Press release submitted on behalf of Gigahertz-Optik and Vektrex.
Gigahertz-Optik, Amesbury, Massachusetts, and Vektrex, San Diego, California, have collaborated on a joint instrumentation for a Differential Continuous Pulse (DCP) test station. The DCP test station includes Gigahertz-Optik’s TV-UV10 fluorescence-free Integrating Sphere Spectroradiometer and Vektrex’s pulsed SMU Source/Measure Unit with the DCP method of measurement implemented in supplied application software or as a Python tool.
The test station meets the requirement for testing UV-A, UV-B, and UV-C LEDs with short pulses. In fact, the Vektrex SMU was used extensively in research that led to the development of the ANSI/IES UV-LED Measurement standard, LM-92-22 and currently ongoing CIE TC2-91.
LM-92-22 specifies pulses of 10 µs and 20 µs, and the DCP test method. The fast µs pulse currents are produced by the SMU, captured by the TVUV10’s100 mm fluorescence-free integrating sphere (25.4mm aperture) and measured by its fast UV optimized spectroradiometer BTS2048. Despite its compact size the BTS2048 features a BiTec Sensor with back-thinned TE cooled CCD (2048 pixels, 0.8 nm optical resolution, electronic shutter) and SiC photodiode.
The current is swept automatically within the desired range and the full scan done within seconds to minutes and is run either with a Python script or in the S-BTS2048 application software.
The DCP method’s minimal heating keeps the LED junction close to the external ambient temperature, eliminating the need to calculate temperature shift, making DCP a natural choice for UV LEDs.
IES LM-92 presents the DCP technique in detail, including tables that provide specific requirements for the pulse widths to be used for various current levels. The standard also details techniques for determining the correct forward voltage (necessary when plotting I-V curves) when the transient voltage effect is present.
Note that a peculiarity of quasi monochromatic LED optical radiation must be considered when designing integrating sphere spectroradiometers for UV LEDs. The monochromatic UV radiation of the LED causes fluorescence of the integrating sphere coating which leads to significant measurement errors that cannot be compensated by conventional correction methods. This DCP test system is based on the know-how of our fluorescence-free TVUV10 UV LED measurement system.
Gigahertz-Optik’s ISO/IEC/EN 17025 optical radiation calibration and test laboratory provides traceable calibration of the TFUV10-V01 system. Unaccredited factory level calibrations are handled in the calibration laboratory using the same quality management procedure which applies to NMI accredited test measurements. NMI accredited testing measurements with an ISO/IEC/EN 17025 testing certificate are optionally available. Optional calibration standards for the DCP test station for recalibration by the user are also available.
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