IR collimation with green in pointer

[ElektroFreak]

I have not done any testing, but people say ---------


I lived through many cycles since ~ 1950 ---
1. Crude oil will be gone by 1980...........
2. We are going into another ice age ...........
3. The Ozone hole will kill us all ............
4.  OMG, the Y2K bug will destroy all of us.
5.  Globule warming -- I'd love to see some of that  

What I'm saying is show me the science.  Things like IR leakage get repeated enough times to become truth and take on life.  The people who repeat these "facts" seldom have the equipment to verify those "facts".



Mike

[highlight]When using a filter, something must be used to account for reflection and absorbtion of the filter.  I have an 808 nM pointer to provide reference on my filters.[/highlight]

The filter in question is AR coated for 532nm, and BG38 glass' absorption at 532nm is negligible, maybe 1%. With my 808 module set to as close to 200mW as I can get it, only ~2mW make it through. This is all based on old research I conducted on a now dead Coherent Lasercheck.

 

[Cyparagon]

Oh boy, where to begin...

you no longer have a single beam, you now have a second invisible beam

With a power density magnitudes less.

What chance is there that you'll be blinded by the IR and NOT the green

Not a good argument, we have a built in blink reflex, if a green beam hits you that reflex may save your vision.... there is no blink reflex with IR.

Regards rog8811

You're missing the point. What is the green beam doing 4mm from your pupil to begin with?

Why do chances with IR "need to be taken?"

What's the word directly before my quote of yours? The IR dangers don't need to be taken, but neither does the UV with light bulbs. We could walk around with a lead bib over our balls because sterility from cosmic radiation is a chance that doesn't need to be taken.

I have not done any testing, but people say that IR may make 10-20% of a cheap greens power. When dealing with a 50mW pointer I would consider 5-10mW of IR potentially dangerous even with its high divergence because you lose the blink reflex and can be completely unaware you are getting hit.

5-10mW at what diameter? The power density is magnitudes less than that of a well collimated beam. Worst case scenario: only a portion of that will enter your eye. You'd have to be taking some monumentally epic drugs to have pupils 2 inches in diameter. And we shouldn't be playing with lasers on drugs. I can't think of a reason why you'd be staring just left of the green beam into the aperture for more than a second anyway.

My tests show little IR leakage as well depending on the setup. I have a 100mW module I bought from DX a year and a half ago that averages about 123mW and loses about 30mW

Not all of the loses are IR. Place TWO filters in the beam path and you'll see the output drop further.

This whole thing is like being next to a bomb about to explode and worrying about the little arc that goes into the C4 stopping your heart somehow. It's ridiculous.

 

[ElektroFreak]

Oh boy, where to begin...

[quote author=691175002 link=1235262582/0#8 date=1235357041]you no longer have a single beam, you now have a second invisible beam

With a power density magnitudes less.

What chance is there that you'll be blinded by the IR and NOT the green

Not a good argument, we have a built in blink reflex, if a green beam hits you that reflex may save your vision.... there is no blink reflex with IR.

Regards rog8811

You're missing the point. What is the green beam doing 4mm from your pupil to begin with?

While this wasn't my post, I agree with you here, your best bet is just to avoid the green beam. The vast majority of the time you'll be fine just doing that..

Why do chances with IR "need to be taken?"

What's the word directly before my quote of yours? The IR dangers don't need to be taken, but neither does the UV with light bulbs. We could walk around with a lead bib over our balls because sterility from cosmic radiation is a chance that doesn't need to be taken.

Sorry to have misunderstood you...  

I have not done any testing, but people say that IR may make 10-20% of a cheap greens power.  When dealing with a 50mW pointer I would consider 5-10mW of IR potentially dangerous even with its high divergence because you lose the blink reflex and can be completely unaware you are getting hit.

5-10mW at what diameter? The power density is magnitudes less than that of a well collimated beam. Worst case scenario: only a portion of that will enter your eye. You'd have to be taking some monumentally epic drugs to have pupils 2 inches in diameter. And we shouldn't be playing with lasers on drugs. I can't think of a reason why you'd be staring just left of the green beam into the aperture for more than a second anyway.

My tests show little IR leakage as well depending on the setup. I have a 100mW module I bought from DX a year and a half ago that averages about 123mW and loses about 30mW

Not all of the loses are IR. Place TWO filters in the beam path and you'll see the output drop further.

In the case of the setup I describe 2-3mW are accounted for by losses other than IR. I said that in the post. The rest is IR. And yes, for every filter you add, the transmission decreases even at the wavelengths that usually have the most transmitted, depending on the filter material.

This whole thing is like being next to a bomb about to explode and worrying about the little arc that goes into the C4 stopping your heart somehow. It's ridiculous.

That's your opinion. We're all entitled to opinions.. Like I've said before.. I'm not trying to overstate the danger, I just want people to be aware of the facts concerning IR as it relates to DPSS lasers. There is a possibility, however remote, that you could catch a concentrated beam of IR under the right circumstances. That's all. I'm not saying we should all freak out, just be aware. Saying that there is absolutely no chance of that happening is untrue. I have described a few possible scenarios, any of which are plausible.

Also, a lot of my concern has to do with the construction techniques used in $20 "100mW" Newwish or whatever kind of Chinese junk is around.. Their construction has improved lately from certain manufacturers, but on the whole, you just never know what you're getting.

[/quote]

 

[Hemlock_Mike]

The posts get longer as everyone makes redundant copys of what came before and it goes on and on forever so there is no end in sight for this thread if no one stops ot somewhere and I'll probably be coppied again to make this longer than ever so like you know it should stop.

Mike

 

[ElektroFreak]

Damn.. just when i was going for a personal record. Way to rain on my parade, Mike..

 

[Benm]

The posts get longer as everyone makes redundant copys of what came before and it goes on and on forever so there is no end in sight for this thread if no one stops ot somewhere and I'll probably be coppied again to make this longer than ever so like you know it should stop.

Hehe... that's what i get for just posting a picture :

 

[Deleted member 8382]

I have not done any testing, but people say ---------


I lived through many cycles since ~ 1950 ---
1. Crude oil will be gone by 1980...........
2. We are going into another ice age ...........
3. The Ozone hole will kill us all ............
4.  OMG, the Y2K bug will destroy all of us.
5.  Globule warming -- I'd love to see some of that  

What I'm saying is show me the science.  Things like IR leakage get repeated enough times to become truth and take on life.  The people who repeat these "facts" seldom have the equipment to verify those "facts".

Mike

When using a filter, something must be used to account for reflection and absorbtion of the filter.  I have an 808 nM pointer to provide reference on my filters.

Totally agree.