How quick can 5mW laser damage an eye?

Should i switch red 5mw for 1mw? I want to be extra safe.
Im just concerned someone at home might pickup my laser and shine it in a mirror to check it out.

I have family over sometimes, and never know. I would keep it locked somewhere.
can 5mW cause damage within hands-reach? shined few seconds in eye?

what about 1mW?

This isn't an easy question to answer. damage varies person to person, based on angle, how much enters the eye and from how far, lighting conditions, etc. etc. A laser should never be pointed into the eyes no matter what power it is. even 1mW is over 60x as bright as looking directly at the sun, which is also a bad thing to do. anything <5mW is considered safe for the average person's blink reflex which is on the order of a tenth of a second. but that does not mean the laser cannot cause damage, and likely it will, it just likely wont be permanent. Always make sure a laser is never pointed at another person, especially their face and eyes. Period.

1mW is 60 times brighter than the sun?!!!

wow, well that makes sense. thankyou, i dont know why i cant find research about this. Complicated to google anyway, other than specs and all that.
I just want one for therapeutic use. Heard of photodynamic therapy? Apparently 635nm is good for acne vulgaris and Rosacea.


Laser and light based treatments of acne Rai R, Natarajan K - Indian J Dermatol Venereol Leprol

Faradayzed said:

1mW is 60 times brighter than the sun?!!!

wow, well that makes sense. thankyou, i dont know why i cant find research about this. Complicated to google anyway, other than specs and all that.
I just want one for therapeutic use. Heard of photodynamic therapy? Apparently 635nm is good for acne vulgaris and Rosacea.


Laser and light based treatments of acne Rai R, Natarajan K - Indian J Dermatol Venereol Leprol

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sorry that was a typo. I meant to put 160x. Someone calculated it making some average assumptions and I think they came up with 167x brighter or something like that. a perfect shot would have a density of some 16W+ intensity on the retina, which is a heck of a lot.

as for theraputics of laser light, professional treatment aside, I dont think there's much you could do in this area, but with your eyes closed and a very diffused beam of a mW or so probably from a HeNe or weak laser diode probably would suffice. the human body is stimulated to heal under red light, which is a well known fact, and is a topic of ongoing study. I'll see if I can find anything for you.

ultimatekaiser said:

sorry that was a typo. I meant to put 160x. Someone calculated it making some average assumptions and I think they came up with 167x brighter or something like that. a perfect shot would have a density of some 16W+ intensity on the retina, which is a heck of a lot.

as for theraputics of laser light, professional treatment aside, I dont think there's much you could do in this area, but with your eyes closed and a very diffused beam of a mW or so probably from a HeNe or weak laser diode probably would suffice. the human body is stimulated to heal under red light, which is a well known fact, and is a topic of ongoing study. I'll see if I can find anything for you.

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to be honest, i dont think laser therapy will be everywhere soon. Because the folks selling those devices, like thor, theralase, k-laser,etc charge thousands of dollars for them.
They have done alot of research, spent alot of time, time is money though.

For example, the sun is source of light/joules, and we create vitamin d in blood, by absorbing sunlight.

but sunlight is lower wavelength. The lasers are higher, and the waves are longer, or more straight, so they penetrate deeper.
check out K-lasers website, they have tons of studies to backup laser therapy. I cant buy more than 5mW, so im curious to see if <5mW will resolve my skin problems.

No. a laser pointer isn't enough to do that.

The devices in question are thousands of dollars because they are quite powerful and very high quality. I've heard of places doing such things, but its not common due to it being kind of a obscure thing and as you mentioned, overly expensive.

there are studies that say pulsed lasers at 2000 hertz or so is best. Some studies recommend different hertz. Thats another reason why their more expensive, because high power is available, "but only safe with pulsing"
you can get away with very high joules without burning cells, as long you pulse.
they cool off between the pulses.

trust me i know this.
Another reason its expensive, the laser is usually equipped with a machine aka laser computer. Meanwhile, the average Scienceguy like me only needs a red beam.
but even then. Its the system, because i met folks who operate the machines, and they dont even know the joules.
they just follow the manual, kind of like a recipe book. they just know what setting to turn on, and how long to point laser at skin.

joules are joules regardless if diode is using convex lens, regardless if using $1000 diode or 10 dollar.
A human body can absorb 1000 joules in one hour bathing in the sun, roughly.

as long the diode delivers the energy, the mitochondria absorb it like sunlight and operate faster, thus person heals faster.

human eye isnt designed really to have lasers been shined at.

mortuus said:

human eye isnt designed really to have lasers been shined at.

