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7W 445nm VS. 4W 470nm

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So as my name suggests, I am looking for the most powerful (brightest) laser I can get my hands on. I already have a 1.3W 520nm on its way so now I am looking into the blues. I have been searching the forums and YouTube for a little while trying to compare the 7W 445nm to the 4W 470nm, but I am having a hard time finding a consistent comparison between them. Some comparisons make the 445nm look pretty purplish and the 470nm a solid blue color while others comparisons make the 445nm look like a bright blue while the 470nm looks right smack in the middle between green and blue. I know neither of these comparisons are very accurate so does anyone who has both of these wavelengths know of an accurate picture/video showing their true colors? How does the divergence on the NUBM07 compare to the divergence on the NUBM44-V2? I would be using the G8 lens with a SanWu 3X BE on both. Thanks!
 
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barthchris

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So as my name suggests, I am looking for the most powerful (brightest) laser I can get my hands on. I already have a 1.3W 520nm on its way so now I am looking into the blues. I have been searching the forums and YouTube for a little while trying to compare the 7W 445nm to the 4W 470nm, but I am having a hard time finding a consistent comparison between them. Some comparisons make the 445nm look pretty purplish and the 470nm a solid blue color while others comparisons make the 445nm look like a bright blue while the 470nm looks right smack in the middle between green and blue. I know neither of these comparisons are very accurate so does anyone who has both of these wavelengths know of an accurate picture/video showing their true colors? Also, how is the divergence on the 4W 470nm (NUBM07) compared to the divergence on the 7W 445nm (NUBM44-V2)? Thanks!
Divergence is much better for the 470nm (without the gball lens) it will appear brighter than the 445nm
as well. IMO the 520nm will blow your mind!
 
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Divergence is much better for the 470nm (without the gball lens) it will appear brighter than the 445nm
as well. IMO the 520nm will blow your mind!
Ok, so less divergence and brighter. Sounds like a no brainer, however, I am still stuck on which color would look better overall. I want the beam to be very blue without looking tealish so that's possibly the one downside with the 470nm. Could you possibly recommend a picture/video accurately showing their real life colors?
 
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If both are the same power and same divergence, the closer the wavelength is to the center of the green wavelengths (to the sensitivity of our eyes) the brighter a beam will appear. The fatter the beam the lower the divergence at a given wavelength using a given laser, but different devices have different inherent divergences. For example, the 7 watt NUBM44 450 nm blue diode has far more divergence than a NDG7475 one watt 520 nm green diode, this is because of the structure of the emitters being different sizes.

That said, if both pointers are using a common 6.33 mm diameter collimation lens the brightness of the beam at night appears about the same to me (regardless of the blue being much more powerful) for the first few hundred feet or more, but the NUBM44 blue will weaken quickly as the beam becomes much fatter in a far shorter distance due to its much higher divergence. Use a larger collimation lens and the divergence can be greatly reduced to that of the green NDG7475 or even less divergence, but then you are starting out with a much wider beam to begin with. Expanding the beam is worthwhile if what you are after is low divergence so the beam will remain tighter in the distance.

Have you tried the relative brightness calculator in my signagure (if you have them visible)? It is fairly close.

Here are some photo's I took showing how expanding the beam from a NUBM44 helps reduce the beam size:

Thanks, but I was actually comparing the NUBM44-V2 to the NUBM07, not the NDG7475. I have used that calculator many times in the past, but it has been far from accurate in my experience. Apparently my 300mW 532nm laser should be over 70% brighter than my 1,300mW 445nm, but its not at all. With a simple side by side comparison, my 1,300mW 445nm is clearly brighter than my 300mW 532nm. That's why I posted here to get input from people who have real life experience with these diodes. I'm sure you have alot of experience with these 2 blues; which would you say looks better/brighter?
 

paul1598419

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I can tell you for certain that a 470nm blue will not look teal at all. I have a 477nm one and it looks blue, but is much brighter to our eyes than a 445nm blue at the same power. Unless you are looking for the most power to burn with, I'd stay away from the NUBM44 as it diverges faster than any other direct diode we have available. You might be able to get better divergence using the G8 lens from DTR. Not sure if it would clip part of the beam as it has a focal length of 8 mm. Good luck.
 
