Small Dot Size at Variable Long Distances

[PoincareBendixson]

Hi all,

I'm currently undertaking a (very much DIY!) long range laser positioning project and would appreciate some guidance. Optics are unfamiliar territory for me!

Is the following possible given my requirements:

- Ability to place a small laser dot (visible spectrum and <3mm diameter) at distances 30-200m
- The solution laser-optics system to be in a small physical package (think handheld)
- It's okay if the system has to be refocused if the distance changes.
- Should be less than $50 - cheaper is better
- Ideally low power output - ideally eye safe.

I've ordered a cheapy focusable laser 303 just to get me going - do you think I could get results at 30m with this ie a <3mm dot?


As I said any help is appreciated,:beer:

 

[Accutronitis]

Hi all,

I'm currently undertaking a (very much DIY!) long range laser positioning project and would appreciate some guidance. Optics are unfamiliar territory for me!

Is the following possible given my requirements:

- Ability to place a small laser dot (visible spectrum and <3mm diameter) at distances 30-200m
- The solution laser-optics system to be in a small physical package (think handheld)
- It's okay if the system has to be refocused if the distance changes.
- Should be less than $50 - cheaper is better
- Ideally low power output - ideally eye safe.

I've ordered a cheapy focusable laser 303 just to get me going - do you think I could get results at 30m with this ie a <3mm dot?


As I said any help is appreciated,:beer:

Many people here will be able to help you understand what is needed or even possible BUT a small physical package, hand held, 3mm dot at 200m for under $50 ??? You have a lot to learn...... :beer:

Hey why not shoot for the moon ? lol Nothing wrong with dreaming BIG !

 

[BobMc]

Welcome to the forum, just a thought you might want to make a post in the welcome section to say "hi" and introduce yourself.

If I understand you correctly you want 3 millimeter dot at 30-200 meters. The distance is no problem for any 301-303 laser you can buy on eBay. It the 3mm, that is a awful small dot, don't know if that's even possible even with a high dollar Beam Expander, your talking 0.118th of an inch in diameter. Best wishes, but I'm scratching my head on this one. If I can ask, what do you need such a small dot for. ?

Anyways welcome again.

 

[PoincareBendixson]

Thanks all.

Without too much unnecessary detail, the laser will be striking a sensor with a small aperture. I need the laser diameter to be comparable in magnitude to the aperture size.

 

[Accutronitis]

Thanks all.

Without too much unnecessary detail, the laser will be striking a sensor with a small aperture. I need the laser diameter to be comparable in magnitude to the aperture size.

Is this to trigger a bomb at a distance ?

Sorry is that question out of line ? Maybe some detail may be necessary ?

To get 3mm at 200m the beam is going to need a lot of expansion and beam expansion done well is never cheap.....

 

[PoincareBendixson]

Is this to trigger a bomb at a distance ?

Definitely not. It's a project to physically position two bodies (yawn!).

It sounds like the dot size I'm asking for isn't achievable at least at my price point. Maybe I should lower my expectations and see what I can do within my budget...

What beam expansion devices are available for <$50? Can I retrofit to my laser 303 or do I need to start buying specific lasers?

Cheers!

 

[paul1598419]

The cheapest BE around is $55.00 and is available from Sanwu Lasers, IIRC. You can get the same BE from laserpointerstore.com for $60.00. They only go up for there.

 

[BobMc]

The cheapest BE around is $55.00 and is available from Survival Lasers, IIRC. You can get the same BE from laserpointerstore.com for $60.00. They only go up for there.

Survival Lasers doesn't sell BE's. Think Paul made a typo and meant Sanwu Lasers. Life happens,

https://www.sanwulasers.org/product/x3beamexpander

If you get a BE you just might be able to find a inexpensive laser that their BE will fit on with their adapter.

https://www.sanwulasers.org/product/adapters

Just maybe???

Still don't know if you can get a 3mm dot but you'll get closer.

 

[paul1598419]

Yeah, it was a typo. It happens. I was thinking it might be wrong when I posted it.... thus the IIRC.

 

[BobMc]

Yeah, it was a typo. It happens. I was thinking it might be wrong when I posted it.... thus the IIRC.

No sweats, I call it having a senior moment, happens to me all the time.

 

[lasersbee]

Thanks all.

Without too much unnecessary detail, the laser will be striking a sensor with a small aperture. I need the laser diameter to be comparable in magnitude to the aperture size.

There is no such thing as unnecessary detail when
looking for help. You have not supplied enough details
on your project for us to know why you absolutely
require a 3mm Laser Dot size at 200 feet and no other
size will do the job.

Garbage in = Garbage out

[EDIT]
That was 200 meters... not feet.


Jerry

 

[CDBEAM777]

W H A T ????????? Let's speculate !!!

2mm geometry at the Nearfield
3mm geometry at the Farfield ( 200M )

The divergence on such a beam....would be....0.005mRad

:crackup:

Is such divergence even possible....at any price ???

Would a BE even deliver this 3mm @ 200 clicks ??...and if it could...mmmm??
the protective cap would cost $50 !!! Sorry...if this is a real quest.....I must say......Getta bigger aperture !!:thinking::thinking: :san::san:

Sorry.....I do not mean to be rude...or dismissive....just....realistic !!
Good luck !! :beer:

CDBEAM

 

[10fenny]

I love this forum!!!
But yes please give more details of what's going on here.

 

[steve001]

Hi all,

I'm currently undertaking a (very much DIY!) long range laser positioning project and would appreciate some guidance. Optics are unfamiliar territory for me!

Is the following possible given my requirements:

- Ability to place a small laser dot (visible spectrum and <3mm diameter) at distances 30-200m
- The solution laser-optics system to be in a small physical package (think handheld)
- It's okay if the system has to be refocused if the distance changes.
- Should be less than $50 - cheaper is better
- Ideally low power output - ideally eye safe.

I've ordered a cheapy focusable laser 303 just to get me going - do you think I could get results at 30m with this ie a <3mm dot?


As I said any help is appreciated,:beer:

The only way I see to do this is with a Galilean variable focus beam expander. Uncoated antireflective (AR) lenses could do the job. AR coated lenses are much more expensive. Custom choosen lenses will be needed.

 

[lasersbee]

Hi all,

I'm currently undertaking a (very much DIY!) long range laser positioning project and would appreciate some guidance. Optics are unfamiliar territory for me!

Is the following possible given my requirements:

- Ability to place a small laser dot (visible spectrum and <3mm diameter) at distances 30-200m
- The solution laser-optics system to be in a small physical package (think handheld)
- It's okay if the system has to be refocused if the distance changes.
- Should be less than $50 - cheaper is better
- Ideally low power output - ideally eye safe.

I've ordered a cheapy focusable laser 303 just to get me going - do you think I could get results at 30m with this ie a <3mm dot?


As I said any help is appreciated,:beer:

How would you even align a 3mm Laser Dot onto
a target at 200 Meters :thinking:
Not to mention the false triggering when the 3mm
dot goes onto and off the target due to terrestrial
vibrations from passing people and vehicles.

Been there... Done that.

Jerry