10 Mile Distance Laser

[wellexcel]

Wow, over 2 meters! That's amazing. I never would have guessed. Thx


That first red laser from is an O-like and if you notice in the spec says the power is <250mW. So that could be as low as 1mW which is technically less than 250mW. Stay away from lasers rated as < than anything. It suggest Bullshit marketing if you ask me. Other wise you would just give a min and state greater than that. thats how a laser should be rated.

I own a few lasers from O-like and feel they have questionable track record. I actually own a supposedly >220mW red from them but haven't put it on an LPM to confirm the output. I have metered a 405 of theirs that was grossly under spec by over 30%. The red 650 I have is this one- Power Rock waterproof Red laser torch 250mW /Focusable [OL-PRRL250] - $45.99 : Zen Cart!, The Art of E-commerce

Considering how important this laser is to your project I highly suggest not getting it from them but rather have it built or buy from a reputably seller like Jet lasers. Jet Lasers is on the higher end of prices but along with the laser you get very knowledgeable customer service that from what I hear really care about your satisfaction with the laser. That's pretty priceless. You wont find that from O-like that's for sure. But, if a 650 250mW would work it shouldn't be terribly expensive anyway. You may want to email Jet Lasers first because that's quite a distance you need to spot.
Sounds like its pretty important for this laser to work as needed. Don't go with O-like mate. Just my 2 cents from owning 3 lasers from them. They're not the company to have your projects success balanced on.

I'm not familiar with Armlaser the other link you had so can't help you there. From what I know about this community I honestly wouldn't go with anyone not vouched for by people here.

Thanks for your recommendation, i wont be going with o-like for sure and the other links dont look as promising either

I'm thinking of this 1w 650nm self-assemble kit now, its the last one so maybe i should get it before its gone

1W 638 to 650nm Red Laser Kit MX 900 Host Copper Heat Sink Focusable Lens | eBay

He's vouched here

I just don't know the aperture size but i sent him an email

I'm sure there is a beam expander that can fit it

One thing though I just read this on Armlasers site about their 2W blue laser and it gives me concern they are full of shit.
"The beam,with 50 miles range, is so bright that it can be seen from outer space! The most powerful and iconic handheld laser in the world is yours with affordable price."

Yes the space station saw a 2W blue laser flashing on earths surface in a controlled experiment but the way this is worded sounds misleading. Like the beam can be seen for 50 miles and that's absolute bullshit. Maybe you could see a flash of light from miles away but you will not see a dot on something nor a beam. The divergence of a 2W blue is too poor for the beam to be seen for miles. This doesn't sound very reputable IMO. Good sellers don't need a bunch of hype to sell their products knock off companies do. Also the wording is broken English and that says Chinese knock off to me.

LOL, yeah, definitely not ordering from those guys. The same claims are on some other websites too

 

[Shakenawake]

no, 1W 638s have the about the worst divergence of any diode hand held

 

[olympus mons]

Hmmmm, I'm not sure if that's a good choice for your needs mate. I'm not saying its a bad laser but a 1W red laser will be multimode and multimode reds are pretty piss poor beams. Plus I'm not sure what this person means by 638-650nm. Not sure why it would be a range of nm's.

I'm no expert but I do know that if your trying to have a dot at miles away you need very low divergence and 1W 638 reds are like ribbons of light rather than beams. You have been suggested the 250mW 650 because its a single mode diode I assume but I doubt its powerful enough.

Its a shame that temprature is an issue because a DPSS 532nm would really be perfect for your needs it sounds like. What you need is a powerful ass laser in either single mode, which they don't come in or a DPSS but are picky about temp. A 1W 532 with a B.E. I'm guessing could travel the distances your talking for about a thousand dollars if you could control the climate around it somehow.

Maybe ask some people here if you could climate control a labby set up somehow. Otherwise from what I have learned I'm not sure how you will be able to get a dot 10 miles away and not have the dot the size of a football field. Which many multi modes will be at that range. You really may need a DPSS to do this on your budget There are things like sodium gas lasers like are used in adaptive optics that can travel many miles and keep a tight beam but these are very expensive pieces of equipment. See below for info about these.
Laser guide star - Wikipedia, the free encyclopedia

 

[Alaskan]

I've had an interest in doing something similar myself and have been collecting large diameter plano convex lenses to build my own uber-expander. If you expand the beam enough, you should easily be able to go ten miles on a clear night and hit your target but finding a big enough lens and the right expander/concave lens to match it is time consuming, if not expensive. Although I have gotten some great deals on ebay for some large PCX lenses cheap enough, I just got a six inch diameter one this week for 25 dollars which has a 1000mm focal length, perfect for what I was planning, using a tube about 4 foot long.

