UV, Violet, or IR which is best for burning?

[Manicorn]

I'm trying to decide what my next laser should be. I have green and red, waiting for my arctic. Does IR burn? 808nm vs 1342nm. So many questions in my mind. I'm looking for max burn here!. any suggestions?

 

[goninanbl00d]

Max burning potential?

For a given output power, shorter wavelengths will burn more. Shorter wavelengths <450nm will also have no problems burning light-colored substances such as white paper.

In reality?

UV lasers aren't very powerful, and they're expensive. 808nm IR is the cheapest in terms of $/mW.

445 is still the best overall burner, though. Packing 1W of optical power and a short wavelength, it makes easy work of anything while still being affordable ($45 diodes).

Also, with ANY burning laser, make sure you know about laser safety, and use protective eyewear. You only get one set of eyeballs.

 

[Manicorn]

Thank you, that's what I gathered in my quest on line. I needed confirmation from an expert

 

[hugo999999]

indeed, a blue photon has twice as much energy as a red photon, UV having even more energy, and IR quite a bit less depending on how long the wavelength

 

[goninanbl00d]

Wavelength is not everything.

A 1W 808nm laser will have extreme difficulty burning white paper, whereas a 500mW 405nm laser will be capable of doing so very easily.

Why?

Because the shorter wavelength is more readily absorbed. When it comes down to burning power with a handheld, how readily the wavelength is absorbed is much more important.

A CO2 laser at 100W can melt rock, while a 808nm diode laser at 100W cannot. The CO2 laser, running at 10600nm, is absorbed by everything- even glass- hence why it is possible to use it to cut glass.

It's all very complicated.

 

[Cyparagon]

It mostly comes down to what you're trying to burn.

indeed, a blue photon has twice as much energy as a red photon

Only if blue has half the wavelength of a red one. 450/650≠½

 

[Arayan]

UV lasers aren't very powerful, and they're expensive. 808nm IR is the cheapest in terms of $/mW.

if properly focused...

 

[leukoplast]

I think I remember reading somewhere or just hypothesizing this myself, but I believe a lower wavelength laser can also focus down to a smaller point. Which from what I understand, is why a blu-ray disk can hold so much more data than a DVD. Because the smallest focus point of the 405nm laser is maybe a 1/5th the size of a DVD laser's smallest focus point, thus giving it more surface area on the disk to read from. And enabling the BD disk to hold much more data than a conventional DVD.

 

[mbessey]

All other things being equal, a shorter-wavelength laser can be focussed to a smaller spot. This translates to a higher energy density, and better burning ability. Other factors (beam size and shape) matter also, but wavelength has a major effect on minimum spot size.

If you start with 405nm and 808nm beams of the same size, focused with the same lens(es), the 405nm beam will make a spot 1/2 the diameter of the 808nm beam. That means the surface area of the spot will be 1/4, and the power level 4 times as high, at the same laser power level.

 

[chipdouglas]

Max burning potential?

For a given output power, shorter wavelengths will burn more. Shorter wavelengths <450nm will also have no problems burning light-colored substances such as white paper.

In reality?

UV lasers aren't very powerful, and they're expensive. 808nm IR is the cheapest in terms of $/mW.

445 is still the best overall burner, though. Packing 1W of optical power and a short wavelength, it makes easy work of anything while still being affordable ($45 diodes).

Also, with ANY burning laser, make sure you know about laser safety, and use protective eyewear. You only get one set of eyeballs.

445nm packs a lot of power in a 5.6mm frame. but it is only good for burning up close. if you want distance burning go for violet. ppl can light matches and pop balloons from over 40 feet with about 500mw

I think I remember reading somewhere or just hypothesizing this myself, but I believe a lower wavelength laser can also focus down to a smaller point. Which from what I understand, is why a blu-ray disk can hold so much more data than a DVD. Because the smallest focus point of the 405nm laser is maybe a 1/5th the size of a DVD laser's smallest focus point, thus giving it more surface area on the disk to read from. And enabling the BD disk to hold much more data than a conventional DVD.

this is true but it is not really relevant to our hobby because our lenses are nowhere near as presise as lab lenses. and our eyes cant see that small.

michael

 

[leukoplast]

this is true but it is not really relevant to our hobby because our lenses are nowhere near as presise as lab lenses. and our eyes cant see that small.

michael

But the focus point can get that small with the lenses we use right?... or at least smaller than a 650nm with the same lenses? Cause my 405nm <100mW lasers can rip through stuff that my >150mW 650nm could never even dream about doing. Ever since I got my first 405nm, I always thought that the focus point looked so much smaller than my 532 and 650nm lasers when I focused them down. Although I suppose that could have just been the result of the color making it 'seem' smaller (with goggles on of course).

 

[chipdouglas]

i'm pretty sure i read it doesnt matter. hopefully pbd will chime in. and your violet is more easily absorbed by materials.

ex. my dilda is 180mw... i can focus it till the sky falls down but i will never burn myself with it. but my violet doesn't even have to be focused for me to even feel heat.

michael

 

[daguin]

i'm pretty sure i read it doesnt matter. hopefully pbd will chime in. and your violet is more easily absorbed by materials.

ex. my dilda is 180mw... i can focus it till the sky falls down but i will never burn myself with it. but my violet doesn't even have to be focused for me to even feel heat.

michael

The red color of the dilda is dissipated out into the lower layers of skin. Try focusing it on a dark freckle or a mole :eg:

Peace,
dave

 

[DrSid]

Also .. if you say blue photon has more energy then red ones, it just means that you will need less blue photons for same power. But 200mW of blue will have exactly same burning capacities as 200mW of red, putting aside different absorption properties of burned material and focus.
Focus imho will make little difference, as those small lens do not reach diffraction limit. There are other distortions with larger effect. For 1W 445 diodes for example their elliptical beam will focus much worse then common red lasers.
For burning skin (and eyes !) 445 will burn much more, as it is several times better absorbed. Still my 200mw red burns me happily.

 

[chipdouglas]

The red color of the dilda is dissipated out into the lower layers of skin. Try focusing it on a dark freckle or a mole :eg:

Peace,
dave

thats kind of what i was getting at. but as i'm sure you have noticed over the years that i don't explain things very well. :cryyy:

 

[pullbangdead]

Ah, a classic question, and I answer it with another question: which color car is the fastest? I personally think red cars are faster than blue cars, what do you guys think? Yellow cars are pretty fast too though. Not a perfect analogy, as color does matter somewhat in some cases for laser "burning"/cutting, but it does get at the heart of the issue, that color doesn't decide burning capability, it more depends on other factors.

really though, it depends what you want to burn, as you need the object to absorb as much light as it can. In most applications that hobbyists encounter, 405nm is absorbed very well, even by many white things around us in every day life, so it seems the best. For some objects, IR may be better. In general, of the visible wavelengths, it seems that the longer 405nm light is absorbed by more objects, but for some objects the extra power available in 445nm may overcome the absorption difference, so it really just depends on what you're trying to do. There is no single answer.

As far as focusable size, it is true that lower wavelengths have smaller theoretical focal limits, but we never get anywhere neat those theoretical limits in practical usage with one single tiny lens straight off of the ugly output of a laser diode. It's largely a moot point. Like yes, a Ferrari may go faster than a Porsche, but I have neither, so why does it really matter?