the DNA binding interactions of N-phthaloyl-β-alanine (NPA) ligand and its Zn(II) and Ni(II) complexes (NPAZn, NPANi). The compounds were further tested for anti-bacterial and anti-tumor activities. Docking analysis depicted that ligand NPA interacted with DNA via intercalation, while its metal complexes showed mixed mode of interactions. Spectroscopic experiments for DNA binding studies were run under physiological conditions of pH (stomach; 4.7, blood; 7.4) and temperature (37 °C). Based on changes in spectral responses, binding parameters for all the compounds were obtained which showed comparatively greater binding constant values (Kb: UV; 1.16 × 105 M−1, Flu; 1.35 × 105 M−1) and more negative free energy changes (ΔG: UV; −30.00 kJ mol−1, Flu; −30.44 kJ mol−1) for NPAZn at pH 4.7. The overall, binding results were also found more significant at stomach pH. Dynamic “KD” and bimolecular “KB” constants were evaluated, and the values affirmed the participation of static process for each compound–DNA binding. The greater binding site size values (n > 1) of metal complexes NPAZn and NPANi indicated other sites availability of intercalative compounds. DNA viscosity variation by increasing compound’s concentration further verified the compound–DNA interaction. Antibacterial and tumor inhibitory activities were observed significant for both metal complexes, while ligand has shown no activity. The greater binding affinity of metal complexes, as evaluated both computationally and spectroscopically, further validated the lower IC50 values of complexes as compared to ligand.

Validation of milk mid-infrared spectroscopy for predicting the metabolic status of lactating dairy cows in Australia

Increased concentrations of some serum biomarkers are known to be associated with impaired health of dairy cows. Therefore, being able to predict these biomarkers, especially in the early stage of lactation, would enable preventive management decision. Some health biomarkers may also be used as phenotypes for genetic improvement for improved animal health. In this study, we validated the accuracy and robustness of models for predicting serum concentrations of β-hydroxybutyrate (BHB), fatty acids, and urea nitrogen, using milk mid-infrared (MIR) spectroscopy. The data included 3,262 blood samples of 3,027 lactating Holstein-Friesian cows from 19 dairy herds in Southeastern Australia, collected in the period from July 2017 to April 2020. The models were developed using partial least squares regression and were validated using 10-fold random cross-validation, herd-year by herd-year external validation, and year by year validation. The coefficients of determination (R2) for prediction of serum BHB, fatty acids, and urea obtained through random cross-validation were 0.60, 0.42, and 0.87, respectively. For the herd-year by herd-year external validation, the prediction accuracies held up comparatively well, with R2 values of 0.49, 0.33, and 0.67 for of serum BHB, fatty acids, and urea, respectively. When the models were developed using data from a single year to predict data collected in future years, the R2 remained comparable, however, the root mean squared errors increased substantially (4-10 times larger than compared with that of herd-year by herd-year external validation) which could be due to machine differences in spectral response, the change in spectral response of individual machines over time, or other differences associated with farm management between seasons. In conclusion, the mid-infrared equations for predicting serum BHB, fatty acids, and urea have been validated. The prediction equations could be used to help farmers detect cows with metabolic disorders in early lactation in addition to generating novel phenotypes for genetic improvement purposes.

COMPARAÇÃO DAS IMAGENS LANDSAT 8 E SENTINEL 2 PARA O MONITORAMENTO DE RESERVATÓRIOS DE ABASTECIMENTO NO CERRADO BRASILEIRO

O uso de imagens de satélite como ferramenta de monitoramento ambiental tem grande aplicabilidade em diversas áreas. Contudo, uma área pouca explorada é o monitoramento de recursos hídricos devido à falta de parâmetros que correlacionem a qualidade da água e as imagens. Esta pesquisa avalia o uso de imagens LandSat 8 e Sentinel 2 no monitoramento de reservatórios de abastecimento do Complexo Capim Branco em Uberlândia, MG. Foram analisadas as alterações da resposta espectral em relação a turbidez e sólidos totais. As imagens do sensor MSI do satélite Sentinel 2 apresentaram precisão espectrais compatíveis com o LandSat 8, mas ao analisar todas as bandas do espectro visível e infravermelho próximo, foi verificado que as imagens LandSat 8 têm maior capacidade de diferenciação de elementos suspensos na água. Os resultados permitiram estabelecer uma equação de correlação entre a turbidez com as bandas das imagens para cada reservatório.

Growth Stages Classification of Potato Crop Based on Analysis of Spectral Response and Variables Optimization.