To get some really large expansion, you might have to do a two stage expander, this is likely what I will end up doing with my 12 inch diameter PCX lens. Expand a 532nm laser to 12 inches diameter and it grows very little for 10 miles of travel which on a clear night, means most of the power gets to where you are pointing it, even if a relatively low power laser. If you start out with a 1.2 mRad 532nm laser, expand it through more than one stage of expansion to 50X, the beam will be close to 18 inches wide ten miles away, but probably closer to 2 foot wide expanding a more common 1.5 mRad 532nm laser. You should be able to make this work with a 150mw laser and a PCX lens of only 5 inches diameter on the final expanders output, perhaps even smaller, but I'm suggesting 5 inches so you don't use the whole aperture of the lens. If you were to make a very low loss expander with only one PCX lens, using the natural expansion of a laser diode to expand the beam enough first, by placing it far enough away from an appropriate focal length PCX lens (no expander lens needed), you could probably make this work with much less power, given clear weather, but aiming it is the problem then, the laser would need to be on a tripod and you would then need to spend quite a lot of time talking over a cell phone to the other end guiding them to the target, or chase after it once it is fixed on something.

Oh, if using a laser diode instead of a DPSS 532nm laser with a relatively low mRad, you will have to expand the beam more and thus a larger lens on the output to achieve the same mRad, since direct diodes have about twice as wide a mRad, some more. That problem and another due to multimode diodes (even the single mode 520nm diodes) have a fairly wide rectangle beam profile, harder to match up with the right lens to expand it properly because most lenses are disk shaped, not rectangles. If you are going to expand a 520nm green laser diode you will just need to use a larger diameter lens than would be necessary for a spot, as you would normally get from a quality 532nm DPSS laser. Of course, you could use corrective optics to turn the rectangle shaped output of a 520nm multimode diode into a more rounded shape, for a price; loss.

 

[olympus mons]

I
To get some really large expansion, you might have to do a two stage expander, this is likely what I will end up doing with my 12 inch diameter PCX lens. Expand a 532nm laser to 12 inches diameter and it grows very little for 10 miles of travel which on a clear night, means most of the power gets to where you are pointing it, even if a relatively low power laser. If you start out with a 1.2 mRad 532nm laser, expand it through more than one stage of expansion to 50X, the beam will be close to 18 inches wide ten miles away, but probably closer to 2 foot wide expanding a more common 1.5 mRad 532nm laser. You should be able to make this work with a 150mw laser and a PCX lens of only 5 inches diameter on the final expanders output, perhaps even smaller, but I'm suggesting 5 inches so you don't use the whole aperture of the lens. If you were to make a very low loss expander with only one PCX lens, using the natural expansion of a laser diode to expand the beam enough first, by placing it far enough away from an appropriate focal length PCX lens (no expander lens needed), you could probably make this work with much less power, given clear weather, but aiming it is the problem then, the laser would need to be on a tripod and you would then need to spend quite a lot of time talking over a cell phone to the other end guiding them to the target, or chase after it once it is fixed on something.

Oh, if using a laser diode instead of a DPSS 532nm laser with a relatively low mRad, you will have to expand the beam more and thus a larger lens on the output to achieve the same mRad, since direct diodes have about twice as wide a mRad, some more. That problem and another due to multimode diodes (even the single mode 520nm diodes) have a fairly wide rectangle beam profile, harder to match up with the right lens to expand it properly because most lenses are disk shaped, not rectangles. If you are going to expand a 520nm green laser diode you will just need to use a larger diameter lens than would be necessary for a spot, as you would normally get from a quality 532nm DPSS laser. Of course, you could use corrective optics to turn the rectangle shaped output of a 520nm multimode diode into a more rounded shape, for a price; loss.

So with all that you just said do you feel a 250Mw 650 expanded properly could actually make a visible spot 10 miles away? I'm not doubting you as you have much more experience than I certainly but its just very surprising. 10 miles!!!! I would think the light would be absorbed or scattered too much to reach the target. Or is the 650nm wavelength not as affected by scattering and absorption?

