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638 or 650nm Whats more popular?

nzoomed

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For my next build, I would like to do a red laser, what wavelength is most popular?
Is there any thats more visible?
This seems to be the brightest 638nm diode I can find, its a Oclaro HL63193MG

Im assuming most of the generic red lasers are typically 650nm?
 



Alaskan

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638 nm is a fair amount more visible, power for power, compared to 650 nm, so for red that wavelength (IMHO) is the best choice between those two. Of course, when at the same output power 532 nm green is far more visible than 638 nm red because the sensitivity of our eyes favor the green wavelengths over red or blue.

The next thing to consider is whether to choose single mode or multimode, single mode will travel much further with less spreading, for a given lens/beam diameter, compared to multimode.

What's more popular? Due to the brilliance of 638 nm compared to 650, it wins for most members. But to each their own, if you like a deeper cherry red color that's also fun.

See: Online Relative Brightness Calculator: https://slickscreen.github.io/laser-tools/brightness







All of this aside, to see much difference between two laser beams of similar diameter at the same wavelength, you would need about twice as much power.
 
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paul1598419

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Don't get the Oclaro as it fails too easily. The Mitsubishi ML501P73 is a much better choice, but both diverge horribly. I have some 400 mW 650nm reds using the LPC840 diode. It is a single mode diode so you don't have the line instead of a dot in the beam profile.
 

nzoomed

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Ok, thats helpful, I did wonder if 638nm would be more visible, so thats good to know.
What diodes are easier to find? I see there are 632.8nm available also, im assuming they would be even more visible?
 

RA_pierce

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Ok, thats helpful, I did wonder if 638nm would be more visible, so thats good to know.
What diodes are easier to find? I see there are 632.8nm available also, im assuming they would be even more visible?
There are 633 nm diodes available but usually wavelengths around there are produced by HeNe gas lasers.

I'd recommend the 185 mW 638 nm diode. You can get one at DTR's laser shop. Its bright and the beam quality is very good. It's not as powerful as the other diodes you mentioned but more fun, in my opinion.
Safety is something you should be concerned about so pick up some safety eyewear.
 

nzoomed

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OK, that helps anyway. I found another diode called the USHIO HL63613.

Anyone heard of this?
 

Alaskan

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Typical divergence of 20 and 45 is not so great, but unless single mode they won't be. Inexpensive diode from some sellers, so who cares, put it in a pointer and have fun. Laser diodes are consumables, especially so the way we over drive them, have fun, then replace.

 

paul1598419

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If you want a powerful 638nm red laser I'd stick to the Mits ML501P73 as they hold up better than the others we've had. That diode can be pushed over 1 watt, but the Ushio, not so much.
 

Lifetime17

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Don't get the Oclaro as it fails too easily. The Mitsubishi ML501P73 is a much better choice, but both diverge horribly. I have some 400 mW 650nm reds using the LPC840 diode. It is a single mode diode so you don't have the line instead of a dot in the beam profile.
Yes ,Yes get the Mitsu they are way more hardy that the 700's and you can get at least 1W out of them with good heat sinking. Yes as said the divergence is crappy but you have a choice of lenses to choose from for that .
Rich:)
 

nzoomed

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Yes ,Yes get the Mitsu they are way more hardy that the 700's and you can get at least 1W out of them with good heat sinking. Yes as said the divergence is crappy but you have a choice of lenses to choose from for that .
Rich:)
OK, thats helpful, What kind of lens would I require?
 

Gianakakis

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OK, thats helpful, What kind of lens would I require?
I'd recommend the G8 from dtr 90% efficient with long focal length, Or the Dtr-3e-r it will give you a cleaner beam with lowered diversion but its efficiency is in the low 70s.
 

nzoomed

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I'd recommend the G8 from dtr 90% efficient with long focal length, Or the Dtr-3e-r it will give you a cleaner beam with lowered diversion but its efficiency is in the low 70s.
OK, that helps, seems a G8 is a good all round lens. I can always mix and match and see what gives a better beam anyways.
 

Lifetime17

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I, 3E or 2E but you will loose some power not much.
Rich:)
 

Alien Laser

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I have a Oclaro almost 4y the divergence is very bad i purchased so many from DTR i love the color ( I also have 650nm ) and i was testing it and i got 1 it was more orange then red :cool:
 

paul1598419

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OK, thats helpful, What kind of lens would I require?
These have such horrible divergence specs that really only a cylinder lens pair will mitigate this awful problem effectively. But, that is more involved that just putting on a different lens. You would need a table in front of the collimating lens to use a cyl lens pair. If you don't mind clipping part of the beam the G8 is a possible answer, but even that won't give you a clean looking dot instead of a line for the beam's profile.
 

Richie89

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Don't get the Oclaro as it fails too easily. The Mitsubishi ML501P73 is a much better choice, but both diverge horribly. I have some 400 mW 650nm reds using the LPC840 diode. It is a single mode diode so you don't have the line instead of a dot in the beam profile.
which is ironic because I blew both my P73s up, my fault more than likely, I kept taking the lens off and exposing the diode because I was far too fascinated in what the diode looked like, got dust into both I believe. me and open can diodes don't get along very well. :(:LOL:
 




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