Accurate channel-resolved spectral characterization of LED arrays based on phase-sensitive detection

Abstract

With the increasing integration of multi-wavelength chips and intelligent control technologies, light-emitting diode (LED) arrays have become widely adopted in advanced lighting and display systems. However, accurately characterizing the spectral contribution of individual LEDs under actual operating conditions remains a significant challenge due to photothermal coupling, and the limitations of conventional measurement approaches that rely on single-channel activation or physical masking. In this study, we present a spectral measurement method for LED arrays based on phase-sensitive detection, in which unique modulation signals are assigned to each LED and lock-in amplification is used to extract channel-resolved spectra while all LEDs are operating simultaneously. This enables spectral decomposition under real operating conditions and supports the construction of a nonlinear spectral synthesis model that accounts for photothermal interactions. The model achieves a spectral optical power prediction error below 1.2 %. Furthermore, by incorporating Grassmann’s color matching law and constraining the Standard Deviation of Color Matching (SDCM), optimal duty cycles can be determined to ensure chromatic stability. As a representative application, we demonstrate several lighting scenes—relaxation, working, and low-blue-light—using an RGBW LED module, achieving a wide correlated color temperature range (2500–6500 K), adjustable luminous flux (20–140 lm), high color rendering index (CRI), and low blue light hazard energy (BLHE). This work offers a robust system for spectral measurement, modeling, and precise control of LED arrays, with broad applicability in intelligent lighting and spectral calibration systems.