Beam divergence problem of high-power pointer.

[wintermute]

A normal Leadlight has a beam divergence of <1.2 mrad correct?

Well someone I know got a laser pointer which tested at 54.3mW using the green LED method. Here's the thing, at 3m the divergence is 14mm, and at 6m the divergence is 28mm. If you extrapolate these numbers to 10m it would test 46-47mm, so 4.6 mrad or so. Does this seem a little excessive to anyone else?

So assuming that the collimating lenses aren't in a good position, and the fact that they don't want to take apart their 1 day old $330 pointer, they go to the vendor. The vendor responds:

"Our units are not the same as before and I do think the specs listed in the products are incorrect for divergance. We had to increase the divergence slightly to make this laser less viable for airplane targeting. The difference will not be noticable in regular use."

Does this sound flaky to anyone else. 4.6 mrad seems quite excessive to just reduce the usefullness to "lase airplanes", I think that the vendor's response is more likely a very poor excuse for a bad pointer, or worse yet a bad trend for a whole new series of pointers.

What do all of you think? /ubbthreads/images/graemlins/confused.gif

P.S. bootleg2go, if you want to copy your reply here, please don't hesitate.

 

[Lasernerd]

Do these units have a set screw for focus adjustment?

 

[wintermute]

No. These units look remarkably similar to a <5mW Leadlight pointer. Although they are Class IIIb laser devices, they don't really comply with Title 21.

 

[bootleg2go]

Hi Wonka,
I think they are talking a lot of bull, if you read my post over there on the subject...if they didn't delete it you would see. They have not adjusted the divergence for aircraft...if they were even concerned about the law at all they wouldn't be selling them period. From what I've the read the divergence is a function of two things, the 1st being the wavelength of the laser which is going to change and is 532nm and the other is clear aperture, here is the link to the calculator.
http://www.us-lasers.com/beam_divergence.htm
I would think that a badly focused laser could have some affect. I think it was a pretty dumb thing for them to say that they are doing this because if they really could, why would anyone want to buy from them. I sure wouldn't want to spend a bunch of money on a high powered laser that was crippled by such an adjustment. Plus it does not explain why some are working just fine...right? I thin they are just shipping these things out as fast as they can and not taking the time to both verify their output as well as the quality of the beam. I guess it really doesn't matter as long as they honor their initial warranty and take back the bad ones.

Jack

 

[bootleg2go]

One more thing,
These leadlights were not designed to be pushed and overdriven to these high levels, they were designed for 5mw or less and the 1.2mrad rating could be valid only when operating at that low level. I not sure about this, but it is a possibility.

Jack

 

[wintermute]

[ QUOTE ]
bootleg2go said:
I think they are talking a lot of bull, if you read my post over there on the subject...if they didn't delete it you would see. They have not adjusted the divergence for aircraft...if they were even concerned about the law at all they wouldn't be selling them period.

[/ QUOTE ]
You don't have to convince me, I am sure that they're making things up regarding this matter. I'm just trying to get other people's opinions on the matter.

[ QUOTE ]
bootleg2go said:
I guess it really doesn't matter as long as they honor their initial warranty and take back the bad ones.

[/ QUOTE ]
That's the real problem here, the person who owns the laser contacted the vendor about the problem to try to send it back, and the vendor refused and stated that the beam divergence was on purpose.

Edit: wording.

 

[bootleg2go]

They will take it back according to their website, I quote.

"If you are not satisfied with our laser, you may return the laser within 7 days for a full refund minus shipping costs and a 0% restocking fee. You may return the laser for any reason between 7 and 45 days for a full refund minus shipping costs and a 15% restocking fee."
As long as he called or emailed them about it within 7 days of delivery he should be fine, and even if it went beyond he only has to pay a 15% restock fee; which is not bad considering the alternative is basically a $300 flashlight.

Jack

 

[Kiessling]

1. Please no foul language as minors read this forum.
2. The way this was worded and the direction it takes ... IMHO this thread would be better placed in Cheers'n'Jeers. I'll leave it here for now though.
3. talking about an unknown vendor seems a little funny.

