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Thread: Perceived brightness 12watt vs 3 watt

  1. #31
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    this is why I fought sooo hard to make an all solid state single mode projector. The pencil thin 1mm beam is just sooo much more satisfying on my wall for graphics. I don't do beams so cant say. However my divergence is very low as single mode and the beam is very tight so my power density is very very high. This means my beams are probably as bright as 1w even though I only have 350mw in the beam. In fact it is almost as bright as my 1.5w larger projector.

  2. #32
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    Halleluja!!! someone gets it.....


    Interested in 6-12W RGB projectors with low divergence? Contact me by PM!

  3. #33
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    Gotta love super thin single mode beams

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    Philipp Wetter

  4. #34
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    How about q-switched versus CW? Will a q-switched beam appear any brighter in the air than a cw laser of the same diameter / divergence / power? I know the eye responds to average power, but I'm wondering if the Raleigh scattering that makes the beam visible in clear air is more pronounced with higher peak power or if it's purely average power density that counts.

  5. #35
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    Quote Originally Posted by masterpj View Post

    For beamshow use the thickness of the beam seems to have an opposite effect then it has with graphics though..
    Due to the fatness of the beam it will appear more dense and fills the area more and seems to be percieved as brighter (though to me it seems a bit unlogical as the energy is less packed.. an american laser company told me this once where they actually increased the size of their beam diameter and not for safety reasons.
    That seems strange. BUT.. I can say that I have a friend with an uncorrected 638 300mw and it looks way brighter than 300mw. And it is super fat and fuzzy in the air.

  6. #36
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    Quote Originally Posted by mccarrot View Post
    Please have look at one of my shows.

    the top 2 projectors are almost 3W
    the bottom 2 are 0,6W!
    so the top projectors got 5X the power

    Attachment 45348
    Hard to tell by the picture. But how much brighter does it appear in real life? Certainly not 5 times brighter... right?

    I was always under the impression you needed 10X the power to appear twice as bright.

    I am in the same boat as brad. I am considering some new projectors in the 6-12 watt range and I am curious as to how much brighter they will actually appear.

  7. #37
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    lower power higher density beams are also more dangerous to the eye. I'd bet my super thin beams could do some serious damage to the eye compared to a higher wattage fatter beam....within reason of course.

  8. #38
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    Interesting opinion about wider beams appearing brighter, I find it's more or less equivalent to a degree. I am actually totally fine with multimode 638nm beams, even in 10,000 seater auditoriums. I like the softer, yet bright look. And of course the price difference helps.

    Below are two of my shows, both have a 16W Green/Blue centre, and 4W Green/Blue on the sides. Kinda embarrassed about the alignment of the beam in the first pic haha please excuse that, and the long exposure makes it look very messy.

    But

    This dramatically demonstrates how power does not equate to brightness. Note the difference between brightness of left and right of the second pic. What makes the most difference to me is
    1. Smoke density
    2. Ambient background light

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  9. #39
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    How about q-switched versus CW?
    I don't think Raleigh scattering is non-linear and if that's correct then it probably is the average power that determines the visibility.

    Brad,
    There comes a time when you want to wrest the value from your investment rather than always reinvesting and chasing the return. With lasers becoming ever more common, before you commit to a couple of expensive projectors and the _____# of shows that the payback requires you might want to look at that helicopter again (been there).

  10. #40
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    Great thread guys, and since everyone is in the same boat here or build boats with wings or fly higher than the treetops while powered by as boatmotor I have just gotta ask Bradfo69 something.

    Brad is that a running motor you have for that project? I have a similar project, a 1968 Manatee 13 foot powered by a 54...5..6.. or 1957 35hp Johnson Seahorse. Is yours a Super Seahorse?. My boat rests upon a rare 50's/60's Gator -foldable- Trailor... OH, I think it is the same Gator company that DZ got some parts from for his Z5 Absract Gen..

    Modulation: I asked both drlava, Bbe and Badpip , both BP & drlava told me their drivers are truly linear with no pwm... PWM there is no such thing as %100, Bbe say his linear supply is PWM'd

    And here he is calling this a MOSFET current regulator
    http://laserpointerforums.com/f51/si...pwm-70812.html

    Am I wrong in thinking this is not correct and 'linear' ?

    What was this thread about again? oh, perception:

    I have wondered why two laser beams shootig thru fog, 660nm and 445nm (with way more power) the red has always produced a beam that appeared to travel further.

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