Spectral Measurement Method Research Articles

Research on Spectral Measurement Method for Content of Bicolor Mixed Ink

Research on Spectral Measurement Method for Content of Bicolor Mixed Ink

Fast compressed sensing spectral measurement with adaptive gradient multiscale resolution

We propose a fast, adaptive multiscale resolution spectral measurement method based on compressed sensing. The method can apply variable measurement resolution over the entire spectral range to reduce the measurement time by over 75% compared to a global high-resolution measurement. Mimicking the characteristics of the human retina system, the resolution distribution follows the principle of gradually decreasing. The system allows the spectral peaks of interest to be captured dynamically or to be specified a priori by a user. The system was tested by measuring single and dual spectral peaks, and the results of spectral peaks are consistent with those of global high-resolution measurements.

Measurement methods for gamma-ray bursts redshifts

In the era of multi-messenger astronomy, gamma-ray bursts (GRBs) with known redshifts, especially high-redshift GRBs, are a powerful tool for studying the structure and evolution of the early Universe. We review the background, the history, and the application of measurement methods of GRB redshifts in astronomy. Based on different observation targets, two measurement methods are mainly introduced. One is on GRB afterglow, the other is on GRB host galaxy. There are various processing methods belonging to measurement methods based on afterglow, including spectral measurement method of afterglow and afterglow spectral energy distribution fitting method with improved methods. There are also numerous measurement methods based on host galaxy, such as spectral measurement method of host galaxy, template matching method of host galaxy, some automatic spectroscopic redshift measurement methods, and machine learning methods. We subsequently introduce the principles, effects, and performance of these methods. We enumerate several detection and measurement instruments, which have been used in observation. The characteristics, advantages, disadvantages, and applicability of the GRB redshift measurement methods are summarized and analyzed. Furthermore, we provide a data set of 611 GRBs with measured redshift. The data set has been collected since 1997. Analysis and statistics are presented based on this data set. We summarize the characteristics of GRBs such as location, time, and accuracy. Finally, we introduce Space-based multi-band astronomical Variable Objects Monitor (SVOM) mission dedicated to searching high redshift GRBs. We also introduce the application prospect of various redshift measurement methods in SVOM mission.

High SBS Threshold Fiber Laser With Spectral Management Using Binarized Multi-Tone Signal Modulation

In the high-power narrow-linewidth continuous fiber laser system based on the master oscillator power amplifier (MOPA) structure, the linewidth and spectral shape of the seed source are directly related to the SBS effect threshold which limits the maximum output power. It is currently under investigation which spectral shape has the highest laser power threshold. In this study, the spectral broadening and shape control of seed sources based on high-order phase modulation of binarized multi-tone signals is proposed. Combined with the heterodyne detected-based high-precision spectral measurement method, the measurement accuracy is improved from GHz to MHz level, which assists in optimizing the spectral shape. The broadened seed sources with rectangular, triangular, concave, and super-Gaussian spectra are experimentally demonstrated. And a maximum power of 2234 W is obtained with a rectangular spectrum with 10-GHz bandwidth. Theoretically, this scheme has multi-dimensional spectra tuning ability and can achieve arbitrary spectral types to explore the optimal seed source spectrum in diverse applications.

Estimation of Pb and Cd Content in Soil Using Sentinel-2A Multispectral Images Based on Ensemble Learning

With the increasing economic growth in developing nations, soil heavy metal pollution has become a growing concern. Monitoring the heavy metal concentration in soil through remote sensing is crucial for safeguarding the ecological environment. However, the current indoor spectral measurement method has limitations, such as the discrete soil sampling space and weak spectral characteristics of soil heavy metals, leading to a poor robustness of remote sensing inversion models. This study presents a novel approach to address these challenges by incorporating a spatial feature of pollution sources and sinks to evaluate the spatial factors affecting pollutant diffusion and concentration. An integrated learning model, combining spatial and spectral information, is developed to estimate heavy metal content in soil using Sentinel-2A satellite data. A total of 235 soil samples were collected in Jiyuan, China, and the effective spectral transformation characteristics of Sentinel-2A data were screened. The impact of spectral characteristics, topographic characteristics, and spatial characteristics on retrieving soil heavy metal lead (Pb) and cadmium (Cd) content were analyzed. The optimal inversion method was determined through various integrated learning models, and the spatial distribution of heavy metals Pb and Cd was mapped. The results indicate that the accuracy of the inversion model was significantly improved by incorporating terrain features and spatial features of pollution sources. The Blending integrated learning method showed a 65.9% and 73.2% reduction in the RMSE of Pb and Cd, respectively, compared to other regression models. With R2 values of 0.9486 and 0.9489 for Pb and Cd, respectively, and a MAPE less than 0.2, the Blending model demonstrated high prediction accuracy.

