At what LUX/LUMEN LEVEL will EYE DAMAGE likely occur?.......

Enderman · 2018-07-07T07:52:30.000Z

toddcshoe:

Lasers are different. The human blink takes place in about 300 milliseconds. Not total blink from eyelid closed to eyelid back open.The eyelid will be closed in 300. Protecting your eyes form lasers, if you live in a place where lasers are being thrown about at peoples eyes, may be difficult. Protecting your eyes from a bright light of any source is as easy as looking away quickly. Or blinking and looking away at the same time. It happens, we all do it everyday. Look into bright lights, you will go blind, don’t look, you won’t. It’s really that easy.

With enough laser power the eye does not close fast enough to prevent permanent damage.
That’s what the entire point of NOHD is.
It is a scientific safety rating of the distance where damage becomes permanent because 300ms is too slow to prevent your retina from burning.

OP is asking about what kind of power is necessary for a regular light to cause damage.
A laser is literally just a very intense source of light.
A flashlight is not somehow fundamentally different from a laser to magically not cause any eye damage…
As I said, for regular flashlights like the type you use it is not an issue, but as power continues increasing then it is certainly possible that a flashlight will become as dangerous as a laser.

Obviously extending the period of exposure increases the probability of damage, but that’s a completely different matter than “will this blind you at X distance or not”

toddcshoe · 2018-07-07T08:00:39.000Z

Enderman · 2018-07-07T08:58:03.000Z

toddcshoe:

That’s exactly how I feel explaining this to you.
Were you not aware that an average 1W 450nm laser will instantly blind you at about 100m distance? In less time than the human blink reaction.

If I built a flashlight with the same power output per steradian it would also blind you at 100m.
That is because the wavelength of light isn’t what matters, the radiated power output intensity is.

Tom_Tom · 2018-07-07T11:16:54.000Z

An important thing to be concerned about is if you use a UV torch, in dark conditions. The UV is bad for you eyes anyway, but when the pupil is wide open, far more so. Always use eye protection, clear plastic lenses usually block it completely, they don’t need to be tinted. Easy enough to test with something that fluoresces, even just some white paper.

Powerful UV torches can be as bright as a good white LED, just you can’t see it, your pupil won’t contract, no blink response, the wavelength is very damaging, altogether quite dangerous, not something to allow untrained people to use, nevermind children.

Natural reaction: “I turned it on but it doesn’t seem to be working. I’ve looked into the reflector and fiddled with it but there’s just a faint glow”. Add a ZWB2 filter … Oops.

The big problem with lasers is that the beam is collimated so will be focussed to a tiny spot on the retina, if visible the natural reaction is to look at it, so it’ll probably burn out the most important part of the retina, in milliseconds. Has happened to airline pilots, and is banned for military use:

Almost any of the high powered lasers that are used as toys are more than capable of blinding, even just a diode pulled from a DVD burner.

en.wikipedia.org

Protocol on Blinding Laser Weapons

The Protocol on Blinding Laser Weapons, Protocol IV of the 1980 Convention on Certain Conventional Weapons, was issued by the United Nations on 13 October 1995. It came into force on 30 July 1998. As of the end of April 2018, the protocol had been agreed to by 109 nations. The Convention on Certain Conventional Weapons and three annexed protocols were adopted on 10 October 1980 and opened for signature on 10 April 1981. In 1986, Sweden and Switzerland pushed for the Blinding Laser Protocol. Dur...

As for the OP’s question, I don’t know. But put your hand in front of a Q8 on turbo and you’ll realise in a few seconds how burning hot it is. Blink reflex is easily overcome if you insist on burning your eyes out, always a few sad cases after solar eclipses. If you are lucky you’ll just have spots before your eyes for a while, but that’s still quite bad, damage has been done, and is accumulative.

nottawhackjob · 2018-07-07T13:11:51.000Z

We’ll I have to be honest here as I have from time to time held certain newly acquired hi-power torches at eye level (especially during daytime) and quickly flashed/scanned it into a mirror from let’s say 10 feet away to gage just how bright the sucker truly is against the human condition. Or if the thing has a particularly different strobe cadence to see its effects.

I don’t think this a good idea anymore. Not with the kind of stuff we’re messing with today. Then with all the gizmos emitting IR or UV even moreso.

Lasers, forget about it. I respect the hell out of them - inexpensive versions or not.

The main point why I brought this up is that we’re used to the blink reflex protecting us but as pointed out above, don’t necessarily rely upon it with the power intensities we’re seeing nowadays. I also didn’t mean to imply a lot of peeps we’re gonna go blind because we’re typically all so stupid enough to continously stare into an emitter and not use common sense otherwise.

DBSAR’s comment that his demo was painful to look at is a case in point. Not that it was dangerous per se like a laser is but just that it’s getting more commonplace that the outputs we’re dealing with is a possible cumulative adverse factor to consider. That’s all.

