Characterising and Testing Deep UV LEDs for Use in Space Applications

TL;DR

This paper evaluates the performance and robustness of commercial deep UV LEDs for space applications, focusing on their electrical, optical, and environmental stability to replace traditional mercury lamps in gravitational experiments.

Contribution

It provides a comprehensive testing campaign of UV LEDs, demonstrating their potential as reliable, space-qualified light sources for future gravitational-wave observatories.

Findings

UV LEDs show stable spectral output under various conditions

They withstand thermal vacuum, radiation, and vibration tests

Performance metrics meet requirements for space applications

Abstract

Deep ultraviolet (DUV) light sources are used to neutralise isolated test masses in highly sensitive space-based gravitational experiments. An example is the LISA Pathfinder charge management system, which uses low-pressure mercury lamps. A future gravitational-wave observatory such as eLISA will use UV light-emitting diodes (UV LEDs), which offer numerous advantages over traditional discharge lamps. Such devices have limited space heritage but are are now available from a number of commercial suppliers. Here we report on a test campaign that was carried out to quantify the general properties of three types of commercially available UV LEDs and demonstrate their suitability for use in space. Testing included general electrical and UV output measurements, spectral stability, pulsed performance, temperature dependence as well as thermal vacuum, radiation and vibration survivability.