scholarly journals Design and performance of a three-wavelength LED-based total scatter and backscatter integrating nephelometer

2011 ◽  
Vol 4 (6) ◽  
pp. 1291-1303 ◽  
Author(s):  
T. Müller ◽  
M. Laborde ◽  
G. Kassell ◽  
A. Wiedensohler
Keyword(s):  
Signal To Noise Ratio ◽  
Ambient Air ◽  
Light Sources ◽  
Light Emitting ◽  
Sensitivity Functions ◽  
A Value ◽  
Commercial Instrument ◽  
And Performance ◽  
Comparison Measurements

Abstract. Integrating nephelometers are instruments that directly measure a value close to the light scattering coefficient of airborne particles. Different models of nephelometers have been used for decades for monitoring and research applications. Now, a series of nephelometers (Ecotech models M9003, Aurora 1000 and Aurora 3000) with newly designed light sources based on light emitting diodes are available. This article reports on the design of these integrating nephelometers and a comparison of the Aurora 3000 to another commercial instrument (TSI model 3563) that uses an incandescent lamp. Both instruments are three-wavelength, total and backscatter integrating nephelometers. We present a characterization of the new light source design of the Aurora 3000 and provide parameterizations for its angular sensitivity functions. These parameterizations facilitate to correct for measurement artefacts using Mie-theory. Furthermore, correction factors are provided as a function of the Ångström exponent. Comparison measurements against the TSI 3563 with laboratory generated white particles and ambient air are also shown and discussed. Both instruments agree well within the calibration uncertainties and detection limit for total scattering with differences less than 5 %. Differences for backscattering are higher by up to 11 %. Highest differences were found for the longest wavelengths, where the signal to noise ratio is lowest. Differences at the blue and green wavelengths are less than 4 % and 3 %, respectively, for both total and backscattering.

scholarly journals Design and performance of a three-wavelength LED-based total scatter and backscatter integrating nephelometer

2010 ◽  
Vol 3 (6) ◽  
pp. 4835-4864 ◽  
Author(s):  
T. Müller ◽  
M. Laborde ◽  
G. Kassell ◽  
A. Wiedensohler
Keyword(s):  
Signal To Noise Ratio ◽  
Ambient Air ◽  
Light Sources ◽  
Light Emitting ◽  
Sensitivity Functions ◽  
A Value ◽  
Commercial Instrument ◽  
And Performance ◽  
Comparison Measurements

Abstract. Integrating nephelometers are instruments that directly measure a value close to the light scattering coefficient of airborne particles. Different models of nephelometers have been used for decades for monitoring and research applications. Now, a series of nephelometers (Ecotech models M9003, Aurora 1000 and Aurora 3000) with newly designed light sources based on light emitting diodes are available. This article reports on the design of these integrating nephelometers and a comparison of the Aurora 3000 to another commercial instrument (TSI model 3563) that uses an incandescent lamp. Both instruments are three-wavelength, total and backscatter integrating nephelometers. We present a characterization of the new light source design of the Aurora 3000 and provide parameterizations for its angular sensitivity functions. These parameterizations facilitate to correct for measurement artefacts using Mie-theory. Comparison measurements against the TSI 3563 with laboratory generated white particles and ambient air are shown and discussed. Both instruments agree well within the calibration uncertainties and detection limit for total scattering with differences less than 5%. Differences for backscattering are higher by up to 11%. Highest differences were found for the longest wavelengths, where the signal to noise ratio is lowest. Differences at the blue and green wavelengths are less than 4% and 3%, respectively, for both total and backscattering.

scholarly journals Introduction of the in-orbit test and its performance for the first meteorological imager of the Communication, Ocean, and Meteorological Satellite

2014 ◽  
Vol 7 (8) ◽  
pp. 2471-2485 ◽  
Author(s):  
D. H. Kim ◽  
M. H. Ahn
Keyword(s):  
Signal To Noise Ratio ◽  
Channel Noise ◽  
Test Results ◽  
User Requirement ◽  
Spacecraft Design ◽  
A Value ◽  
Improved Performance ◽  
And Performance ◽  
Shortwave Infrared ◽  
Meteorological Satellite

