A couple questions before my first laser purchases.. :)

Hey there guys! Glad to finally get around to registering here at LPF..been reading this place for awhile, and it's such a great forum,

Moreover to the point, hollidays are rolling around, as well as my birthday (it's nice having one close to Christmas!), and I decided to "wish" for lasers this year.

I say lasers, because I want two. One that I can burn with, and another that I can actually use safely and bring with me to places.

With that in mind, I've decided on the wattage (and color), two greens at 200mW and 5mW. Now the only part is to find them, and this is where I'd appreciate your guys' advice.

I found two different lasers on Lazerer.com . I used Lazerer because of the recommendations on this forum, as I've read (and their website states) that the company power tests all lasers before shipping.
RIFLE532nm - 200mW Focusable Burning Green Laser
LZCB - 532nm 200mW Focusable Green Laser Pointer

The first one, the Rifle, seems to have a better host, and is available to upgrade to the Deluxe package, which is excellent as I will need a batter/charger/eyewear, and the projector heads are a nice bonus.

As for the 5mW, I found this one on Rayfoss.com;
5mW Green

It doesn't seem bad, and I'm not looking for a bulky host for this particular wattage.
My main question concerning the 5mW laser is whether or not the beam is particularly visible at night.

What do you guys think? Have I chosen well?
Thanks in advance!
~Steve

The rifle host laser is nice, but you're paying a premium for the host itself. Personally I would go with the Cyber host instead, since it's also waterproof.

Instead of the 5mW from rayfoss, order the overspec green from swimminsurfer here on the forum.

Being over 5mW it is NOT a completely safe laser, but if you're careful with it, you should be fine. The divergence on them isn't great, so that's kind of a safety plus.

If you want a 100% safe laser, order a 5mW greenie from laseglow or optotronics, as they will be <5mW and IR filtered.

Also don't expect to burn too much with 200mW... I mean you should be able to light a match, but don't expect to slice through CD cases

With the 200mW... goggles are a must. See the links in my signature.

Yeah I know I won't be slicing cases (that's what...400mW?), but I want to at least burst some balloons for the amusement of kids.

Speaking of that -- would (kids especially) people be fine to look at the dot on the laser (more than 10 feet away)? And if not, would me holding the laser be fine without glasses to point the laser away from myself?

And yes I know even 5mW isn't 100% safe, but I want to stay under 15mW, as I've read that's the line where lasers start getting optically dangerous.

And then would you know about the beam visibility (at night) of a 5mW green?

At 200mW you will be able to light a match and pop a balloon easily.

The dot is fine to look at (though uncomfortable) from 10 feet away, so long as it's on a non reflective surface... basically anything with matte finish.

There is a danger with balloons in that they are actually very reflective/shiny, so what I do personally is pop them from below, pointing straight up at the ceiling or sky, with the laser directly on the balloon under it. No it's not as cool as popping one from five feet away... but it's safe with no danger of reflection. Otherwise you will need goggles for people.

The 5mW or 15mW limit really doesn't take beam diameter, and divergence into account. Some lasers have a thick beam... so while they are in fact of a stated power, the beam power density is lower, and they are not as dangerous. Others have very very thin beams and good divergence... that's where true danger comes into play with lower powered lasers, and how some people end up with damage from weaker lasers while others are fine from much more powerful ones.

As for visibility, again beam diameter and divergence are a factor, but even more so, ambient lighting, and particulate matter in the air... meaning if you're in a dark dusty room you will see a beam from a 5mW laser, but if you're on a well lit street... you won't.

I see. Assuming that what you said about visibility pertains to a 5mW, how would one of swimminsurfer's overspec lasers fare? Not in a lit area like a street, probably more like a dark back yard.

And on a side note, have you ever released helium balloons in the air and then popped them? Is that able to be done at 200mW? Reasonable distances, of course (less than 25 feet? ).

Again thanks for taking the time to help!
Good information like this is going to help my case in convincing my folks to let me experiment.

Swimminsurfer's overspec, and super overspec pens would be visible in a dark backyard with no problem.

Never tried to pop helium balloons when they are actually flying, but I think you might need more power for that since the balloon will be moving your only option will be to have it focused to infinity, and it takes a more powerful laser to do anything when focused to infinity...

Also it would be pretty hazardous since you'll be hitting the side or bottom of the balloon and it will be reflecting down at an angle.

I considered the danger but thought it rather unwarranting of concern, as the beam would be travelling not a small distance, and it would have been reflected off of an object that does not reflect well. Thank you for the amendment.

Very well, then I have one last question. As accidents do indeed occur, and a 70mW laser is by no means weak, would flashing a laser into an eye or the side of an eye cause damage? I'm talking about one that was, say, pointing to the sky then deciding to point Earthward.
I recall a term that measured the distance at which the laser did not best the blink reflex (approx. .25 seconds?) and that a 50mW laser had more than 20meters of this measurement. That is what sparked that question.

And yes I will be practicing safety quite well, but as I have said before, accidents do occur.

Not a 100% sure what you're talking about when you say

would flashing a laser into an eye or the side of an eye cause damage?

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because of course it would.

As yourself this... would getting hit with a hammer just once cause damage? If you're going to try to experiment please use a rubber mallet instead

The biggest concern with a 70mW laser is whether or not the beam enters your pupil. If it does, then you're in trouble. It really make no difference from what angle the beam enters, you're still in trouble. It can make a difference in how bad the damage is, for example you might end up with a blind spot on the side of your vision instead of directly in the center.

If you're talking about the sclera, I don't think a 70mW laser would do any damage from momentary exposure, but I would still avoid it.

This also makes no sense whatsoever:

I recall a term that measured the distance at which the laser did not best the blink reflex (approx. .25 seconds?) and that a 50mW laser had more than 20meters of this measurement.

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Light travels at the speed of almost three hundred million meters per second... Regardless of how powerful the light is... the speed of light is constant, in so far as we're concerned.

The average human reflex is .1 second. So no matter how you play around with the math, if your eye is hit with a laser beam, even if it's from a hundred miles away, it will hit you faster than you can blink.

The only way distance comes into play is with initial beam diameter and divergence.

Ah I'm terribly sorry for being difficult with that previous comment. I was in the middle of reading Inheritance (from the Eragon series, if you've heard of it) and they speak in an older-English dialect, which I kind of absorbed.

Anyways, I was mainly asking about having the beam flashed by (or maybe even in) a person's eye for less than a 0.1 seconds. Say I was pointing to the sky, then suddenly to the ground with a jerk of my wrist. If the beam happens to hit somebody, would it cause damage still?

Also here's that technical term I described:

NOHD

The Nominal Ocular Hazard Distance (NOHD) is the distance that a laser beam does not cause immediate or long term damage to a person. Calculated based on a 0.25 second accidental (unaided eye) exposure.

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source: www.wickedlasers.com