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Need some advice..

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Hey everyone, im addicted to lasers lol..

Anyways i need some help understand somethings..i have some knowledge on some lasers..example i made a red burning laser..
I have some cheap 5mW green lasers..

I really like beam pointing, and from what i understand green is the best since the human eye sees it best..
And i thought that blu ray was best for burning..is this so?
What im really looking for is something that does both..
A powerful beam, and also be able to burn..

I dont anything much about 445nm diode, but i realise its a very powerful diode..and you can build hand help pointers that run above 1watt..
I was very impressed by that..
But i would like to know if it is the best choice for beam pointing..
Is it as visible as the green? and what about burning? do i have to concentrate the beam down to small point that only burns a few inches away (like what i have to do with my red)?
Im fascinated by what ive learned about the 445nm, but i need more information..
I know this is a noob question..but is the 445nm diode the most powerful when it comes to hand help pointers?
Any advice would be greatly appreciated..and once everything sounds good, im off to the 445nm thread lol..thanks..
 

Eudaimonium

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First it's "hand HELD" pointers, not help :D

Second, no, bluray burning the best is not true, and least partially.

Green is at peak of human eye sensitivity to colors, at least closest to it from all other available lasers.

445nm lasers, as powers they are normally being run, do not require focusing at all to burn the cr*p out of everything. When focused down, they make a nice mess out of the object unfortunate enough to be there at the focal point. Make sure it's not your finger or something. (Keeping eyes out of beam's range is implied).

Make sure you got good safety goggles for that.

Greens still have wavelenght for visibility, against sheer power of 445nm photons.

I have found my 445nm handheld to be roughly equivalent to 100 mW green in therms of visibility.

See some of my videos here-
Some words about safety :


This is for fun:
 

Ash

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For burning, yes 405nm is better than 532nm as the near-UV light is absorbed more readily by most surfaces, but the beam is difficult to see.
For a visible beam + burning, a 532nm laser is fantastic, but even with 200mW, you will need to focus the laser to a "point" to be able to burn, just like you do with your red laser, and even when focused, 532nm (green) requires "darker" material. A 100-200mW 532nm laser will not burn white paper.
A 1W 445nm laser will burn many things even when the beam is not "focused" as it is a large amount of power over a small area. If you focus the 445nm laser, it will be a very strong "burning laser" and melt/burn through almost any soft material (wood, paper, bugs, plastic) but it is not strong enough to melt metal or anything.
Beam pointing? Well, a 1W 445nm laser is about as bright as a 300mW 532nm laser. So, 445nm is not as good as a green for "beam pointing"
Yes, at the moment (for visible wavelengths) 445nm is the most powerful you can get for a handheld. Some members here have built +1.5W 445nm lasers, but there are also >2.5W IR (808nm) handheld lasers available.
 

RA_pierce

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These 445nm diodes are good for short range burning.
The beam characteristics make them useless for burning at a distance due to the very elliptical output (like a line or bar rather than a dot).

Beam visibility is good at high powers, and at 1W, it will be roughly equivalent to ~150mW to photopic vision and ~300mW to scotopic vision (compared to 532nm). But it will be much more "intense" and it will leave after images.
However, the human eye does not focus the short wavelength exactly on the retina, so at a distance the beam or "dot" will appear out of focus and washed out.

There are more powerful diodes in existence, and some have made hand-held lasers out of them, but they are in the IR spectrum. Power can exceed 2W easily.

To highlight some characteristics of different wavelengths:

405nm: High power, poor visibility, very dangerous, very good burning capability at long range, high $/mW ratio.

445nm: Very high power, poor visibility & burning capability at medium range, very dangerous, low $/mW ratio.

532nm: Medium to high power, very high visibility, good burning capability at medium range, medium $/mW ratio, less eye hazard (due to lower power needed for high visibility).

650nm: Medium to high power, medium visibility, good burning capability at long range, low $/mW ratio, little to no lasting after-images with use (assuming no direct or short range exposure).

At least, that's how I would summarize it.

Get goggles. Play safe.
 

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Thanks for all the information guys!!!! much appreciated..and yeah its hand held lol..

Ok so hear this..im satisfied with something around line of a 100mW green and according to u guys a 1watt 445nm, would give u about that brightness, right?

Now about burning, u all say that 445nm is good for burning, and i wont have to focus to burn..
But is it the best hand held burner around? (meaning that we can access and NOT IR, im afraid of that!! lol)..

Another very important question is, what is the burning range of a 445nm laser? if the beam is tightened to give long distance pointing, how far would the burning range be?
 

RA_pierce

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Another very important question is, what is the burning range of a 445nm laser? if the beam is tightened to give long distance pointing, how far would the burning range be?
With 1W of 445 and an aixiz lens, maybe ~20 feet give or take a few. Keep in mind that Dr. Lava offers cylindrical correction for these 445nm diodes that will allow much better beam characteristics.

