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2020 – UV sensors for hydrogen flame detection

von

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

UV sensors for hydrogen flame detection

Abstract
Pursuing the goal of decarburization of the energy use, the substition of petroleum gas by hydrogen gas produced with renewable energy is a very promising approach.

This requires a certain modification of the heaters. A major change will be the modification of the EN298 compliant flame sensing feature. Currently, sensing petroleum gas flames, electric ionization sensors are used – a rugged, reliable and inexpensive method. However, if hydrogen gas is added to the petroleum gas or if the gas entirely consists of hydrogen these ionization sensors can not be further applied. The reason is a changed reaction kinetics where the ionization effect can not be detected by these conventional sensors. This challenge can be mastered by use of opto-electronic UV sensors. These sensors reliably detect all kind of flames while “seeing” their characteristic emission spectrum in the ultraviolet light range. As UV sensors are more expensive than ionization detectors currently the UV sensors are only applied in highly priced industrial burners but not in household burners. However, according the current state of the knowledge, no other method than opto-electronic UV sensors are able to reliably detect a hydrogen flame.

Since 2006 we produce the TOCONs ABC1 and ABC2 for the EN298 compliant detection of petroleum gas flames in household burners. Our new TOCON_F series is designed for the detection of hydrogen flames.

The difference of the new TOCON_F to the standard ABC1 and ABC2 TOCONs is a reduced off dead-time. This off dead-time occurs with the standard TOCONs when they are saturated and can extend to several 100 milliseconds. The TOCON_F with its logarithmic amplifier shrinks this dead-time to less than 70 milliseconds. Accordingly the reaction time after the flame’s (unwanted) distinction could be strongly increased. Even if the standard TOCONs ABC1 and ABC2 are fast enough (compliant with EN298) to be applied in flame sensing modules (EN298 claims a reaction time of less than 1000 milliseconds) – the requirements of the EN298 standard could be tightened in the future. The reason of this assumption is the significantly higher rate of spread and ignition range of a hydrogen flame compared with a petroleum gas flame. Hence a UV sensor module that works with a TOCON_F offers shorter reaction times than currently required by the standard. This makes these flame sensing modules future-proof in case of a possible revision of the standard.

2020 – Inter-Comparison Campaign of Solar UVR Instruments under Clear Sky Conditions at Reunion Island (21°S, 55°E)

von

Jean-Maurice Cadet¹, Thierry Portafaix¹, Hassan Bencherif¹², Kévin Lamy¹, Colette Brogniez³, Frédérique Auriol³, Jean-Marc Metzger⁴, Louis-Etienne Boudreault⁵, Caradee Yael Wright⁶⁷
¹LACy, Laboratoire de l’Atmosphère et des Cyclones (UMR 8105 CNRS, Université de La Réunion, Météo-France), 97744 Saint-Denis de La Réunion, France.
²School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4041, South Africa.
³Laboratoire d’Optique Atmosphérique, Université Lille, CNRS, UMR 8518, F-59000 Lille, France.
⁴Observatoire des Sciences de l’Univers de la Réunion, UMS 3365, 97744 Saint-Denis de la Réunion, France.
⁵Reuniwatt, 97490 Sainte Clotilde de la réunion, France.
⁶Department of Geography, Geo-informatics and Meteorology, University of Pretoria, Pretoria 0002, South Africa.
⁷Environment and Health Research Unit, South African Medical Research Council, Pretoria 0001, South Africa.

Int J Environ Res Public Health. 2020 Apr 21;17(8):2867. doi: 10.3390/ijerph17082867

Abstract
Measurement of solar ultraviolet radiation (UVR) is important for the assessment of potential beneficial and adverse impacts on the biosphere, plants, animals, and humans. Excess solar UVR exposure in humans is associated with skin carcinogenesis and immunosuppression. Several factors influence solar UVR at the Earth’s surface, such as latitude and cloud cover. Given the potential risks from solar UVR there is a need to measure solar UVR at different locations using effective instrumentation. Various instruments are available to measure solar UVR, but some are expensive and others are not portable, both restrictive variables for exposure assessments. Here, we compared solar UVR sensors commercialized at low or moderate cost to assess their performance and quality of measurements against a high-grade Bentham spectrometer. The inter-comparison campaign took place between March 2018 and February 2019 at Saint-Denis, La Réunion. Instruments evaluated included a Kipp&Zonen UVS-E-T radiometer, a Solar Light UV-Biometer, a SGLux UV-Cosine radiometer, and a Davis radiometer. Cloud fraction was considered using a SkyCamVision all-sky camera and the Tropospheric Ultraviolet Visible radiative transfer model was used to model clear-sky conditions. Overall, there was good reliability between the instruments over time, except for the Davis radiometer, which showed dependence on solar zenith angle. The Solar Light UV-Biometer and the Kipp&Zonen radiometer gave satisfactory results, while the low-cost SGLux radiometer performed better in clear sky conditions. Future studies should investigate temporal drift and stability over time.