Indirect spectrum measurement via random phase modulation and detection in temporal domain.

Spectroscopy continues to provide possibilities for a deeper understanding of fundamental physical phenomena. Traditional spectral measurement method, dispersive Fourier transformation, is always limited by its realization condition (detection in the temporal far-field). Inspired by Fourier ghost imaging, we put forward an indirect spectrum measurement to overcome the limitation. The spectrum information is reconstructed via random phase modulation and near-field detection in the time domain. Since all operations are realized in the near-field region, the required length of dispersion fiber and optical loss are greatly reduced. Considering the application in spectroscopy, the length of required dispersion fiber, the spectrum resolution, the range of spectrum measurement and the requirement on bandwidth of photodetector are investigated.

Remote Sensing of Seawater Temperature and Salinity Profiles by the Brillouin Lidar Based on a Fizeau Interferometer and Multichannel Photomultiplier Tube

Brillouin spectroscopy is a powerful tool to measure the water temperature and salinity profiles of seawater. Considering the insufficiency of the current spectral measurement methods in real-time, spectral integrity, continuity, and stability, we developed a new lidar system for spectrum measurement on an airborne platform that is based on a Fizeau interferometer and multichannel photomultiplier tube. In this approach, the lidar system uses time-of-flight information to measure the depth and relies on Brillouin spectroscopy as the temperature and salinity indicator. In this study, the system parameters were first optimized and analyzed. Based on the analysis results, the performance of the system in terms of detection depth and accuracy was evaluated. The results showed that this method has strong anti-interference ability, and under a temperature measurement accuracy of 0.5 °C and a salinity measurement accuracy of 1‱, the effective detection depth exceeds 40.51 m. Therefore, the proposed method performs well and will be a good choice for achieving Brillouin lidar application in seawater remote sensing.

Features of the use of food simulators used when testing packaging for the study of food aluminum foil

Introduction. Aluminum foil is one of the most widely used food packaging, since it has a set of high consumer characteristics. At the same time, the food foil can serve as a source of aluminum entering the human body, but there is no specific method of testing foil. In this regard, the study of the spectrum and features of the application of food simulators is relevant to improve various stages of food aluminum foil testing. The purpose of the study is to investigate the features of the use of food simulators and testing stages used as a whole for any food packaging in the study of aluminum foil. Materials and methods. With the application of the elements of the PRISMA systematic reporting reports on systematic reviews, the analysis of scientific and technical literature on the features of the use of food simulators when testing the food aluminum foil were performed. Measurement of aluminum content in food simulators after contact with aluminum foil was carried out by spectrometry methods. Results. When testing the food aluminum foil, it is impractical to the use of the entire list of food simulators recommended by TR TS 005/2011. It was established to be advisable to improve the current instructive methodological base, in particular the pre-analytic stage of sample preparation. A method of sample preparation and spectral measurement methods was carried out by a comparative experimental measurement of real samples of food simulators after contact with the foil. Limitations. The limitation of the study was the use in the experiment exclusively of samples of aluminum foil with a thickness of 0.009 mm from aluminum alloy 8011 and aluminum foil with a thickness of 0.02 mm from aluminum alloy 1200. account the features of the use of aluminum foil into everyday life, therefore, the methodological approaches to the stages of its testing need to be improved. The developed method of sample preparation allows applying unified requirements in the process of testing food aluminum foil to safely use it in everyday life. Conclusion. The list of model environments for the study of any food packaging does not take into account the specifics of the use of aluminum foil in everyday life, therefore, methodological approaches to the stages of its testing need to be improved. The developed method for sample preparation allows applying unified requirements in the process of testing food-grade aluminum foil for the purpose of its safe use in everyday life.

Method of characterizing the multicomponent spectrum of a VCSEL in devices based on the CPT effect

We propose and experimentally demonstrate a method of spectral measurement of multicomponent radiation emitted by a modulated vertical cavity surface-emitting laser (VCSEL) relying on peculiarities of absorption in alkali metal vapor. The method consists in determination of the radiation spectrum (which is formed due to RF modulation of the injection current of a diode laser) from the dependence of transmittance of rubidium vapor upon the radiation wavelength. We show that the proposed method allows fairly precise measurement of the spectrum of multicomponent radiation used in devices based on the coherent population trapping (CPT) effect when the frequency difference between the radiation components matches that between absorption lines of an alkali metal.

