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2024 Digital UV Sensors – The Smartphone becomes a Radiometer

von

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

Abstract

Sensor Magazin 4/2024 (c) Magazin Verlag

UV radiation is used in many areas of industrial production, in medical devices and for disinfection. Precise measurement of irradiance is important for the controlled and efficient use of UV radiation. The UV measuring devices used for these applications must be able to measure the UV irradiance reliably, reproducibly and traceably over 13 orders of magnitude, from a few pW/cm2 up to 10 W/cm2. This is where digital measuring probes show their strengths.

2021 – TOCONs with reduced dead times used for the detection of fire and combustion burner flames

von

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

TOCONs for the detection of fire and combustion burner flames

Abstract
The standard sglux TOCONs are featured by a relatively high time constant that extends from 30 ms (low sensitivity TOCONs) until 80 ms (high sensitivity TOCONs). Most of the TOCON applications benefit from this high time constant because usually the TOCON’s application is to measure a UV irradiation that slowly changes. Such applications are e.g. the control of UV disinfection and UV curing sources. Short changes of signal caused by electromagnetic or high frequency influences are averaged – which is a benefit. However, looking at flame detection in heaters or looking at fire detection applications this relatively high time constant may cause problems. The present report presents opportunities to reduce the dead time of the TOCONs.

2021 – Sensing ultraviolet light emission from hydrogen flames: Flame detection and flame monitoring in CO2 emission free domestic boilers

von

Bielefeld, S.E., TU Delft Electrical Engineering, Mathematics and Computer Science


Master Thesis

Abstract
As a contribution to the decarbonisation of domestic heating, the graduation project investigates the feasibility of the application of UV sensor technology for flame detection and flame monitoring in hydrogen-powered domestic gas boilers. The research includes empirical studies and an analytical approach to describe influences on the sensor signal strength.

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 – 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.

2012 – Highly reliable Silicon Carbide photodiodes for visible-blind ultraviolet detector applications

von

D. Prasai¹, W. John¹, L. Weixelbaum¹, O. Krueger¹, G. Wagner², P. Sperfeld³, S. Nowy³, D. Friedrich³, S. Winter³ and T. Weiss⁴,
¹Ferdinand-Braun-Institut, Leibniz-Institut fuer Hoechstfrequenztechnik, Berlin, Germany, ²Leibniz-Institut fuer Kristallzuechtung, Berlin, Germany, ³Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ⁴sglux GmbH, Berlin, Germany

J. Mater. Res., first view (2012).

Abstract
Highly efficient polytype 4H silicon carbide (4H-SiC) p–n diodes for ultraviolet (UV) light detection have been fabricated, characterized, and exposed to high-intensity mercury lamp irradiation (up to 17 mW/cm²). The behavior of the photocurrent response under UV light irradiation using a low-pressure mercury UV-C lamp (4 mW/cm²) and a medium-pressure mercury discharge lamp (17 mW/cm²) has been studied. We report on long-term UV photoaging tests performed for up to 22 mo. Results demonstrate the robustness of SiC photodiodes against UV radiation. The devices under test showed an initial burn-in effect, i.e., the photocurrent response dropped by less than 5% within the first 40 h of artificial UV aging. Such burn-in effect under UV stress was also observed for previously available polytype 6H silicon carbide (6H–SiC) p–n photodetectors. After burn-in, no measurable degradation has been detected, which makes the devices excellent candidates for high irradiance UV detector applications.