2016-2019 – Development of optics, electronics and software for miniaturized UV spectrometer and camera modules

von

Partner: Leibniz Ferdinand Braun Institut für Höchstfrequenztechnik (FBH), Leibniz Institut für Kristallzüchtung (IKZ), sglux GmbH
period: 2016 – 2019
acknowledgements: BMBF 03ZZ0119A

Abstract
This project aims at the development of optics, electronics and software for miniaturized SiC UV spectrometers and camera modules. sglux as the first company worldwide is working on a new product family of Silicon Carbide (SiC) based UV spectrometers (up to 1024 pixel resolution). The advantage of such UV spectrometers results from the extreme radiation hardness and very high visible blindness of SiC compared with Silicon (Si) based UV spectrometers leading to negligible degradation and zero stray light effects caused by visible light. This new spectrometer technology allows precise UV spectrometry also at presence of strong visible light such as UV measurements in the bright sun (e.g. UV Index spectroscopy) or under room light. Another advantage of the SiC UV spectrometer results from the high radiation hardness and low dark current of this material. These features lead to a broader dynamic range of the spectrometer compared with conventional Si based spectrometers. Spectrometers with a 128 pixel resolution are available for evaluation purpose.

2014-2019 – Creation of novel industry-oriented calibration services for radiometric measures at high irradiance levels

von

Partner: Physikalisch-Technische Bundesanstalt in Braunschweig und Berlin (PTB) und sglux GmbH
period: 2014 – 2019

Abstract
Measurement and calibration facilities and calibration methods for high UV irradiation will be established within this project. These methods will accord to the calibration procedures of the Physikalisch-Technische Bundesanstalt (PTB) and will allow sglux to offer novel industry-based calibration services. Hereby the project is focussing on the UV curing industry. Based on results of a corporate BMWi ZIM project, reference radiometers and standard sources with high UV irradiation will be optimized for this application field.

2019 – UV degradation anaylsis of SiC and AlGaN based UV photodiodes

von

Dr. Niklas Papathanasiou, sglux GmbH, Berlin, Germany

SiC AlGaN Aging Report

Abstract
SiC and AlGaN based UV photodiodes had been irradiated by Hg medium pressure lamps for 90 hours and a UV irradiation intensity of 60mW/cm². The SiC photodiodes showed no measurable degradation whereas the AlGaN photodiodes lost 80 % – 85 % of sensitivity.

2018 – UV measurements for medical applications using SiC photodiodes

von

Dr. Niklas Papathanasiou, Gabriel Hopfenmueller, Dr. Tilman Weiss
sglux GmbH, Berlin, Germany

Presentation on IoT-SNAP2018: IoT Enabling Sensing/Network/AI and Photonics Conference at
Optics & Photonics Intenational Congress OPIC 2018, Pacifico Yokohama, Yokohama, Japan

Abstract
In this contribution we report about SiC based UV photodiodes as the core component of smart UV sensors for various medical applications. In dialysis machines the transparency of urea is monitored by a SiC UV photodiode based UV transmission measurement module. A photodiode combined with an optical filter which reproduces the erythermal action spectrum helps Lupus patients to monitor their daily dose of solar UV radiation. sglux UVC sensor “UV-Safester” is a smartphone based tool to detect harmful UV radiation at a workplace employing the ICNIRP regulation. A wireless UV sensor module monitors the UV disinfection applied by disinfection robots in operating rooms.

2018 – A new instrument for the hazard assessment of UV radiation

von

Stefan Langer¹, Dr. Niklas Papathanasiou¹, Johanna Luise Krueger², Gabriel Hopfenmueller¹, Dr. Tilman Weiss¹
¹sglux GmbH, Berlin, Germany, ²University of Freiberg, Germany

50th Annual Conference of the Radiation Protection Association 2018, Dresden, Germany
Download article (noch nicht veröffentlicht)
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Abstract
Industrial application of ultraviolet radiation requires not only the evaluation of the effectiveness for the desired process but also an assessment of hazards for the operating personnel. Therefore rules and regulations have been established for the assessment and limitation of health-related threats. A variety of instruments are available on the market for this kind of risk assessment. These devices measure the radiation weighted according to applicable regulatory standards. But the final appraisal of risks such as maximum tolerable exposure time must still be computed manually afterwards.
The new approach presented here is based on a sensor with a spectral response characteristic tailored to a specific regulatory standard. This sensor is connected to a smart-phone. An application on the smart-phone will present the measurement value but also the maximum allowed exposure time in a graphical and acoustical manner. Each radiation source or regulatory guideline requires a specific sensor characteristic for an accurate risk assessment. Therefore the system extensively checks the requirements regarding the suitability of the connected sensor for the selected regulatory norm. These measures reduce the effort and the failure rate and also lower the burden for risk assessment in daily operation.