Potato is the world’s fourth-largest food crop, following rice, wheat, and maize. Unlike other crops, it is a typical root crop with a special growth cycle pattern and underground tubers, which makes it harder to track the progress of potatoes and to provide automated crop management. The classification of growth stages has great significance for right time management in the potato field. This paper aims to study how to classify the growth stage of potato crops accurately on the basis of spectroscopy technology. To develop a classification model that monitors the growth stage of potato crops, the field experiments were conducted at the tillering stage (S1), tuber formation stage (S2), tuber bulking stage (S3), and tuber maturation stage (S4), respectively. After spectral data pre-processing, the dynamic changes in chlorophyll content and spectral response during growth were analyzed. A classification model was then established using the support vector machine (SVM) algorithm based on spectral bands and the wavelet coefficients obtained from the continuous wavelet transform (CWT) of reflectance spectra. The spectral variables, which include sensitive spectral bands and feature wavelet coefficients, were optimized using three selection algorithms to improve the classification performance of the model. The selection algorithms include correlation analysis (CA), the successive projection algorithm (SPA), and the random frog (RF) algorithm. The model results were used to compare the performance of various methods. The CWT-SPA-SVM model exhibited excellent performance. The classification accuracies on the training set (Atrain) and the test set (Atest) were respectively 100% and 97.37%, demonstrating the good classification capability of the model. The difference between the Atrain and accuracy of cross-validation (Acv) was 1%, which showed that the model has good stability. Therefore, the CWT-SPA-SVM model can be used to classify the growth stages of potato crops accurately. This study provides an important support method for the classification of growth stages in the potato field.

Detection of chlorophyll content in growth potato based on spectral variable analysis

Monitoring the chlorophyll content in tuber formation and tuber bulking stage has great significance for the nutritional status diagnosis in the potato field. In this paper, the 314 canopy spectra of potato crops were collected at four stages, respectively. The leaves were collected simultaneously to measure the chlorophyll content. After spectra pre-processing, the dynamic changes in chlorophyll content and spectral response during growth were analyzed. Two variable selection algorithms (successive projection algorithm, and random frog algorithm) were employed to select chlorophyll characteristic wavelengths. The partial least square algorithm was used for modeling analysis. The performance of sensitive wavelengths selected by two algorithms was compared, respectively, from the perspective of correlation with chlorophyll, reflecting leaf information, and model result. The sensitive wavelengths selected by random frog was optimal. The determination coefficient of calibration and validation set of the detection model established based on above sensitive wavelengths was respectively 0.827 and 0.798. The results showed the chlorophyll content of potato could be detected accurately based on the spectroscopy method.

Effect of bending test on the performance of CdTe solar cells on flexible ultra-thin glass produced by MOCVD

The development of lightweight and flexible solar modules is highly desirable for high specific power applications, building integrated photovoltaics, unmanned aerial vehicles and space. Flexible metallic and polyimide foils are frequently used, but in this work an alternative substrate with attractive properties, ultra-thin glass (UTG) has been employed. CdTe solar cells with average efficiency reaching 14.7% AM1.5G efficiency have been produced on UTG of 100 μm thickness. Little has been reported on the effects on PV performance when flexed, so we investigated the effects on J-V parameters when the measurements were performed in 40 mm and 32 mm bend radius, and in a planar state before and after the bend curvature was applied. The flat J-V measurements after 32 mm bending test showed some improvement in efficiency, Voc and FF, with values higher than the first measurement in a planar state. In addition, two CdTe solar cells with identical initial performance were subjected to 32 mm static bending test for 168 hours, the results showed excellent uniformity and stability and no significant variation on J-V parameters was observed. External quantum efficiency and capacitance voltage measurements were performed and showed no significant change in spectral response or carrier concentration. Residual stress analysis showed that no additional strain was induced within the film after the bending test and that the overall strain was low. This has demonstrated the feasibility of using CdTe solar cells on UTG in new applications, when a curved module is required without compromising performance.

Synthesis, characterization and DFT studies of complexes bearing [Re(CO)3]+ core and reactivity towards cyanide ion

Mononuclear rhenium(I) complexes having fac-[Re(CO)3]+ core of general formula fac-[Re(CO)3(L)Cl] have been synthesized in excellent yield by reacting [Re(CO)5Cl] with L1 and L2in a ratio of 1:1 in toluene under inert atmosphere. Here L1 and L2 are N-((quinolin-2-yl)methylene)-9H-fluoren-2-amine and N-((anthracen-10-yl)methylene)quinolin-8-amine respectively. Spectroscopic measurements such as NMR, ESI-MS and IR spectroscopy were used to ensure the formations of desired complexes. Molecular structures of fac-[Re(CO)3(L1)Cl] and fac-[Re(CO)3(L2)Cl] were confirmed by single-crystal X-ray diffraction. The ligands are emissive whereas the metal complexes are weak emitter. A remarkable change in absorption as well as emission behavior was observed in complex 2 upon addition of cyanide ion. Interruption in intraligand charge transfer in complex 2 is the probable reason for the obvious change in spectral response of the same. 1H NMR titration was performed as the evidence of the previously stated fact. The ground and excited-state geometries, absorption properties of rhenium(I) complexes were examined by DFT and TDDFT methods. The natural transition orbital (NTO) and analysis reveal the nature of excitations.