Abstract. The first geostationary Earth observation satellite of Korea – the Communication, Ocean, and Meteorological Satellite (COMS) – was successfully launched on 27 June 2010. After arrival at its operational orbit, the satellite underwent an in-orbit test (IOT) that lasted for about 8 months. During the IOT period, the main payload for the weather application, the meteorological imager, went through successful tests for demonstrating its function and performance, and the test results are introduced here. The radiometric performance of the meteorological imager (MI) is tested by means of signal-to-noise ratio (SNR) for the visible channel, noise-equivalent differential temperature (NEdT) for the infrared channels, and pixel-to-pixel nonuniformity for both the visible and infrared channels. In the case of the visible channel, the SNR of all eight detectors is obtained using the ground-measured parameters with the background signals obtained in orbit. The overall performance shows a value larger than 26 at 5% albedo, exceeding the user requirement of 10 by a significant margin. Also, the relative variability of detector responsivity among the eight visible channels meets the user requirement, showing values within 10% of the user requirement. For the infrared channels, the NEdT of each detector is well within the user requirement and is comparable with or better than the legacy instruments, except for the water vapor channel, which is slightly noisier than the legacy instruments. The variability of detector responsivity of infrared channels is also below the user requirement, within 40% of the requirement, except for the shortwave infrared channel. The improved performance result is partly due to the stable and low detector temperature obtained due to spacecraft design, i.e., by installing a single solar panel on the opposite side of the MI.

scholarly journals Ambient LED Light Noise Reduction Using Adaptive Differential Equalization in Li-Fi Wireless Link

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1060
Author(s):  
Yong-Yuk Won ◽  
Sang Min Yoon ◽  
Dongsun Seo
Keyword(s):  
Forward Error Correction ◽  
First Generation ◽  
Weighting Function ◽  
Signal To Noise Ratio ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Ambient Light ◽  
Light Emitting ◽  
Reduction Efficiency ◽  
Forward Error

For Li-Fi wireless links based on a white light emitting diode, an adaptive differential equalization (ADE) technique that reduces various noises such as interference noise and shot one generated from ambient light sources is pro-posed. The ADE technique reduces noise by taking advantage of the fact that the derivative between adjacent sampling points of signal with digital waveform is very different from that of noise with the random analog waveform. Furthermore, a weighting function that reflects the Poisson characteristics of shot noise is applied to the ADE technique in order to maximize the reduction efficiency of ambient noise. The signal-to-noise ratio of input non-return-to-zero-on–off keying (NRZ-OOK) signal is improved by 7.5 dB at the first-generation forward error correction (FEC) threshold (the bit error rate (BER) of 8 × 10−5) using the optical wireless experimental link. In addition, it is confirmed that it is possible to maintain the transmission performance corresponding to the BER of 1 × 10−5 by using the proposed ADE technique, even when the intensity of the ambient light source increases by 6 dB.

Synthesis, characterization, and optoelectronic properties of phenothiazine-based organic co-poly-ynes

2021 ◽  
Author(s):  
Idris Al-Busaidi ◽  
A. HAQUE ◽  
Rayya Al Balushi ◽  
Jahangir Ahmad Rather ◽  
Abdul Munam ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Optoelectronic Properties ◽  
Synthesis And Characterization ◽  
Light Emitting ◽  
Polymer Light Emitting Diodes ◽  
And Performance

We present the synthesis and characterization of seven new organic co-poly-ynes P1-P7 incorporating the phenothiazine (PTZ) motif and evaluate their optoelectronic properties and performance in polymer light-emitting diodes and polymer...