2017-2018 – A comparison of measurement uncertainty of solar UV-Index values obtained by spectroradiometers and radiometers

von

Partner: Universiät Freiberg und sglux GmbH
period: 2017 – 2018

Abstract
The UV-Index according to ISO 17166 is a measure of the risk of sunburn (erythema solare) at a given solar irradiance. Governmental meteorological institutes measure the UV-Index with spectroradiometers. Due to high investment and maintenance costs of these spectroradiometers, the use of small, rugged and low maintenance UV-Index-Radiometers should be a matter of evaluation, in particular when meteorological networks are planned to be extended.
To evaluate the performance these UV-Index-Radiometers, basically the measurement uncertainty needs to be investigated and compared with the measurement uncertainty obtained by spectroradiometers. Egli et al.¹ report the typical UV-Index-spectrometer measurement uncertainty with ± 5 %. To investigate the measurement uncertainty of UV- Index-Radiometers, a bundle of 2073 different sun spectra with a range from UVI 0.5 until UVI 13.5 was used. They were traceably obtained at different places at the earth where the solar situation was influenced by latitude, altitude, season and daytime. Using the formula reported by ISO 17166 the UV-Index was calculated for each of the different sun spectra. Subsequently spectral responsivity curve of seven different UV-Index-Radiometers (manufactured by sglux GmbH) was integrated with the 2073 different sun spectra (according to ISO 17166) and in total 14,511 different UV-Indices were calculated. The differences of spectral responsivity of the seven candidates result from inevitable production tolerances of the UV-Index-Radiometers. These 14,511 different UV-Indices obtained by the UV-Index- Radiometer were compared with the related UV-Indices calculated by the formula stated in ISO 17166.
As a result we could demonstrate that the spectral responsivity variance of the seven different UV-Index-Radiometers did not result a measurable influence on the measurement uncertainty. However, we saw an influence caused by the different sun spectra. In particular at extremely low UV-Indices of below 0.5 the measurement uncertainty increased. We saw that this measurement uncertainty follows a definable rule which allowed us to develop a gain matrix programmable into the radiometer’s firmware. After applying of this matrix the measurement uncertainty could be reduced down to ± 5 %, also for extremely low UV-Index values.
Accordingly, the study shows that the measurement uncertainty of the sglux UV-Index- radiometers is at the same level as reported from UV-Index-spectroradiometers. This result encourages to expand the investigation into the area of the UV-Index-Radiometers field of view (FOV). The ISO 17166 standard claims a FOV close to the cosine curve. If this FOV investigation would also result good results compared with UV-Index-Spectrometers one may regard the UV-Index-Radiometers as a reliable completion or even substitution of the spectroradiometers. This would create new opportunities to measure the UV-Index in regions where skilled personnel needed to maintain the spectroradiometers is not available.

¹Egli et al. Quality assessment of solar UV irradiance measured with array spectroradiometers, Atmos. Meas. Tech., 9, 1553–1567, 2016

2018 – UV Index measurements with SiC-based radiometers

von

Johanna Luise Krueger², Dr. Niklas Papathanasiou¹, Stefan Langer¹, Gabriel Hopfenmueller¹, Dr. Tilman Weiss¹
¹sglux GmbH, Berlin, Germany, ²University of Freiberg, Germany

50th Annual Conference of the Radiation Protection Association 2018, Dresden, Germany

Abstract
Environmental data are collected to improve health-related quality of life of citizens. The solar UV-Index provides a good indicator for reasonable sun protection measures and duration of sun light exposure for safety officers and individuals. In Germany the “Bundesamt für Strahlenschutz” manages a solar UV-measurement network to monitor the UV-Index. At ten sites distributed all over Germany spectroradiometers are operated to measure the solar spectrum. The spectroradiometers are expensive and need highly qualified personnel to be operated. Robust and low-maintenance SiC-based UV-Index-radiometers are a viable option to increase the density of this measurement network at low cost. The spectral sensitivity function of such UV-Index-radiometers must reproduce the erythemal action function according to ISO 17166 with high precision.
In this contribution we investigate the effect of production tolerances in the spectral response of SiC-based UV-Index-radiometer (SiC-UVI-radiometer) onto the precision of the measured UV-Index. This is performed by folding a large number of different sun spectra with a variety of spectral responses of actual SiC-UVI-radiometer and the erythemal action curve as defined in the ISO 17166. We can show that the measurement uncertainty of SiC-based UVI-radiometers is ±5 % and therefore in the range of spectroradiometers. We simulated UVI measurements for SiC-based UVI-radiometers with over 2000 different sun spectra and determined a discrepancy-correction-function, which allows a precise UVI-measurement.