Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



Lowest and highest visible laser wavelengths?




Rivem

Well-known member
Joined
Feb 16, 2016
Messages
1,242
Points
83
So, how do you guys feel about 405nm and 690nm as the edges of visibility? Do they seem like good starting points for the visible spectrum set?
 

Hap

Super Moderator
Staff member
Joined
Sep 5, 2013
Messages
8,646
Points
113
So, how do you guys feel about 405nm and 690nm as the edges of visibility? Do they seem like good starting points for the visible spectrum set?
I would start with 405nm as the bottom wavelength. It's right on the edge of what we see and anything lower is pretty expensive :(

-Alex
 

Pi R Squared

New member
Joined
May 14, 2013
Messages
3,798
Points
0
So, how do you guys feel about 405nm and 690nm as the edges of visibility? Do they seem like good starting points for the visible spectrum set?
That sounds about right to me, I don't remember hearing of a 690nm diode, I know there are 670nm and I have heard of a 685nm. If you go beyond diode lasers to DPSS and gas then there are additional wave lengths available if you have the money to spend, but for the upper and lower limits of visibility that sounds about right, anything outside that range will seem useless unless you have some special use for it.

Alan
 

Rivem

Well-known member
Joined
Feb 16, 2016
Messages
1,242
Points
83
That sounds about right to me, I don't remember hearing of a 690nm diode, I know there are 670nm and I have heard of a 685nm. If you go beyond diode lasers to DPSS and gas then there are additional wave lengths available if you have the money to spend, but for the upper and lower limits of visibility that sounds about right, anything outside that range will seem useless unless you have some special use for it.

Alan
The 690nm may have been 688. I'm not sure since a buddy told me about them.

I don't want to do any DPSS or Gas lasers for this project. I'm a semiconductor geek, and I just want to make a bunch of matching pure diode laser pointers to cover as much of the spectrum as possible.

Gas lasers I like more for their looks and beam quality, but I don't really want a rainbow of them. I'd like a GreeNe and ArKr gas laser to go with my 633 HeNes though.
 

Rivem

Well-known member
Joined
Feb 16, 2016
Messages
1,242
Points
83
I would start with 405nm as the bottom wavelength. It's right on the edge of what we see and anything lower is pretty expensive :(

-Alex
I've already got the 405nm, so I think I'll start with the 690nm and work up in frequency to the 405nm. Not a high priority project, but I'll probably get an assortment of red spectrum diodes after my science project.
 

Hap

Super Moderator
Staff member
Joined
Sep 5, 2013
Messages
8,646
Points
113
I've already got the 405nm, so I think I'll start with the 690nm and work up in frequency to the 405nm. Not a high priority project, but I'll probably get an assortment of red spectrum diodes after my science project.
Got it! 635nm-690nm is going to be pretty easy, but once you start getting below 635nm you'll start noticing huge gaps between colors unless you are willing to drop a lot of cash.

Actually, I've managed to make a pretty complete rainbow with such the following:
405/473/532/593.5/635/650

:)
-Alex
 

diachi

Well-known member
Joined
Feb 22, 2008
Messages
9,793
Points
113
Got it! 635nm-690nm is going to be pretty easy, but once you start getting below 635nm you'll start noticing huge gaps between colors unless you are willing to drop a lot of cash.

Actually, I've managed to make a pretty complete rainbow with such the following:
405/473/532/593.5/635/650

:)
-Alex

You're missing 454.6 nm, 457.9 nm, 465.8 nm, 476.5 nm, 488.0 nm, 496.5 nm, 501.7 nm, 514.5 nm. **Hint hint** ;) :D *cough*Argon*cough*
 

Hap

Super Moderator
Staff member
Joined
Sep 5, 2013
Messages
8,646
Points
113
You're missing 454.6 nm, 457.9 nm, 465.8 nm, 476.5 nm, 488.0 nm, 496.5 nm, 501.7 nm, 514.5 nm. **Hint hint** ;) :D *cough*Argon*cough*
Blah blah blah close enough :D

-Alex
 

Benm

Well-known member
Joined
Aug 16, 2007
Messages
8,113
Points
113
The visibility of light is not a hard limit, it just gets less bright per watt at the outer ends of the visual spectrum. 400 nm is still somewhat visible, although it drops off pretty quickly at the UV end.

On the red/IR end the drop off is much slower. 800 nm will be FAR less bright than 700 nm, and for example 635 nm is FAR brighter than 700 nm per watt. They all appear red though.

You can definitely see the output of a 808 nm pump diode (0.5 watts) on a piece of paper. It looks about as bright as an underperforming 1 mm 650 nm presentation pointer.

On the UV end it's harder to examine since everything starts fluorescing and it's hard to tell what you are actually seeing. As i'm not stupid enough to look directly into a laser i'll probably never experience where it ends precisely ;)
 

Atomicrox

Well-known member
Joined
Jun 22, 2011
Messages
2,432
Points
83
I can see 780nm, 808nm and 750nm just fine, even at <10mW. They're a dim/dull red color (and I'm sure it's the laser I'm seeing because the speckles are there). I can't see 980nm at all, so my limit has to be somewhere inbetween.

BTW: every single person I've shown a 808nm laser was able to see it.
 
Last edited:

DashApple

Well-known member
Joined
Jan 14, 2009
Messages
1,467
Points
83
I've seen 808nm at rather low powers , 940nm was invisible .
 

Isaac Clarke

Banned
Joined
Feb 26, 2015
Messages
1,360
Points
0
*cough* *cough* i have seen all the way down in the UV range when i got my eye poked by a machine with a needle.... (whitish /over saturated blue/violet color)...apparently i achieve 20/20 vision after a few week....
 

CurtisOliver

Well-known member
LPF Site Supporter
Joined
Jun 12, 2015
Messages
6,881
Points
113
808nm is visible as a faint blurry red dot. You need to go beyond 900nm to be truly invisible. I have only tested a high power 808nm laser on threshold (which was still around 10W) so am unaware of whether it is visible at low power.
 

abciswell

Member
Joined
Jan 31, 2016
Messages
112
Points
18
So, how do you guys feel about 405nm and 690nm as the edges of visibility? Do they seem like good starting points for the visible spectrum set?
This laser set sounds pretty awesome! Great idea; which host do you plan on using for all of them?
 

Rivem

Well-known member
Joined
Feb 16, 2016
Messages
1,242
Points
83
This laser set sounds pretty awesome! Great idea; which host do you plan on using for all of them?
Thanks man. I've actually got a little pen host design that I've been wanting to machine for a while. I was planning some Laser66 hosts at first, but I'm thinking a continous switch and a little bit more heatsinking would be better.
 




Top