507nm Night Vision Sensitive Light

What do you experienced gurus think about this idea? I am sure many people have seen this

http://www.instructables.com/id/Ultimate-Night-Vision-Headlamp---500+-lumens-with-/

Basically, he uses cyan colored 1W Luxeon LEDs for riding in pitch black, because our night vision is more sensitive to that wavelength (2.5 times more sensitive).


Seem viable? Anyone tried it?

kuksul08 said:

What do you experienced gurus think about this idea? I am sure many people have seen this

http://www.instructables.com/id/Ultimate-Night-Vision-Headlamp---500+-lumens-with-/

Basically, he uses cyan colored 1W Luxeon LEDs for riding in pitch black, because our night vision is more sensitive to that wavelength (2.5 times more sensitive).


Seem viable? Anyone tried it?

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That won't preserve a human's natural nightvision, in fact in will KILL your nightvision very very fast. You will still be able to see, but you'll being seeing with your daylight vision cone cells because that light is so bright.

Also, cyan is the wrong color for preserving your natural scotoscopic nightvision. The fact that the rod cells are most sensitive to it means that it will deplete your nightvision faster, not slower. The only color that will save your nightvision is red. The reason is that red light is almost completely invisible to the rod cells, which are responsible for seeing in very low light conditions. The red light can be seen by the cone cells, allowing you to see while the light is on, but won't affect the rod cells, so you should still be able to see dim ambient light when you turn the light off.

There tends to be extra confusion these days about the use of red vs. green or cyan light because green/cyan has some special uses when working around nightvision equipment.

It's been a while since cyan emitters were somewhat common. Actually, the product mentioned in the OP doesn't actually claim to preserve night vision (at least from what Step 2 says).

The point is more about how to best illuminate a night scene with a power efficient method. Since non-white LED's, like cyan, are more efficient (that is, more light per watt), and since our eyes are most sensitive to that cyan/green range, the logic is that our eyes can see the scene adequately, and with the least energy consumed, by using an underdriven cyan emitter. It's an idea that's been around since when Lux I and III emitters were the king of the hill and putting red, amber, and cyan emitters was fairly common. I've never played with a cyan light, but I think the concept is sound.

But then again, we all have preferences when it comes to light. E.g. some people can't stand greenish-tinted light, some people find blue light too harsh on their eyes, some can't really see well at all with red and prefer amber for low light use, etc. So YMMV.

Actually, considering our current LED fascination with emitters that are nearing quadruple digit output, it's refreshing to talk about products that use the least amount of light to get a job done. Kind of reminds me of Milky's philosophy with his Project-M mods.

OceanView said:

Actually, the product mentioned in the OP doesn't actually claim to preserve night vision (at least from what Step 2 says).

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While they don't mention "preserving" night vision, they seem to think that the high intensity cyan light will improve or make better use of their natural night vision, which just isn't the case.

"The latest LED technology is much more efficient than a standard light bulb to begin with, but using the special turquose color gives us even much better night vision than white, and is more efficient than even the fanciest HID lights."

"To get the best possible vision at night, we'd like to build a lamp that puts out the most light at the 507nm that our rods are most sensitive to."

"1) use cyan or green LED's. these will give 2.5x their rated lumen output using your night vision, because they are rated based on your day vision. (see http://hyperphysics.phy-astr.gsu.edu/hbase/vision/bright.html )"

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The rod cells are pretty much blinded at such a high output, so the fact that the light is the rod cells' peak wavelenth of 507nm is actually working against them. If a light at that wavelength is bright enough to be seen as the color cyan instead of grey, it's bright enough that it's being detected by the cone cells, and at that point the rod cells will be bleached out very quickly.

Wow interesting.

darknessemitter said:

While they don't mention "preserving" night vision, they seem to think that the high intensity cyan light will improve or make better use of their natural night vision, which just isn't the case.

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I was just reading through some of those webpages again. I don't think that they care if you're totally blind when you turn off this cyan light at night. They're only concerned with how well you can see while this light is on. But I finally read that outside webpage they linked to. After reading that, I'd have to agree that they seem to be mixing apples and oranges some here. Seems like they're trying to extrapolate scotopic vision sensitivity of the rods into a brightness range where it's not really applicable. OK, so that's where they get this "perceived" 500-lumen rating for this headlamp.

But I do remember back when some people were choosing to use a green or cyan LED because it did seem brighter than what the most powerful Lux I or III white emitters were capable of. So, for a given amount of light, you could see "more" or "farther" at night with the colored beam. Of course, your color perception is all screwed up but that was the trade-off back then. And if this product were limiting their argument to just this idea, then that would seem more reasonable to me. But I don't think they've got all their science right.