635-640nm >100mW diodes with cleanish beams?

Rivem · Mar 8, 2016

You guys convinced me of a high power red laser for star pointing, so I'd like to build one. One concern I have is that I'd really like a decently clean and round beam/dot with low divergence, and it seems that might be a bit tricky to find in this wavelength. I know the Mitsubishi ones are pretty bad, but what about the others? Any recommendations for particular diodes?

Also, this will be my first complete laser pointer build, so any other recommendations would be apreciated. I at least know the electronics and am pretty good soldering sensitive electronics.

Side note: If you're looking to get rid of anything I could use for this project, I may be interested. Otherwise, I'll probably place some orders sometime next week.

Dr_Evil · Mar 8, 2016

Does it have to be 635 to 640? 660s such as the LPC 815 and 826 are pretty clean. You can get 250 to 300mW with the right lens.

Deleted member 16589 · Mar 8, 2016

IDK who suggested High power red But there an idiot I would not use High power red for star pointing. go with 5mW green.
go with a single mode Green diode Much safer since you wont need high power.

Bionic-Badger · Mar 8, 2016

Those single-mode 638nm diodes will do. $30-40 or so at DTR's laser shop.

Isaac Clarke · Mar 8, 2016

using green will ruin your night vision... there fore blue or red are use as alternative....

parts:
Diode combo with lens/driver from DTR laser shop...
Pen host from Laser66...

BowtieGuy · Mar 8, 2016

Rivem, Bionic is correct. Of those, my favorite is the Opnext/Oclaro 120mW single mode 638nm.
It's the lowest power single mode red that DTR sells, but still plenty for your purposes, even when set at a moderate output for long life.

Dr_Evil · Mar 8, 2016

Isaac Clarke said:
using green will ruin your night vision... there fore blue or red are use as alternative....

parts:
Diode combo with lens/driver from DTR laser shop...
Pen host from Laser66...

Green must not be that bad for your night vision considering that NVG output is green and you can find green backlighting in aircraft cockpits.

Rivem · Mar 8, 2016

Dr_Evil said:
Green must not be that bad for your night vision considering that NVG output is green and you can find green backlighting in aircraft cockpits.

The interesting thing is that green is much more detrimental to night vision for equivalent luminosities, but since our eyes are much more sensitive to it and can pick contrast up more easily in green light, it's becoming much more common. My concern was that by the time the beam from a green is intense enough to be easily visible in a crowd, it'd be too far. Shining my pointer at the ground is already bad enough.

lazerman121 said:
IDK who suggested High power red But there an idiot I would not use High power red for star pointing. go with 5mW green.
go with a single mode Green diode Much safer since you wont need high power.

I have what's likely around 20mW of 532nm, and people still have a bit of trouble seeing it at an angle. I'm still a bit unsure of whether or not a high power red would be all that much better though. Still open to suggestions. I do know that blue over 150mW is way too much.

Rivem · Mar 8, 2016

Dr_Evil said:
Does it have to be 635 to 640? 660s such as the LPC 815 and 826 are pretty clean. You can get 250 to 300mW with the right lens.

I'm much more interested in the shorter wavelength as I've already got plenty 660s, and the increased visibility would be nice. Beam doesn't have to be perfect, just not as messy as some of these seem to be.

Razako · Mar 8, 2016

Rivem said:
I'm much more interested in the shorter wavelength as I've already got plenty 660s, and the increased visibility would be nice. Beam doesn't have to be perfect, just not as messy as some of these seem to be.

If you don't care about a clean beam, a high power 638 will have great beam visibility at night. I have a 500ish mw 638 and I have no problems seeing the beam(even from side angles). The downside of course is that the output is bar shaped and it has really bad divergence.

If you want good beam specs I'd recommend that link given by Bionic.

Bionic-Badger · Mar 9, 2016

Yeah, I've used those 500mW @700mW 638nm lasers at night and the bar is definitely very visible. The nice thing about a really tight beam is that it will have a much more concentrated beam that could even look brighter than the highly divergent beams.

RB astro · Mar 9, 2016

Dr_Evil said:
Green must not be that bad for your night vision considering that NVG output is green and you can find green backlighting in aircraft cockpits.

I use a 20mW Green for my astronomy all the time, never had any issues.
Even better to use 5mW or 10mW but I love my 20mW Greenie, it's perfect for star pointing etc.

Lifetime17 · Mar 9, 2016

HiRivem,
If you really want some high out put get the Mitsu 500 set at 900mA's, with a 3 element lens 638nm is fine for what you want to do. The 660nm diode are awesome as well i have a few of them and they perform very well and the 660nm is a deep red a lot less orange in it, but you won't get the higher power from them, they are limited on the high power part of your project 200mW to 300mW's tops As stated from the other guys replying to this post they are correct. And the 638's and the 660's will keep the cost of the build low. Single mode 520nm's are a good choice for a visual beam as well taking out the equation for night vision compatibility .

Rich

Pman · Mar 9, 2016

I didn't read the whole thread yet but you can get 400mW out of the LPC-826 actually

Just about to post another build with one that hits 380mW at about a 620mA setting with a G.

635-640nm >100mW diodes with cleanish beams?

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