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I can tell you for certain that a 470nm blue will not look teal at all. I have a 477nm one and it looks blue, but is much brighter to our eyes than a 445nm blue at the same power. Unless you are looking for the most power to burn with, I'd stay away from the NUBM44 as it diverges faster than any other direct diode we have available. You might be able to get better divergence using the G8 lens from DTR. Not sure if it would clip part of the beam as it has a focal length of 8 mm. Good luck.
Thanks, yeah I didn't think that picture showing the 470nm as teal was accurate. Since these two blues are not the same power though, which would you say look brighter/better?
 

paul1598419

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A four to five watt 470nm should look brighter than a seven watt 445nm one. Also, the seven watt needs extra optics to tame its horrid divergence specs.
 
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NUBM07
A four watt 470nm should look brighter than a seven watt 445nm one. Also, the seven watt needs extra optics to tame its horrid divergence specs.
Would you happen to know the divergence for the NUBM07 and the NDG7475? I can't find a consistent answer online.
 

Alaskan

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See: Much depends upon the collimation lens used too, even if the same diameter lens a longer or shorter focal length can make a substantial difference in the amount of divergence produced. For example, if one 6.3 mm lens has a 30% longer focal length compared to another of the same diameter, that lens will produce a beam which is 30% wider which will have 30% less divergence out of the same diameter lens, due to using more of its aperture.

Same thing said a different way: For some diodes, a short focal length 6.33 mm diameter G2 lens may produce a 4 mm wide beam through it while a longer focal length 6.33 mm diameter G8 lens may produce a 6 mm beam through it, that is a beam which is 1/3 wider which reduces how fast the beam will spread after collimation by the same amount (1/3 less divergence).


The problem of collimating the NUBM44 laser diode with small diameter lenses:

When using some of these small 6 mm diameter lenses with the NUBM44 laser diode the focal length can be a bit too long for that diode which causes some of the beam to be too wide to go through the diameter of the lens causing some loss of power, but even if some of the beam cannot get through, the reduction of divergence can be worthwhile if that is your main goal, instead of maximum smoke.

For myself, 10% lost due to truncating is acceptable because I like low divergence, but as a lower divergence tradeoff for photons produced in the distance they are equal. As an extreme, if the back reflection didn't kill the diode, if 1/2 the output power is lost due to truncating this isn't so bad (if lower divergence for a given lens size is your goal) as this will also produce 1/2 the amount of divergence but regardless of the truncating, due to the lower divergence (1:1 ratio of power loss to decreased divergence) will produce the same amount of photons in the great distance within a spot diameter.

For those of us who aren't into lasers for burning or maximum photons delivered in the distance this isn't as much about that, we want to see a blow your socks off bright ass beam. For that, buy a 532 nm green DPSS laser, these diodes won't produce high power in nearly as thin or as bright a beam as a DPSS laser can which can also have fairly low divergence at the same time, but for the best specs be prepared to spend $$$ and to use a lab laser instead of a laser pointer configuration which can be made to produce much higher quality beams.

Guessing you will stay with the inexpensive NUBM44 laser diode, if you want maximum power output and don't care about divergence, use a G2 lens. There are other suitable lenses for the NUBM44, this is just one choice which won't truncate with that diode at its short focal length.
 
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Arcygenical

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I will say that around 125mw of output, the ~488nm diode I'm running looks about as bright as a ~800mw 445nm. That's to my eyes, with some degree of tritanopia... Not sure how that affects perceived output, as I'm not fully colour blind to blue wavelengths.
 

Snecho

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One thing that could be of note I've heard about is spectral sensitivity. With night adapted eyes, i.e. Pointing at night, the color sensitivity of the human eye shifts from 555nm to about 505nm. Much closer to the blue spectrum making blues practically as bright as green. That would make 470nm Considerably brighter.

From Wikipedia, "It has been established that the maximum spectral sensitivity of the human eye under daylight conditions is at a wavelength of 555nm while at night the peak shifts to 507nm."

Very interesting food for thought 😃
 
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