Beam Expanders Explained

[Sta]

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

No - when a beam is focused onto a certain point, it narrows up to that point, then gets larger once it's past it. You get an hourglass kind of shape.

 

[dden4012]

Take a look at the pics. About 2' from the BE i can get a small concetrated channel of energy. So much more control of the beams shape with a BE. Without one you cant control the spread of the beam, the further the object you are pointing at the bigger the line or box. :wave:

 

[HighPowerObsession]

Ohhh wow ha I completely misunderstood what focusing was so thats pretty interesting.

Now I have a bunch of questions about focusing so I'm gunna go try to find a thread about it or something.

 

[HighPowerObsession]

That's really cool dden4012, I'll be getting a beam expander now that I understand the point of them more. Is that a 445nm with a 10X BE?

I just need to learn all about focusing now and how that all works.

 

[dden4012]

It is on the 7w 450. The primary lense is a G2. The 3x BE has 2 lenses in it. So the way i go about the setup is to adjust the primary lense to project the correct "image" onto the first lense of the BE. The size of that image is expanded by 3 out of the BE. I usually keep the image a few mm from the edges of the output side. Once the image size is set i can adjust the focus with the BE. I dont really burn with my lasers. I like the column of the beam to be as uniform as possible. I have lit fireworks and campfires with the 7w. Having some distance on a gasoline soaked pile of wood is a good thing when it catches and fahpoofs the vapors :drool:
Oh and you will never get a circular output from a high ppwer blue diode with everyman optics. It will always be a rectangle except for at the convergence of the beam.

 

[HighPowerObsession]

Ha all that stuff you just said is out of my league. I am still trying to understand how focusing works.

I searched "focusing" on this forum and found a thread titled "Focusing at long distance" and in that thread Alaskan made some interesting points (or at east they were interesting to me since I don't know much about focusing) but he said using a BE for long distance burning will actually work against you. THAT is what made me so confused about the whole point of a BE. The whole point of lasers are to make the beam as narrow as possible (for burning at least) and I couldn't understand how a BE could help with that. Now for looks, I can see why a 5mm beam would look good (idk if that even exists, but I'm just using it as an example), but I don't understand how a 10X BE makes the beam look good since that's just too huge of a beam. Those two points are what makes me not understand why a BE is such a good thing to have. I'm not sure that the "PL-E 465nm 3.5W" is even a good laser for long distance burning since the diameter isn't that narrow and the divergence isn't so good either. I'm also not just talking about burning; if you wanted your beam to go as far as possible with expanding as little as possible wouldn't having a very narrow beam diameter and a very small divergence be a better way to go rather than just blowing up the beam 10X?

 

[dden4012]

Nothing wrong with the 465 diode. Its the nicest blue available imo. If you get it and plan on burning with it you must get eye protection! Really. Its so damn bright.
Your point of diluted intesity is true when using a BE. Depends on the WL your considering. I wouldnt bother using a BE with 405nm.
Since your in the US, google dtr and survival lasers. Illumination supply for batteries. Good luck in your choices.

 

[HighPowerObsession]

Its hard for me to even understand what you are talking about; I'm a nube to all of this but that looks like a super cool collection you got there even though I have no clue what alot of it is haha.
I am currently reading about focusing lasers online so hopefully I will understand all this soon.

 

[HighPowerObsession]

....uh hey bro, why'd you read the first sentence and close it?? I spent like 15 minutes writing that message btw...

"Hey Alaskan, I'm fairly new to this forum and I decided to join because I have a great interest in high powered lasers and I know there is alot to learn." .....is there something wrong with this sentence??

 

[steve001]

Ha all that stuff you just said is out of my league. I am still trying to understand how focusing works.

I searched "focusing" on this forum and found a thread titled "Focusing at long distance" and in that thread Alaskan made some interesting points (or at east they were interesting to me since I don't know much about focusing) but he said using a BE for long distance burning will actually work against you. THAT is what made me so confused about the whole point of a BE. The whole point of lasers are to make the beam as narrow as possible (for burning at least) and I couldn't understand how a BE could help with that. Now for looks, I can see why a 5mm beam would look good (idk if that even exists, but I'm just using it as an example), but I don't understand how a 10X BE makes the beam look good since that's just too huge of a beam. Those two points are what makes me not understand why a BE is such a good thing to have. I'm not sure that the "PL-E 465nm 3.5W" is even a good laser for long distance burning since the diameter isn't that narrow and the divergence isn't so good either. I'm also not just talking about burning; if you wanted your beam to go as far as possible with expanding as little as possible wouldn't having a very narrow beam diameter and a very small divergence be a better way to go rather than just blowing up the beam 10X?

Have you not ever used a magnifying lens and the Sun to burn something? You had to focus to as small of a spot the sun's light too burn. The same with a laser beam. You have to adjust the optic to focus.

Answer to the red part. The natural behavior of light, it likes to spread out after it leaves the source, prevents that. You can't have a narrow beam and low divergence with diode lasers. The beam created by the diode generally has a wide divergence. So a positive optic is used to lower the diverging beam. A narrow beam will spread faster than a wider beam. If what you ask could be done there'd be little need for beam expanders right? It's not hard to understand. Here's a video I'd like you to watch it uses a refractor telescope to focus a beam. https://www.youtube.com/watch?v=_9QotAtxrmc A beam expander using two or more optics is a refractor telescope.

 

[diachi]

Have you not ever used a magnifying lens and the Sun to burn something? You had to focus to as small of a spot the sun's light too burn. The same with a laser beam. You have to adjust the optic to focus.

Answer to the red part. The natural behavior of light, it likes to spread out after it leaves the source, prevents that. You can't have a narrow beam and low divergence with diode lasers. The beam created by the diode generally has a wide divergence. So a positive optic is used to lower the diverging beam. A narrow beam will spread faster than a wider beam. If what you ask could be done there'd be little need for beam expanders right? It's not hard to understand. Here's a video I'd like you to watch it uses a refractor telescope to focus a beam. https://www.youtube.com/watch?v=_9QotAtxrmc

You messed up the formatting in that quote there a little - the colour isn't working.

Good example video though!

NOVALasers, now that takes me back...

 

[steve001]

You messed up the formatting in that quote there a little - the colour isn't working.

Good example video though!

NOVALasers, now that takes me back...

A typo fixed.

 

[diachi]

A typo fixed.

Looks much better! Wasn't complaining, just thought you should be made aware. :beer:

 

[HighPowerObsession]

Damn that video is crazy and he is probably only using a 50mw-100mw green laser since its 2007. Not that I really care to talk about Alaskan after he pulled his little stunt, but he also said a telescope is a much better choice rather than a BE, but you basically just said a BE is the same thing? (I'm guess the JL 10X BE has 2 or more optics)

 

[diachi]

Damn that video is crazy and he is probably only using a 50mw-100mw green laser since its 2007. Not that I really care to talk about Alaskan after he pulled his little stunt, but he also said a telescope is a much better choice rather than a BE, but you basically just said a BE is the same thing? (I'm guess the JL 10X BE has 2 or more optics)

That's a lab laser, could easily have been over a watt, even back in 2007. Pretty sure my two Melles Griot 532s are dated 2006 and are rated at 2W each (Although they're dead now...).

 

[HighPowerObsession]

Oh um ok, my bad. Thank for all the help and the explanation; I'll be picking up an extender for which ever laser I end up going with.