A question regarding laser power with different wavelengths

[drummerdimitri]

Hey guys, I was wondering if a 10 mW 473 nm laser would have the same power as a 650 nm 10 mW, a 10 mW 532 nm laser etc... in terms of burning power. Also, if I were to use a magnifying glass and the sun to burn things, what would be the laser equivalent in terms of mW roughly? I just wanted to clear things up. Thanks!

 

[Scotty 757]

Color does not take into effect when it comes to power but it does when it comes to burning.

 

[drummerdimitri]

Thanks for partially answering my questions, so what exactly are you saying? The shorter wavelength lasers with the same power will burn better? Elaborate a little more please...

 

[ElektroFreak]

a mW is a mW is a mW.. regardless of the color. What changes is how various wavelengths affect various colored surfaces. As an example, a red laser has a very hard time burning objects that are red, but they'll burn most other colors, especially dark colors much more easily. A DVD burner diode won't burn your skin but it will burn a piece of purple plastic very well. Violet lasers tend to burn the widest variety of colors, but the shorter the wavelength of the light (red being longer, violet shorter) the more energy per photon.

 

[AndyR]

I believe Elektrofreak summed it up nicely.

About the sun / magnifying glass thing, I think there are too many variables to accurately calculate that.
Cloud cover, the sun's location in the sky, your location on the earth, the size/quality of your magnifying glass...

 

[Bijeebus]

watts are joules(energy) per second, so the burning power of different wavelengths is the same if they are the same mW. but like elektrofreak said the color odf the thing your burning matters.

 

[randomlugia]

I saw a few threads on Fresnel lenses a while ago. And I think someone said that the sun's energy is around 88 watts per square meter, correct me if I'm wrong.

 

[Bijeebus]

I saw a few threads on Fresnel lenses a while ago. And I think someone said that the sun's energy is around 88 watts per square meter, correct me if I'm wrong.

If this is true then my 4.5cm radius magnifying glass should create a focal point that puts out about 560mW. but it would probubly be less because i dont think a magnifying glass focuses ALL the light into a single point. somebody with a LPM should test this though.:thinking: It would also probubly depends on where you live and what time of year it is.

 

[RA_pierce]

I saw a few threads on Fresnel lenses a while ago. And I think someone said that the sun's energy is around 88 watts per square meter, correct me if I'm wrong.

I recall 0.9-1.2kW/m^2


When it comes to burning, beam diameter, wavelength of the laser, and color of the surface are most important.

You won't do much burning with 10mW, by the way.

 

[Crazy Jay]

Blu=ray is my favorite and I bet tons of people agree that it's just amazing. It causes things to fluoresce like white T-shirts and many many things. I noticed that it turns into a bright blue dot when shone onto most white fabrics and plastics... at least mine does.

Plus it's just plain beautiful.

 

[drummerdimitri]

What about divergence? It would make sense that a laser with a lower divergence would be able to burn things better at longer distances because the beam diameter increases less significantly over distance. I heard that as beam diameter increase, divergence decreases as well, so if the beam diameter is infinitely large, the laser's divergence would be equal to zero? Correct me if I am wrong, but that's just my interpretation on the subject matter.

 

[roddenberry]

And to come back to the OP's question... I doubt that a 10 mW of any wavelenght, even if tightly focused, could burn anything...
- Robert

 

[Rafa]

And to come back to the OP's question... I doubt that a 10 mW of any wavelenght, even if tightly focused, could burn anything...
- Robert

If you focus 10mW you can burn, but it has to be VERY well focused and for example you can do micro-holes into black palstic and things like that. 10mW are a lot of mW's lol.

 

[drummerdimitri]

Guys, the 10 mW lasers was just an example. I could have picked 100mW instead and the same principle would have been applied.

 

[kingdave2357]

Blu=ray is my favorite and I bet tons of people agree that it's just amazing. It causes things to fluoresce like white T-shirts and many many things. I noticed that it turns into a bright blue dot when shone onto most white fabrics and plastics... at least mine does.

Plus it's just plain beautiful.

Yeah, I second that