whats the most powerful wavelength?

not just for shows,

i am having a discussion with a friend aboout how he thinks some blue laser is more powerful that a red of equal power with cutting power.

i guess his karate instructor that supposedly works for the university of oregon told him a few years back that from a football field length away a blue laser of equal power to a red laser the blue would cut through more metal.

i thought higher numbered wavelengths (1000nm+) were stronger than (less than 400nm) of equal power.


anyways its a weird question but im sure one of you can give me a good explanation oh which wavelength packs more power.


thanks and good morning.

If 1 watt of blue and 1 watt of red were as close to similar design as possible and If both of the lasers are tem00 mode and had exactly the same beam characteristics the blue laser could be focused to a tighter spot due to its shorter wavelength which would produce more power per unit area.

your question as asked can not be answered IMHO.

Im sure Mixedgas or Frothy could phrase it better than I.

thank you kind sir! that makes sense i guess.
i mean if you break it down to the common diodes 405nm (blu ray burners) can burn a disc better than a 660nm dvd burner.

and thats because it can be focused in.

thanks for the input

short wavelength - more energy/photon


edit:

look here - the first tab , but it is in german:
http://de.wikipedia.org/wiki/Licht

In my own personal experience, what laserman said is factual. My blu-ray lasers all burn MUCH better than any of the others, and their burning ability is less dependent on the color of the object being burned. I also remember reading something about how short-wavelength photons have more energy that longer wavelengths, but I don't know the details of that.

What matters when you're trying to burn/cut something is simply absorbed power per area. The wavelength does however have an effect on both of those factors. A short wavelength means that the beam can be focused into a smaller spot.

If we assume that two beams of different wavelengths have the same radiant flux (power/area), the irradiance is indeed the same for both beams, but the absorbed power may not be. This is because every material has its unique absorption spectrum. Any irradiance that is not absorbed is useless if you're trying to cut something! Now, this is where the wavelength becomes interesting again. Anyone who has tried sticking his finger in the beam of a 100 mW red laser knows that this is completely harmless. Doing the same trick with a violet laser will be an almost instantly painful experience. Why? Skin does not absorb red light, but it does absorb violet light. This is also true for many more materials. It is in fact far easier to absorb light of shorter wavelengths, so this is true for most materials. However, as you get into the IR region of the spectrum absorbtion will go up again. Materials that don't absorb any visible light can be excellent IR absorbers.

In conclusion: Shorter wavelengths are generally better for cutting/burning materials, because they can be focused into a smaller spot. However, a longer wavelength may be superior in a certain case, depending on the target material's absorption spectrum.

I think what Tocket is saying is that it depends what colour the object is.

The color is only relevant for lasers in the visible region. A UV, IR or microwave laser does not care about color.

Quote:

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Originally Posted by tocket

The color is only relevant for lasers in the visible region. A UV, IR or microwave laser does not care about color.

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I speak of "colour" as a physicist; UV has colour, as does IR. Even microwave has reflectance that varies with frequency...

Quote:

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Originally Posted by heroic

I speak of "colour" as a physicist; UV has colour, as does IR. Even microwave has reflectance that varies with frequency...

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Well then, how long is a piece of string and who can throw it the farthest and would it make any noise if it never lands?

The OP question was vague at best and too many variables to answer correctly.:D

1W is 1W is 1W.... but if we're talking about cutting then I think Tocket's answer is dead on. It all depends on the material :D

If you have 1W of 405 and 1W of 650, then you could achieve higher energy density with the 405 because it can be focused smaller, but as we know the overall power is still the same.

thanks everyone this all makes sense and i now have some more info to refer to

As far as cutting is concerned, the material being cut determines what wavelength is to be used.
NdYAG (1.06u) is great for aluminum, for instance. CO2 (10.6u) has a real hard time with it unless you get into fairly high power (what Tocket said).

Tim

Thread resurrection time.
Only one person said that there is more energy per photon in shorter wavelengths. Now as energy relates directly to power vs time, does this mean that fewer photons per second are emitted for 1W of blue light than 1W of red light? Even assuming this is true, and that some sheet of substance were not fussy about absorption wavelengths, wouldn't the ability of shortwave light to smack electrons out of its atoms count for more than the smaller diffraction limited spot? As red is (roughly) twice the wavelength of violet, I image the difference in spot area theoretically reaches about four-fold power density for violet compared to red, but I don't know whether the ability to cut black tape or carbon paper would be fourfold better with violet. I suspect more, and I'm not sure how much difference if any would be due to the greater energy per photon...

Can anyone spare me a dry and boring Google search, followed by links I'd probably have to pay to read anyway, and which would go straight over my head if I did? I bet this stuff has been quantified somehow..

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Quote:

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Originally Posted by trwalters001

As far as cutting is concerned, the material being cut determines what wavelength is to be used.
NdYAG (1.06u) is great for aluminum, for instance. CO2 (10.6u) has a real hard time with it unless you get into fairly high power (what Tocket said).

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And you can reverse that selection for acrylic. :)

I used a 10 watt 1064nm laser for etching tools and dog tags in the military. It had a rather small focal point. You could set it it one spot and it would never puncture a dog tag. BUT if you put it on wood it would quickly dig into the wood before it came out of its focal point.

(It was also fun to use it to remove the reflective backing on a mirror. Just load up in image in the CAD program and focus on the back pane of glass. Looked like the laser was just wiping off the reflective material)

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^ this was probably a 1mm beam at its focal point

E=HC/Wavelength where H is planks constant and C is the speed of light Thus energy is inversely proportional to the wavelength . The shorter the wavelength the higher the energy in a photon packet. That means the lower the nm number the more energy. Red has less than violet. That is an absolute but doesn't answer the issue of "burning". That is based on the ability of a an object to absorb the energy. This is why CO2 lasers in the far infrared can burn better then 660nm lasers as an example. There is an absorption band in this region that includes the Hydroxyl group and water group. This is also why a microwave oven with even lower energy can burn by causing the water molecules to vibrate translationally and hence move faster which his the definition of heat. Didn't want to get more technical than this but happy to if you really want it but expect a few pages. BTW Einstein developed the photoelectric effect which is the above statement "sort of" before he was famous for the relativity stuff. That is why we have solar cells. higher energy than a threshold can knock free electrons and cause an electric flow.

The above post also point out that the shorter the wavelength the smaller the spot size(that's why they can pack more electronics in a 37nm pattern than a 22nm pattern) can be made and hence the larger the amount of energy that can be applied to a spot. What I state is physics. That is a practical matter of focus. Two beams of the same intensity erg/cm2 will be as I state the shorter wavelength will need less photons to achieve the same energy density.

1 pound of feathers is the same as one pound of lead The lead takes up less space because it is more dense. Take that analogy over to energy and you have the idea though not for the same reason.

what is truly weird is back in 2009 when this thread was started...i still had hair :)