Re: violet LED\'s
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by pappasom:
Telephony (or whoever)
Do the new near-UV LED's (395-410nm) output enough visible light to be useful as a flashlight? Is there a big difference in visible output between say a 395nm and a 410nm? Thanks
CJ<HR></BLOCKQUOTE>
They're ineffective at best, but LEDs closer to 410nm can be used as flashlights if you're at least partially adapted to the dark already.
When you are in the dark and then turn one of these on, one of the first things you notice will be numerous small objects in the room glowing some odd color. This could be anything from pieces of paper & discarded underwear that glow a blue-white; price stickers and other stickers glowing blue-white, orange, or green; and other flashlights glowing blue, orange, or green.
A string of Christmas lights with a white cord will appear to be "beheaded" as the cord will glow bright blue-white but the bulbs & bulb sockets won't. And when you hit a TV, the screen will glow a greenish white color; more pronounced at shorter wavelengths below 400nm.
The shorter the wavelength, the dimmer the visible light will become and the brighter other objects will appear to glow.
A 408-410nm LED will work much better as a low-level flashlight than a 395nm LED will.
But either LED will light a scene in front of you more brightly than a handheld 4W fluorescent blacklight tube.
The LEDs are also usable as a flashlight better at close range than they are 15 or 20 feet out.
So you can use them to read an alarm clock or look around on the floor for another bedside flashlight, or to make sure the toilet seat is in the proper position without blinding yourself with the bathroom light. For these kinds of usage, the 410nm may be *too* bright for some people.
Usefullness in all of these situations may boil down to a matter of personal preference.
These LEDs weren't specifically intended to be used as flashlights; and would be more of a novelty or special use item if they're put in one. In my case, I've been using a 393-394nm LED in my LEDTronics Mini FlashLED for those late night trips to the can. Not because it's the absolute best LED to use for that, but because the novelty has not yet worn off.
Violet LEDs are still so...
new.
P.S.
An informal test, done just now, shows a 408-410nm LED is usable to find ones way around a dark room with no adaptation necessary unless coming in from a *very bright* area. And the test room is carpeted with very dark carpet, making it a challenge for any light source.
