Why no RGB flashlights?

gcbryan · Oct 7, 2011

Why are there no RGB flashlights? The single die emitters are out there but no one has put them into a flashlight. Not a custom builder, an individual DIY type or a major or minor company. I know there was the Quark RGB but that was just a MC-E with each emitter a different color (and a relatively useless UI).

There was one exception I found in a cheap novelty light that used one LED (RGB) to make 10 colors that one would cycle through. It was $25 so it can be done and doesn't have to be expensive so I'm wondering why it hasn't been done by others. The Quark was $100 and (although well made) didn't come close to maximizing the potential.

I realize there are issues in getting various colors to focus at the same point but a diffuser or optic for a floody beam solves that (apparently judging by the cheaper light that I mentioned).

There has been no flashlight that allowed the use to mix colors.

With all the flashlights out there that are more or less the same you would think there would be a few RGB ones. With all the DIY experimenters you would think there would be a very homebrew models as well.

It might not be the most practical of lights but it would be interesting and there are plenty of custom lights that aren't practical either but no RGB.

I'm not looking for an expensive customer RGB light by the way. I'm just mentioning all the usual players.

Actually, it would be practical as a teaching tool and I'm sure in several other areas. The white light (all the colors mixed) should be better as far as CRI than a standard emitter.

What am I missing as to why there aren't a few of these lights?

As a side note, the fact that an inexpensive RGB light with premixed colors came out of China inexpensively should lay to rest all of the talk that other lights (U.S.) are so expensive relative to the cheaper Chinese ones because the cheap ones are copying all of the expensive design work that U.S. companies are credited with. Here is a case of a $25 light that wasn't a knock-off since no one else has done it yet. Here it would cost $200 and we would be posting about how we are glad to pay that to support an innovative company.

B0wz3r · Oct 7, 2011

I'd guess there just isn't much of a market for something like that, other than for Halloween parties or something.

Also, making a 'pure' white light out of three separate R, G, and B emitters isn't as easy as it sounds. For one thing, our eyes are differentially sensitive to different colors; we see red and yellow as brightest, because of the no. of long wavelength cones in the retina. About 65% of all cones are L cones. So, if shown three lights of equal objective intensity, lux, candela, whatever, with one red, one green, and one blue, we'd see the red one as brightest, and the blue one as dimmest. This is because in comparison, we have about 25% of our cones as the medium wavelength, or green, cones, and about 10% of all cones in the retina are the short wavelength, or blue, cones. And this difference in perceived brightness is because the brain encodes brightness as total signal strength received, in other words, the number of action potentials reaching it in the visual input.

So by default, we have more L signal coming in than G signal, than B signal because of the differential cone ratios in the retina. So any light that would make white light from those three emitters would have to be specially balanced to account for the differences in perceived brightness between those three colors. Otherwise, it wouldn't look white to us. The blue emitter would have to put out a lot more photons to be perceived as equally bright to the R and G lights to make white. This doesn't even address the issue of the fact that if you have three narrow spectrum emitters working together, that they will even produce the right set of frequencies so that if you could compensate for perceptual differences, you still have the technical problem of the emitters producing the appropriate frequencies. All this gets even more complicated if you want a multi-level light, because the visual system doesn't respond in a linear fashion... none of our sensory systems do. Rather a logarithmic response curve is what they follow, so now you've got to find a way to get all three of those response curves for the three different colors to meet at three different intensities to produce a balance of perceived brightness to give the perception of the light as white. I'm also omitting the fact that even when you have three different light sources, even if you could tune them close enough to the spectral response peaks of each of the three cone types, don't always produce a 'white' light, because there are small individual differences from person to person, so one person might see the light as white, while another might see it as slightly red, or green, or whatever.

I'm glossing over a lot of specific detail here about the visual system, and generalizing to the electronics from what little I know about it, but the point is that apart from the lack of a market for such a light, the technical issues in making something like that are tremendously complex, and include not just the engineering, but a significant portion of perceptual psychophysics as well. I doubt any flashlight maker is going to be willing to invest that kind of R&D into a light that would really be nothing more than an oddity to most people, and appeal solely to flashaholics, and people with advanced degrees in cognitive neurophysiology and psychophysics.

calipsoii · Oct 7, 2011

B0wz3r, the second I saw this thread title I wondered how long until you'd post. You certainly know this stuff inside and out!

@OP No one makes RGB lights because they won't sell. The aluminum is better spent on a cool white that will. You've already touched on custom builders, which is about the only place you'd find a light like that. I've tried a red, green, blue in my A2 and it's not a pretty beam.

