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Long distance ~2km invisible laser

Encap

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Dear all
With due regards, please de-link the purpose from requirement. We just focus on laser the way it is required. Rest of the ballistics,delay etc, I can manage. Big issue is LASER.
Regards.
What size dot/spot do you imagine you want at 2km distance?
 

Alien Laser

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I was thinking your making a laser IR sniper you need to place a sing next to your house Warning IR Glasses Required, even if you do make it i don't think you will be able to see the IR Dot in 2Km in the distance in day time, in night time you may see it from a helicopter using a camera kind complicated i have a IR laser and i can only see it at 20/25F, I never use it will post pics at the distance i can only see it using a cell phone ! :undecided:
 

sotic

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Encap
A spot size of max 5mm would be ok for this project at 2km.
Alien Laser
We have a target system which can sense the IR signature and convey us remotely where the shot has hit. So, visibility is not an issue.
 

Encap

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Encap
A spot size of max 5mm would be ok for this project at 2km.
Alien Laser
We have a target system which can sense the IR signature and convey us remotely where the shot has hit. So, visibility is not an issue.
5mm?

Contrary to popular imagined properiies, all laser beams diverge with distance, so don't expect the beam to remain the same size as it was when it emerged from the laser.

Beam divergence (mRad) is a measure of the spreading of the beam with distance.

At long distance a typical good quality 532nm green laser with 1 mrad divergence makes a 'spot' with a diameter of 1m per 1km distance---diameter of spot increases by 1mm per 1meter. So at 2km the spot/dot would be 2 meters.
Depends upon wavelength also but you get the idea

So if you want a 5mm spot at 2km you need a laser with a 0.0025 mRad divergence.

Neglecting divergence due to poor beam quality, the divergence of a laser beam is proportional to its wavelength and inversely proportional to the diameter of the beam at its narrowest point. For example, an ultraviolet laser that emits at a wavelength of 308 nm will have a lower divergence than an infrared laser at 808 nm, if both have the same minimum beam diameter. So "invisible" IR say 980nm or 1064nm will have a higher divergence than say 532nm---the higher you go in wavelength the greater the divergence.

As an example, a 1064nm IR beam from a Nd:YAG laser with perfect beam quality (M2 = 1) and a beam radius of 1 mm in the focus has a half-angle divergence(radius) of 0.339 mrad = 0.019°. So spot/dot (diameter) of a laser beam with minimum half angle divergence of .339mrad that can be theoretically achievable at 2km would be about 678 mm .

I think you are SOL for many reasons need to reconsider your conceptualizations.
 
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Dear all
With due regards, please de-link the purpose from requirement. We just focus on laser the way it is required. Rest of the ballistics,delay etc, I can manage. Big issue is LASER.
Regards.
Look, a number of us are gun enthusiasts here and it is understandable that at times it is necessary to reach out and touch somebody... quietly.

Tesla gave my grandfather the plans for his death ray before he died. My grandfather gave them to me for safe keeping. I would not mind sharing that with you if it would help you in your mission.
 

Alien Laser

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you could try a 405nm will a 405nm work tare have a very small divergence in distance ! then IR i think !
 
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try an IR laser diode, single mode, and use the longest focal length lens you can find. you will not get 5mm at 2 km, but you can get close. i think you would be better off, as others have said, with a blue or violet diode, since they have lower divergence due to their wavelength, and the shooter would likely not see the dot if it just flashed momentarily.
 
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Encap
A spot size of max 5mm would be ok for this project at 2km.
Some theoretical math.

An ideal Gaussian beam at 1064 nm [a good quality beam can be generated at this IR wavelength] with the waist diam 5 mm will spread to ~0.5 m beam at 2 km. Your real case is reverse - you need to expand your beam to ~0.5 m and than focus to 5 mm at 2 km. A 0.5 m beam will require a huge optics.

Decreasing requirement for the spot to ~50 mm, optics become ~75 mm. It's a manageable size.
 

sotic

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Dear all
Please help!
lazeristasUVISIR
Yes,the requirements can be relaxed, if optics are so difficult to achieve. For 50mm spot@2km, is there any commercial solution available?

regards
 

Alien Laser

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Use a telescope insert the laser in i have a telescope 90mm lenses i will try it for fun using the 405nm, :thinking:
 

Encap

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Dear all
Please help!
lazeristasUVISIR
Yes,the requirements can be relaxed, if optics are so difficult to achieve. For 50mm spot@2km, is there any commercial solution available?

regards
Go back as reread posts #20 and #24.

