IN THE SAFETY LIMBO: SIMULTANEOUS ILLUMINATION AND OPTICAL WIRELESS COMMUNICATIONS WITH LIGHT-EMITTING DIODES

摘要

The high-speed modulation capabilities of white light-emitting diodes (LEDs) offer a unique combination of illumination and simultaneous free-room data transmission, and therewith enable a range of novel and promising applications. However, the optical radiation safety requirements for this dual use of LEDs are currently provided by two standards: free-space optical communication with LEDs is still covered by the application-related part of the laser-safety series, IEC 60825-12, whereas almost all other applications of LEDs, including lighting, are since 2006 covered by the lamp safety standard IEC 62471. Primarily, due to big differences in the underlying safety philosophies, the application by both standards to the same source results in noticeably different assessments and usage regulations. Hereby, the laser-related requirements are most restrictive. However, there is no added hazard for a lamp due to high-speed modulation that happens to convey data. A simple exclusion of LEDs from the scope of IEC 60825-12 would help but not really solve the situation, since the lamp standard does not yet provide adequate assessment criteria for pulsed sources. This contribution addresses this apparent safety limbo and recommends a resolution of this paradoxical situation through a revision of the lamp safety standard. Such a revision would include porting the pulse criteria of IEC 60825-1 into the lamp safety standard IEC 62471, and providing guidance to devisers of LED-based optical wireless links by publishing a vertical extension to IEC 62471 in the spirit of IEC 62471.