Old 01-11-2011, 01:02 AM #1
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Default Brightness of Greenlasers

I just received my first green laser. It's only a 20mw model come as a gun laser kit, that I bought from DealExtreme. I'm very impressed with this green laser. The color is so rich and pure. I can totally see why this forum exist.

In day light, I can easily look at the dot this laser makes on the wall. it's very bright, but it's like looking into a really bright flashlight, or the sun. Not very good for you, but I'm not going to go blind. I sure wouldn't want to shine this laser directly into me eyes though.

In the evening, or at night, the beam becomes faintly visible.

I'm condemplating buying another laser and I'm wondering if anybody can give me an idea of the brightness different power levels achieve. If I buy a 50mw or a 100mw green, would I be able to look at the dot on a wall without goggles? Based on the brightness of my 20mw model, I'm thinking I wouldn't.

How visible is the beam (in an normal unfogged room) at 50mw and 100mw?
How about at night?

How bright is a blue laser compare to a green laser? I don't need a technical answer, just something along the lines of "100mw blue looks as bright as 20mw green" sort of answer.

Either way I will be getting some safety goggles when I get a new laser. These babies are amazingly bright.


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Old 01-11-2011, 01:17 AM #2
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Default Re: Brightness of Greenlasers

Light goes logarithmic so 20 mW to 40 mW is 2 times as bright ,then 160 mW is again 2 times as bright and so on ( non technical answer )
and for blue you need more milliwatts then for green ,i guess like 3 - 4 times the power to get the same brightness

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Old 01-12-2011, 03:45 AM #3
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Default Re: Brightness of Greenlasers

405nm blue is like .5% on the luminosity scale, while 532nm green is around 90% AFAIK.
Also, the specs may/may not be accurate and measurements might have IR included.

Last edited by hellokittyhk; 01-12-2011 at 05:00 AM.
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Old 01-12-2011, 04:55 AM #4
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Default Re: Brightness of Greenlasers

Yes, human perception isn't logarithmic. You need 4 times the power to perceive double the brightness.

50mW is fairly visible in a lit room (looking down the beam). Beam visibility is always greater when the beam is viewed parallel to the beam (not perpendicular)

50mW would be the upper limits on comfortable visibility against a white wall. Anything higher, and goggles are a must, else they will leave afterimages in your vision.

To answer your question regarding blue, it depends on what sort of blue. With 445nm, I find that 700mW is more or less identical to 200mW of green in terms of beam visibility.
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