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5mW limit too conservative?

Joshuan

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Hello everyone.

I was discussing this in the middle of another thread of mine but since the theme wasn't exactly on-subject of the thread it makes more sense to open a new thread dedicated to this discussion.

I have read conflicting reports, ideas and theories, here and elsewhere, about the 5mW power limit for lasers to be used without goggles being too conservative. It's confusing having so many different and even opposed ideas so I really don't know what to think and where's a middle ground. That's why I'm opening this thread to read what you have to say about it and what is your educated opinion on this subject.

I will start by quoting what is stated on a sticky FAQ within this forum:

Q: How much power is bad for my eyes?

5mW is the "limit" for taking a direct hit to the eye. This is because a laser above 5mW can cause damage before the blink reflex kicks in, shutting out the beam. This is also why the FDA doesn't let lasers above 5mW get into the US. So kids don't blind themselves. The usual maximum for looking a the dot of the laser is 30mW, although I definitely wouldn't stare at a dot of that power for long. There is no limit for looking at the beam, so you can point any laser at the sky and stare at any beam as long as you want.


This is a little rant I'm adding in (more recent), you can skip it if you want. First of all, some of you guys are taking this FDA limit thing WAY to seriously. The FDA states that laser damage CAN occur from a >5mW beam, this is the lowest power that they could come up with. They have done scientific tests to find the absolute lowest power that could damage your eyes, with every worse possible condition (basically point blank range, low divergence, the most sensitive part of your eye, etc.).
UNDER NORMAL CONDITIONS a 6mW laser is extremely unlikely to cause damage. Especially considering that almost every hit will come from a distance, or a reflection which will distort the beam, double the distance, and lower the power of the laser. With most accidents, the beam will have diverged/diffracted to a point where it isn't even a danger. Most people picture getting hit with a laser beam as the beam being exactly as it comes out of the device, and if you could recreate the incident, the beam would most likely not be the same.
Now I'm NOT saying that a close ranging hit from a 20mW+ laser wouldn't harm you, it would, I'm just saying that you don't have to go yelling that a 6mW laser is completely unsafe and you can't do any reflections with it, just because the FDA says not to. Those people are wrong.
Bottomline, they are just exaggerating to the point of telling you the worse conditions, and under normal conditions, you could probably get hit with a random reflection from a 15mW laser with no problems. Thanks for listening, and please don't go test this. lol
This quote is from a sticky in the green laser section. (Link: http://laserpointerforums.com/f45/guide-buying-your-first-green-laser-30608.html)

I am looking for different opinions and experiences, so what do you think, is this opinion true?
Because following his idea, it wouldn't be that dangerous using a 15mW without goggles as long as not staring directly into it. Isn't the 5mW a little bit too conservative, and green lasers around 7-15mW are in fact not that dangerous as long as used responsibly and not pointing directly at eyes, but not causing that permanent damage from a normal accidental reflexion as we're led to believe?

Thanks in advance for voicing your opinion and sharing your thoughts.
 

Blaster

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Hello everyone.

I was discussing this in the middle of another thread of mine but since the theme wasn't exactly on-subject of the thread it makes more sense to open a new thread dedicated to this discussion.

I have read conflicting reports, ideas and theories, here and elsewhere, about the 5mW power limit for lasers to be used without goggles being too conservative. It's confusing having so many different and even opposed ideas so I really don't know what to think and where's a middle ground. That's why I'm opening this thread to read what you have to say about it and what is your educated opinion on this subject.

I will start by quoting what is stated on a sticky FAQ within this forum:



This quote is from a sticky in the green laser section. (Link: http://laserpointerforums.com/f45/guide-buying-your-first-green-laser-30608.html)

I am looking for different opinions and experiences, so what do you think, is this opinion true?
Because following his idea, it wouldn't be that dangerous using a 15mW without goggles as long as not staring directly into it. Isn't the 5mW a little bit too conservative, and green lasers around 7-15mW are in fact not that dangerous as long as used responsibly and not pointing directly at eyes, but not causing that permanent damage from a normal accidental reflexion as we're led to believe?

Thanks in advance for voicing your opinion and sharing your thoughts.
I agree totally with the quote how much power is too much that you had in the first post you have attached and it answers your question at the same time
 
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Eudaimonium

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Like I always say, you need goggles if you are in danger of getting the beam into your eye:

Laser show calibration, mirror alignment, various optics alignment like PBS cubes or whatever else, and when doing burning/engraving with very powerful lasers.

