Re: led as illuminator


"Kevin Cunningham" <smskjv@xxxxxxxxxxxxxx> wrote in message
news:yX_5h.6183$L6.1462@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Are you sure this would be classed as a laser? LED's usually are
classed with light bulbs even if they emitt one color. Lasers work
completely differently and a 7 watt laser is kinda big.

Not for optical characteristics but for safety purposes; warnings on
class 1 and 2 lasers are present in the design guide of my led:
http://www.lumen.com.ua/files/custom.pdf
About the led's classification from an eye's safety point of view, I
read things are still confused:
From a photobiological safety standpoint, the spectral characteristics,
radiance and apparent source size of the LED are all important. Apparent
source size dictates the size of the light patch on the retina after it
has travelled through the light focussing parts of the eye. In safety
standards LEDs have been treated both as lasers, IEC 60825-1 and as
lamps CIE S 009/E:2002 "Photobiological Safety of Lamps and Lamp
Systems". This has caused some confusion relating to the actual risk on
the part of both customers and, more importantly, manufacturers.
Measurement errors add to the confusion as LEDs sources often have some
form of lens incorporated, and this means that the "apparent source
size" or "optical size" is not the same as the actual physical size of
the LED chip or "die". Both standards for LEDs mentioned above require
consideration of apparent source size, and NPL has carried out research
for the UK Health and Safety Executive in order to develop a method of
measuring this. If, as expected, LEDs are removed from IEC 60825-1 and
moved to CIE S 009, which has been submitted to the IEC to allow it to
become a joint IEC/CIE standard, it will make the issue of LED safety
clearer. This will also impact on compliance for European conformity CE
marking, though it must be noted that this has often not been rigorously
followed by manufacturers to date. Also on the horizon is the EC
physical agents, (optical radiation), directive "on the minimum health
and safety requirements regarding the exposure of workers to the risks
arising from physical agents (optical radiation)". This so-called
"sunshine directive" deals with risks arising from exposure to optical
radiation, and may have an impact on some LED applications. It is set to
be incorporated into European law by 2010, and will perhaps benefit from
the clarification of LED safety requirements discussed above, but those
responsible for its enforcement will need to keep pace with ongoing
developments of LEDs.
http://www.photonicscluster-uk.org/pdf/LED_Future_Brochure.pdf




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