Long distance burning - Question

chipdouglas said:

At leo.... Please delete the name of the company you posted. The are a pain in the ass and give the admin hell.

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Sorry, what is the name of the company I posted? (Is the name of the 445 nm diode?)

Burnsy said:

I don't think you can buy very high powered blurays.

But check this out =)

http://laserpointerforums.com/f48/freak-12x-405nm-diode-1w-1000mw-yes-you-read-right-d-65765.html


So you should be able to get a >600mW 405nm custom built laser from some members here.
Using a G1 Lense or a LarryDFW Lense will be about 15% more power compared to the Aixiz405 glass lense but about 50$ more expensive.
I'm not sure which lens gives the best dot in the distance though.

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hi,
after owning a 445nm from Yob my next laser is going to be a 405nm for sure.

hi Leonardo,
the 1.2W 445nm that I had had no problem burning at 1m not to mention 2W of power.
the longest i had tried is 1.5m and target got to be dull color object (dry leave for my case). note that i had it hand-held NOT on stand and it burns almost immediately.

Leo.... Yep because they get mad for the bad publicity especially since they dont actually make it. They bjy it in bulk from a diode manufacturer.

Leoprix said:

Yes, DrSid.
This is exactly what I mean. If I can have very good burning beam for a 2W 445 nm laser at 1 m distance, I can reach more or less the same dot (so the same burning energy) also at 20 or 30 m distance, obviously with a suitable lens. Could you tell me when you will have test your 1,5 W with a standard 50 mm relfex lens? I have two old glass 50 mm lens for relfex and I am courios to know.
Thanks.
Leonardo

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Sure .. I will report .. but I really can't tell when. I have at least one busy month ahead of me and I won't be able to do it sooner.
You can always just try. Simply remove all lens you have on your laser, and use the photographic lens. You should place the diode into the focal point of the lens, which is about 4cm from the lens end for photographic lens .. ie where the film would be if it was in camera.
The angle of raw diode beam should cover the lens entry well from this distance too. Generally you want to fit all the beam cone inside the lens, and use most of it. This is more important then putting the diode exactly into the focal point, as focal point can be shifted by using lens focus ring. Also remember to open the lens stop blades. They especially are often greasy and you should not shine the laser at them.
You have to have the diode exactly in the lens axis, shining exactly in the axis direction. This is very hard to achieve by just holding it in your hand. You should get clean dot with no splash. By clean I mean same shape as with your normal lens, so for 445 nm it should be the same rectangle. If you get triangle, or something else, you are probably not aligned well.

Wear goggles for SURE, as the lens will cast reflections everywhere.
It would be better to test it on lower power, to minimize all possible dangers.

PS. there are some tricky properties of this 445nm beam. The beam at the diode is wide in one direction, and thin in another direction. But the divergences are the opposite .. so the beam is lets say tall rectangle from the start, then it turns into square, and at a distance it's wide rectangle. With normal small lens the distance where it 'flips' is about 1-2m, when focused to infinity. With lens 10 times bigger, you may be surprised to see square or almost round dot at 5m .. but it's just the same thing, the beam will turn into rectangle at bigger (or shorter) distances.

DrSid,
Considering that is true. Could be good the 1 W 445 nm diode (pumped at near 2 W) or better a 12 x 405 nm diode driven up to 700/800 mW??

Can't really tell. I don't have any 405nm. 405nm could be better. It would depend on the distance.

405 will definately be better.

If you use the same lense at the same distance (I tried at 2 meter) then 405 beats the 445 diode easily.
Even when the power of the 445 is more than doubled like with my lasers for example.

Now if you would change that lense to a 50mm lense why should it be different?

Sure the 445nm will have a better (bar shaped) dot than with a G1 lense but the 405nm will profit the same way which means he'll burn the crap out of the 445 :eg:

I mean on short distances the advantage of better beam might not be as big as the power difference. There will be some 'critical distance' .. below it beam shape does not matter .. above it it, 405 will be better.

BTW here is a "classic" movie on a 1.7W green laser that is able to burn over 50 m

o.0
is that vid legit?
if so, how much was it??? 0.o

DrSid said:

I mean on short distances the advantage of better beam might not be as big as the power difference. There will be some 'critical distance' .. below it beam shape does not matter .. above it it, 405 will be better.

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Yeah that's true. But for me that distance is only at about 0.5 meter already...
That's about the distance when I do some burn experiments where the 1.6w 445 and my 600mW 405 are equal.


And the 532nm vid is awesome. I'd like to try this once

what about 1064 nm lasers? The divergence (and the beam diameter) is similar to that of 532 nm but the price should be lower...

Correct me if I'm wrong, but I thought strong IR lasers are all multimode, or even multi-chip.

PS: I tried my 500mm x 90m long range lens with my 1.5W. And I was not impressed. The dot looked great at 5m . Round, under 1mm in size. Still it did not burn at all, I could compare it to focused 50mW green. It did some damage to CD case, but really minor. It could not burn through. It did not smoke black paper, and it did nothing to a match. I guess there is too many glass surfaces inside. It is Schmidt–Cassegrain type, with Barlow at the end. I could remove the Barlow element, which would make it only 2 glass/air surfaces (and 2 mirrors) .. hope it helps.

So a good focused standard 600 mW green laser (2,5 mm round dot and <1 rad divergence) could be better than a 445 nm, 1,5W focused with a reflex lens?
Sorry but now I am a bit confused.
The way are:
a) a 2 W 445 nm focused with a long length lens (as a 50 mm standard relfex lens)
b) a 700 nm 405 laser (12x) focused with the same reflex lens (glass lens)
c) a good TEC green laser 600 mW (would be enough?)

The lens I used lowered divergence .. but they have high loses because of inner reflections. Lens we use on lasers usually have special coating tuned to specific color, to avoid that. So this part is still open.
Anyway comparing green and 405nm seems somewhat simpler to me. I can't see any advantage for the green.