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Thread: Need some helping explaining power vs. brightness

  1. #1
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    Default Need some helping explaining power vs. brightness

    Hey all -

    So I have run into a bunch of difficulty lately trying to explain the relationship between power and "brightness" to people. Everyone wants to know whether x will be brighter than Y, whether 1w is twice as bright as 500mW, and all of those usual kinds of questions. I am finding myself to be... inarticulate trying to explain that these relationships are not always linear and proportional. Everyone is so BRAIN LOCKED on 50 is half of 100, etc. that I need some reinforcements. So, I am looking for some help... how would you - very simply - explain to someone who knows nothing about lasers all of the relationships between specification and effect?

    I would also mention that much in the same way that Columbus and the Native Americans were best dinner pals right up until you got into middle school, the answer does not have to be totally technically accurate... that's where I am having them problem. It has to be understandable and any help would be most appreciated.

    Thanks!

  2. #2
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    Default

    Would a flashlight example work?

    X flashlight is 50mw and at 10ft very bright.
    Y flashlight is 100mw and at 10ft same brightness as the 50mw.


    X flashlight is dim at 100ft.
    y flashlight is very bright at 100ft.

    is this what you are looking for?

    Len

    ps call me when you get a chance working 7-7 right now.

  3. #3
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    Default

    Assuming they are familiar with audio, you could say that apparent brightness works a lot like hearing.. for something to sound twice as loud the volume has to increase 10dB (10 times power increase). The ratios aren't the same, but it gets the point across.

  4. #4
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    I really never got it how people are able to quantify their bio-sensory inputs.
    Somehow my sensors never were factory calibrated. Even apart from all subjective noise, if I try a manual calibration, it appears to be valid for just a instant.


    I can sense that a surface A is hotter than surface B, but I can't say if it's *twice* as hot.
    I can sense that sound A is louder than sound B, but I can't say if it's 2,3 or 10 times as loud.
    I can sense that a surface A is brighter than surface B, but I really can't say if it's 25% or 50% brighter.

  5. #5
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    Doing a demonstration using an appropriate meter to detect
    variations at different distances and power levels would be
    the way I would explain it...

    A demonstration speaks volumes.... IMO


    Jerry
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  6. #6
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    Default

    Try adding wavelength into the mix....

    I struggle quite a lot explaining to the 'layman' that my 1.5W projectors (640 red) are at least the match of another RGB projector using 1 more watt of 660nm.... but all they hear is 'two and a half watts, it must be better!'

    Sound system owners experience the same thing where people are so hung up on K's of rig!! It's got 50 "K's" of amps so it must be louder than your 30 K's (completely disregarding the 6db sensitivity difference in the cabs....) meh...

  7. #7
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    Lightbulb

    Quote Originally Posted by X-Laser View Post
    ...So, I am looking for some help...
    I'd email or call Greg Makhov, of 'LSDI', in FL - he wrote, a few years-back, an *excellent* article called "What's Watt" and (IIRC) it was published in 'The Laserist'.. you might be able to find it, via search @ ILDA... if not, I'm sure he'd be happy to email it to ya... not my work, so, sorry, I can't 'post' it... but it was very, well... 'illuminating'... (sorry...

    Not necessarily 'laymans-terms', but well-written, clear, and excellent diagrams / data to back up the points... If you call him sometime (I usually find > 9-10pm, EST, at their 'shop' #, is usually-best...) I'm sure he'd be glad to chat it up with ya / some other suggestions, based on his research, than might be a little more 'publicly-digestible'...

    Hope this helps....
    cya
    j
    ....and armed only with his trusty 21 Zorgawatt KTiOPO4...

  8. #8
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    Default

    Thanks guys - I appreciate the input... and so I toil away. If anyone has more ideas I am certinally all ears and I would love to read the What's Watt piece. Thanks for that Jon.

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