hello all ive just registered as i need some help

[laserhelp]

i just need a little help and i thought you is the place to come.

im woundering if its possiable to get a laser that is adjustable to upto around 40-50mm beam and it needs to shine a minium of 50yds.

 

[Trevor]

What you want is a beam expander. What are you willing to spend? Commercial ones aren't cheap... might want to look into building one yourself if you're patient enough.

-Trevor

 

[laserhelp]

what will i need? ive got soldering gear

 

[Trevor]

You'll need to pair a short focal length lens with a much longer focal length lens. The ratio of these focal lengths is the expansion factor.

-Trevor

 

[laserhelp]

ive got a old air rifle scope, the end lens screws off. could this be used?

 

[Trevor]

Well... you could try. Monoculars work too.

I've got the lenses here somewhere to build a 22x expander. Never got round to it.

-Trevor

 

[laserhelp]

laser wise what should i look be looking at? i dont want to spend alot of ££ (as it might not work) and i really could do with it being green

 

[Trevor]

Well... any module should do really. You could probably even make it work with a 5mW module.

If you use a 20x expander, you'd have a 20-30mm beam and ridiculously low divergence. This would give you a pretty easily visible dot at range at night.

What is this for?

-Trevor

 

[laserpyro]

Don't mean to be rude trevor but he hasn't actually stated the use of such a laser why not get one which is readily adjustable focus.

 

[laserhelp]

im looking to try and make something along these lines without the major cost of the unit.

ND3 Green Laser Designator for Military, Law Enforcement and EMT | Laser Genetics

 

[Trevor]

Don't mean to be rude trevor but he hasn't actually stated the use of such a laser why not get one which is readily adjustable focus.

He needs a tight beam at range. You don't get that with your run-of-the-mill focusable laser. A cheap Chinese focusable laser will not cut it.

im looking to try and make something along these lines without the major cost of the unit.

ND3 Green Laser Designator for Military, Law Enforcement and EMT | Laser Genetics

I figured. A module with a beam expander is just what you need. You could probably get away with a 10x expander. That would give you a 15mm beam or so at the aperture, and a 20mm beam by the time you get to ~50m out.

-Trevor

 

[laserhelp]

so how much would module + beam expander cost together?

 

[Trevor]

It depends on the quality of module you want.

If you want to get the expander affordably, you'll need to build it. There's a calculator out there somewhere that will help you pick lenses... let me see if I can find it.

Building an expander will require mounting optics in some sort of tube and mounting them to the module.

-Trevor

 

[laserhelp]

a £20 module be any good?

 

[Trevor]

Probably. Link?

You want something that's going to stay relatively stable, is well-heatsinked, and will stay in TEM00 generally.

The device you linked is purpose-built for firearms and is self-contained and gun mountable. The cost and effort involved in building something similar is going to add up quick. Make sure you consider that before diving in. ><

-Trevor

 

[laserhelp]

i havent got a link it was a question. ive come on here to see if its possiable and what cost it would be at before i started thinking about doing it hahah.

the idea is for to be gun mounted like that unit, but without the £200 price tag