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Lowest and highest visible laser wavelengths?

Rivem

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I know it's been asked before, but what are the lowest and highest wavelengths you've seen at a fairly low power (<100mW). I figure if I'm going to collect laser pointers, I want good "bookends". The general definition for visible light is around 390nm to 700nm, but it seems like higher and lower have been reported.
 



Pi R Squared

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390nm to 700nm is what Wikipedia says is the visible spectrum but I have read other sources that say 400nm to 800nm. I doubt most would see 390nm but I can't say for sure, for a laser wave length I'll say the upper limit is 405nm, these are very dim and I consider them more dangerous because they aren't so visible, I have heard that some people can't see 405nm at all, but I expect that is few people. The lower limit is the beginning of IR, I would guess 780nm but I am not sure because I don't have one, some people say they see a faint red light from 808nm but this is considered beyond the visible spectrum. Hopefully someone with a 780nm or 808nm laser will say something here.

Alan
 

Hap

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Yep, 405nm is pretty dim indeed. Funny enough, my Electra can be easily seen in a dark room or inside during the day but outside(in daylight) the dot is completely invisible. I mean, we're talking about 5mW of 405nm!!!! Borderline what we can see!

I also can sometimes catch a beam indoors during nighttime when shinning it around :yh:

-Alex
 

Rivem

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Yep, 405nm is pretty dim indeed. Funny enough, my Electra can be easily seen in a dark room or inside during the day but outside(in daylight) the dot is completely invisible. I mean, we're talking about 5mW of 405nm!!!! Borderline what we can see!

I also can sometimes catch a beam indoors during nighttime when shinning it around :yh:

-Alex
I think that's due to scoptic vision. The comparison between the brightness of my red and 405nm definitely seems to shift toward the 405nm the more dark adapted I get. I feel like I could see a shorter wavelength though.
 
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Hap

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I think that's due to scoptic vision. The comparison between the brightness of my red and 405nm definitely seems to shift toward the 405nm the more dark adapted I get. I feel like I could see a shorter wavelength though.
Completely forgot about that, ugh. Yeah, it shifts to 507nm I believe which would make 405nm appear a little brighter :eek:

-Alex
 

Rivem

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Looking around, there aren't any good prices with availability on anything below 405nm. Nichia has a 390-400 nm diode, but I don't expect it to be worth it. Let's just focus on the upper limit of red/near IR that's visible at Class 3 levels.
 

Rivem

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I know a few lower power 808nm owners have to be around. Can you see it, or is this more at high powers?
 
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Hap

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I know a few lower power 808nm owners have to be around. Can you see it, or is this more at high powers?
I've never owned a true 808nm laser, but I re-call some members reporting able to see the dot(although faintly) at around 500mW-1W.

-Alex
 

diachi

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I've never owned a true 808nm laser, but I re-call some members reporting able to see the dot(although faintly) at around 500mW-1W.

-Alex
I still recall reading somewhere that the dim red glow from 808nm lasers isn't actually 808nm, but a visible spontaneous emission. I can't however find any sources that verify that claim so we'll stick to it just being not very visible at all. Edit: The idea of a spontaneous emission causing the red output does seem reasonable, other diodes to exhibit the same phenomenon - although not necessarily with a red output. That said - no good if there is no proof. :eek:

Anyway, yes, it is very dim (1mW 650nm would easily over power it, by far) to the naked eye - even at 1W 808nm. It kind of reminds me of 405nm in the same way that I have trouble focusing on that.

It's hard to find something to compare to that isn't that bright...
 
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Rivem

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I still recall reading somewhere that the dim red glow from 808nm lasers isn't actually 808nm, but a visible spontaneous emission. I can't however find any sources that verify that claim so we'll stick to it just being not very visible at all. Edit: The idea of a spontaneous emission causing the red output does seem reasonable, other diodes to exhibit the same phenomenon - although not necessarily with a red output. That said - no good if there is no proof. :eek:

Anyway, yes, it is very dim (1mW 650nm would easily over power it, by far) to the naked eye - even at 1W 808nm. It kind of reminds me of 405nm in the same way that I have trouble focusing on that.

It's hard to find something to compare to that isn't that bright...
Anything in the 700nm range you think is more visible?
 

diachi

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Anything in the 700nm range you think is more visible?

CD Writer diodes (~780nm) would be a little more visible, but still barely visible - less visible than 405nm. Someone on here has a ~680nm diode IIRC - that'd be a good choice. I haven't seen that in person but I imagine the brightness is comparable to 405nm.
 

InfinitusEquitas

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I still recall reading somewhere that the dim red glow from 808nm lasers isn't actually 808nm, but a visible spontaneous emission. I can't however find any sources that verify that claim so we'll stick to it just being not very visible at all. Edit: The idea of a spontaneous emission causing the red output does seem reasonable, other diodes to exhibit the same phenomenon - although not necessarily with a red output. That said - no good if there is no proof. :eek:
If you remember more about this, or where you read it... would be interesting.
 

diachi

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If you remember more about this, or where you read it... would be interesting.
I've been searching and I can't find the source. I remember reading it, and I remember the source being reliable. I'll need to post it again when I find it.

Best I can find so far is:

If that's the case, the 808nm diode does produce a tiny bit of visible light in the form of red.
From Adam Bourassa on PL. Not quite the source I was looking for ...

Edit: LASERFAQ (Steve R) could probably give a definitive answer to this question - if he sees the thread that is.
 
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Encap

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I know it's been asked before, but what are the lowest and highest wavelengths you've seen at a fairly low power (<100mW). I figure if I'm going to collect laser pointers, I want good "bookends". The general definition for visible light is around 390nm to 700nm, but it seems like higher and lower have been reported.
Low and high wavelength sensitivity depeds upon the particular individuals eyes. Some can see wavelengths at the the extreme ends of the visable spectrum better than others some can't see them at all.

Wavelength charts give a range of wavelengths that in their opinion most can see and call that the continious "visable spectrum" .
As you have noticed the are seveal of these that give different ranges.

Why do you want lasers at the extreme ends that are very difficult to see and least visable especially at low <100mW output levels?
 
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Rivem

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Low and high wavelength sensitivity depeds upon the particular individuals eyes. Some can see wavelengths at the the extreme ends of the visable spectrum better than others some can't see them at all.

Wavelength charts give a range of wavelengths that in their opinion most can see and call that the continious "visable spectrum" .
As you have noticed the are seveal of these that give different ranges.

Why do you want lasers at the extreme ends that are very difficult to see and least visable especially at low <100mW output levels?
I would like to make a range of somewhat eye-safe, similarly-powered lasers in a similar custom host. Just want to get an idea of the edges.
 

Rivem

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Anybody have a 690nm laser? Past them, the only deep red/near IR diodes are a bit pricey until significantly longer wavelengths.
 




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