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Dead on!

The human eye is the most sensitive organ in the body. It's main job? Use the cones and rods located within it to absorb light and turn it into something we can comprehend. This is, our eye can only handle so much light. Too much and rapid eye damage occurs, and one an eye cell is gone, it's gone!

Follow ultimatekaiser's advice: no lasers pointed into you/anyone's eyes. Only at a board

-Alex

Faradayzed said:

Should i switch red 5mw for 1mw? I want to be extra safe.
Im just concerned someone at home might pickup my laser and shine it in a mirror to check it out.

I have family over sometimes, and never know. I would keep it locked somewhere.
can 5mW cause damage within hands-reach? shined few seconds in eye?

what about 1mW?

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I doubt if you can really get a regulated 1mW laser as these low power laser are usually overspec .

Luis

Hibro said:

I doubt if you can really get a regulated 1mW laser as these low power laser are usually overspec .

Luis

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i could do this laser test, but maybe i need to buy some special intruments then. I really want to make sure.

Faradayzed said:

i could do this laser test, but maybe i need to buy some special intruments then. I really want to make sure.

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I think you should go ahead and do your test and see if it works with a laser pointer instead of something that costs thousands of dollars. At least two people have claimed to have cured toenail fungus with a laser, and there was another guy with a skin problem that was going to try this but I never found out what the results were or if he went through with it. I have a skin problem too I could try this on, I also have toenail fungus. I am a bit paranoid about having direct contact with the beam of a laser though, I once burned myself. I have a 635nm that was guaranteed to be between 4.9 - 5mW, it is bright enough that I don't trust it to be eye safe. I have another red laser that is probably 650nm judging by its color that is supposed to be <1mW and it's not a real cheap laser either so that's probably correct, I expect my blink reflex would save me with that one but I am not going to test this. I would say go ahead and see if it will work, unless your skin problem is around your eyes then just wear proper laser safety glasses if there is a chance of getting a hit to the eye, be aware that some of the cheap blue safety glasses for red lasers aren't very good, but at up to 5mW I expect they should be more than ok. Let us know if it works at all.

Alan

Yea theres even $580 laser, usually salons buy this one for the girls. But really, over 500 bux...lol
they dont say the specs of their laser, neither if its continous wave or if it pulses.
Anti-Aging Laser Treatment: Age-Defying Skin Care | TriaBeauty.ca

i bet its overpriced. and the way you count joules, for continous wave, a good laser that is. 5mw times 15 seconds gives .75 joules. I know Theralase and Thor(most expensive cold lasers) say its not accurate to divide power by area.
But if you dont spend over 5k or whatever, then you cant get their manual, which tells you how to calculate dosage using wavelength and like 8 other parameters?

so for the layman, you're stuck taking joules/skin-area in cm square
I found this method by skimming through some studies.

maybe one day ill buy the k-laser. Best one, has multiple wavelengths, cost over 10 grand.

I don't see why you would have to use lasers for this purpose. A 660nm led has about the same wavelength, and is 1/200 of the price per watt. It's also way less dangerous, while you still can have better(!) power density.

because of this
http://www.ncbi.nlm.nih.gov/pubmed/24301435
http://www.ncbi.nlm.nih.gov/pubmed/10809858

or just scrim through here,
http://www.ncbi.nlm.nih.gov/pubmed?term=laser-therapy[Title%2FAbstract]%20AND%20acne[Title%2FAbstract]


ill look for a 660nm though, ty.

ultimatekaiser said:

sorry that was a typo. I meant to put 160x. Someone calculated it making some average assumptions and I think they came up with 167x brighter or something like that. a perfect shot would have a density of some 16W+ intensity on the retina, which is a heck of a lot.

as for theraputics of laser light, professional treatment aside, I dont think there's much you could do in this area, but with your eyes closed and a very diffused beam of a mW or so probably from a HeNe or weak laser diode probably would suffice. the human body is stimulated to heal under red light, which is a well known fact, and is a topic of ongoing study. I'll see if I can find anything for you.

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Gonna have to call bullshit on that.

Sunlight's power density over the atmosphere (which is higher than on ground) = 1367W/m^2 = 1.367mW/mm^2
Considering a *very good* 5mW pointer with a 2mm beam diameter we get 0.39 mW/mm^2. Even with 1mm diameter we get 1.59 mW/mm^2.

Both sunlight and the laser's beam would enter the eyes approximately collimated, divergence makes little difference.