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Thread: Power vs Brightness

  1. #1

    Default Power vs Brightness

    I am slowly making my way through past threads to gain knowledge.

    My question is about comparing brightness of a 532nm green. What I have read is usually people's observations of how bright it is, like 35mW looks like a welder's arc where the spot hits.

    Does doubling the power, double the brightness? Or is it exponential?

    I have a 5mW, and will have a 250-300mW in about a month. I am wondering about the brightness of the beam at night, as well as the dot. My 5mW looks pretty good at night, so I'm very interested in how 300mW will look.

  2. #2
    Join Date
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    Default

    there are a lot more pros in this forum than me who will provide a better explanation i am sure, BUT-

    as far as what i have learned, when it comes to laser light, power vs. brightness averages out to
    4X the power = 2X the brightness.

    a 100mW laser will have to be around (im not sure if the figures are absolute or not) 400mW to appear double the brightness.

    and yes, 532nM appears the brightest to the human eye becasue of the way the human eye sees lighht. there is a really cool chart floating around here somewhere which plots wavelength vs. i believe overall brightness.

    i am pretty sure the "sweet spot" for the brightest the eye sees is approx. 555 nM. (if im wrong, some of the other guys will correct me. but its right around there)

    this is why Nd:Yag Lasers (lasing at 532nM) appears SOOOO much brighter than say a 650 red laser when compared watt to watt.

    the close a lasers wavelength is to the "sweet spot," the brighter it will appear.

    -Marc

    PS- you own a ___nM 5mW and getting a _____nM 250-300mW laser soon? red? greenie? overall brightness will be different dpeending on wavelength.

  3. #3

    Default

    It's a green. The pic below is the model, taken with incense in the room by drlava. It's a laserbtb 200mW that peaks around 290mW and could be pushed to over 300mW with adequate cooling. At this green, is the 4X power = 2X brightness formula still valid?


  4. #4
    Join Date
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    No you are right about 555nm. It's a peak. Then everything goes down the hill. Farther you go from the center more power you need to keep it a same intensity as 555. We don't have 555nm so 532nm is used as a base. To get 473nm blue as bright as 532nm you need a 1.5 times the power of 532nm. Farther you go down the spectrum more power is needed. 447nm needs 3-4 times the power of 532. 407nm.....I say 10-12 times. Same story for the red. 635 needs only 2 times the power of 532 but 650 needs 4 and 671 needs 8 times the power. Most people cheat on blue a bit. And it's fine. But I would not recommend to cheat on red. Get as much blue as you can afford then get as much red you can afford and then balance it with a green. Can't guaranteed 100% white but will be close enough.
    I hired an Italian guy to do my wires. Now they look like spaghetti!

  5. #5
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    I love the way nanoWatt nicely placing shill inside the topic.)
    I hired an Italian guy to do my wires. Now they look like spaghetti!

  6. #6

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    Oh, I didn't realize it would be taken that way. I don't yet own this. I'm waiting for it to arrive. I don't have ties with any laser company. I've been going by others feedback and advice. When I receive it then I'll know better.

    Quote Originally Posted by Dr Laser View Post
    I love the way nanoWatt nicely placing shill inside the topic.)

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