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Mobile Monitoring—Open-Source Based Optical Sensor System for Service-Oriented Turbidity and Dissolved Organic Matter Monitoring
摘要： The protection and sustainable use of aquatic resources require a better understanding of fresh water sources, limnic ecosystems, and oceans. The effects of global change, intensive use of natural resources and the complex interactions between humans and the environment show different effects at different scales. Current research approaches are not sufficient to appropriately take account of the heterogeneity and dynamics of aquatic ecosystems. A major challenge in applied environmental research is to extend methods for holistic monitoring and long-term observation technologies with enhanced resolution over both space and time. In this study, turbidity and the content of dissolved organic matter (DOM) are key parameters, as they are of importance for assessing the health of aquatic ecosystems and the state of ecosystem services (e.g., the provision of drinking water). Photonics and optical sensors as well as integrated circuits and open-source based components open interesting possibilities to overcome the current lack of adaptive and service-oriented sensor systems. An open source based optical sensor system was developed, which enables a user-specific, modular and adaptive in-situ monitoring of the turbidity and the dissolved organic substance content almost in real time. Quantification is based on attenuation or transmission measurements with two narrowband LEDs and corresponding detectors in the ultraviolet (DOM content) and infrared range (turbidity) of the electromagnetic spectrum. The developed in-situ sensor system shows a very high agreement with the results obtained using a laboratory photometer but with less methodological effort. First tests carried out in the area close to the city of Leipzig (Saxony, Germany) show promising results. The in-situ sensor system is able to acquire the optical attenuation with a sampling rate up to 0.1 Hz. Due to the fact that data is visualized directly with the help of web services, even the quality of data collection can be improved by assisting the selection of sampling points or a direct spatio-temporal data feedback. What this approach illustrates is the fact that open-source technologies and microelectronics can now be used to implement resilient and promising sensor systems that can set new standards in terms of performance and usability within applied environmental research.
关键词： internet of things,assisted monitoring,attenuation sensor,water quality,photonics sensing,in-situ measurements
更新于2025-09-16 10:30:52
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Propagation of circularly polarized laser in strongly magnetized over-dense collisional plasma
摘要： Permittivity of a circularly polarized (CP) laser in magnetized collisional plasma is obtained in simpli?ed form. The propagation of a CP laser in magnetized homogeneous over-dense collisional plasma was investigated, and characteristics such as attenuation length, speci?c energy deposition and blue shift are obtained. Potential applications in ?elds such as inertial con?ned fusion are discussed.
关键词： energy deposition,collisional plasma,permittivity,inertial con?ned fusion,attenuation length,blue shift,circularly polarized laser,magnetized plasma
更新于2025-09-16 10:30:52
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Steady State X-Ray Radiation Induced Attenuation in Canonical Optical Fibers
摘要： So-called canonical optical fibers are samples especially designed to highlight the impact of some manufacturing process parameters on the radiation responses. Thanks to the results obtained on these samples, it is thus possible to define new procedures to better control the behaviors of optical fibers in radiation environments. In the present work, we characterized the responses, under steady state X-rays, of canonical samples representative of the most common fiber types differing by their core-dopants: pure silica, Ge, Al and P. Their radiation induced attenuation (RIA) spectra were measured online at both room temperature (RT) and liquid nitrogen temperature (LNT), in the energy range [~0.6 - ~3.0] eV (~2100 nm - ~410 nm), highlighting the RIA growth kinetics during the fiber exposure up to an accumulated dose of ~200 Gy(SiO2) at a constant dose rate of 100 mGy/s at RT. At LNT, the deposited doses varied between 100 and 180 Gy, with a time dependent dose rate. In order to understand the origin of the excess losses and the difference between the RIA spectral shapes observed at the two temperatures, a spectral decomposition of the optical losses has been performed using a set of Gaussian absorption bands related to the already known point defects. As a result, if the RIA in the visible domain is quite well understood, the knowledge on RIA origin in the near-IR remains incomplete, justifying new and deeper studies to clarify the fibers response under steady state irradiation.
