How does the RA Twisty do a low Red?

[schiesz]

I just recently realized that people were talking about a low RED on the RA twisty, and while I have never really looked at the RA lights before (and never owned a HDS or Novatac) I am intrigued by a low level red. Is there a second LED, or does it use a different emitter that has a red die, or what?

 

[alibaba]

this should help:

http://light-reviews.com/ra_twisty/

 

[LukeA]

What LED is that?

 

[Noxonomus]

http://hdssystems.com/Articles.html

Read "Using the new Osram Dragon LEDs for bi-color lights"

 

[Enzo Morocioli]

I just recently realized that people were talking about a low RED on the RA twisty, and while I have never really looked at the RA lights before (and never owned a HDS or Novatac) I am intrigued by a low level red. Is there a second LED, or does it use a different emitter that has a red die, or what?

Basically the LED is an Osram Golden Dragon which has a primary LED die as well as a protection diode which is separate from the primary, and much much smaller. The reverse polarity protection diode on the LED assembly happens to emit Red light when activated.. The Ra Twisty makes use of this diode by allowing it to share the same reflector as the primary LED and engineering the electronics to safely activate the protection diode for extended periods of time without having to reverse polarity..

The diodes beam pattern has a large hole in the center, but luckily, it is also bright enough to be very very usable. Plenty of beam pictures and info in my sig line if you're interested.

 

[alibaba]

Basically the LED is an Osram Golden Dragon which has a primary LED die as well as a protection diode which is separate from the primary, and much much smaller. The reverse polarity protection diode on the LED assembly happens to emit Red light when activated.. The Ra Twisty makes use of this diode by allowing it to share the same reflector as the primary LED and engineering the electronics to safely activate the protection diode for extended periods of time without having to reverse polarity..

The diodes beam pattern has a large hole in the center, but luckily, it is also bright enough to be very very usable. Plenty of beam pictures and info in my sig line if you're interested.

Just checked out your sig line and saw these pics: http://www.candlepowerforums.com/vb/showthread.php?t=202487

Some SERIOUS macro that shows the dual emitters

 

[octaf]

What is this low red for ?

 

[Reima]

Preserving night vision.
RC

 

[Enzo Morocioli]

Basically the LED is an Osram Golden Dragon which has a primary LED die as well as a protection diode which is separate from the primary, and much much smaller. The reverse polarity protection diode on the LED assembly happens to emit Red light when activated.. The Ra Twisty makes use of this diode by allowing it to share the same reflector as the primary LED and engineering the electronics to safely activate the protection diode for extended periods of time without having to reverse polarity..

I noticed this on the HDS website: "However, a clever application of this "feature" would be in a flashlight that provides power in the forward direction for white light and power in the reverse direction for red light."

So when I say "engineering the electronics to safely activate the protection diode for extended periods of time without having to reverse polarity" I actually mean without having to reverse the polarity of the battery in a physical sense. The electronics were designed to change the direction of power in order to make use of the protection diode.

 

[ElectronGuru]

Preserving night vision.
RC

In military applications, red also has the benefit of being hard to see from a distance. Green, for example, is also good at preserving night vision but is even easier to see at a distance than white, making it a liability.

 

[jchoo]

Green doesn't preserve night vision, only red.

http://www.flashlightreviews.com/qa/nightvision.htm

 

[PhantomPhoton]

While Red is better than green at preserving night vision, any color of significantly lower lumens will "preserve" night vision better than a source of higher lumens. Red just happens to biologically, based upon the construction of cones in our human eyes, to have the least effect.
Just the fact that the color is red does not make it night vision preserving. A 1 lumen source in white will "preserve" night vision better than a 300 lumen red source. I just want to make sure that is clear.

 

[jchoo]

Oh, I'm not questioning that a lower level of a different color is better at preserving night vision than high levels of red; I'm simply tired of the notion that green "preserves night vision" as well or better than red at the same output level.

 

[octaf]

While Red is better than green at preserving night vision, any color of significantly lower lumens will "preserve" night vision better than a source of higher lumens. Red just happens to biologically, based upon the construction of cones in our human eyes, to have the least effect.
Just the fact that the color is red does not make it night vision preserving. A 1 lumen source in white will "preserve" night vision better than a 300 lumen red source. I just want to make sure that is clear.

That helps a lot !
one more question;
when you say "preserve the night vision", is it for bare eyes? or vision with some special gadgets? or both?

 

[PhantomPhoton]

Oh, I'm not questioning that a lower level of a different color is better at preserving night vision than high levels of red; I'm simply tired of the notion that green "preserves night vision" as well or better than red at the same output level.

Wasn't targeting your post really, just trying to clear it up a bit more :wave:

That helps a lot !
one more question;
when you say "preserve the night vision", is it for bare eyes? or vision with some special gadgets? or both?

"night vision" in this context is just your bare eyes' natural ability to adjust to a tremendouls range of lighting situations. Once your eyes have adapted to the dark you have what we call "night vision." Healthy eyes are capable of seeing very well with very little light... say just a half moon and can are even functional with just starlight. This high performance in low light state can be disrupted by bringing your eyes back into an environment with significantly more light. A chemical reaction in your eyes controls this, and once exposed to a lot of light your eyes take some time to convert back to the low light "mode"
Red has been proven to produce the least amount of chemical reaction. There are a couple posts around here (I don't have links to em, sorry) that give far better details and science that what I'm putting out just off the top of my head.

 

[octaf]

Thanks PhantomPhoton !