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685nm Pen Build - The Inspiraton

joeyss

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Besides being dimmer per mw do they look any different then a 660/650nm laser?
Like are they redder cause my 650 or 650 50 mw looks red as could be to me
 

joeyss

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I've seen 808nm from a 1 watt diode muiltimode with no lens on it. it spreads out fast but I only seemed to see it slightly redder than a dim 660 defocused next to it. I mean I can see it appearing on cameras weird depending how the red processing is done. I'm curious how a red laser can be seen pinkish though? has anyone compared it to a 720nm laser?
I might have to get one myself. Wouldn't you need to hit the blue cones somehow too to get it to appear even a bit pinkish? I might have to get one myself to see if there is a difference. maybe it has something to do with only being 15 nm away from 660 and the red is dimmer per mW and it allows you to see some other cone activity?
 

The Lightning Stalker

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Yes, definitely get one! You can never
know for sure what it will look like to
your eyes until you see it for yourself in
person. I don't have an explanation for
the pinkish/purpleishness either. Some
days it looks that way and some days it
doesn't. It is getting into the range
where your brain is like "what the heck is
that?" similar to 405nm. It's a bit hard
to explain until you have seen it for
yourself. For me, it's sort of like
looking at an optical illusion. I just
keep staring at it because there is
something about it that is intangible.
 

joeyss

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Yes, definitely get one! You can never
know for sure what it will look like to
your eyes until you see it for yourself in
person. I don't have an explanation for
the pinkish/purpleishness either. Some
days it looks that way and some days it
doesn't. It is getting into the range
where your brain is like "what the heck is
that?" similar to 405nm. It's a bit hard
to explain until you have seen it for
yourself. For me, it's sort of like
looking at an optical illusion. I just
keep staring at it because there is
something about it that is intangible.
have you tried using fog to compare the beam to a 660 and see if it's 685 is pink in the beam? Have these diodes been spectroed? Could it be the dimmer red lets you see another line in the dioide? This is just really weird.
 

The Lightning Stalker

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I just measured the divergence. It comes in
at 0.4mrad with the plain uncoated AixiZ style
acrylic lens. I'm pumped. I think I'm going to
try a G3E.

have you tried using fog to compare the beam to a 660 and see if it's 685 is pink in the beam? Have these diodes been spectroed? Could it be the dimmer red lets you see another line in the dioide? This is just really weird.
Nope, the 685nm line does that all by itself.
 

ultimatekaiser

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Very nice. I have a few different deep red wavelengths. the diodes are getting better and better everyday. changing from an ellipse into a circle more and more as time passes. they do however, like to stray and don't stay the same wavelength as they heat up if they're poorly heatsinked or overdriven. they have to be run at spec to keep them at that wavelength. I have 670, 680, and 690nm in monitored lab-diode form all at about that 20-40mW range and they get successively dimmer and dryer red toward 780 and 808 nm ish appearance as you move down toward IR. 670/671dpss is like a brilliant dark brick or fire-engine red, and 680 and 690 are a very dark ruby color. not always on the wall, but if you diffuse them into crystal or something, you can see just how dark they are. (careful of reflections!) odd how looking at a HeNe (633nm) it looks nice and red, but then one of these comes by and it suddenly you realize just how orange the red HeNe looks by comparison!
 
Last edited:

will manners

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Thanks for the wright up LS. I need to get me one of these :)

If only someone still sold chrome leadlights :(
 




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