You do not seem to "get it" ---you don't comprehend what experienced and knowledgeable people are telling you.

Because of your lack of knowledge of and about lasers, laser beams and spot size, in your imagination you thought that there could be an invisible laser that would produce a spot size of 5mm @ 2km. Such a device only exists in your imagination. There are no laser systems commercial or non-commercial that can do this. Now you want 50mm @ 2km.

No -- there is no commercial solution or non-commercial solution. There is no specification, call, or requirement for anything even remotely close to what you want/need for your application.

It is very doubtful that even a specialized research and development project established to create a laser system, at any price, specifically for your application would be successful, even with a large bulky stationary/fixed position mounted laser system and optics much less with anything portable that could be mounted on a rifle to simulate a bullet fired from it at a target 2km away.

Here is a good diagrams/images that will allow you to better understand the nature of laser output: https://www.google.com/search?q=laser+beam+divergence+and+spot+size&sa=X&rlz=1T4FUJN_enUS494US494&biw=1350&bih=535&tbm=isch&tbo=u&source=univ&ved=0ahUKEwj43OjV_b7KAhUDVT4KHcZhBUAQsAQITA

See: https://www.rp-photonics.com/beam_divergence.html

and http://vlab.amrita.edu/?sub=1&brch=189&sim=342&cnt=1
 
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sotic

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Ricker
Thanks for citing a nice product! I am in contact with jetlasers.
Can you tell me if I am correct if I say that 10x beam expander with PL-E Pro 808nm laser will give a spot size of 230mm at 1km.
I am using this article to calculate.
http://www.edmundoptics.com/technical-resources-center/lasers/beam-expanders/
Encap
I am sorry in case my lack of knowledge is hurting you and other members here. I am spending money...so i wanted to be extremely sure that right solution comes and I have also relaxed my spot size requirements. If you click the link I have given to Ricker, you will understand that I have acquired some basic knowledge also.

regards.
 

Laser Chick

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Hi sotic, please realize that your original request was equal to wanting a 2 year old child to pick up a bowling ball and throwing it the length of a football field or wanting them to pick up a HK416 and hit a dime at 2km 30 out of 30 times within 5 seconds. It ruffled some feathers for sure because unfortunately we have people come on here frequently and request impossible things.
Good luck with your project!! :beer:
 

Encap

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Encap
I am sorry in case my lack of knowledge is hurting you and other members here. I am spending money...so i wanted to be extremely sure that right solution comes and I have also relaxed my spot size requirements. If you click the link I have given to Ricker, you will understand that I have acquired some basic knowledge also.

regards.
You are not hurting me or other members, nothng of the sort---just attempting to let you know the key piece of technology that will enable your envisioned system to function only exists in your imagination. Everything is possible in imagination, not so in the real world.

My point was---no need to waste money chasing an imaginary laser system that doesn't exist

Example: the theoretical minimum physically possible divergence of a diffraction limited 1064nm laser ---a 1064-nm beam from a Nd:YAG laser with perfect beam quality (M2 = 1) and a beam radius of 1 mm in the focus has a half-angle divergence of only 0.339 mrad = 0.019°--this means the spot will increase in size by .339mm every 1 meter---339 mm every 1000 meters, so 678mm at 2000meters. This is an ideal theoretically possible minimum divergence --not something you can buy in the real world.

A JetLaser PL-E Pro,1.5W, 1064nm handheld has a 1mm diameter beam and divergence of approx. 2mrad--this means the spot increases in size by 2mm every 1 meter, 2000mm at 1000 meters , and 4000mm at 2000 meter---with an ideal 10X beam expander you would get a spot that is about 400mm at 2000meters.
(PS the JetLasers 808nm, which is still visable to most people as a pinkish dot, has a 3mm beam and approx. 2mrad divergence)

There is no laser or laser system commercially available anywhere that will fit your application--nothing that will make an invisible(1064nm) 5mm spot @ 2km nor anything that will make a 50mm spot @ 2km which could conceivably be mounted on a rifle to simulate a bullet fired even if a valid simulation were possible.

As an example: I spoke with Newport who make optimized for 1064nm beam expanders---none of these beam expanders --nothing they make will do what you want. High-Energy Laser Beam Expanders

In any case good luck in finding a way to make your project a success. You might want to have a look at what Tracking Point has done which reportedly allows a person to hit a target at .75 miles moving up to 20mph http://tracking-point.com/precision-guided-firearms/precision-guided-bolt-action-338-lm as well as their other products.
 
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