 

[Atomicrox]

A few more considerations:

-I'm not sure you gave it some thought - the beam is actually a cone and under the very best hypothesis it will have a diameter of about 40cm at the middle of the lake. More likely around 1m. This is going to make it hard to make any measurements other than seeing if it hits the target or not. And it will affect the minimum distance from the water.
-Don't buy from Olike.
-Don't buy anything above 300mW, almost certainly multimode (doesn't mean anything below is single mode...)
-532nm DPSS isn't necessarily lower divergence. Specially cheap ones. And they are unstable.
-I'd go with the 200-300mW 650nm. Lots of cheap ones on ebay/ali but you can't be sure it's a good one until you order it. Might be better to ask a forum member to build you one that will fit a BE.

-Edit - one thing I forgot - there's not way in hell you're gonna be able to see the beam sideways at that distance.

 

[starlight]

I say "hire" a forum member that lives close to your location if possible. They could provide several different lasers to try and probably get some excitement out of it also. I'd be out there helping if location was close.

 

[Alaskan]

I am leaving out an important factor in my estimations for what can be done with beam expanders, that is atmospheric losses, perhaps someone who has this info can help. Regarding spot size, if the spot is too large at 10 miles, use another stage for more expansion to reduce the divergence further (but adding more optics=more loss), worse case, you will have to up the power or reduce the distance but the question is, how much?

Who knows the average loss from impurities in the air over distance? I don't have that information to know how bright the spot would be, but I'm thinking this ought to work as I can make a fairly bright spot on a cloud deck over a mile above my head with 150mw at 532nm @1.2 mRad divergence and no added expansion. Based on that alone, my thoughts are this will work with a quality laser, optics and enough expansion. I'm not an optics guy, but I'm learning and this is the same path I'm going down too.

Here's a question I have, what is the relationship of loss through the air compared to the loss on a given sized target from expansion due to divergence? Which is worse? I think divergence takes away power much faster. I've been trying to nail this one down, I bet divergence causes more problems for a 10 mile path in reducing the power than loss from particles in the air on a dry night without dust being stirred up into the air, or smog etc.

 

[wellexcel]

Nano Series | Red, Purple, Green Laser Pointer | Wicked Lasers
100mW 650nm 0.5 mRad

Aixiz 650nm 200mW Laser Diode Driver and Case Kit | eBay
300mW 650nm Red High Power Laser Diode Module Kit with Glass Lens Heatsink | eBay

If I can get this 300mW kit then I can spend more money on a beam expander

Jetlasers,

Dear sir,
Thanks for your inquiry - to minimize the divergence and longest range, it requires both max beam visibility and minimum divergence, so i recommend 800mW 532nm green plus 10X beam expander.

Pls let us know if you have further questions,
Thanks,
Gray

Cone shape is fine because we really only need part of it to make it to the other side, and I will factor in subtracting the bulge from the final measured height. We can also try tilting the laser down at a slight angle

After reading about nwfreefly's posted laser guide stars last night, I've been thinking of renting something lab style perhaps from a local shop, but as said before if worst comes to worst then I can try this on a smaller body of water and then if the results are interesting enough, I'll decide on renting/buying expensive pieces of equipment and expanding

And yes, I'm prepared to aim it down the lake with a tripod at several diff fixed heights. I was thinking he could have a flare or something but well think about that more after I decide on a laser. I want the tripod to be in the water so it's as close to water level as possible

If I can find the lens and everything for making a beam expander then I'll just (try) to do it myself

So it's basically a telescope, aand I'm assuming that the lens and focal length must be appropriately shaped/sized for the specific wavelength and aperture of laser? I know you cant just duct tape any beam expander to any laser and expect to have good results, lol.. but if you could then I'de do it

http://www.edmundoptics.com/technical-resources-center/lasers/beam-expanders

It has more to do with the shift between hot - cold air, and the thermal boundary that meets the air + water may actually sustain the beam's path (or worsen)

Like in the case of superior mirages, when warm air is above cold, the light will travel the warmer path.. causing an object to appear higher than it is

Cold is generally better because the overall weather will be colder but it's non-uniformity that makes it bend

Here's a question I have, what is the relationship of loss through the air compared to the loss on a given sized target from expansion due to divergence? Which is worse? I think divergence takes away power much faster.

