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Meanin of beam expanders

Laha

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I have been doing some searching on the forum about beam expanders. Could you guys just give me a short feedback if I understood right?

With a beam expander one can decide how far one places the focus point of the laser beam. The higher X you have (like 10x or 20x) the larger distance you can have your focus point from your laser, but it also means like in case of a 30x beam expanader the shortest distance of your focus will not be so close to your unit.
 

lasersbee

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You got the basics of it....
I see that you have done your research...:gj:

Jerry
 

Laha

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Thanx, the next step is to get one! I wonder what my RPL 425 would do with it... Probably quite high burning power and for that a 3x would be enough. 10x would put the focus too far... just assuming though..
 

Laha

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I also saw a Melles Griot 10x. Last week it was for $199, but nobody seemed to be interested and now the seller went down to $185. May be I wait a little more. Anyway perhaps a 3x would be more humble, but more useful..
 

BShanahan14rulz

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Beam expanders have always confused me.

They decrease divergence; ok.
They increase beam diameter; ok.

Now, I think of divergence as just what it sounds like, but now I am wondering, changing the focus of a focusable laser, that is just changing the divergence?

So since my laser is focusable, I really don't have any use for a beam expander? Whereas my dpss laser pointer that isn't focusable would benefit from a larger beam diameter and hence a lower divergence?

I also hear you can use binoculars as a beam expander. What about a scope?
 

Laha

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I think I red here in the forum that scops can be used to make an expander too, however I am really not an expert.
 
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Well, if your laser is focusable, you can probably archive very low divergence values, but even then, it still diverges. Use a 10X beam expander and it will be 10x lower, it's that easy.

@laha:not only scops, any binocles, scopes, telescopes... Those "beam expanders" are just "very specialized" systems with AR coatings and such, not a big deal. I use a monocle and it works like charm
 

Laha

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Well, if your laser is focusable, you can probably archive very low divergence values, but even then, it still diverges. Use a 10X beam expander and it will be 10x lower, it's that easy.

@laha:not only scops, any binocles, scopes, telescopes... Those "beam expanders" are just "very specialized" systems with AR coatings and such, not a big deal. I use a monocle and it works like charm
Wow, do you thik I could make one for my RPL 425 it's probably not easy..,
 

Meatball

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A beam expander increase beam diameter and decreases minimum divergence. That is just a simply indirect relationship to follow. The focus adjustable models will allow you to focus at some pretty incredible distances. A dozen meters away for some. These don't cut out very much power either (if the expander was designed for your model), so burning at large distances becomes easy. Even simply pointing a couple hundred feet away becomes easy.

Look for at least a 5x.
 

steve001

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With the wrong type of Anti-reflective coating on the optics will result in a loss of light. So, make certain the expander has the appropriate coatings. In other words make sure the expander is designed for the wavelength of your laser. In other words don't buy an expander designed for red light if you have a green light laser.
 
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If you're trying to burn at 100 feet, then get a proper one. If all you want is to project a decent dot at 100 feet, get a cheap binoculars and you're done. You can even use the other half to look at it lol
 




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