关键词： point defects,radiation effects,attenuation,pure silica core and doped optical fibers,canonical samples
更新于2025-09-16 10:30:52
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Measurements of High Power Levels of Laser Radiation by Pass-Through Receivers
摘要： The problem of developing measuring instruments for high levels of laser power of the pass-through type was posed and solved. Methods for solving the problem are presented. A measuring instrument has been developed, in which a two-step circuit design is applied for power attenuation of the laser beam to an operating level as measured by the radiation detector. It is shown that due to the original design of the attenuation steps and their arrangement in relation to the laser beam it is possible to achieve values of the attenuation coefficient of (0.2–0.4)·1010 and to measure power up to 10–15 kW without forced cooling of elements of the measuring instrument. Application of the design of steps makes it possible to reduce the dimensions of the measuring instrument and pass practically all radiation to the output without changing the characteristics of the initial laser beam. The measuring instrument that was developed differs from known analogs and is suitable for work with process lasers. For reliable measurement of laser radiation power, the conditions were determined for selecting the time constant of integration of the radiation detector. The connection between the time constant of integration of the radiation detector and the geometrical characteristics of the measuring instrument is shown.
关键词： attenuator,reflector,integrating sphere,laser power,attenuation coefficient
更新于2025-09-12 10:27:22
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Physical implementation of underwater optical wireless system using spatial mode laser sources with optimization of spatial matching components
摘要： This article numerically investigates the e?ect of absorption and scattering loss in the presence of underwater. Presenting optical wireless channel, system is considered for fundamental mode (LP01) and its higher order modes (LP11, LP21 & LP31). The system performance is examined in terms of bit error rate (BER) with the function of wavelength, distance, attenuation and beam divergence. This implementation also shows the optimized results with respect to spatial mode matching component using spatial aperture and collimating lens as well. The graded results producing the new sight and will have greater attention among the optical wireless technology. The overall analysis of system design promises for better performance even at the treaty of high attenuation loss 49.34 dB/m on the propagation of all spatial modes. Each results obtained in this paper reaches the stability at the greater attenuation with the wavelength range from 1000 nm to 1600 nm.
关键词： Absorption,Attenuation,Underwater,BER,Scattering loss
更新于2025-09-12 10:27:22
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Effect of Laser Ablation on Microwave Attenuation Properties of Diamond Films
摘要： Thermal conductivity is required for developing high-power microwave technology. Diamond has the highest thermal conductivity in nature. In this study, a diamond ?lm was synthesized by microwave plasma chemical deposition, and then long and short conductive graphite ?bers were introduced to the diamond ?lms by laser ablation. The permittivity of the samples in the K-band was measured using the transmission/re?ection method. The permittivity of diamond ?lms with short graphite ?bers increased. The increase in real part of permittivity can be attributed to electron polarization, and the increase in the imaginary part can be ascribed to both polarization and electrical conductivity. The diamond ?lms with long graphite ?bers exhibited a highly pronounced anisotropy for microwave. The calculation of microwave absorption shows that re?ection loss values exceeding ?10 dB can be obtained in the frequency range of 21.3–23.5 GHz when the graphite ?ber length is 0.7 mm and the sample thickness is 2.5 mm. Therefore, diamond ?lms can be developed into a microwave attenuation material with extremely high thermal conductivity.
关键词： high thermal conductivity,laser ablation,diamond ?lms,microwave attenuation,permittivity
更新于2025-09-12 10:27:22
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Implementation of Optical Fiber Post-Mortem Dose Measurements: a Proof of Concept
摘要： We describe the implementation of a versatile system and corresponding method to perform fast post-mortem optical attenuation measurements on irradiated Optical Fibers (OFs) for dosimetry purposes. The measurement is based on the Radiation Induced Attenuation (RIA) phenomenon. We employ a dual wavelength Optical Time Domain Reflectometer (OTDR) coupled with a suitable radiation sensitive OF. We demonstrate that radiation dose levels higher than 100 Gy(SiO2) can be measured efficiently with 1 m long samples. The accuracy of the measurement increases with the increasing radiation dose if the length of the sample is kept fix. We also highlight possible limitations of our approach and, more generally, limitations related to perform accurate RIA measurement (online or post-mortem) on short single mode OF samples. The technological solution we propose can be tailored to address different radiation environment.