We'll find out, this is also a learning experience for me. Because the light isnt spreading as much with lower divergence, I would think that it can pierce through the air more than it could with a higher divergence, but with how much output power I have no idea

EDIT;
http://laserpointerforums.com/f44/interested-beam-expanders-91430.html

I'm reading up here now

http://assets.newport.com/webDocuments-EN/images/How_to_Build_a_Beam_Expander_5.pdf

 

[vortish]

There are a few factors that every one seems to be missing. Ten miles is long distance. and do the atmospheric pressure the beam is going to diffuse faster than people realize. That is why the Air Force Scraped there their dragon air borne laser. even up at higher altitudes the laser needs to be powerful which is why they went with a C.O.I.L laser. Which stands for Chemical Oxygen Iodine Laser. and it was good for x amount of miles. here is a article Airborne Laser System (ABL) YAL 1A - Airforce Technology and that is a ir laser. The biggest hurdle i think for this project is getting a diode laser that can cover the distance. Blue and Ir are to dangerous to use. red they dont make one in diode form that is over a couple watts. and five twenty is not powerful enough. To cover that amount of distance your going to need at least 5 watts or more. mw is not going to cover it. you could set up reduction stations every mile but I dont know if this project is possible with current generation lasers IMO

 

[wellexcel]

There are a few factors that every one seems to be missing. Ten miles is long distance. and do the atmospheric pressure the beam is going to diffuse faster than people realize. That is why the Air Force Scraped there their dragon air borne laser. even up at higher altitudes the laser needs to be powerful which is why they went with a C.O.I.L laser. Which stands for Chemical Oxygen Iodine Laser. and it was good for x amount of miles. here is a article Airborne Laser System (ABL) YAL 1A - Airforce Technology and that is a ir laser. The biggest hurdle i think for this project is getting a diode laser that can cover the distance. Blue and Ir are to dangerous to use. red they dont make one in diode form that is over a couple watts. and five twenty is not powerful enough. To cover that amount of distance your going to need at least 5 watts or more. mw is not going to cover it. you could set up reduction stations every mile but I dont know if this project is possible with current generation lasers IMO

Well, as said before. If I can rent/lease a lab device, or reduce the distance down by 75%, that could work. Maybe I naively thought that this would be possible with todays handheld lasers, but i still think it could potentially work (perhaps with just a lower distance)

There is also the 2w 445nm blue with safety goggles, I know it's dangerous but if that's my best bet (at even 2.5 miles).. Im willing to take the risk. I just wouldnt use it a lot, other than in this type of application. Infrared would require a detector I'm assuming

Otherwise, I agree, although ive never owned anything higher than 5mW, I cant see how 100-300mW would make it across, but since it's so much cheaper/safer + with a divergence of 0.5 mRad, it would be better to buy than to have negative results with the 2w 445nm 1.8 mrad

The second problem is the beam expander, with the jetlasers 2w 445nm I can just buy the full kit and be done with it

With choosing a 650nm, output power is significantly lowered and ide have to build a beam expander, but cost is reduced and divergence is 0.5mRad (wickedlasers)

There is also the 520nm but I'm not sure if they are affordable in 2w+ range

EDIT;
Couple of more finds

http://biglasers.com/red-laser-pointers

http://biglasers.com/laser-optics-kit

 

[Alaskan]

I have a JetLasers 532nm pointer with a 10X beam expander which works well, I really like their expander because the build is quality and price low compared to many other beam expanders, i.e. Wicked Laser or LaserGlow expanders cost three or more times that amount (WL has a temporary sale right now, but still more expensive). The difference a 10X expander makes is the diameter of the beam ten miles away is the same as it would have been 1 mile away without it. I've seen expanders as high as 40X, but I believe there are challenges for a single stage expander with that much increase in beamwidth. You could contact Edmund Optics and ask them for the recommended optics to build your own, but at high expense. There are a few other vendors of optics which are less cost who could help, I am sure.

I'd stay with 532nm for the project, 445nm lasers have a very wide beamwidth compared to DPSS, although you can make up for it with the right optics, likely more expensive in the long run, that and 532nm is many times brighter to the eye than 445nm, mw per mw.

