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ustink007
Modified 10mW Greenie
Joined: 22 Oct 2007
Posts: 10
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 Posted: 10/31/07, 7:23 AM Post subject: Focusing L |
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I've tried searching an answer to this but i can't seem to get the keyword correct. Anyways, I need to find a focusing lens and the only knowledge of optics is from a physics class.
What do i need to know about focusing lenses for a laser? What are the safety precautions i need when playing with a focusing lens, What is the chance of the beam reflecting or scattering from the lens? Any recommendations of manufacturers of lenses?
I don't know how wide the beam is, I haven't read about it in the manual. But it did come with a burn pattern sample and using a ruler, it seems to have a diameter of 5 mm. Don't know if this information helps or if it's even needed. I do know, from the Final Test Data Sheet, that the wavelength is 1064 nm. |
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fnugget
Elite Laser
Joined: 21 Jul 2005
Posts: 131
Picture(s): 2
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| Posted: 11/01/07, 8:37 AM Post subject: gaussian b |
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| so yeah, lasers kind of work differently than as you see it in high school physics. It's called gaussian beam optics. Basically, the rays dont cross at a point, they curve out (away from optic axis). And in your case, the biggest influence is how to focus it. Focusing it from the beam directly won't make it much smaller. Instead, you should expand it, and then focus it back. Or better yet, expand, collimate (make parallel), then focus. If you just want burn, I don't think you really need to learn much. Get a diverging lens with equal focal length of a converging lens. That's to collimate. The third lens can be converging any focal length, preferably really short. So, you can use a tiny expander, but the next two lens need to be big ones. |
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ustink007
Modified 10mW Greenie
Joined: 22 Oct 2007
Posts: 10
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| Posted: 11/02/07, 8:59 AM Post subject: |
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| Okay, thank you very much for the information. I'm assuming this is the case for every laser of every wavelength and any duration? I need to focus a pulse laser with a 1064 nm wavelength. My professor would like it to focus on a spot about half a meter away from the laser head. |
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fnugget
Elite Laser
Joined: 21 Jul 2005
Posts: 131
Picture(s): 2
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| Posted: 11/04/07, 10:24 PM Post subject: hw |
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I'm not doing your homework am I?
Well, I'm not sure. I'm only an undergrad. But I do know high pulse rates make it funky. |
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ustink007
Modified 10mW Greenie
Joined: 22 Oct 2007
Posts: 10
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| Posted: 12/10/07, 9:04 AM Post subject: |
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Ah, sorry, completely forgot that i didn't reply.
No, this isn't a homework assignment, but a research my professor wants me to do but i don't have a clue about lasers. I spoke with him and he was told that there is no need for anything other than a lens. My guess is that he just wants it to focus and not have a specific focusing length, as long as it does converge. He told me to have it focus about 0.5 meter +- 0.2 meter.
The project i'm working on is not about the laser, but the ignition of a fuel droplet using the laser. Thanks in advance for the help. |
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