DEVELOPMENT OF PHOTOBIOLOGICAL SAFETY STANDARDS AND MEASUREMENTS FOR LED PRODUCTS
Tongsheng Mou
Abstract:
Photobiological safety related to LED products is currently being addressed in IEC 62471-2006 / CIES009/E：2002. High-power LEDs with attached output optics generally have complex beam profiles. The measurements of weighted radiance and irradiance for maximal exposure related to photobiological safety classification of LED optical radiation are very different from those of traditional luminance/illuminance, and are not tractable yet to any national laboratories. The main features include, a. Photobiological response weighted, e. g. by BLH spectral function b. Field of view related to the exposure duration c. Incidence aperture as eye’s pupil d. Accessible maximal exposure e. Focusing on the apparent sources, not true sources The retinal hazard caused by LED optical radiation is a considerable dominant effect, which includes thermal burn and photochemically induced retinal injury. For white LEDs based on blue LED chips and yellow phosphor, the main hazard is the photochemical retinal injury caused by blue radiation of high color temperature, high luminance area of LED products. The hazard functions for both thermal and photochemical hazard assessment and the spectral response V(λ) of photopic vision are entirely different. Thus it is necessary to determine the spectral radiance of LED from 300 nm to 1400 nm, whose spectral range is wider than that of normal commercial instruments, and the measurement shall be in accordance with the optical hazard principle to human eyes.
