LEDs and eye safety

[R.Lewis]

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How are white leds quantified with regard to eye safety standards?
60825 does not appear applicable as it stands - is there some other
applicable standard?




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[John Woodgate]

I read in sci.electronics.design that R.Lewis <[email protected]>

How are white leds quantified with regard to eye safety standards?
60825 does not appear applicable as it stands

In what way is it not applicable?

- is there some other applicable standard?

No, 60825 is meant to be THE one, AFAIK. But there are many parts and
amendments. If you go to the public part of the IEC web site, at:

http://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?wwwlang=e&wwwprog=TCpubs
..p&progdb=db1&committee=TC&number=76

there is quite a bit of information available if you click on each
standard number and read the resulting page. For some of the standards
(but not IEC 60825-1 for some reason), there is an extensive preview
available free of charge.

I would have expected that the diffuse emission from the phosphor of a
white LED would not be anywhere near as hazardous as the intense
emission from a monochrome LED.

 

[John Larkin]

I read in sci.electronics.design that R.Lewis <[email protected]>


In what way is it not applicable?


No, 60825 is meant to be THE one, AFAIK. But there are many parts and
amendments. If you go to the public part of the IEC web site, at:

http://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?wwwlang=e&wwwprog=TCpubs
.p&progdb=db1&committee=TC&number=76

there is quite a bit of information available if you click on each
standard number and read the resulting page. For some of the standards
(but not IEC 60825-1 for some reason), there is an extensive preview
available free of charge.

I would have expected that the diffuse emission from the phosphor of a
white LED would not be anywhere near as hazardous as the intense
emission from a monochrome LED.

Are any visible-wavelength LEDs eye hazards?

John

 

[John Woodgate]

I read in sci.electronics.design that John Larkin

Are any visible-wavelength LEDs eye hazards?

IEC TC76 thinks so, and since they write the standard....

Seriously, if you have a narrow-angle bright LED and put it up close to
your eye, but no so close that the image isn't focused, there could be a
problem. So you have to be able to prove that there ISN'T a problem with
that there LED on your product.

When first introduced, the requirements for LEDs were (either really or
apparently) very stringent - the same as for lasers. Since then, there
has been a lot of review and explanation. You can see the long list of
amendments, revisions and explanatory documents on the web page whose
sesquipedalian URL I posted.

 

[John Fields]

Are any visible-wavelength LEDs eye hazards?

 

[martin griffith]

On Sun, 2 Oct 2005 21:32:13 +0100, in sci.electronics.design John

sesquipedalian

Word of the Day for Monday October 25, 1999

sesquipedalian \ses-kwi-pi-DAYL-yun\, adjective:
1. Given to the overuse of long words; "sesquipedalian orators"
2. (Of words) long and ponderous; having many syllables; as,
"sesquipedalian technical terms"
--sesquipedalian, noun:
A very long word (a foot and a half long)

llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch


martin

 

[Spehro Pefhany]

On Sun, 2 Oct 2005 21:32:13 +0100, the renowned John Woodgate

You can see the long list of
amendments, revisions and explanatory documents on the web page whose
sesquipedalian URL I posted.

Ah, the Long Dong Silver of URLs.


Best regards,
Spehro Pefhany

 

[Pooh Bear]

On Sun, 2 Oct 2005 21:32:13 +0100, in sci.electronics.design John

sesquipedalian

Word of the Day for Monday October 25, 1999

sesquipedalian \ses-kwi-pi-DAYL-yun\, adjective:
1. Given to the overuse of long words; "sesquipedalian orators"
2. (Of words) long and ponderous; having many syllables; as,
"sesquipedalian technical terms"
--sesquipedalian, noun:
A very long word (a foot and a half long)

llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch

martin

Floccinaucinihilipilifaction to you Sir !

Graham

 

[martin griffith]

Floccinaucinihilipilifaction to you Sir !

Graham

Search
From Wikipedia, the free encyclopedia.
You searched for "Floccinaucinihilipilifaction " [Index]
Results 1-1 of 1

*


Relevancy: 0.0% - -

hmmmmmmm. +-3dB maybe, or -1 Boki


martin

 

[John Larkin]

---
Sure.

I don't have a part number in front of me, but some of the LASER
diodes must be.

Certainly. They have thousands (or is it millions?) of times the power
density of LEDs.

Incidentally, you *can* see an 850 nm VCSEL laser!

John

 

[John Woodgate]

I read in sci.electronics.design that martin griffith

From Wikipedia, the free encyclopedia.
You searched for "Floccinaucinihilipilifaction " [Index] Results 1-1 of
1

*


Relevancy: 0.0% - -

hmmmmmmm. +-3dB maybe, or -1 Boki

Surprising; this sort of trivia usually gets posted to anywhere that
will accept it. I don't suppose the Master Wickis deleted it.