Compressed sensing method for measuring absorption spectrum of liquid samples

For low-light or near-infrared absorption spectrum measurements, it is challenging to obtain high resolution spectra due to limitations of exotic array detectors. In this paper, a new spectral measurement method based on compressed sensing (CS) is reported. An experimental spectrometer is constructed and calibrated, and the absorption spectra of two liquid samples are measured. Along with a high resolution, the new method has a better signal-to-noise ratio (SNR) than the conventional scanning spectroscopy technique. The measurement resolution of our experimental system is 0.38 nm. The result of wavelength position calibration is accurate. The peak value of characteristic spectrum of red sample is 730 nm, and that of blue sample are 440 nm and 740 nm.

A multidirectional spectral measurement method and instrument to investigate non-image-forming effects of light

Light directionality, spectrum and relevant radiometric or photometric quantity are believed to be essential factors influencing the magnitude of non-image-forming effects. In this paper, a measurement method and an instrument (the multidirectional spectroradiometer—MuS) is proposed, which considers different light incidents and spectra simultaneously, therefore enabling the measurement of light characteristics relevant for non-image-forming effects. The MuS consists of four spectroradiometers measuring in different directions. Four spectrometers using optical fibers were configured to measure the spectral irradiance within a wavelength range from 200–1100 nm with ~5.7 nm pixel resolution. Application of the MuS facilitates a better understanding of the non-image-forming light characteristics of space. The MuS was tested with stable electric lighting as well as dynamic daylight conditions and proved reliable to perform continuous spectral measurements for different directions simultaneously. Results of the test measurements in dynamic daylight conditions show differences in the spectral distribution and measured irradiance of up to 30 times in different directions.

Комбинированные методы спектрального анализа неоднородного потока зерновых смесей

The problem of detecting Fusarium fungi infected grains and identifying the varieties of the components of grain mixtures based on the combined use of various spectral measurement methods in various wavelength ranges is considered. A method for measuring combined reflectance and transmittance spectra of the elements of non-uniform grain flow is described. The results of the spectral measurement are processed using neural network based classification algorithms combined with data dimensionality reduction techniques. The probabilities of incorrect recognition for various numbers of features and combinations of spectral methods are estimated

Single shot, double differential spectral measurements of inverse Compton scattering in the nonlinear regime

Inverse Compton scattering (ICS) is a unique mechanism for producing fast pulses---picosecond and below---of bright photons, ranging from x to $\ensuremath{\gamma}$ rays. These nominally narrow spectral bandwidth electromagnetic radiation pulses are efficiently produced in the interaction between intense, well-focused electron and laser beams. The spectral characteristics of such sources are affected by many experimental parameters, with intense laser effects often dominant. A laser field capable of inducing relativistic oscillatory motion may give rise to harmonic generation and, importantly for the present work, nonlinear redshifting, both of which dilute the spectral brightness of the radiation. As the applications enabled by this source often depend sensitively on its spectra, it is critical to resolve the details of the wavelength and angular distribution obtained from ICS collisions. With this motivation, we present an experimental study that greatly improves on previous spectral measurement methods based on x-ray $K$-edge filters, by implementing a multilayer bent-crystal x-ray spectrometer. In tandem with a collimating slit, this method reveals a projection of the double differential angular-wavelength spectrum of the ICS radiation in a single shot. The measurements enabled by this diagnostic illustrate the combined off-axis and nonlinear-field-induced redshifting in the ICS emission process. The spectra obtained illustrate in detail the strength of the normalized laser vector potential, and provide a nondestructive measure of the temporal and spatial electron-laser beam overlap.

Construction of Data-Measurement Systems for Operational Measurement and Evaluation of the Major Parameters of Oil and Petroleum Products

A theoretical framework for building a data-measurement system that combines adsorption and laser fluorescence spectral measurement methods with estimates of the basic parameters of crude oil is discussed. An internal calibration principle for the spectral absorption system is examined. The duality of this principle is noted and the possibility of using it in laser fluorescence measurement systems is considered.