Thermal damage evaluation in nickel plate by nonlinear electromagnetic acoustic resonance technique

2020 ◽  
Vol 64 (1-4) ◽  
pp. 835-842
Author(s):  
Weibin Li ◽  
Chang Jiang ◽  
Zifeng Lan ◽  
Mingxi Deng
Keyword(s):  
Thermal Damage ◽  
Signal To Noise Ratio ◽  
Energy Transition ◽  
Ferromagnetic Material ◽  
Acoustic Resonance ◽  
Metallic Structures ◽  
Electromagnetic Acoustic Transducers ◽  
Acoustic Transducers ◽  
And Performance

Nickel and nickel-based composites are of vital importance in many fields, while temperature loading can greatly influence the strength and performance of the materials. Nondestructive evaluation and characterization of such thermal damage can be used to predict the failure of metallic structures, thermal barrier coatings and so on, especially in a non-contact way under certain strict circumstances, such as testing at high temperature or in radiative environment. Herein, a contactless ultrasonic technique employing electromagnetic acoustic transducers (EMATs) combined with the resonance ultrasound spectroscopy is applied to make up the low energy transition efficiency of EMATs and enhance the signal-to-noise ratio of ultrasonic testing signals. The method is adopted to assess the thermal damages of different levels in artificially heat loaded nickel plates. The damage sensitivity of third order harmonics generated from shear waves is discussed, along with linear ultrasonic features including wave velocity and attenuation. Experimental results show that the proposed nonlinear electromagnetic acoustic resonance (EMAR) technique can be used to evaluate the thermal damage in ferromagnetic material with improved reliability and sensitivity over linear ones.

scholarly journals Fiber-coupled light-emitting diodes (LEDs) as safe and convenient light sources for the characterization of optoelectronic devices

2021 ◽  
Vol 1 ◽  
pp. 98
Author(s):  
Jorge Quereda ◽  
Quinghua Zhao ◽  
Enrique Diez ◽  
Riccardo Frisenda ◽  
Andrés Castellanos-Gomez
Keyword(s):  
Electrical Transport ◽  
Light Emitting Diodes ◽  
Low Cost ◽  
Optoelectronic Devices ◽  
Optoelectronic Device ◽  
Light Sources ◽  
Light Emitting ◽  
Figures Of Merit ◽  
Limited Budget

Optoelectronic device characterization requires to probe the electrical transport changes upon illumination with light of different incident powers, wavelengths, and modulation frequencies. This task is typically performed using laser-based or lamp + monochromator-based light sources, that result complex to use and costly to implement. Here, we describe the use of multimode fiber-coupled light-emitting diodes (LEDs) as a simple, low-cost alternative to more conventional light sources, and demonstrate their capabilities by extracting the main figures of merit of optoelectronic devices based on monolayer MoS2, i.e. optical absorption edge, photoresponsivity, response time and detectivity. The described light sources represent an excellent alternative for performing optoelectronic characterization experiments on a limited budget.

Application and characterization of light-emitting diodes for photodynamic inactivation of bacteria

2018 ◽  
Vol 51 (4) ◽  
pp. 612-624 ◽  
Author(s):  
P Ogonowska ◽  
A Woźniak ◽  
MK Pierański ◽  
T Wasylew ◽  
P Kwiek ◽  
...  
Keyword(s):  
Protoporphyrin Ix ◽  
Food Preservation ◽  
Water Disinfection ◽  
Homogeneous Distribution ◽  
Light Sources ◽  
Bacterial Cells ◽  
Light Emitting ◽  
Microbial Infections ◽  
Power Densities

Light- and photosensitizer-based antimicrobial photodynamic therapy (aPDI) is a very promising approach to control microbial infections. Other applications of aPDI are also being studied, for example, in water disinfection or food preservation. Because this technology is based on the use of light, the proper characterization of light sources is of prime importance. The aim of this study was to prepare and characterize three irradiation systems constructed for research purposes. These LED-based light sources produce visible light in the range of blue, green and red wavelengths. The efficacy and light distribution produced by the light sources were verified on a Staphylococcus aureus model sensitized with three photosensitizers: protoporphyrin IX diarginate, N-methylpyrrolidinium fullerene iodide (Full), and rose bengal. Antimicrobial blue light treatment was likewise investigated. The survival of bacterial cells after photoinactivation was determined for irradiance at three power densities. Based on the proper characterization of light emitted by each LED at each point of the illuminated area, a homogeneous distribution of light can be achieved, which is crucial for precise dosimetry.

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