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ArcticMyst Security by Avery

Focusing at long distance

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Jun 8, 2014
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Hi

I have a 150mW 405nm Blu-ray Blue-Violet Laser diode and I would like to burn things at several meters (2-3 meters). The laser was sold housed in an aixiz module with adjustable lens (don't know the details of the lens).
With some calibration, I could find the distance of the target to burn so I could automate the focus on the target.
Searching on the website, I saw I would need a beam expander to focus at long distance (I got a brunton http://laserpointerforums.com/f49/super-cheap-beam-expander-86604.html to make some tries) but I don't know what is the best to put after it ? a moving convergent lens ? if yes where could I found such lens please ?

Thanks for any advice

Karim
 





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Hello Karim, a beam expander won't help you burn things at a distance, but it will help you put a smaller dot on something far away. 150mW has very limited burning ability, although 405nm is good for burning. I suggest getting something more powerful in either a 405nm or 445/450nm.

Alan
 
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true more more powerful diode needed with a beam exspander i have a Sinner Cypreus3B host with a Sinner beam exspander and adapter thats unique to that host. it burns awsome at 32ft. it has a 445nm NDB7875 3W+ diode a SXD 4.0A driver with G2. going to try a further distance.
here are some pics the hole goes thru the shirt.:drool:
i also changed the 4mm set screws to nylon tipped to avoid marking the finish on the host.
This might be rebuilt using DTR's new 6+W 445nm Big Boy diode
 

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Joined
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true more more powerful diode needed with a beam exspander i have a Sinner Cypreus3B host with a Sinner beam exspander and adapter thats unique to that host. it burns awsome at 32ft. it has a 445nm NDB7875 3W+ diode with G2. going to try a further distance.
here are some pics the hole goes thru the shirt.:drool:

It certainly looks like you believe in staying physically fit.

Alan
 
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yes like it thats only about half of my gym in the pic its sick PI R. i pick things up and put them down lol
 
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Thanks for the replies !
Ok will have to find a more powerful laser but what is the focal of the lens you use after the beam expander ?
 
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Beam expanders are set to infinity focus, but I believe some beam expanders can be adjusted to focus the beam at a distance too. Using a beam expander to burn something at a distance is working against yourself, you want the spot smaller, not wider, to increase the power delivered to a small spot. Just use a cheap telescope and focus the beam at a distance that way.
 
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yes as Alaskan said some have a focus ring on them. on mine i focus the g2 first without the exspander. Then i apply the exspander mine is the focusing type, it has a focus ring area on it. So once your G lens is focused you just focus the expander from there. In my pics its lases at 32ft. Have tested at a further distance yet but i will be doing so in time. Hope this helps you a little :))
 

APEX1

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Grab a bdr-209 16X It's a 700mw 405! burns like a bitch. But most importantly, what type of safety glasses do you have???
 
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I bought glasse on ebay for laser green 532nm, blue 445nm, purple 405nm
Many thanks for the replies
I will try to make first a setup with a not very powerful laser
 
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Hello, with that 16X 405nm laser diode, it will burn something 20 feet away with no problem using a G2 type of lens, or 3 element lens, you just turn the lens until it is focused 20 feet away to the smallest dot you can get and it's burning a hole in the wall. No need for anything more!
 
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The beam expander will be nice, but unless you focus the light back to a point it won't burn anything.
 
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Probably should qualify your question with a specific amount of power into the expander, the type of diode and what the amount of expansion is. If you have a lot of power into a beam expander and don't expand the beam very much, yes it will burn. Apparently, according to one member if you put 3 watts of blue into a 10X expander you can deliver enough energy at 30 feet to burn something but as a rule, the more you expand the beam, the weaker the beam gets and harder it is to burn something. That same expander probably won't burn something at 100 feet when using a multimode diode because even though the expander reduces the divergence, you are starting out with a fairly high amount of divergence, as lasers go, when using a high power blue multimode diode, and even with an expander, the beam spreads out much further at a distance than if you were using a much lower divergence 532nm DPSS laser.

For example, a 150 mw 532nm laser can burn something if your target is close enough to the pointer, but put a 20X beam expander on it and there is no way it will burn something. Take a 1 watt output laser and expand it to 5X, it probably will burn something, even if expanded that much. Take a 50 watt FAP laser and expand it to a collimated 2 inch wide spot and it will burn the hell out of something a long way away.... the power density is key, the amount of power and how far the beam is expanded affects the power density but the easiest way to burn something is to have a small diameter high power beam, especially if it is focused to as tiny a spot as you can get.
 
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Hi

Just got this beam expander (see picture attached) :
Laser Beam Expander - New Generation

and I use a 180 mW 650nm diode in a aixis module.

Without the beam expander, I can focus the aixis module to burn something at 10cm for example.
When I put the aixis module on the beam expander (see picture), I can not focus when I turn the first ring ...

Karim
 

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Joined
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Hi

I have a 150mW 405nm Blu-ray Blue-Violet Laser diode and I would like to burn things at several meters (2-3 meters). The laser was sold housed in an aixiz module with adjustable lens (don't know the details of the lens).
With some calibration, I could find the distance of the target to burn so I could automate the focus on the target.
Searching on the website, I saw I would need a beam expander to focus at long distance (I got a brunton http://laserpointerforums.com/f49/super-cheap-beam-expander-86604.html to make some tries) but I don't know what is the best to put after it ? a moving convergent lens ? if yes where could I found such lens please ?

Thanks for any advice

Karim
A beam expander comes in two types basically, Keplerian and Galilean. What you have made is a Galilean type likely or a refractor telescope. Focusing is accomplished by moving the lens the light comes out of in or out. It's that easy. See this video. https://www.youtube.com/watch?v=_9QotAtxrmc

The difference lens wise between the two in order as above is the first uses two positive focal lenses. and the other uses a negative and positive lens.
 
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