Otherwise, for pointing around and playing around, you do not need goggles as long as you are careful and responsible!
 

Trevor

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For taking a direct hit, yes, 5mW is the limit for taking a direct hit "safely."

Like Eudaimonium says, if you're going to be using lasers where you have ANY risk of taking a beam (or specular reflection) to the eye, you are risking your eyesight if you're not wearing goggles. I am not saying you WILL take a hit, or if you do that you WILL lose your sight; I am saying that you are taking that RISK.

1W+ lasers have caused people to become more cavalier with their safety habits. Many enthusiasts have come to view lasers that output under 100mW as "safer" or "boring" and don't take precautions.

High powered 445nm lasers have made us callous to the risks of lower powered lasers.

Trevor
 

Zom-B

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Lower powered? 100mW?

In the days of blu-ray diodes, 100mW was very high power, as ~50mW was more mainstream. I don't agree with people calling 100mW low power just because there's something 10 times as strong now. I'd call that super high power. (just short of 100W ultra high power lasers)
 

Trevor

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Lower powered? 100mW?

In the days of blu-ray diodes, 100mW was very high power, as ~50mW was more mainstream. I don't agree with people calling 100mW low power just because there's something 10 times as strong now. I'd call that super high power. (just short of 100W ultra high power lasers)
Yeah. The presence of lasers fifty times as powerful makes it hard to explain to newcomers that a 50mW laser is still a hazard. :(

+1 when the system allows!

Trevor
 

Cyparagon

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green lasers around 7-15mW are in fact not that dangerous as long as used responsibly
Grenade launchers are in fact not that dangerous as long as they are used responsibly. That doesn't mean they should be available at wal-mart. The operative phrase here is "as long as they are used responsibly."
 
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Joshuan

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Grenade launchers are in fact not that dangerous as long as they are used responsibly. That doesn't mean they should be available at wal-mart. The operative phrase here is "as long as they are used responsibly."
I understand. I didn't mean that they should be freely available for sale. What I meant was, say if you're using a 15mW green laser indoors without goggles and it happens to reflect on some surface and hit you in the eyes (which is not that easy to happen if used responsibly), even then it is most likely that it won't cause any permanent damage. Correct?
 

Zom-B

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If you hit a window, most of it is transmitted and your eye maybe gets 2mW. If you shine in a mirror, you might get the full load until your reflex kicks in. That would only happen if you're not using it responsibly and hold the laser still, because if you'd be swinging the laser around and you'd get maybe 0.001s of exposure.
 

Eudaimonium

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15mW off the mirror? Yeah, you are going to get permanent damage.

15mW diffused? No danger.

When using the laser, simply avoid everything shiny and reflective. How hard can it be? Not much point in discussing what happens when you get a reflection hit in your eye, since everything we do around here is making sure that does't happen. If it does happen, it's too late to do anything anyway.
 

Joshuan

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15mW off the mirror? Yeah, you are going to get permanent damage.

15mW diffused? No danger.
Doesn't the laser decrease power when being redirected off a mirror? That, adding to the distance, even if something small as 2 meters, won't make the impact on the eye considerably smaller than a short range direct 15mW, probably resulting in no permanent damage?
 

Spooky

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"They have done scientific tests to find the absolute lowest power that could damage your eyes, with every worse possible condition (basically point blank range, low divergence, the most sensitive part of your eye, etc.)."
If the test says >5mW is dangerous based on actual test then all the theory in the world becomes worthless. Experiment always always always overrides theory.

As soon as variables are introduced things get complex, the water gets muddied and accidents happen.

Is a </=10mW laser dangerous to the eyes, empirically speaking yes it is. (note the lack of variables)

Is a </=10mW laser used sensibly dangerous to the eyes. probably not (note the sudden variable "used sensibly")

Is a </=10mW laser used in another room to the one you are in dangerous with all the access doors closed , clearly not (again, a different variable)

Variables tend to get added to known values by new / uninformed laser users to justify behaviour patterns. They are also stated by experienced users to demonstrate conditions but in one case the results are safe, in the other the answer is cherry picked to suit a purpose (possibly to justify to one's self not buying expensive goggles).

