638nm as dim as a 405?

ApexProxy said:

I would not really suggest going over board with optics on 445nm lasers because of their interaction with the air. Something like that would benefit a Mitsubishi 500mW 638nm diode far more IMO. For 445nm lasers I think a high grade single element long focal length lens is about as much as I will do.

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Atomicrox said:

I can also see a 400mW 638nm's dot at a far longer distance than a 1.3W 445nm's, even though at short distance the dots are very comparable.


As for the OP's question - part of the problem is that older CIE data is *very* off on the blue side of the spectrum. You can use newer CIE data on that tool, which is more accurate (but still off): Beam: (638nm 483mw) vs. (445nm 731mw)

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EpicHam said:

So... is there anything better than an AxiZ 3 eles lens for a 638nm?

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Atomicrox said:

It's the same tool but I used the "ChromaCompat=yes" parameter, which switches to newer CIE data IMHO this should be the default.

I'm not aware of any other tools...

BTW another effect that matters here is the fact that our eyes have more difficulty focusing on blue light. Ever notice how 405nm looks "ghastly" and 445nm looks unfocused after a few hundred meters? Red and green look good all the way.

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ApexProxy said:

EpicHam said:

So... is there anything better than an AxiZ 3 eles lens for a 638nm?

There are lots of lenses that are superior to what we use standard but they are usually bare lenses that require custom holders to be made for them. This makes them impractical and significantly more expensive to work with. An example of such a lens is a G1/2 lens but we have grown to use them so much that people like DTR make holders for them readily. The stock acrylic lenses from Aixiz work exceptionally well for lasers less than about 300mW, any higher and you risk melting the holders.



The comparison for beams on that little tool is horrifically off but it is fairly accurate if you look at it when comparing dots. Its still not possible for it to be exact anyway because everyone's eyes are sensitive to different wavelengths in different amounts. I for one see 405nm and 445nm significantly better than average as well as near IR a little better than average from what I have gathered by talking to people around here.

Also, 405nm and 445nm aren't so much difficult to focus on(they are a little, more so 405nm) as rather the beam scatters in midair causing the air to actually glow around it which goes back to Rayleigh scatter. This is shown by putting a 532nm laser less than an inch away from a 445nm beam and allowing your eyes to use that beam as a focus point. The 445nm beam still is just as ghost like as ever and it makes almost no difference even though your eyes are focused fine.

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Well the G series lens isn't really "better" , the module just has a higher transmittance , but at the cost of a less collimated beam profile....
So .. Is there a lens better than the 3 eles AxiZ at collimation?

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EpicHam said:

Well the G series lens isn't really "better" , the module just has a higher transmittance , but at the cost of a less collimated beam profile....
So .. Is there a lens better than the 3 eles AxiZ at collimation?

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ApexProxy said:

Technically saying just about anything is "better" is subjective.

G lenses have a higher transmittance than the other lenses we use which means they allow more light to pass. They are also in modules that block less light which means even higher output. The design of the lens is also very good for semi close range burning because it allows for a very tight focus. More so than 3-element lenses, at least from my exp.

On the other hand 3-element lenses produce beams with superior divergence and cleaner dots.

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EpicHam said:

So after all ...
3 eles lens is the only option I have if I want to improve upon the poor divergence intrinsic to 638nm diodes

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ApexProxy said:

That is your best option of the very readily available standard lenses. Otherwise you can ask Lazeerer about one of his long focal length lenses he calls the X-Lens. They are better than 3-element lenses but unfortunately I have yet to run across a lens that really makes those ugly ass diodes much better LOL.

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ApexProxy said:

EpicHam said:

Also, 405nm and 445nm aren't so much difficult to focus on(they are a little, more so 405nm) as rather the beam scatters in midair causing the air to actually glow around it which goes back to Rayleigh scatter. This is shown by putting a 532nm laser less than an inch away from a 445nm beam and allowing your eyes to use that beam as a focus point. The 445nm beam still is just as ghost like as ever and it makes almost no difference even though your eyes are focused fine.

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The problem is that focus varies with wavelength - when red is focused blue isn't:

In my experience it's a lot harder to focus shorter wavelengths properly and I think that makes the dot (not the beam) harder to see at a distance, because it looks blurred. But scattering also makes the range worse.

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Atomicrox said:

The problem is that focus varies with wavelength - when red is focused blue isn't:

In my experience it's a lot harder to focus shorter wavelengths properly and I think that makes the dot (not the beam) harder to see at a distance, because it looks blurred. But scattering also makes the range worse.

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