 

[wellexcel]

I have a JetLasers 532nm pointer with a 10X beam expander which works well, I really like their expander because the build is quality and price low compared to many other beam expanders, i.e. Wicked Laser or LaserGlow expanders cost three or more times that amount (WL has a temporary sale right now, but still more expensive). The difference a 10X expander makes is the diameter of the beam ten miles away is the same as it would have been 1 mile away without it. I've seen expanders as high as 40X, but I believe there are challenges for a single stage expander with that much increase in beamwidth. You could contact Edmund Optics and ask them for the recommended optics to build your own, but at high expense. There are a few other vendors of optics which are less cost who could help, I am sure.

I'd stay with 532nm for the project, 445nm lasers have a very wide beamwidth compared to DPSS, although you can make up for it with the right optics, likely more expensive in the long run, that and 532nm is many times brighter to the eye than 445nm, mw per mw.

It sounds like JetLasers is one of the top picks. I'm almost ready to buy the 445nm or 532nm from them with their beam expander

The customer rep for wickedlasers just sent me this youtube video

https://www.youtube.com/watch?v=V8Gex8S6Rjw

They covered 7 miles in the city with heavy light and air pollution using a 2w 445nm WITHOUT a beam expander! The lakes I had in mind are going to be much darker and emptier than this, and i still intend on getting the expander

So with 532nm being more perceivable than 445nm, but scattering more, would it still make a better option? Visibility is not much of an issue if its going to look like this video

It's come down between Wickedlasers or Jetlasers, JetLasers is cheaper but wickedlasers has a sale + claim that they arent selling them after tomorrow to the USA (and the customer service is great so far)

I still would want to build an ultra expander one day for other projects, but I'de like something already made and simple to work with first so I can get a good feel for this

 

[Encap]

are you forgetting geographical visability --- a person of average height can see almost three miles at sea level, actually 2.8 nautical miles to be exact. However, that answer assumes that the person's eyes are at six feet above sea level and the conditions are near perfect. Geographical visibility—refers to the distance at which any object can be seen. This distance is limited by the curvature of the earth, and it's greatly influenced by height. Of course atmospheric conditions will also influence this distance, but the above assumes they are perfectly clear: no clouds, no haze, no smog.

To be able to see something 10 miles away at sea level either source or object would have to be 75 feet above sea level.

See: http://navyadministration.tpub.com/14220/css/14220_106.htm and http://navyadministration.tpub.com/14220/css/14220_108.htm also http://www.usc.edu/dept/LAS/arc/ugaritlight/ugarit/Pages/The%20Investigation/Geographic%20Range%20of%20Visibility.htm

 

[Alaskan]

My assumption was he would be at height, no way can you get that far without one end or the other being elevated. Being one end is a lake, that leaves the origin end needing a high spot. I believe WL are out of high power 532nm lasers, at least, they said out of stock when I looked a couple of days ago. WL are probably more stable than JL, but you pay for that too.

 

[wellexcel]

are you forgetting geographical visability --- a person of average height can see almost three miles at sea level, actually 2.8 nautical miles to be exact. However, that answer assumes that the person's eyes are at six feet above sea level and the conditions are near perfect. Geographical visibility—refers to the distance at which any object can be seen. This distance is limited by the curvature of the earth, and it's greatly influenced by height. Of course atmospheric conditions will also influence this distance, but the above assumes they are perfectly clear: no clouds, no haze, no smog.

To be able to see something 10 miles away at sea level either source or object would have to be 75 feet above sea level.

See: Visibility of Lights - 14220_106 and Visibility of Lights, Continued - 14220_108 also New Page 0

This is exactly what we're testing for. As said before, this will be done at many different fixed heights above water level. I've gone through terrestrial refraction and horizon distance formulas with them factored into it, those will be put to test as well

There is a difference between a visible horizon and a physical geometric horizon in respect to a given distance, and in this case it is not a 75 foot physical geometric bulge due to the curvature of the Earth (for a 7.5 mile lake, its about 9.5 ft)

We are going to find out more about the curvature and horizon in this experiment

I predict that the laser will reach the opposite side of the shore at a height less than what the predicted bulge should be (so we will also see if its really 75 ft).
What height it stops reaching the other side at is what I would really like to know.

If it could reach across at say 10cm above water level, that would be significantly amazing.

I'm most likely going to order the 2w 445nm with expander tonight from jetlasers after seeing a wickedlasers version perform in the city with severe light and air pollution, so if anybody wants to stop me now is your chance