Fresh Light · Oct 7, 2011

Getting the presets right might be a little difficult to choose to make everyone happy. But, I never got why there isn't a RGB that allows for control of each color independently. Yes, I know it might require a novel control system or a min of 3 knobs. Another thing is that without a bigger reflector or it'd be a flood, but something like a TK40 reflector would be nice.

bkumanski · Oct 7, 2011

How about this one? http://www.basspro.com/Browning-Pro-Hunter-RGB-LED-Flashlight/product/10215473/69864

[url]http://www.candlepowerforums.com/vb/showthread.php?183222-RGB-Multi-color-flashlight

http://www.botachtactical.com/rerm3.html

http://www.walmart.com/ip/Smith-Wesson-Galaxy-4-Color-LED-Flashlight/12347126

http://www.inforce-mil.com/color.php

http://www.mypilotstore.com/mypilotstore/sep/3374

http://www.phoebus.com/spectrum.html
[/URL]

skyfire · Oct 7, 2011

ive wondered the same thing... i really like the idea of the quark RGB, but its UI is something i know i wouldnt.
id love to see somebody use Cree's MC-E with a simpler UI. something like a control ring. or using 2 switches.

B0wz3r · Oct 7, 2011

calipsoii said:
B0wz3r, the second I saw this thread title I wondered how long until you'd post. You certainly know this stuff inside and out!

@OP No one makes RGB lights because they won't sell. The aluminum is better spent on a cool white that will. You've already touched on custom builders, which is about the only place you'd find a light like that. I've tried a red, green, blue in my A2 and it's not a pretty beam.

LOL! Thanks Calipsoii... It's what I do... I used to stick needles in monkey's brains to record what was going on in there, but I like teaching a lot better now.

gcbryan · Oct 8, 2011

bkumanski said:
How about this one? http://www.basspro.com/Browning-Pro-Hunter-RGB-LED-Flashlight/product/10215473/69864

http://www.candlepowerforums.com/vb/showthread.php?183222-RGB-Multi-color-flashlight

http://www.botachtactical.com/rerm3.html

http://www.walmart.com/ip/Smith-Wesson-Galaxy-4-Color-LED-Flashlight/12347126

http://www.inforce-mil.com/color.php

http://www.mypilotstore.com/mypilotstore/sep/3374

http://www.phoebus.com/spectrum.html

The only one of those links (unless I missed one) that is close to what I'm talking about is the second link. The light referred to there (sold by ThinkGeek) is the one I referred to as the 10 Color model available for $25 that is actually using one RBG emitter.

The others are just using multiply emitters to offer red or blue or green.

I'm talking about a single RGB emitter. I think Cree makes a XP-E RGB emitter (but I'm not sure).

bkumanski · Oct 8, 2011

Ahh, single die RGB. The BassPro one has a single RGB in with white LEDs, but I think I understand what you are looking for. The Phoebus light has a single die, but is missing the "B" in RGB. Its an RGW.

gcbryan · Oct 8, 2011

B0wz3r said:
I'd guess there just isn't much of a market for something like that, other than for Halloween parties or something.

Also, making a 'pure' white light out of three separate R, G, and B emitters isn't as easy as it sounds. For one thing, our eyes are differentially sensitive to different colors; we see red and yellow as brightest, because of the no. of long wavelength cones in the retina. About 65% of all cones are L cones. So, if shown three lights of equal objective intensity, lux, candela, whatever, with one red, one green, and one blue, we'd see the red one as brightest, and the blue one as dimmest. This is because in comparison, we have about 25% of our cones as the medium wavelength, or green, cones, and about 10% of all cones in the retina are the short wavelength, or blue, cones. And this difference in perceived brightness is because the brain encodes brightness as total signal strength received, in other words, the number of action potentials reaching it in the visual input.

So by default, we have more L signal coming in than G signal, than B signal because of the differential cone ratios in the retina. So any light that would make white light from those three emitters would have to be specially balanced to account for the differences in perceived brightness between those three colors. Otherwise, it wouldn't look white to us. The blue emitter would have to put out a lot more photons to be perceived as equally bright to the R and G lights to make white. This doesn't even address the issue of the fact that if you have three narrow spectrum emitters working together, that they will even produce the right set of frequencies so that if you could compensate for perceptual differences, you still have the technical problem of the emitters producing the appropriate frequencies. All this gets even more complicated if you want a multi-level light, because the visual system doesn't respond in a linear fashion... none of our sensory systems do. Rather a logarithmic response curve is what they follow, so now you've got to find a way to get all three of those response curves for the three different colors to meet at three different intensities to produce a balance of perceived brightness to give the perception of the light as white. I'm also omitting the fact that even when you have three different light sources, even if you could tune them close enough to the spectral response peaks of each of the three cone types, don't always produce a 'white' light, because there are small individual differences from person to person, so one person might see the light as white, while another might see it as slightly red, or green, or whatever.

I'm glossing over a lot of specific detail here about the visual system, and generalizing to the electronics from what little I know about it, but the point is that apart from the lack of a market for such a light, the technical issues in making something like that are tremendously complex, and include not just the engineering, but a significant portion of perceptual psychophysics as well. I doubt any flashlight maker is going to be willing to invest that kind of R&D into a light that would really be nothing more than an oddity to most people, and appeal solely to flashaholics, and people with advanced degrees in cognitive neurophysiology and psychophysics.

I thought I covered a lot of this in my original post (or at least I attempted to). Just for reference as a starting point consider this light:
http://www.thinkgeek.com/gadgets/lights/8db4/?srp=20

It uses a true RGB single emitter and has an output of 9 colors plus white. There is not a great review or a detailed description at this site but it was sold under another name in 2007 and I found a few reviews under that name.

