Measuring the low divergent luminous flux emitted by LED torch lamps using a simple detector and a spectrometer as an alternative to an integrating sphere

The widespread use of light emitting diodes (LEDs) in various applications has necessitated accurate measurement of their photometric parameters, particularly luminous flux. While traditional methods employing integrating spheres offer precise measurements, simpler and often cheaper techniques utilizing radiometric detectors and spectrometers present viable alternatives, especially for directional emissions. This article presents a comprehensive methodology for measuring luminous flux using a simple detector and a spectrometer, discussing equipment calibration, uncertainty analysis, and validation of the described method. The study delves into the intricacies of detector and spectrometer calibration, offering insights for traceability to a known reference standard in lumen measurement practices. Additionally, the article addresses uncertainties associated with luminous flux calculations and validates the proposed method against measurements from an independent laboratory. Limitations such as spectral response variations and temperature effects on measurements are mentioned. Moreover the article encompasses formula derivations and calculations, empowering readers to create and validate their own computation tools.