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



Laser Pointer Store

351nm 5mm LED


Cyparagon

Well-known member
Joined
Sep 12, 2007
Messages
9,569
Likes
1,063
Points
113
0.26% efficient? 0.2mW output? Ouch.

Looks cool... but compared with your typical 1W (0.2W out) 365nm die, it's twice the price for one thousandth the power.
 

TheDukeAnumber1

Well-known member
Joined
Jun 7, 2012
Messages
2,064
Likes
221
Points
63
Yeah it is pretty abysmal, I'm hoping they get cheap quick though. They'd be fun to toy with but like you said $20 is a lot for the power you get.
 

Benm

Well-known member
Joined
Aug 16, 2007
Messages
8,082
Likes
688
Points
113
It is a novelty you pay for. UV leds have been limited to 395 and the odd 375 nm ones for quite some time, with shorter wavelength at astronomical prices.

Surely the output power of these is very small, but they are relatively affordable. I'm not really sure what you would need them for, but if there is some application that works much better on 351 nm compared to 375 i'm sure the market will mature eventually.

I can imagine they'd be useful for curing resins or something like that when output power picks up a bit.
 
Joined
Sep 5, 2015
Messages
122
Likes
18
Points
18
Last edited:

styropyro

New member
Joined
Jun 13, 2007
Messages
5,385
Likes
477
Points
0
That's really cool that these exist, even if they are low power as of now. 351nm is getting low enough for use in photoinitiation reactions.
 

Benm

Well-known member
Joined
Aug 16, 2007
Messages
8,082
Likes
688
Points
113
Indeed, the photoelectric effect can be very important for some applications.

351 nm could be very good for applications like uv-curing resins and such. 395 nm may not cut it there no matter how intense, the energy per photon is just too low to initiate the reaction.

I'm sure sure application whould be niche for now, but once these things roll off the production lines with more power and affordable prices i can see them used in applications like sterilization, ozonation and such.
 

TheDukeAnumber1

Well-known member
Joined
Jun 7, 2012
Messages
2,064
Likes
221
Points
63
You might better compare them to 365nm LED's. I would be very interested to see their spectral graphs overlapped to see if the 351nm really has a good edge over the 365nm.

Still want some though. I think it would be really neat to have a room completely lit by fluorescence with no visible output from the LED's.
 

Benm

Well-known member
Joined
Aug 16, 2007
Messages
8,082
Likes
688
Points
113
The proof is in the measurements ofcourse, but i'm assuming they are what is advertised unless proven wrong.

I'm not really sure what the limit of wavelength is where UV becomes totally invisible. Perhaps even 350 nm may be somewhat visible if looking directly into the source, although that would not be a wise thing to attempt.
 

styropyro

New member
Joined
Jun 13, 2007
Messages
5,385
Likes
477
Points
0
My experience with a 5mW average 355nm laser was that it was completely invisible, although that was hard to test because nearly everything fluoresced under that light. I miss that laser...
 

Benm

Well-known member
Joined
Aug 16, 2007
Messages
8,082
Likes
688
Points
113
Hehe, i can imagine, the so called cancer-ray ;)

There is a big difference between lasers and leds when in comes to monochromaticity. A 351 nm led will probably have a gaussian wavelength profile that perhaps drops to 1% at 375 nm or something like that.

The 355 is a dpss with an extremely narrow output bandwidth, and would be under 1% within a few nm of its operational output.
 

styropyro

New member
Joined
Jun 13, 2007
Messages
5,385
Likes
477
Points
0
Hmmm...we could take the gaussian function describing intensity as a function of wavelength and multiply it by the curve describing relative human eye visibility as a function of wavelength to get a weighted curve of the visibility of LEDs vs. lasers in these wavelengths. :)

Too bad the visibility curve probably has a lot of variation from person to person at these wavelengths...but this would be fun to investigate.
 

Cyparagon

Well-known member
Joined
Sep 12, 2007
Messages
9,569
Likes
1,063
Points
113
A 351 nm led will probably have a gaussian wavelength profile that perhaps drops to 1% at 375 nm or something like that.
It works the other way, too. A 1W 365nm LED still has a bit of power at 351nm. Probably more than the 5mm LED mentioned at the beginning. (my spectrometer's response drops off rapidly under 370nm or so.)

 
Last edited:

Benm

Well-known member
Joined
Aug 16, 2007
Messages
8,082
Likes
688
Points
113
Surely it works both ways :)

The problem with near-UV sources is that they just make everything fluoresce, so it's very hard to tell true invisibility without looking directly into them. And even then, if it fluoresces a bit within your eye, does it could as invisible?
 




Top