Well anyway, it’s good I think that occasionally we get reminded.

eas · 2018-07-07T15:40:00.000Z

“clear plastic lenses usually block it completely, they don’t need to be tinted.”

I’d be cautious of this rule of thumb.

I have a ~5” magnifying lens on a gooseneck stand I bought at Costco ~5 years back. It’s clear plastic. I tested it recently. It passes enough UV that an old Inova UV flashlight I have lit up flux residue when shined through it. It emits enough visible light that I guess it could be the shortest visible wavelengths causing the florescence.

In any case, it’s worth doing a quick test by shining the UV source through the lens at something florescent (like, say, an unpowered white LED emitter) to verify.

I just tested my reading glasses against an unlit LED. They failed too.

FWIW, cheap plastic sunglasses do block UV. I tested a few pairs back when I had access to a UV/VIS spectrophotometer.

eas · 2018-07-07T15:46:48.000Z

Ok. Now I don’t know what to think. I gathered 4 pairs of sunglasses, three cheap and one pair of RayBan Cateys.

When I shined UV source was shined through them, as expected, all cut much but not all of the visible light.

When a white LED emitter was illuminated with the filtered light, florescence was significantly lower than when illuminated with the unfiltered source. However, that reduction seemed more closely related to the reduction in the visible blue light, than to elimination of UV.

Of course, I don’t know what the emission spectra of these UV LEDs are. It could be that most of their energy is actually visible blue, rather than UV. They are, probably 10y old.

nottawhackjob · 2018-07-07T16:22:36.000Z

I was planning to use a UV flash for scorpion a lot this summer. Now only with protective glasses after reading this.

Lux-Perpetua · 2018-07-07T16:34:04.000Z

Did I get this right? When using a UV flashlight it is highly recommended to put on glasses that block UV radiation? I’m not planning to direct the lightbeam into my eyes, of course. But is there an immanent danger of UV radiation reflected from illuminated objects such as white walls etc.?

I once used my Convoy S2+ with Nichia UV at home while it was dark outside. I was shocked how intense objects like white curtains started to glow.

WalkIntoTheLight · 2018-07-07T16:45:04.000Z

Direct sunlight at mid day is about 50k - 100k lux. You don’t want to look at the sun for more than a few seconds, and probably shorter than that.

I’m guessing the BLF Q8 is close to 50k lux at 3 feet. So, consider it like the sun. Don’t look at it. If you do this for several minutes, you’re probably going to get permanent eye damage. If you do it for several minutes, you probably already have permanent mental damage.

Lux-Perpetua · 2018-07-07T17:39:57.000Z

WalkIntoTheLight:

[…]If you do it for several minutes, you probably already have permanent mental damage.

:laughing: :+1:

Tom_Tom · 2018-07-07T18:45:10.000Z

I have a very good set of laser range finding binoculars for another interest.

IR laser.

They are the civilian spec. so artificially limited to 1760 yards (one mile), more than good enough for me, but up to then they work superbly. And the spot size is small and precise.

I’ve measured the current draw whilst pinging and it is massive. I seriously would not want one pointed at me, whilst looking at it.

Nor would I try pinging e.g. a military plane.

As for keeping the button pressed down and continuously measuring, including velocity measurement

Coming soon to a laser trap on the roads near you …

(A modern windscreen will block it, not so for a biker with their visor up)

nottawhackjob · 2018-07-07T18:47:29.000Z

Can I ask where did you get those laser binos? :sunglasses:

Tom_Tom · 2018-07-07T19:23:50.000Z

nottawhackjob:

Can I ask where did you get those laser binos? :sunglasses:

Yes, but I’m not going to say. It is hard enough getting a good Schmidt & Bender these days.

The_Driver1 · 2018-07-07T21:43:52.000Z

Enderman:

That is because the wavelength of light isn’t what matters, the radiated power output intensity is.

Actually it does, very much so. In the visible spectrum the blue part of the spectrum is more dangerous than the other parts (“blue light hazard”).

higherlogicdownload.s3.amazonaws.com

Photobiological%20Safety%20of%20Lighting%20Products%20-%20ZVEI%20-%202013.pdf

downloads.cree-led.com

XLamp-Eye-Safety.pdf

652.13 KB

Electronics Weekly – 8 Nov 12

Ensuring safety in LED lighting

Lighting LEDs are a route to energy efficiency that also allow creative effects that were not possible with incandescent bulbs and fluorescent tubes. But the output spectrum, like that of fluorescent tubes, is nothing like the sunlight human eyes...

Est. reading time: 18 minutes

Some German Infos:

bildschirmarbeit.org

Einflüsse blauen Lichtes |

Taschenlampen Forum

Forschungsbericht Risikobewertung / Photobiologische Sicherheit von LEDs

Die Bundesanstalt für Arbeitsschutz und Arbeitsmedizin hat gerade einen sehr interessanten Forschungsbericht veröffentlicht: Photobiologische Sicherheit von Licht emittierenden Dioden (LED) (der komplette Bericht ist dort als PDF verlinkt, gibt...

baua.de

BAuA - baua: Bericht - Photobiologische Sicherheit von Licht emittierenden...