Try the alternative 'Floccipaucinihilipilifaction'.

Both mean 'the act of estimating as worthless'. Definite connection to
'Boki' there. (;-)

But the chemical name of any protein is far longer than any normal word.
Of course, no-one uses them.

 

[Frithiof Andreas Jensen]

Incidentally, you *can* see an 850 nm VCSEL laser!

John

Briefly, anyway ;-))

 

[Ian Stirling]

**** Post for FREE via your newsreader at post.usenet.com ****

How are white leds quantified with regard to eye safety standards?
60825 does not appear applicable as it stands - is there some other
applicable standard?

Hmm.
Real world.
The sun has at .5 degree diameter a power density of 1Kw/m^2.
Call it 25mw into a semi-dilated pupil.
The eye survives this just fine, if you don't try to stare at the sun.

If the LED has a 10 degree beam, and all of it goes into the eye,
you need 5W of light, to equal the brightness of the sun.
(The illuminated area of the retina is far higher - but over the short term
the difference between a .5mm illuminated spot and a 5mm one won't be big.)

I'd say that 1W sources are probably safe - unless extrordinary efforts
are made to make them eye harmfull.

 

[Tim Shoppa]

I'd say that 1W sources are probably safe -

unless extrordinary efforts are made to make
them eye harmfull

The concern I've heard is about ultraviolet LED's, which have a tail of
emission that's just barely visible. The concern is that someone will
look into/focus on the faint purple glow directly not knowing that
there's a lot more power in the UV which they cannot see.

But that seems quite orthogonal to Mr Lewis's concern about white LED's
and regulatory standards. I would naively believe that white
phosphors would be the most benign.

Tim.

 

[Roger Hamlett]

The concern I've heard is about ultraviolet LED's, which have a tail of
emission that's just barely visible. The concern is that someone will
look into/focus on the faint purple glow directly not knowing that
there's a lot more power in the UV which they cannot see.

But that seems quite orthogonal to Mr Lewis's concern about white LED's
and regulatory standards. I would naively believe that white
phosphors would be the most benign.

What you are thinking about, is the 'blink reflex', or 'aversion reflex'.
This is the reason why safety levels for IR/UV lasers are set lower than
fot the visible light lasers, where the instinct to blink away, is
considered to provide extra safety. This is the difference between
Class-1, and Class-2 laser standards.
You might look at some of the laser standards, and see where the power
levels are for these classes. Try:
http://www.mykid2.org/software/ael.htm
Which has a nice little calculator, allowing you to try different light
frequencies and see how the classes change.

Best Wishes

 

[Pat Ford]

Are any visible-wavelength LEDs eye hazards?

John

We had some green ultra brights that had a warning on them about damaging
eyes. They were incredulibly bright!
Pat

 

[Clive Mitchell]

We had some green ultra brights that had a warning on them about
damaging
eyes. They were incredulibly bright!

There's also a certain marketing spin on eyesight damage warnings. If
you tell someone that an LED can damage your eyes then you think "Cool!
It must be really bright."

What they don't mention is that in order to damage your eyes the LED has
to be loaded into an air rifle and fired at close range.

 

[Dirk Bruere at Neopax]

There's also a certain marketing spin on eyesight damage warnings. If
you tell someone that an LED can damage your eyes then you think "Cool!
It must be really bright."

What they don't mention is that in order to damage your eyes the LED has
to be loaded into an air rifle and fired at close range.

http://optics.org/articles/ole/8/6/5/1

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org

 

[Douglas G. Cummins]

http://optics.org/articles/ole/8/6/5/1

So, in other words, it's not that LEDs can cause eye damage - only that
they can be *too* bright. Just like any other light source/system.
Makes sense to legislate just for LEDs instead of requiring a maximum
permissible intensity or luminance dependent on the application.
Luckily, automotive applications (as the article mentions) already have
these limitations in place. The requirements are also there for traffic
signals now - unfortunately, not when the systems were first implemented
- and they're not limited to just LEDs.

 

[Dirk Bruere at Neopax]

So, in other words, it's not that LEDs can cause eye damage - only that
they can be *too* bright. Just like any other light source/system.
Makes sense to legislate just for LEDs instead of requiring a maximum
permissible intensity or luminance dependent on the application.
Luckily, automotive applications (as the article mentions) already have
these limitations in place. The requirements are also there for traffic
signals now - unfortunately, not when the systems were first implemented
- and they're not limited to just LEDs.

Well, eventually I expect there will be visible light LEDs capable of causing
eye damage just because a great deal of power will radiate from a very small
area. However, I don't expect that will be for a few years.

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org