Optical radiation hazard analysis of active lighting units in video surveillance systems

Abstract

Photobiological safety experiments of two typical active lighting units in video surveillance systems, white LED lamp and Xenon lamp, are performed according to the photobiological safety requirements (GB/T 37958 and IEC 62471). The white LED lamp working in stroboscopic mode is in low risk level, while the lamp working in pulse mode shows moderate risk, due to the reason that the radiation energies release in a short time range (~2 ms). The spectrum is located in the visible region with the correlated color temperature (CCT) of ~4000 K and the retinal blue light hazard and the retinal thermal hazard are the dominant mechanisms. The Xenon lamp shows high risk level with an ultra-wide spectrum, of which the pulse duration is ~1 ms and CCT is up to ~22400 K. Thus, six types of hazards all can be generated, where the photochemical ultraviolet hazard E S , near-ultraviolet hazard E UVA and retinal thermal hazard L R exceed moderate risk level and E S is nearly two orders of magnitude larger than the emission limit. When the input power of Xenon lamp is turned down, CCT decreases to ~6000 K. The lamp is in low risk level, and the photochemical ultraviolet hazard E S is too weak to be detected. Therefore, Xenon lamps of high CCT and white LED lamps in pulse mode should be used cautiously in video surveillance systems to avoid possible injury. White LED lamps in stroboscopic mode and Xenon lamps of low CCT can be a priority to apply in video surveillance systems.