My "400mW" PGL 532nm (peaks in the high 700's) has very low divergence. I considered it a better burner than my 980mW 445nm (now sold).
With a 10X beam expander I could light white matches from over 60 feet.



/showoff
 

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Sorry man but i dont really understand..how were u able to light matches with a green over 60 feet which was weaker than the 445nm..can u please explain what u were using..because if that is possible then it makes no sense for me to go for a 445nm..since the green would give a very good beam and now im hearing that it can burn over 60 feet..please explain this to me..im confused..thanks..
 

RA_pierce

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Sorry man but i dont really understand..how were u able to light matches with a green over 60 feet which was weaker than the 445nm..can u please explain what u were using..because if that is possible then it makes no sense for me to go for a 445nm..since the green would give a very good beam and now im hearing that it can burn over 60 feet..please explain this to me..im confused..thanks..
That green laser averages ~650mW and ~700mW on a good day. It peaks in the high 700's and occasionally ~800mW.
Combine that with the superior beam characteristics of DPSS vs multimode diode, then add a 10X beam expander to it, and you get one helluva "burner."

The 980mW 445 I built was a few hundred mW more powerful, but the beam quality sucked, so the range was limited even though it was focusable.

Even without the beam expander, divergence of that green laser is ~0.8mRad, so it has no problem smoking most combustible materials without being focused.

The catch is... the green cost me ~$720 + $200 for the beam expander.

A beam expander "expands" the beam to reduce divergence (divergence and diameter are inversely related) as a function of it's expansion... so the laser's divergence is 0.8mRad, and the beam expander reduces divergence by 10X, so the divergence after the expander is 0.08mRad (theoretically). And the beam expander can be focused so I can focus this laser at a few tens of meters.
 
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WLHostage

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He indicated that the beam on his 532nm was much better (ie more focused) than the beam on his 445nm. The more dense you can keep the light the better it will burn, that is why focusing the beam makes it burn faster because you have more particles moving through the same area.

I'm fairly new to lasers as well but here is what I have learned so far in regards to burning (if I make a mistake someone please feel free to correct me :)).


Laser Power: This is the single biggest factor in burning. The more powerful your laser the faster it will burn (this assumes all else is equal). A 1w laser will burn better under the same conditions than a 500mw laser will. Change those other conditions however, and you may have different results

Light Density: There are several factors that come into play here such as divergence of your beam, focusing etc... Focusing the beam allows you to get the maximum power at a single point. This in its self does not increase the power of your laser, ie a 1w laser is still a 1w laser, you are simply getting full use of that 1w instead of a fraction of that power by spreading it over a larger surface area.

Light Color: Certain colors are absorbed better than others which is why most people use dark surfaces such as black balloons to increase burning potential, another option is to carry a sharpie around with you and simply blacken any area you wish to burn. The optimal colors to use depend on the wavelength of your laser. IR light is absorbed easier by more objects making it probably the best for burning potential though it clearly has other drawbacks such as visibility. But a 1w IR laser would be just as powerful as a 1w Green laser assuming the same density of light and that the rate of obsorbtion on your target was the same for both wavelengths.

Visibility: This has no direct relation to the lasers burning potential, however it is a factor for safety and one of the reasons people generally shy away from the IR lasers. Not being able to see the beam has several drawbacks such as the potential to damage someone or something without knowing it. The other drawback is that it is much harder to tell what is happening with the beam without special equipment to help visualize the beam profile.

Cost: This is probably one of the biggest factors for people when making a decision on which lasers to buy. As mentioned before the raw burning potential of the laser is determined by it's output power, the more powerful the laser generally the more expensive the laser. However, with the recent advancements in technology we have seen a very sharp decrease in cost for the 445nm diodes which have made them one of the more popular lasers for burning since you can get an amazing 1w of power at a fraction of the cost for other wavelengths. Green lasers for example are still far more complex to produce as it requires a crystal assembly instead of a simple diode, this complexity in creating the laser module means that a 532nm laser module will cost more per mw than a 445nm laser diode will.

Summary:
Total power of the laser determines raw burning potential
IR Lasers are probably the best for burning due to their range of obsorbtion.
445nm Laser are probably the most cost efficient burning lasers.
Focusing your laser allows you to get full use of the power being used.


Hopefully that is helpful. I decided to get a green laser around 200mw for pointing, and will be using a 445nm laser for burning.
 

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Thanks alot man..that information was really good!!..thank you for taking the time..
I think i would try my hand a a 445nm laser..and i would also use it for pointing..since at 1watt the beam should be pretty bright..thank you all..
 




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