Hi All, Thanks to everyone who pointed me in the right direction earlier when I asked about maximum exposure limits for LEDs. Having now read through IEC 825-1, I am a little confused about the definitions of a maximum permissible exposure (MPE) with respect to an LED.
IEC states in the foreword of the standard that the word LED is included wherever the word laser is throughout 825-1. When calculating the MPE for LEDs, I am not sure whether the duration of exposure (t) pertains to the complete duration of usage or to the length of the pulse. Specifically, in a medical application, if two wavelengths of LEDs are activated alternately at a high frequency and are incident upon the skin, does length of exposure describe the period of each pulse for each LED, or the total duration over which the device is used? My calculations for MPE seem quite high when assuming the former, so does anyone out there have information that could clarify this? Much appreciated, S. George _________________________________________________________________________Sha wn George Biomedical Engineer Lightwave Medical Industries 2660 Oak St., Vancouver, BC Canada V6H 3Z6 Tel 604-875-5329 fax 604-875-5390 e-mail [email protected]