Bundesanstalt für Arbeitsschutz und Arbeitsmedizin - Fünfzig Jahre nach ihrer Erfindung erobern Licht emittierende Dioden (LED) immer mehr Anwendungen und halten zunehmend Einzug sowohl im beruflichen als auch im privaten Bereich. Da die rasanten...

The research is not perfectly clear yet, but it seems to point in this direction.

nottawhackjob · 2018-07-07T20:01:08.000Z

@TomTom……

Prolly best anyway. :laughing:

Enderman · 2018-07-07T20:06:26.000Z

The_Driver:

Enderman:

That is because the wavelength of light isn’t what matters, the radiated power output intensity is.

Actually it does, very much so. In the visible spectrum the blue part of the spectrum is more dangerous than the other parts (“blue light hazard”).

Well that’s because the radiated power also depends on wavelength, I worded that badly.
What I meant is that the wavelength alone doesn’t really tell you anything about the danger.
A laser at 445nm isn’t strictly more dangerous than a flashlight that emits form 300 to 700nm.
An invisible UV or IR laser can blind you easily if it has enough power.

Your sources even specifically say this, “the hazard is dependent upon the size of the source and the maximum limits are expressed in terms of radiance. ”

en.wikipedia.org

Radiance

In radiometry, radiance is the radiant flux emitted, reflected, transmitted or received by a given surface, per unit solid angle per unit projected area. Radiance is used to characterize diffuse emission and reflection of electromagnetic radiation, and to quantify emission of neutrinos and other particles. The SI unit of radiance is the watt per steradian per square metre (W·sr−1·m−2). It is a directional quantity: the radiance of a surface depends on the direction from which it is being observed...

As I said earlier, it depends on watts per steradian, which is a measure of power intensity.

The_Driver1 · 2018-07-08T08:53:51.000Z

Enderman:

The_Driver:

Enderman:

That is because the wavelength of light isn’t what matters, the radiated power output intensity is.

Actually it does, very much so. In the visible spectrum the blue part of the spectrum is more dangerous than the other parts (“blue light hazard”).

Well that’s because the radiated power also depends on wavelength, I worded that badly.
What I meant is that the wavelength alone doesn’t really tell you anything about the danger.
A laser at 445nm isn’t strictly more dangerous than a flashlight that emits form 300 to 700nm.
An invisible UV or IR laser can blind you easily if it has enough power.

Your sources even specifically say this, “the hazard is dependent upon the size of the source and the maximum limits are expressed in terms of radiance. ”
Radiance - Wikipedia

As I said earlier, it depends on watts per steradian, which is a measure of power intensity.

Yes, you are right. It’s the radiance that matters. I just wanted to point out that the frequency does make a difference and this is especially important for flashlights. It’s almost impossible to damage your eye with a warm-white LED. A cool-white LED can damage your eye though if it’s bright enough, you are close enough to it and you look at it for an extended period of time under high discomfort. To damage your eyes with an LED that emits visible light in a short period of time (seconds/minutes/hours) you need to go beyond the point of discomfort, but it’s certainly possible.

Lasers are a whole other topic. As has already been discussed they are completely unnatural light sources that the human eye has no protection against. Because of their extreme focus, even with very small optics, they present additional dangers which in practise don’t apply to LEDs.

nottawhackjob · 2018-07-07T23:35:56.000Z

“It’s almost impossible to damage your eye with a warm-white LED. A cool-white LED can damage your eye though……”

We’ll amongst the other new things I learned today from this thread is if you especially have young kids milling about it’s better to inadvertently leave a warm white flashlight unattended than the others.

Good to know.

Enderman · 2018-07-08T00:27:29.000Z

The_Driver:

Yes, you are right. It’s the radiance that matters. I just wanted to point out that the frequency does make a difference and this is specially important for flashlights. It’s almost impossible to damage your eye with a warm-white LED.

Ok but it is certainly possible to take a big lens in front of a high power warm white LED and lights stuff on fire.
At that small focal point, the intensity is high enough to cut through stuff like tape or plastic and would do the same to your retina.
So it really depends on the intensity of the light source and optics combined whether it will cause immediate damage or not.

Obviously there isn’t currently a flashlight like this, unless you put a big converging lens in front of one, but in the near future as we try to increase throw without increasing head size the intensity will keep getting higher and higher until it reaches a point where NOHD will be a specification just like with a laser.

Currently this isn’t an issue with flashlights because the beam has such a large diameter that the amount of light entering through your pupil is only a fraction of the total beam power.
But as per my example, if you take a lens and concentrate that beam power into a smaller area, then more of that power can enter through the pupil and cause damage faster than the blink reflex.