Frequency vs. Eye Damage Potential

[LarryDFW]

This is a chart from LED professional that relates frequency to eye damage for 100 second exposure.

It is taken from a safety study which pointed out the 400nm to 500nm band as an area where high-brightness LED's non-coherent light could cause damage.
The black dotted lines are hi-power white LED power spectrums.

LarryDFW

 

[Benm]

What is the vertical scale?

 

[LarryDFW]

Benm;

The vertical scale is in milliwatts /nanometer-sr ...
but the scale divisions are not shown.

LarryDFW

 

[caleb]

So 405nm doesn't look to bad compared to green and red...

I thought BR was worse as it can cause cataracts :-/

 

[Benm]

It all depends on what exactly is graphed there - it might be the threshold for acute eye damage, whilst cataracts are a symptom of prolongued exposure. Also, the maximum safe exposure seems to decrease at near-uv frequencies, so the chart would actually indicate that blu-ray is more dangerous.

Still, a vertical scale is required to say someting sensible about it - perhaps it is in W/m2 with some arbitrary values per division - but there is now way to tell from the picture as such.

I doubt this graph is in any way valid for laser dangers such as retinal burns - there should be no reason for the safe limit increasing from 700 nm onwards. The lens of the eye works perfectly well for such wavelengths, so any damage curve should be near-flat from 500 to 800 nm (and beyond) for our purposes here.

 

[milantheone]

hello guys, i am just wondering what does it mean??? is it dangerous because of looking at the dot or beam??? i dont undertand.. could anyone enlighten me please??
i know that DPSS lasers without IR filter are dangerous because emits IR which could be reflected but is it same by BR and red as well??? i mean if reflection in BR and RED is dangerous???

 

[Benm]

Reflections aren't usually dangerous, as long as they are from matte surfaces (such as paper) and looked at from some distance (arms length or so).

The dot on a matte surface is just as dangerous as a broad-beam emitter of the same power at the same distance. Like that, for example, the dot of a 200 mW red laser on a sheet of paper is about as dangerous as looking into an unfocussed 3 watt (electrical, should be ~300 mw optical) power led from the same distance.

However, things do get dangerous with reflective surfaces that can bounce the beam right back into your eyes - such as mirrors, (window) glass, but also some high gloss paints on flat surfaces.

 

[Ace82]

Laser light in the visible to near infrared spectrum (i.e., 400 - 1400 nm) can cause damage to the retina resulting in scotoma (blind spot in the fovea). This wave band is also know as the "retinal hazard region".
Laser light in the ultraviolet (290 - 400 nm) or far infrared (1400 - 10,600 nm) spectrum can cause damage to the cornea and/or to the lens.