Total radiant flux measurement of UV LEDs using a gonio-spectroradiometer

Abstract Reliable measurement of the total radiant flux of ultraviolet light-emitting diodes (UV LEDs) is essential for performance evaluation but remains challenging. We report an SI-traceable gonio-spectroradiometer developed at KRISS to measure UV LEDs across 250 nm–500 nm. The system integrates a double-grating spectroradiometer with a goniometer, effectively suppressing spectral stray light and fluorescence that affect integrating-sphere methods. Total radiant flux values of 119 mW, 164 mW, and 176 mW were obtained for LEDs with nominal peaks at 279, 368, and 410 nm, with expanded uncertainties of 1.6%–2.6% ( k = 2). Results agreed with integrating-sphere measurements within uncertainties, while demonstrating superior accuracy for UV sources. This work establishes a traceable and robust method for UV LED flux measurement, supporting standardization in research and industry.