I see big potential for a trainwreck here ...

bk

 

[LaserMod]

Come on guys as Kiessling said. I don't want to see anymore locked threads too soon. We were doing fine...

This appears to be yet another continuation of a now well known dispute...

I can't understand why the divergence would be different. I know the focus if set wrong can produce some strange results...sometimes as much as a tight-beam flashlight. True they are now a 9mm diode...the new divergence might be down to a new MCA with a greater surface area. The older MCA's will NEVER take 500mw of IR beleive me. If it is down to a greater surface area... great.

What is the stability like bootleg?

 

[bootleg2go]

I'm sorry lasermodifier,
What are you referring to when you said?
"What is the stability like bootleg?"

 

[bootleg2go]

Hi Lasernerd,
When you take out copper/brass laser assembly, the silver endcap that gets pressed into the tube can be unscrewed from the laser assembly. Then when you look inside you will see the lens in a black lens assembly that is threaded into the laser assembly. This is usually locked in place by soem hot-melt glue or something. You need to cut away the glue on the threads, after you do this black lens holder will screw in or out and that adjusts the focus. After you get it just right, then use something to lock the thread again so it doesn't move.

Jack

 

[comozo]

To collimate the beam correctly you must sight on a distant surface or if you have the cash buy a Shear Plate Interferometer. If you do collimate using a distant surface you'll need one of two things, one is a spotting scope which will enable you to see the spot or a friend at the distant location to tell you when the spot is smallest. I use an object that is about 1000 feet distant. This is the formula for divergence.
4*wavelength divided by
3.14*beam diameter

To use Sam's Laser FAQ formula, the units have to be the same
for the wavelength and beam diameter.
So, if we are using nanometers, we use the
fact that 7 mm is 7,000,000 nm:
4 * 532 nm = 2128 nm
3.14 * 7,000,000 nm = 21,980,000 nm
or 2.198 * 10^7 nm
2128 / 2.198*10^7 = 9.7 * 10^-5
So the beam divergence would be 9.7 * 10^-5 radians,
or 0.097 milliradians (abbreviated mr)

If I change the beam diameter to 70 and Pi to 314 I get the same answer.
Like this:
4*532= 2128
314*70 = 21980
2128 / 21980 =0.096 millirads

 

[LaserMod]

Bootleg, you should be able to loosen the focus control with a sharp turn - it usually works. /ubbthreads/images/graemlins/smile.gif

I was referring to the stabilitity of the pointer am I right is assuming it is 70 or 80mw? I was just wondering what the stability of the pointer was like i.e. do you get straight full power whe you turn it on or does it need to warm-up. I was also wondering if there are any flickers during operation and what power you estimated it to be at after 1min of use? /ubbthreads/images/graemlins/thumbsup.gif

 

[Spec]

I read the "sellers" comments as unbridaled paranoia.

Pop the pointer and rotate the collimation ring forward or back and see if that squares the unit if the manu is "unable/unwilling" to take care of this.

Thats a joke. 4.6 mrad for "safety" Bah. Ill do it for your friend if theres a problem. Ill even measure the unit.

 

[bootleg2go]

Hi LaserModifier,
The laser with the divergence problem was not mine so I don't know. It belonged to someone over at the wickedlaser forum. My laser however is pretty unstable, I'm getting about 40mw right when it is turned on, but within seconds the output begins slowly dropping off.

Jack

 

[LaserMod]

Oh right, sorry /ubbthreads/images/graemlins/ohgeez.gif

So is that an ext-40mw you have there?

 

[bootleg2go]

What do ya mean by ext-40mw?
It's 40mw as measured by using the LED and ampmeter on my glp-110. removing and shorting the 102 resistor to the right of the pot boosted it from about 25mw to 40 or so, but like before the latest mod, power output quickly drop off. Any ideas?

Jack

 

[LaserMod]

Will post in GPL-110 Modification thread... /ubbthreads/images/graemlins/smile.gif