Is flying safe...yes

Is flying then crashing safe...no

Inanimate objects are inherently safe, it is how we use and treat them that can make them dangerous.

cheers

Dave
 

firelaser

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here is my safety guideline .. is there really a chance of me getting in the eye .. ?
yes, goggles no no goggles

basically , pointing it at distant objects there is no real danger so no goggles are needed for even 1 W + lasers for astronomy / showing off ect... outside,,

burning popping balloons starting fires or other things where you will point the laser at something 2 feet from your face, wear goggles,,

otherwise dont be going to the hall of mirrors at the carnival or something and spinning your laser around.. its pretty easy to be safe if you scan the aera where you are pointing ... i.e -i see a window, a truck a car mirror and a chrome motorcycle, lets avoid hitting those,,
 

Blaster

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Is anyone aware any actual test cases for lack of a better word where they have had human guiena pigs to test actual power, .hitting an eye and increasing it bit by bit with breaks between to see where actual permanent loss starts, obviously this is rather extreme but how did the FDA come up with the level of 5mW as the end of safe and after that it starts to become a risk of permanent damage.I cant see pardon the pun anyone offering to have this done to them in the name of scientific research but I'm just asking did they use another animal to test somehow how much will cause permanant damage.given enough money someone somewhere may have offered to be used as a test case in one eye obviously, with the power being turned up until they had some permanent damage but not being made blind ,its an out there question but anyone heard of such data, or just Johnny shinned a 30mW eBay pen into his little sisters eye and now she has a permanent spot she cant see out of on the affected eye as kids my do because they are kids
 

EpicHam

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Hello everyone.

I was discussing this in the middle of another thread of mine but since the theme wasn't exactly on-subject of the thread it makes more sense to open a new thread dedicated to this discussion.

I have read conflicting reports, ideas and theories, here and elsewhere, about the 5mW power limit for lasers to be used without goggles being too conservative. It's confusing having so many different and even opposed ideas so I really don't know what to think and where's a middle ground. That's why I'm opening this thread to read what you have to say about it and what is your educated opinion on this subject.

I will start by quoting what is stated on a sticky FAQ within this forum:



This quote is from a sticky in the green laser section. (Link: http://laserpointerforums.com/f45/guide-buying-your-first-green-laser-30608.html)

I am looking for different opinions and experiences, so what do you think, is this opinion true?
Because following his idea, it wouldn't be that dangerous using a 15mW without goggles as long as not staring directly into it. Isn't the 5mW a little bit too conservative, and green lasers around 7-15mW are in fact not that dangerous as long as used responsibly and not pointing directly at eyes, but not causing that permanent damage from a normal accidental reflexion as we're led to believe?

Thanks in advance for voicing your opinion and sharing your thoughts.
According to a recent report by Dr. David Sliney, who is one of the leading "gurus" of laser safety, there are no confirmed accidents or injuries caused by laser pointer of 5 milliwatts radiant power or less. There is an awful lot of nonsense and false claims about this. Pointers are extremely bright, can cause visual distraction, afterimages, and other effects, such as headaches, but under most any typical usage condition, DO NOT cause eye injury. Dr. Sliney works for US Army, and has published papers and books on laser safety for over 20 years.
As according to Dr Sam of Sam's FAQ. A retired electronics engineering professor who's now going to SELEM with Hak .





The main danger of lasers comes from its highly diffraction limited collimation energy .
Direct hits are where the dangers are mostly are.

As we've previously told you , assuming the laser hits a matte surface , its intensity decreases by a factor of a million once it reaches 1 m away.

HOWEVER!
Despite of the diffused reflection due to microscopic imperfections of the surface , within a short distance the laser's photons still reflect by generally the same method as one hitting a smooth reflective surface , albeit now with a cone .

Its still dangerous.
 

Blaster

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As according to Dr Sam of Sam's FAQ. A retired electronics engineering professor who's now going to SELEM with Hak .





The main danger of lasers comes from its highly diffraction limited collimation energy .
Direct hits are where the dangers are mostly are.

As we've previously told you , assuming the laser hits a matte surface , its intensity decreases by a factor of a million once it reaches 1 m away.

HOWEVER!
Despite of the diffused reflection due to microscopic imperfections of the surface , within a short distance the laser's photons still reflect by generally the same method as one hitting a smooth reflective surface , albeit now with a cone .

Its still dangerous.
A meter away it drops by a million well that's good to know
 




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