Spectral estimation of soil water content in visible and near infra-red range

Soils can be examined on the basis of spectral data, using such methods with which the reflected radiation can be divided into a large number of (several hundreds) small spectral channel (some nm). Based on the spectral characteristics of the soils, or the different index numbers calculated from hyperspectral data water content of soils can be well characterized. The examined soil samples were coming from different apple orchards of which soils had different physical characteristics (sandy loamy and clay). The goals of my experiments were the evaluation of spectral measurement method for soil content detection, and to carry out algorithms for fast field scale spectral evaluation of different soil water content. The spectral measuring was carried out by laboratory scale AvaSpec 2048 spectrometer at 400 – 1000 nm wavelength interval with 0.6 nm spectral resolutions and by ASD FieldSpec Junior at 350 – 2500 nm. After drying, dry soil samples were watered by 2.5 m/m% till maximal saturation, and each wetting was measured spectrally. Based on spectral properties, reflectances were decreased in the whole spectral range within the continuous wetting due to the high absorption characteristics of water. The most water sensitive spectral ranges were selected by principal component, and such algorithms were created, with which the water content can be detectable in the certain soil. The algorithms can facilitate farmers for irrigation scheduling of their orchards. These results can also be utilizable in precision water management, since it can be a basis for such integrated active sensors with LED or laser light source, measuring reflectance at the certain spectral range, which can facilitate real time water status assessment of orchards.

Processing method of spectral measurement using F-P etalon and ICCD

A processing method for the precise acquisition of 1D interference spectrum from the 2D Fabry-Pérot(F-P) fringe pattern is proposed in the paper. Current methods can only measure the spectrum with full-pixel accuracy. The new method is capable to achieve the sub-pixel accuracy as well as reduce the noise by taking full advantage of the 2D image information and analyzing the statistical values of pixels in a comprehensive way. Experimental results show that the accuracy of the measured Brillouin shift and linewidth is around several MHzs, which is significantly improved compared to methods with full-pixel accuracy.

X-ray tube spectral measurement method for quantitative analysis of X-ray fluorescence analysis

Lα and Lβ X-ray fluorescence spectra of a lead metallic sheet were measured using an energy dispersive X-ray spectrometer by changing the X-ray tube voltage and the material of the primary filter. The Lα to Lβ intensity ratio changed from Lα: Lβ = 3: 1 at 15 kV to Lα: Lβ = 1: 1 at 50 kV depending on the X-ray tube voltage and the filter. The scattered X-ray spectra of an acrylic slab instead of the sample in the sample holder were measured by changing the applied voltage and the material of the primary filter. The calculated values of the Pb Lα/Lβ intensity ratio of the metallic sheet using the Shiraiwa–Fujino formula by inserting the scattered X-ray spectra of an acrylic plate as incident X-ray spectra and the fundamental parameters taken from the Elam database were in good agreement with the experimental ones. We conclude that we can obtain an incident X-ray spectrum approximately by measuring the scattered X-ray spectrum without measuring the direct incident beam. Copyright © 2010 John Wiley & Sons, Ltd.

Dose calculations of photon beams using a finite‐size pencil beam model

This work investigates the finite‐size pencil beam (FSPB) model for calculating dose deposition from photon beams generated by a clinical linear accelerator. The FSPB model, first published by Bourland and Chaney, uses the superposition of preconvolved “finite‐size pencil beams” of small cross‐sectional area to determine the dose deposition in a uniform water phantom. In the dose computation, FSPBs for a range of energy bins are pieced together like mosaic tiles to collectively form the cross section of the full beam. Depending on the full beam resolution, the superposition calculation can be much faster than full convolution. The results stress the importance of a knowledge of the photon spectrum of the beam for accurate dose calculations. However, published methods of indirect spectral measurements using transmission measurements through beam attenuators require mathematical fits with a large number of parameters and constraints. A simple strategy is presented for fitting transmission data that models important physical characteristics of photon beams produced in linear accelerators. The fitting equation has these advantages over previous methods: (1) the equation describes the shape of a bremsstrahlung spectrum based on physical expectations; (2) only three fit parameters are required with a single constraint. Results are presented for 4 and 6 MV photon beams. Comparisons of calculated and measured TMRs and output factors of open fields show excellent agreement. Results include discussions of FSPB generation, the method of spectral measurement, the effect of beam softening across the field cross section, and the method for modeling this effect using different FSPB weighting factors as a function of energy and location.

FFTアナライザを用いた分光放射測定

FFTアナライザを用いた分光放射測定

The photoemission method of spectral measurement and a new method of data reduction

The photoemission method of spectral measurement and a new method of data reduction