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NIR modulated laser system - Need advice

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  1. Jun 28, 2016 #1
    I'd like to perform experiment on NIR laser (around 800nm) with modulated signal (varying duty cycle), with peak power around 1000mW, the output is desired to be connected to fiber optic.

    I am new to laser technology, and have googling around but can't find suitable laser module (complete set).

    Any advice will be appreciated on what kind (brand, model) of laser module that suit my criteria.
     
  2. jcsd
  3. Jun 28, 2016 #2

    Mech_Engineer

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    What kind of an experiment is this, and why do you need such a powerful laser?
     
  4. Jun 28, 2016 #3
    Be careful with that amount of IR energy!
    We had a dark humor joke in our IR labs, "the last thing you never saw".
    That said I think you can get some laser diodes that produce those
    power levels centered around 800 nm,
    http://www.armlaser.com/808nm-1w-laser-diode-p-137.html?zenid=VDoFESbh4AKn8lTvo4PEk2
    You would do better to find a completed design and the components are rather finicky, and
    can burn up quickly. (My data is old).
    If you want to modulate something like that, You should use a dummy load, so you are not switching the current
    on and off, but simply changing it's path.
     
  5. Jun 29, 2016 #4
    @Mech_Engineer: I need a laser that able to goes deep into bulk thing (e.g. fresh wood). Well, I am not really sure if 1W is too high, it's my rough bet after googling around, and since I will modulate it (pulse) and not continuous. It will be desirable if there is something (laser driver or laser diode) that can vary the peak power while maintaining similar wavelength.

    @johnbbahm: Thanks for advice, I will have to be careful then (will laser safety glasses help?)
    For dummy load, will it be something like transistor(gate)+resistor parallel to the laser diode?

    Actually I am not looking at component level, but prefer something "plug and play". Maybe something like: Laser Driver + Signal Generator (for modulation, input to Laser Driver) + Laser Diode (pigtailed?).
    (I will also need photodetector system, but let's put that later)

    Thanks and welcome any advises.
     
  6. Jun 29, 2016 #5

    Mech_Engineer

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    Will this be a laser engraving or cutting system?
     
  7. Jun 29, 2016 #6

    Mech_Engineer

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  8. Jun 29, 2016 #7

    berkeman

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    @LightHero -- We do not allow dangerous discussions here at the PF, and this is coming pretty close... Have you read and understood the government regulations concerning high-power lasers?

    https://en.wikipedia.org/wiki/Laser_safety

    It looks like the laser you are looking to use is either Class 3B or Class 4, depending on how reliable the pulsing is. You really need to be working with an in-person mentor on this, one who has a lot of experience with high-power lasers. The danger is not just to you, it is to others who come near whatever you are working with.

    Can you say what the final application is? There may be a better (and much safer) way to do what you want.
     
  9. Jun 29, 2016 #8

    mfb

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    Use them, but don't rely on them. At that power level, even reflections from metallic surfaces can be dangerous, and the direct beam can be dangerous to the skin as well. This assumes long pulses or cw operation - but you probably don't want to trust your electronics/software to be 100% bug-free.

    A completely closed case with an interlock (so laser operation is possible only with everything closed) would be the best approach.
     
  10. Aug 2, 2016 #9
    @Mech_Engineer : not for engraving or cutting, it is for non-destructive test, e.g. inspection of wood (amount of contained water, etc). And thanks for the link, yes seem I need to revisit the requirement.
    @berkeman : what I need is laser with deep penetration (e.g. into fresh wood). I search around to find out at what power usually laser is used, even I found laser for Vet use 1W (continuous) even 30W (peak power, modulated), https://respondsystems.com/laser-products/ , for therapy. That's why I chose 1W as first guess.
    @mfb : thanks for the advise. It make me rethink again whether I really need 1W, but if less I worry it will not penetrate deep enough.
     
  11. Aug 2, 2016 #10

    berkeman

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    Why don't you just use a drill or a spike? Why go to all the trouble (and danger) of using a high-power laser?
     
  12. Aug 3, 2016 #11
    @berkeman : able to penetrate into fresh wood is one of the proof-of-concept, while the application may be wider. The point here is non-destructive test.

    Appreciate any info on suitable laser module.
     
  13. Aug 3, 2016 #12

    berkeman

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    How is punching a hole in the wood with a laser a non-destructive test?

    Or are you wanting to somehow only have light penetrate into translucent material to give you some information in reflection? Also, why does it have to be laser light? Can it just be a focused bright light from an incandescent or non-coherent LED light source?
     
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