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Thread: Playing With Pulses

  1. #1
    Join Date
    Jun 2009
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    Default Playing With Pulses

    As much as I look forward to making holograms with a pulsed ruby laser, poking holes in razor blades is a close second. Here's a nice bunch of sparks made as the 1 Joule pulse of light sends molten steel spitting out of the hole. I should probably protect the face of my lens with a piece of glass! Anyway, always a fun thing to see.

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    This one has me stumped. Notice the particle track that impacts on the top edge of the lens holder. How can THAT happen?!? The lens is perpendicular to the input beam. A particle should not be able to hit the top edge like that. And notice the ricochet path (and its reflection). Where did a glowing particle, traveling on that apparent path, come from if not the hole being poked? I'm stumped!

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  2. #2
    Join Date
    Oct 2012
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    Default

    ... I don't see anything wrong - all the "weird" traces are secondary or tertiary particles/childs, coming from exploded "parents"

    Viktor

  3. #3
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    Default

    This is the trace that confuses me. The hole is being poked on the axis of the lens. The shutter was held open for one second. The laser pulse was 30ns long in the second half of the exposure.
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  4. #4
    Join Date
    Apr 2007
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    Default

    Maybe it's not really impacting the top of the lens holder? Maybe the particle trail is splitting/forking in mid-air right above the lens holder. Many of the other trails appear to fork or split without impacting anything. Puzzlin' evidence. Cool photos!

  5. #5
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    Oct 2012
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    ... this should be a "spontanous" explosion in air, not an impact.

    Here some "sparkling" too with much less power - around 50 Watts CW (modulated with maybe 500 nanoseconds per pulse) on a spot of roughly 30 microns:

    https://vimeo.com/207474893

    Pulsed or Q-switched lasers will give some hundred Kilowatts to Megawatts with some nanoseconds pulse times, so will be much more "impressive" too - I'm rewiring the scanner and drivers, to insert pulsed lasers -- will test this next week ...

    Viktor

  6. #6
    Join Date
    Feb 2011
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    Default

    Dealing with pulsed lasers as well, I find it convenient to mix in an "aiming laser" with a very different wavelength such as a low power green. A long or short pass filter can do this. That way when you want to know where the pulse will land or where it will focus, you don't have to do it by trial and error.

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