Beam Expanders Explained

Hey everyone, I know there are many threads out there already talking about beam expanders, but after doing multiple searches and looking at over a dozen threads I couldn't find anything explaining WHY beam expanders are so great. I think making a thread on this could help alot of people like me who are fairly new to high powered/class IV lasers and who are confused by beam expander's pros and cons. I have also spoken to now 2 people on this forum who are also confused about beam expanders benefits and negatives so I think it is time to start a thread explaining them.

What started all this was I'm about to purchase a "PL-E Pro 465nm 3.5W" from JetLasers and as you may know, there is an option for a 10X beam expander (which isn't cheap). I'm aware this beam expander will make the beam 10X larger and will improve the beam divergence/ making the beam go further, but how does this effect the burning factor? How does this effect the brightness of the beam? It seems to me that making the beam 10X larger would make it 10X less powerful at burning stuff and also 10X less bright when being shined up into the night sky.

Also, as a side note, I'll be purchasing a pair of 26650s to use with the extension and a pair of 26350s to use without the extension with my new "PL-E Pro 465nm 3.5W". I haven't yet decided whether or not to get protected 26650s or non protected 26650s (they are about the same capacity), but these are the best 26650s I could find. If you can think of anything wrong with using any of these batteries please let me know or if you have a better recommendation for what 26650s to get, please let me know that as well.

26350s I will be using WITHOUT laser extension (for length purposes):
https://www.fasttech.com/product/5363800-inr-26350-3-7v-2000mah-rechargeable-li-ion

Protected 26650s to use WITH laser extension (5250 mAh):
https://www.fasttech.com/products/0/10013037/3753900-authentic-aweite-awt-imr26650-3-7v-5200mah

Non-Protected 26650s to use WITH laser extension (5100mAh):
https://www.fasttech.com/products/0/10025377/5512400-authentic-keeppower-icr-26650-3-7v-5200mah

Thank you to everyone ahead of time for replying to this thread and helping me and other nubbies out! :beer:

Get one and find out. I'm not sure if the JL BE is compatible with the standard platform we typically use. The Sanwu 3x BE is very versatile. I intend to get a Sanwu 3x for each of my handhelds. If you buy the JL 465nm you will want to get the 10x BE. IMO I wouldn't buy a JL 465nm for burning. It can with no issue but idk I just don't like to cook that diode. There are plenty of cheaper diodes to beat down.

Well first of all I would be using very good batteries and I wouldn't ever keep it on for more than a 45s-1min at a time so I don't think I would be beating down the diode too much.
I'm also not buying it for just burning purposing; actually I'd say I would be mostly using it for shining into the sky and pointing at things far away like tree,cell towers, mountains, ect.

What cheaper lasers would you recommend for burning uses?
Btw the whole point of this thread was to find out if I want a beam extender or not. If I wanted to just "buy one and find out" I would have done that, but thank you for replying. I'll look into the SanWu 3X extender.

HighPowerObsession said:

Well first of all I would be using very good batteries and I wouldn't ever keep it on for more than a 45s-1min at a time so I don't think I would be beating down the diode too much.
I'm also not buying it for just burning purposing; actually I'd say I would be mostly using it for shining into the sky and pointing at things far away like tree,cell towers, mountains, ect.

What cheaper lasers would you recommend for burning uses?
Btw the whole point of this thread was to find out if I want a beam extender or not. If I wanted to just "buy one and find out" I would have done that, but thank you for replying. I'll look into the SanWu 3X extender.

Click to expand...

A beam expander makes it incredibly good at long distance. With a 10x beam expander, basically if you can see what you are pointing at you can see the dot.

With the JL handhelds, the BE they sell is designed to work superbly with their host. If you have owned a multi mode diode before you will notice that the beam is only adjustable on one axis. For lasing along long distances you will want a beam expander. I'm not the one to give you a deep explanation of why you would want one I'm just trying to save you some shipping costs when you order your 465. I have been looking at the JL 532nm's. I just haven't had the nerve to pull the trigger. But I will eventually and I'll get the BE just because.

Thank you guys for your responses but can someone tell me how it effects the burning power and brightness?
Like I said in the original post, it seems that it would make the beam 10X less bright and 10X less powerful at burning (for short distances at least).

HighPowerObsession said:

Thank you guys for your responses but can someone tell me how it effects the burning power and brightness?
Like I said in the original post, it seems that it would make the beam 10X less bright and 10X less powerful at burning (for short distances at least).

Click to expand...

A thin beam pokes holes in objects; a beam expander makes it much better at lighting things on fire, from what I've heard. The larger surface area that is heated appears to make it easier to light objects on fire (though it can take a bit longer.)

It take longer than it would with no beam expander? If it takes longer to burn things with the beam expanded how is that a good thing? At that point I just wouldn't use the beam expandeer and use the normal laser.

And what about the brightness factor?

HighPowerObsession said:

It take longer than it would with no beam expander? If it takes longer to burn things with the beam expanded how is that a good thing? At that point I just wouldn't use the beam expandeer and use the normal laser.

And what about the brightness factor?

Click to expand...

If you're burning up close then it'll take longer than an unexpanded beam would. Unless of course you focus the beam to a point.

If you're trying to do something like what RCB does and burn stuff at 50ft down range, you need the beam expander because it'll give you a smaller spot at 50ft than you'd get with an unexpanded beam.

The benefit is decreased divergence so that you can pot a dot on a surface further away, or a smaller dot at an equal distance.

Alright thanks diachi. Someone in a private message told me that it narrows the beam through distance, is that true?
Or will the beam be the narrowest its going to get at the aperture of the expander?

I can focus a point better with a BE. Without one you end up with a focused line. With one you can create a polyhedron sort of. The brightness factor, considering the 465nm , you will not be losing visibility of the beam. It also depends on how you focus your primary lense into the BE. Without a BE you are missing out on a neat mechanic of handheld beam shaping. Do you need one, no, do you want one, yes you do.

dden2012, that's interesting. If its really that essential I' not going to be ignorant and not get one but are you saying the 10X diameter expanded beam will be just as bright at the none extended beam?

HighPowerObsession said:

Alright thanks diachi. Someone in a private message told me that it narrows the beam through distance, is that true?
Or will the beam be the narrowest its going to get at the aperture of the expander?

Click to expand...

Just like you can focus an unexpanded beam at a distance, you can focus an expanded beam at a distance too. That distance will be further out with the expanded beam.

Ok I get it now...it seems to me that having both the laser and the extender focused as much as possible would make the most sense right? Like why would someone ever want to not have their beam focused all the way?

HighPowerObsession said:

Ok I get it now...it seems to me that having both the laser and the extender focused as much as possible would make the most sense right? Like why would someone ever want to not have their beam focused all the way?

Click to expand...

If you focus your beam at a distance less than infinity, more energy will be directed onto that spot. That means that you will have more destructive power at that particular location.

...that is super confusing. Isn't focusing a beam meaning making the diameter narrower or wider?