An informative presentation explaining stray light as a significant error source in UV array spectroradiometers and minimization correction methods was presented by Mike Clark of Gigahertz-Optik GmbH at the recent UV LED Technologies & Applications Conference (ICULTA) in Berlin, Germany.
Topics included definitions/illustrations of an array type and double monochromator spectroradiometer, stray light, its causes and significance for UV measurement, suppression techniques through optical design, mathematical correction based on signal distribution function (SDF) characterization matrix using a tunable laser, and long pass plus bandpass filtering with associated limitations. The implementation of stray light suppression techniques into the spectroradiometer, subsequent characterization, actual on-site testing and consequences for UV LED measurement were also main topics.
The limiting factor for the use of array-based spectroradiometers in the UV spectral region has been their inadequate stray light suppression. Therefore, many UV applications could previously only be implemented with double monochromators. Such systems are inconveniently large and slow due to their mechanical scanning. Typically, they require complex installation and operation.
The innovative BTS2048-UV-S instrument series is able to demonstrate the necessary quality for UV spectroradiometry thanks to its filter-based scattered light suppression of several orders of magnitude and its DAkkS traceable calibration.
Additionally, it offers much shorter measurement times (a few seconds compared to many minutes), lower energy consumption, a considerably smaller design and a weather-proof enclosure for field applications.
The system is well suited for solar UV and ozone measurements, for instance. Other typical applications include radiation risk assessment in occupational safety and the measurement of UV LEDs.