Stability of light-emitting diodes in the solar UV spectral range

Nowy, Stefan; Nevas, Saulius; Lopez, M.; Lindemann, Matthias; Sperling, Armin; Blattner, Peter; Foaleng, Stella M.

doi:10.1063/1.4804899

Cited by 1 publication

(2 citation statements)

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“…In the beginning of these studies, the nine-element UV-LED emitter was attached to a port of a PTFE-based integrating sphere with a diameter of 50 mm as the sphere was planned to be used as part of the UV-LED source. The emphasis was to study the behaviour of the chips in the multielement unit as from the earlier studies it was known that the change rate of the UV-LED output depends on its design wavelength and total operation time [5]. The radiometric output of the UV-LEDs was monitored by a CAS-140CT array spectroradiometer from Instrument Systems.…”

Section: Ageing Of the Uv-ledsmentioning

confidence: 99%

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LED-based UV source for monitoring spectroradiometer properties

et al. 2018

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A compact and stable UV monitoring source based on state-of-the-art commercially available ultraviolet light emitting diodes (UV-LEDs) has been developed. It is designed to trace the radiometric stability-both responsivity and wavelength scale-of array spectroradiometers measuring direct solar irradiance in the wavelength range between 300 nm and 400 nm. The spectral irradiance stability of the UV-LED-based light source observed in the laboratory after seasoning (burning-in) the individual LEDs was better than 0.3% over a 12 h period of continuous operation. The integral irradiance measurements of the source over a period of several months, where the UV-LED source was not operated continuously between the measurements, showed stability within 0.3%. In-field measurements of the source with an array spectroradiometer indicated the stability of the source to be within the standard uncertainty of the spectroradiometer calibration, which was within 1% to 2%.

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Section: Ageing Of the Uv-ledsmentioning

confidence: 99%

“…The ageing properties of the single LEDs with nominal peak wavelengths of 365 nm, 375 nm, and 400 nm (measured peaks at 371 nm, 374 nm, and 402 nm, respectively) are shown in section 3.4. Based on the previous studies [5], these LEDs were expected to have a short burn-in time to reach steady drift values.…”

Section: Ageing Of the Uv-ledsmentioning

confidence: 99%