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Thread: Apparent beam brightness vs diameter? Is there a calculator?

  1. #1
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    Default Apparent beam brightness vs diameter? Is there a calculator?

    I'm searching for a rule of thumb, or calculator to determine the apparent beam brightness to beam diameter at different powers. i.e., 1 mm beam diameter at 1 watt compared to 5 mm beam diameter at one watt, how much brighter does the 1 mm beam appear to the eye? Is it a straight linear ratio relationship?
    Glowing green eyes is a camera photoflash reflection.

  2. #2
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    ... for some "comparison" here a clip, where I've stacked 1 to 8 beams wit 4,5Watts each ... the camera can't show it like the eye sees, but maybe interesting though

    https://www.youtube.com/watch?v=JVKoijksK0I

    Viktor
    Aufruf zum Projekt "Müll-freie Meere" - https://reprap.org/forum/list.php?426
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  3. #3
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    Great to see the effect of adding more beams, thanks.
    Glowing green eyes is a camera photoflash reflection.

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  5. #5
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    I happened upon someone selling a multiple watt output laser with a 1 mm beam diameter, the seller had made reference to a 1 mm beam at such and such a power level was just as bright (when viewed from the side of course) as a far more powerful 5 mm diameter beam. I can't find where I saw it now, wish I had copied that link or written down his rule of thumb, so far not finding it. I know, depends upon air purity and or the amount of moisture in the air, but on average, if there is such a thing...
    Glowing green eyes is a camera photoflash reflection.

  6. #6
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    ... if you look into my videoclip with the 8x 4,5W diodes, especially when switching from 1x to 2x beams or at the end, when from 2x to 1x, you can see the "amount" of visible power ar 4,5W and 9W.

    Another interesting point is the brightness over the beam and the focus, wher it's changing from some millimeters to a "focus area" of around 0,3mm diameter.

    Could be, this is because of the cameras "saturation", but the beam looks like "solid" over the complete range ...

    Viktor
    Aufruf zum Projekt "Müll-freie Meere" - https://reprap.org/forum/list.php?426
    Call for the project "garbage-free seas" - https://reprap.org/forum/list.php?425

  7. #7
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    Where they converge it is essentially the same thing, agreed. It would make sense from the side, a 5 mm wide beam at 5 watts would look like about the same intensity to that of a 1 mm wide beam at 1 watt, wouldn't it?
    Glowing green eyes is a camera photoflash reflection.

  8. #8
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    ... the beam is a "volume", so could be different in respect to energy density and "thickness", if compared 1Watt with 1mm "thickness" to a 5mm "thick" beam ...

    Viktor
    Aufruf zum Projekt "Müll-freie Meere" - https://reprap.org/forum/list.php?426
    Call for the project "garbage-free seas" - https://reprap.org/forum/list.php?425

  9. #9
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    True, diode beams aren't square, more rectangle.
    Glowing green eyes is a camera photoflash reflection.

  10. #10
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    Area of 1mm 0.005. Area 5mm 0.12. That’s 24 times the area so 1/24 the power density. In db that’s an 18db difference so what 3 time doubling so one should be three times brighter. Or you need 24 w vs 1 w. In reality you might not see much of a difference by eye and just adding fog will do far more than power.

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