Dynamic change in rice leaf area index and spectral response under flooding stress

Analysis of the canopy structure change and spectral response mechanism of rice under flooding stress is an important prerequisite for large-scale monitoring of rice flooding disasters. The leaf area index (LAI) was used as the characterization indicator. The response rule of the canopy spectrum to flooding stress intensity was analyzed. The sensitive spectral characteristic parameters were screened to construct the LAI spectral response model of rice under flooding stress. The results showed that the rice LAI under flooding stress decreased with an increase in waterlogging depth. The spectral reflectance of the rice canopy under flooding stress significantly changed in the near-infrared band and decreased with an increase in waterlogging depth. In 680–760 nm, the double peak in the first-order differential spectrum of the rice canopy was more obvious with advancement of the growth process and a multiple peak appeared during the late growth stage. The blueshift of the red edge parameters was the most obvious in the submerged top during the tillering stage. A power function regression model based on the ratio of the first-order differential spectral amplitude at 737 nm to 719 nm in the red edge range was the optimal LAI response model for rice under flooding stress. A field waterlogging experiment was used to simulate and analyze the influence of flooding on the rice canopy structure and the canopy spectral response rule, providing a reference for the subsequent analysis of rice growth and disaster loss assessment under flooding stress.

Lattice Resonances in Transdimensional WS2 Nanoantenna Arrays

Mie resonances in high-refractive-index nanoparticles have been known for a long time but only recently have they became actively explored for control of light in nanostructures, ultra-thin optical components, and metasurfaces. Silicon nanoparticles have been widely studied mainly because of well-established fabrication technology, and other high-index materials remain overlooked. Transition metal dichalcogenides, such as tungsten or molybdenum disulfides and diselenides, are known as van der Waals materials because of the type of force holding material layers together. Transition metal dichalcogenides possess large permittivity values in visible and infrared spectral ranges and, being patterned, can support well-defined Mie resonances. In this Communication, we show that a periodic array of tungsten disulfide (WS2) nanoantennae can be considered to be transdimensional lattice and supports different multipole resonances, which can be controlled by the lattice period. We show that lattice resonances are excited in the proximity to Rayleigh anomaly and have different spectral changes in response to variations of one or another orthogonal period. WS2 nanoantennae, their clusters, oligomers, and periodic array have the potential to be used in future nanophotonic devices with efficient light control at the nanoscale.

Preflight calibration of the Chinese Environmental Trace Gases Monitoring Instrument (EMI)

Abstract. An environmental trace gases monitoring instrument (EMI) is a nadir-viewing wide-field imaging spectrometer, which aims to quantify the global distribution of tropospheric and stratospheric trace gases, and is planned to be launched on 9 May 2018. The selected wavelength bands for EMI are ultraviolet channels: UV1 (240–315 nm), UV2 (311–403 nm) and visible channels: VIS1 (401–550 nm), and VIS2 (545–710 nm). The spectral resolution is 0.3–0.5 nm, and the swath is approximately 114∘ wide to achieve a one-day global coverage. The preflight calibration of the EMI is discussed in this paper. A tunable laser and rotating platform are adopted for an EMI wavelength calibration of the entire field of view. The accuracy of the wavelength calibration is less than 0.05 nm. In addition, the solar calibration mode shows the same results compared with Earth observation mode. A thermal vacuum test is performed to investigate the influence of in-orbit thermal vacuum conditions on the EMI, and EMI spectral response changes with pressure, optical bench temperature, and charge-coupled device (CCD) detector temperature are obtained. For a radiometric calibration of UV1, a diffuser plate with a 1000 W xenon lamp, which produces sufficient UV output, is selected. An integrating sphere system with tungsten halogen lamp is selected for the UV2, VIS1, and VIS2. The accuracies of radiance calibration are 4.53 % (UV1), 4.52 % (UV2), 4.31 % (VIS1), and 4.30 % (VIS2). The goniometry correction factor and irradiance response coefficient of the EMI are also calibrated on the ground for an in-orbit calibration of the solar. A signal-to-noise ratio (SNR) model of the EMI is introduced, and the EMI in-orbit SNR is estimated using the SNR and MODTRAN radiance models.