关键词： Optical fibers,P-doped,radiation sensitive,Dosimetry,Radiation Induced Attenuation,CERN
更新于2025-09-11 14:15:04
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Design of Substrate Integrated Gap Waveguide and Their Transitions to Microstrip Line, for Millimeter-Wave Applications
摘要： This paper offers an approximate, but very convenient and accurate, manner to find the desired strip width for substrate integrated gap waveguide (SIGW) with a given characteristic impedance and the conductor and dielectric attenuation constants, without any complicated manual calculations or time-consuming full-wave simulation and optimization iterations. Moreover, the investigation of the transition between SIGW and microstrip lines will prove that an additional transition structure, such as a conventional microstrip taper, is not required any more at millimeter-wave frequencies for the desired transmission performance. This is a useful feature in circuit design and compactness. Both of the above works will be of great help to realize future feeding networks for SIGW antenna arrays or other types of cost-effective SIGW passive components at high frequencies. Two SIGW prototypes, working at Ka and V bands, are fabricated and offer experimental verifications, which present good agreement with the simulation results.
关键词： 5G,characteristic impedance,Gap waveguide,transition,attenuation constant,millimeter waves
更新于2025-09-11 14:15:04
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Effect of Temperature and Gamma-Ray Irradiation on Optical Characteristics of Fiber Bragg Grating Inscribed Radiation-Resistant Optical Fiber
摘要： A new radiation-hard germano-silicate glass optical fiber with a pure silica glass buffer and a boron-doped silica glass inner cladding was fabricated for temperature sensor application based on the fiber Bragg grating (FBG) under γ-ray irradiation environment. The temperature dependences of optical attenuation at 1550.5 nm and Bragg reflection wavelength shift from 18 ℃ to 40 ℃ before the γ-ray irradiation were about 4.57×10–4 dB/℃ and 5.48 pm/℃, respectively. The radiation-induced optical attenuation at 1550.5 nm and the radiation-induced Bragg reflection wavelength shift under the γ-ray irradiation with the total dose of 22.85 kGy at 35 ℃ were about 0.03 dB/m and 0.12 nm, respectively, with the γ-ray irradiation sensitivity of 5.25×10–3 pm/Gy. The temperature and the γ-ray irradiation dependence of optical attenuation at 1550.5 nm in the FBG written fiber with boron-doped silica glass inner cladding were about 6 times and 4 times lower than that in the FBG written fiber without boron-doped silica glass inner cladding under a temperature change from 18 ℃ to 40 ℃ and the γ-ray irradiation with the total dose of 22.85 kGy at 35 ℃, respectively. Furthermore, the effect of temperature increase on the Bragg reflection wavelength of the FBG written fiber with boron-doped silica inner cladding was much larger about 1000 times than that of the γ-ray irradiation. However, no influence on the reflection power of the Bragg wavelengths and the full width at half maximum (FWHM) bandwidth under temperature and the γ-ray irradiation change was found. Also, after the γ-ray irradiation with the dose of 22.85 kGy, no significant change in the refractive index was found but the residual stresses developed in the fiber were slightly relaxed or retained.
关键词： Optical fiber,radiation-induced attenuation,fiber Bragg grating,temperature sensor,radiation resistance
更新于2025-09-11 14:15:04
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A Field Assessment of a Rain Estimation System Based on Satellite-to-Earth Microwave Links
摘要： This paper describes the results obtained by the application of an innovative environmental monitoring technique able to estimate rainfall intensity in real time by processing the attenuation of microwave satellite link signal measured by low cost sensors. The satellite that has been used during our work, Turksat 42° E, belongs to the plethora of satellites operating for television and radio channel broadcasting. Each sensor exploits off the shelf components, is equipped with a radio frequency power-measuring unit, and provides connectivity to the server over a wide area network. A validation of the approach with a field comparison experiment at the urban scale, comprising three measurement sites equipped with such sensors, was established since autumn 2016 in the municipality of Genoa, Italy. Point-scale rainfall intensity measurements made by two calibrated tipping-bucket rain gauges constitute the reference for the comparative analysis of the microwave sensors performance. The dynamic calibration of the rain gauges was carried out by using an automatic calibration rig and the measurements have been processed with advanced algorithms to reduce counting errors. The experimental setup allowed a full characterization of the microwave signal trends as a function of different precipitation. The results showed a strong correlation between the microwave signal attenuation and the reference rainfall observations and demonstrated the possibility to retrieve ten-minute rain accumulations from the microwave links by adopting a proper electromagnetic model. The comparison between the different measuring systems is performed by computing the time series statistics and the frequency of the rain conditions for each precipitation event.
关键词： microwave measurements,attenuation measurements,geophysical measurement techniques,Atmospheric measurements
更新于2025-09-11 14:15:04