led & eye safety

What about a candle?

John

Reply to
John Larkin
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The class definition is for lasers. LED sources are generally safe because they can be shut off in time by the blink reflex. An exception is for radiation outside the visual bandwidth.

Reply to
rrllff

It is the power density that is the thing that is important. A laser has a very high power density as the beam is not spread out like a LED or incadesent source is.

-- Why isn't there an Ozone Hole at the NORTH Pole?

Reply to
Bob May

I answered this ozone problem previously.

It is the unstable wind patterns in the northern hemisphere due to the assymetrical land masses that clears away any stable layers required for an ozone hole to persist. However, if polutants continue to increase, a semi stable hole will appear in the north. There is already some evidence of this.

Reply to
rrllff

Which appears to be ol' Sol playing tricks rather than hairspray. Better get him to clean up his act!

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--
  Keith
Reply to
Keith Williams

The sun should simply be banned!

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Christopher R. Carlen
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Reply to
Chris Carlen

And here are some claims (published in New Scientist) that hydroelectric power can more greenhouse gases than burning fossil fuels.

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Best regards, Spehro Pefhany

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"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
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Reply to
Spehro Pefhany

EN60825-1 is a bit of a quagmire (to me anyway).

For a class1 device I believe that no label is required to be fixed to the product but in the instructions and/or manual there should (must?) be a reference to it being class 1.

Is this correct?

Does this mean that, say, a simple torch (with a 1W incandescent lamp - way way below the limits of class1) needs to be referred to as class 1 in its instructions? What if there are no instructions? Must there be some just for somewhere to write class 1 ?

Reply to
R.Lewis

That's what Ray-Bans are for!

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
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Reply to
Spehro Pefhany

I read in sci.electronics.design that Bob May wrote (in ) about 'led & eye safety', on Thu, 3 Mar 2005:

I'm not sure that there isn't, but basically the temperatures in the upper atmosphere are not right.

--
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
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Reply to
John Woodgate

No. The class definition is for lasers *and* leds.

(note that 608325 is not for incandescent lamps so please read '1 lumen led' for '1W incandescent lamp' in my original post.)

Reply to
R.Lewis

Many incandescent lamps exceed Class 1 (.4 microwatt in the

400-1500 nm band being able to enter a pupil 7 mm wide and be focused onto a spot on the retina of angular size smaller than .0002 steradian will exceed Class I if I correctly read and understand 21 CFR 1040.1)

In the USA, the regulation by the Center for Devices and Radiological Health that defines these classes does not have regulatory force on light sources other than lasers, including not on incandescent lamps nor LEDs if I understand correctly. In addition, Class 1 does not require a label even for lasers if I read and understood 21 CFR 1040.1 correctly.

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

It's not the speed of light that matters it's the illumination value on the retina. A laser is a point source which creates a diffraction pattern of very high illumination on the retina. An LED is an extended source which does not.

Reply to
rrllff

In any safety document you have to watch your shoulds and shalls. "Shall" means you must. "Should" means it is a good idea if you do this. To quote from the 60825-1 manual section 5.2

Class 1 Each class 1 laser product SHALL have affixed an explanatory label (figure 15) bearing the words: CLASS 1 LASER PRODUCT or instead, at the discretion of the manufacturer, the same statement may be included in the information for the user.

--end quote--

To interpret this means you MUST either put a label on the device or include the same verbiage as the label in the user manual.

60825-1 is for Lasers 60825-2 is for optical comm systems that include LEDs or lasers

Neither document covers incandescent illumination. Hazard calculations are based on power per unit area per unit time and are wavelength dependent. Do NOT do these calculations unless you fully understand them. If you miscalculate in the wrong direction you could loose an eye.

Best Regards, P. Danek

D> >

Reply to
danek

Last time i checked, the "blink reflex" was a tad slower than LED light. Also, LED light travels just as fast as laser light?

Reply to
keith

AIUI the point is that LEDs have a much smaller source than any other non-LASER light source, and so are approaching luminance levels otherwise seen only in LASERs.

IMBW...

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If not himself / Then not a lot"
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Reply to
Simon Waldman

And one should note that it isn't the fact that laser light is coherent that is the danger. It's that being coherent and appearing to originate from a point source, this allows collimation and focusing options not possible (or extremely difficult) with conventional light sources.

As the size of the emitter gets smaller, the risks approach those of a laser if the beam is collimated or focused.

If it were possible to build an LED or arc lamp with an infinitesimal source size, then the dangers would be similar.

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Reply to
Sam Goldwasser

Such as? Actually all light is partially coherent - it is only the amount of coherence that differs. (Sure to start a flame war I'm afraid.)

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Vic Roberts
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Reply to
Victor Roberts

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