How do I reduce the divergence?

Does anyone here know how I can reduce the divergence in a elegant way? A one foot radius spot at 1km is quite annoying.. makes the LASER seem more like a searchlight thatn a LASER

Yea, Instead of spending $60-$600, buy one that costs $12,000-$25,000. You have to spend the big buck for such specs.
Why is it annoying, 1km is a rather long distance and if it were only a few mm diameter as it was when it left the laser, you would probably not even be able to see it from a km away.

Jack

Instead of slamming posters with acquisitions, lecturing them for "thinking bad thoughts", then spinning off into a wild tangent about FBI agents making crank calls to your walmart cellphone-- lets just stick to answering their question in a matter-of-fact way. We aren't the thought police, ya know.

Note that 1km can be acheived using mirrors, too. No laws broken there.

marv: beam divergence is one of those factors that drive up the cost of the optics exponentially.

Hi Racoon,
Your right, I'll edit that out of my post. I'm just still a little steamed about some nut in my area pointing at a home and me getting called on it along with a threat of having my stuff confiscated next time.
By the way, I like and compleatly agree with your signature. It is just not quite what Ben quoted, here is exactly what ben said...
"They that can give up an essential liberty to obtain a little temporary safety,
deserve neither liberty nor safety" (Ben Franklin)

pretty much the same though, and very true. I guess the actions of the past few years show we don't really deserve either liberty or safety.


Jack

I have no idea what you mean by elegant. What do you mean?
The simplest way is swapping the collimating optic for one with a longer focal length. There are some postings on this subject at Wickedlasers[WL] pages 2,3,4 that will answer your question. If you live in the US you can purchase a lens(es) from www.edmundoptics.com. Ask for free catalog. They have a wider selection than other companies. I'd would buy an anti-reflective[AR] coated lens like MgF2, better yet is VIS 0. The optics used in pointers are probably uncoated and you may be loosing as much as 4% per surface do to reflections. If memory serves an expanded beam can be focused to a smaller spot.That would require another lens like a BI-Convex.This would be useful if you are of a mind to burn things. A setup like this would use a Plano-concave or Bi-Concave, Plano-Convex, then a Bi-Convex. Sorry I digressed.
In my pointer I use a 48mm focal length PCX lens, this gives a divergence of approx. 0.18mrd or a beam width at the lens of 7mm. I measured the diameter out to a distance of 1500 centimeters[49.21feet] and it is still 7mm. As you may be starting to realise optics and beam characteristics are just as important maybe more so than just power output alone. The diameter of my lens is 12mm. Take a look at the post at WL titled "Impressive"

This is a bit of an aside, but along the same lines er vectors.
I know, NEVER shine a laser pointer at critters, humans included, but...
I hope pen sized greens could be safely used as a rescue locater device as they fit so well in survival/emergency kits. I'm thinking a sort of road flare thing without the need for fire. Imagine floating in the North Pacific or huddling in a snowy mountain forest for several hours/days while Search and Rescue craft pass you by and by and by. What if you could flash them with a mirror or something? What if it's nightime or cloudy? Have laser pionters been evaluated or used for this purpose yet??? What is the safe distance for the standard =5mW 1.2-1.5 divergence for flashing a beam briefly at critters to get attention? Would a =5mW green get attention at ? miles? Are there water-resistant, insulated models yet. How bout a 'high power' with greater divergence to guide them right in? Is this as stupid as my last post?

There are those laser flare thingies, I think Greatland makes them. Supposedly there's a greenie in the works. It's mostly designed to signal aircraft from the wilderness.

Of course, if you've got AAA batteries in enough quantity to do that, you're okay. If I were in my car, I'd just grab for Thor, it'll throw a beam far enough to see pretty easily. .