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Thread: Perceived brightness 12watt vs 3 watt

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    Quote Originally Posted by mixedgas View Post
    Go from lasers to HMS Hole in the Water? Perhaps you just get it over with and try buying a full size plane........
    Nah... helicopter. Since the age of 5 when I first saw it in an aviation book, the dream has been a Rotorway Scorpion. Runs on an Evinrude boat motor.

    http://www.aviastar.org/helicopters_...orpion_too.php


    Seriously ??? Boats are relaxing, if you get a 440$ two seat plastic Kayak. Anything more then a 12 foot aluminum Boat with a six Horse results in even more pain then lasers.
    Actually... I already have the Johnson 6 horse and had the 12 foot aluminum boat. We left the boat with the lake house when we sold it but, I kept the outboard motor. I also have a 1956 Larson Falls Flyer runabout with a 35 horse that sits out back of the house. It hasn't seen the water since about 2001

    http://www.woodyboater.com/classic-b...-falls-flyers/

    Funniest looking damn thing on the water I've ever seen.

    I notice that most of the 7-12 watters list divergence as <1.6. So makes me wonder how much brighter the 7-12 watter will actually look.

    What is the general rule of thumb for power vs venue size or crowd size? Isnt it about 1 watt per thousand of people?
    I'm not certain. Like edison says, it may be all dependent on divergence. That was an interesting comment about how a 3 watt .5mR would be equal to a 9 watt with 1mR. Is there an accurate formula for that?

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    Quote Originally Posted by Bradfo69 View Post


    I'm not certain. Like edison says, it may be all dependent on divergence. That was an interesting comment about how a 3 watt .5mR would be equal to a 9 watt with 1mR. Is there an accurate formula for that?
    Thats my biggest question.

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    I don't realy agree with the fact that dividing the divergence by two results in increasing the perceived brightness by 3x.

    For example, when I use 2x projectors with the same red cue displayed, each fited with single mode red modules with the following configuration ; first projector : 0.7W 637nm and 0.65mrad, second projector : 1.2W 637nm and 1.3mrad -> the second one is greatly brighter, even if the divergence is twice as the first one.

    Same situation between 2x projectors, consider the second one with a single mode module (1.2W 637nm and 1.3mrad) and a third projector fitted with a multimode red module (1.6W 638nm and 1.6 mrad) : the third projector will be equal or a bit brighter compared to the second one. At l east, this situation is valid for a room less than 50 meters depth, the size of the room where my projectors were used .


    In conclusion, of course a 3W laser projector with lower divergence will have higher beam density and the same way, better visibility compared to a 3W projector with higher divergence. However power is power, that means a 9W with 1.0mrad WILL ALWAYS BE GREATLY BRIGHTER than a 3W 0.5mrad (or even less divergence) for our application, if you keep in mind that crowd is never situated 2000 meters away from the lasers .

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    Acually its even more. Its 4x as bright according to Bart. He might be able to give you the formula or maybe Planters can explain it. I don,t see any reason to these guys because both have much more knowledge about this matter

    http://www.photonlexicon.com/forums/...307#post300307


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    Also, its not JUST about divergence.

    In my example earlier I was referencing the initial beam diameter. So even a laser with worse divergence but starting with a tighter beam will be brighter at close range, as at that distance it DOES have a higher power density. At some point away from the projector the module with the better divergence but worse beam diameter will take over and 'win' in the farfield.

    As logsquared is a soundguy I can totally relate to his reference to 'throw' being better on the better diverged beam - its the same difference between Turbosound Flashlight and Floodlight
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    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

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    Quote Originally Posted by edison View Post
    Its 4x as bright according to Bart
    Yes, 4x time the power density!

    We can simplify what I try to explain in a simple 1D dimension representation : a perpendicular beam with higher divergence will have less power density, however as the beam has a larger diameter, the finale luminosity will be affected by the length of the line segment crossed by the beam.

    In this 1D representation, a second perpendicular beam with lower divergence will have, of course higher power density, but will irradiate a smaller line segment.


    The brightness ratio between a beam with "x" divergence and an other one with "x/2" divergence is situated somewhere between 1 and 4. I will think about how to find a formula tomorrow.

    --- www.neodym.be ---

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    Your right (yeah call the newspapers i totally agree with norty ) its also depends on other factors like electronics. A driver that is damn fast will result in a much brighter laser. China is know for their crappy DPSS drivers so the normal driver will not be much better. The first time i went to Prolight i have seen a show by LOBO and that blew me away. Damn sharp beams that looked stunning. Recenly Dave shared a picture with me, and i found another one on the net. You can see the difference. Dave his one (left) is damn sharp, while the right looks like additional lighting.
    Attached Thumbnails Attached Thumbnails 1.jpg  

    1009858_10153969074500298_15717502_n.jpg  



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    So, the ultimate laser for all scenarios is probably one of moderate power, but with a very narrow beam at aperture (good in the nearfield), low divergence (good in the farfield), and good, responsive modulation characteristics (so it hits full power quickly).

    Is that a gasser and PCAOM?
    Frikkin Lasers
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    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

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    What do you define as moderate?

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    Quote Originally Posted by norty303 View Post
    So, the ultimate laser for all scenarios is probably one of moderate power, but with a very narrow beam at aperture (good in the nearfield), low divergence (good in the farfield), and good, responsive modulation characteristics (so it hits full power quickly).

    Is that a gasser and PCAOM?
    Talk about an OPSL

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