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Thread: How poweful must a laser be to perform these tasks?

  1. #1

    Default How poweful must a laser be to perform these tasks?

    1. Laser surgery on a human eye
    2. Sharpen kitchen knives

    I ask out of curiosity because I recently got into lasers, and have been thinking about them a lot lately.

    My grandfather had laser eye surgery, and I have a kitchen knife I know is laser sharpened.

    Now I'm thinking, while I'm sure a tissue-cutting surgery laser would require quite a lot of power (compared to the 5-50mw pointers I'm used to), a laser would require an insane amount of power to peel / cut stainless steel.

    Could someone enlighten me on this?

    Regards,
    Harald

  2. #2
    Flashaholic* allthatwhichis's Avatar
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    Lightbulb Re: How poweful must a laser be to perform these tasks?



    Greetings and welcome... This is an uneducated guess, but I would think in both situations it would be more the focus of the photons that the power. I may be wrong. Both of those actions require precision more than force. They may require a lot of both...

  3. #3
    Flashaholic jkaiser3000's Avatar
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    Default Re: How poweful must a laser be to perform these tasks?

    For cutting metal, CO2 lasers are most often used, which lase at 10.6 um. They can range from a couple of watts to a couple of kilowatts. I don't know whether they use these lasers for sharpening knives, though. In fact, I'm not sure lasers are actually used for sharpening, but I may be wrong, of course .

    As for eye surgery, they use excimer lasers, I believe in the UV part of the spectrum. I'm not sure of the powers used, though

  4. #4

    Default Re: How poweful must a laser be to perform these tasks?

    Thanks for the answers.

    I remember that the box containing my kitchen knife said "laser sharpened" or something to that effect, but I don't know. Could be a sales trick I guess.

    After having read a little on the forum, I've learned that focusing lenses for laser exist. Could anyone tell me, what lasers use focusing lenses, and are these adjustable like for example a pair of binoculars, and maybe even digital?

  5. #5
    Flashaholic jkaiser3000's Avatar
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    Default Re: How poweful must a laser be to perform these tasks?

    All lasers use lenses to some extent. Some more than others .

    For instance, all diodes need a focusing lens to collimate the beam. This is done because the beam, upon exiting the diode itself has too much divergence and produces a sort of cone-shaped beam. Some laser modules use a variable focusing lens, which means you can focus the laser to a small dot close to the laser, and then collimate it for far field use, as needed.

    You can accomplish the same by using, like you sugested, a binocular or other similar aparatus. Use two lenses with equal properties to focus the beam and not change the divergence, or use one short focal length lens close to the laser and a long focal length lens farther from it. This last option will allow you to focus as well, and has the benefit that the beam will have lower divergence when collimated for far field.

    Gas lasers use collimating optics too, but of a different sort .

    Now, if all you want is to focus the light, all you need is one lens. That will increase the burning capabilities of your laser, but won't be of help for long distances.

  6. #6

    Default Re: How poweful must a laser be to perform these tasks?

    Alright, I understand more now, thanks a lot for your informative answer.

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