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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 – Temperature Coefficient of SiC UV Photodiodes

von

Stefan Langer, sglux GmbH, Berlin, Germany

SiC Temperature Coefficient

Abstract
This report assigns the temperature coefficient (TC) of sglux SiC-photodiodes in relation to the incident wavelength. It demonstrates that the temperature coefficient is slightly negative for incident wavelengths below 270nm. At appox. 270nm is it almost zero and then strongly rises towards positive values with increasing wavelengths. The report further explains the physical background of this phenomena.

2020 – Where SiC can replace discontinued GaP?

von

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

Technical Report «Where SiC can replace discontinued GaP?»

Abstract
For measurement applications with a peak radiation between 210 nm and 346 nm (e.g. UV sterilization lamp or combustion flame control) a SiC UV photodiode can replace a GaP photodiode without restrictions – it will even output a higher photocurrent. A SiC device irradiated with a peak radiation from 346 to 380 nm will output a lower photocurrent compared with GaP (at same active area). However, if the radiation intensity is high, e.g. curing applications at 365 nm the SiC’s current output will remain at a usable level.

2020 – UV sensors to control UVC surface disinfection

von

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

UV sensors to control UVC surface disinfection

Abstract
Besides chemical treatment, UVC sterilization is applied to disinfect air and tools in hospitals, doctor’s offices, pharmacies as well as food and pharmaceutical production facilities and public washrooms. These applications require measurements of the UV radiation either at its place of generation or at the position of the goods to be disinfected. This procedure is crucial to ensure that a sufficient germ killing UV dose hits the goods. The report presents further details and suitable sensor and radiometer products.

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.

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.

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 – Quantification of harmful UV LED radiation at workplaces

von

G. Hopfenmüller, N. Papathanasiou, T. Weiss,
sglux GmbH, Berlin, Germany

Presentation on International Conference on UV LED Technologies & Applications 2018, Berlin, Germany

Abstract
Artificial UV radiation is applied in many processes such as UV disinfection, UV curing or biological activation. Besides discharge tubes, LEDs are becoming more important for a rising number of applications in particular UV curing or medical treatment. In general, exposure to UV radiation may cause health problems such as skin aging, eye damage or skin cancer. The potential danger varies with the irradiated wavelengths and the exposure time. The limits and the spectral weighting function of the UV irradiance are given in the directive 2006/25/EC published by the European Comission. The hereby submitted lecture will introduce a radiometer that precisely evaluates the hazard potential while displaying the maximum daily exposition time at a certain measurement point. The digital SiC based UV sensor has a spectral responsivity close to the biological weighting function and is calibrated to different UV LEDs with typical half widths. The sensor can be connected to any Android smartphone.