So, you see that it can be done and cheaply. Not that it would be as good for any one color as a standard one color flashlight but that isn't the point. This is more a proof of concept type of thing.

As I also mentioned in my OP since our cones are responsive to different wavelengths to different degrees if someone makes a similar light where you could mix the colors (as opposed to preset) you would weight the current for the blue more heavily than for red, and red more heavily than for green as a rough approximation. The idea isn't to get a precise color standard output as much be needed for an optical laboratory.

I don't think the obstacles are all that great. I could come up with many reasons why a standard white LED based flashlight isn't perfect considering how our eyes work but that isn't the point either.

The fact of the matter than flashlight linked to does everything (roughly speaking) that I'm talking about except allow the user to do the mixing. The RGB emitter itself is actually mixing however to get the 10 preset colors.

mamelo · Oct 8, 2011

gcbryan said:
I could come up with many reasons why a standard white LED based flashlight isn't perfect considering how our eyes work but that isn't the point either.

gcbryan, this is exactly what I am looking for, in my thread over there:
http://www.candlepowerforums.com/vb...-White-quot-LEDs-stimulate-our-eyes-red-cones

If usual LEDs' light is composed of blue and yellow, does that mean that red is nearly missing , and if so, is reflected light from objects also missing the red wave lengths, are the red cones stimulated or not?

I tend to believe that, if certain wave lenghts are missing or reduced (compared to day light), the perception of objects, i.e. depth, contrast etc. is inferior...

mamelo · Oct 8, 2011

These videos of a TriStar RGB LEDs look quite promising in terms of white light...

http://www.luxeonstar.com/Predfined-Tri-Star-LED-Assembly-p/mr-000015-20t.htm (Click on "Product Videos & Renderings")

gcbryan · Oct 8, 2011

bkumanski said:
Ahh, single die RGB. The BassPro one has a single RGB in with white LEDs, but I think I understand what you are looking for. The Phoebus light has a single die, but is missing the "B" in RGB. Its an RGW.

Yeah, my interest really isn't to get a flashlight with green beam and a red beam or even a blue beam for something practical like hunting or whatever. I want a flashlight where a single RGB emitter has been used to its full capacity to actually mix colors. The light I referenced can output 10 different colors but it does it by mixing just the three colors (by varying the current going to each).

In that light you can choose for instance "yellow". There is no yellow emitter just the single RBG emitter. Yellow in that case comes from red and green.

The BassPro did indicate that it used a single RGB but there was not enough detail to know for sure and in any event they didn't fully utilize it to the extent I'm talking about. I hadn't heard of that one however so there are a few lights around at least using RGB I guess.

gcbryan · Oct 8, 2011

mamelo said:
gcbryan, this is exactly what I am looking for, in my thread over there:
http://www.candlepowerforums.com/vb...-White-quot-LEDs-stimulate-our-eyes-red-cones

If usual LEDs' light is composed of blue and yellow, does that mean that red is nearly missing , and if so, is reflected light from objects also missing the red wave lengths, are the red cones stimulated or not?

I tend to believe that, if certain wave lenghts are missing or reduced (compared to day light), the perception of objects, i.e. depth, contrast etc. is inferior...

I don't have a great answer for that except to say that I don't think the situation is that bad. First of all you can have great contrast with only black and white. I personally can see all of the colors pretty well when I use a standard blue phosphor based LED.

I think in theory it's better with a RBG approach but with the technical difficulties and the practical realities I don't see a big issue particularly as it relates to flashlights.

There is too much blue in the spectrum but it's not all that bad as far as I can tell.

Th232 · Oct 8, 2011

The issue I have with mixing RGB is due to the difference between shining red + green into your eyes vs shining red + green onto a yellow object. In the former you'll see yellow light since the right receptors will be stimulated, but in the latter, since an actual yellow object reflects yellow light (and not red or green light), it won't be illuminated well since the majority of the power will be at the wrong wavelengths.

I believe lux-rc had an RGB setup (3 separate LEDs though), and the results looked quite vivid, but not natural compared to when the objects were photographed under sunlight. If you analyse the spectrum you'll see that it's very spiky, centred over red green and blue (surprise surprise!). In a similar way to why regular blue die + phosphor LEDs have a relatively low CRI due to the huge trough around the 475 nm area, the output of such an RGB setup is likely to suffer in a similar way.

This isn't just applicable to white light, if we mix RGB to get, say, a purple light for whatever purposes, if you shine it on something with purple pigment, again it'll be quite dark since neither red nor blue will be reflected from the pigment.

Edit: I'm aware of the debate on how useful CRI is, but I hope we can agree that having huge troughs in a light's spectrum is probably not a good thing to have.

Erzengel · Oct 8, 2011

Only very few people need colored light to illuminate objects and they are usually satisfied with one additional color. Most users need the colors only for marking or signalling and are satisfied with colored 5mm LEDs.
Mixing light from RGB LEDs is difficult because every color has a different Vf and delivers a different amount of lumen per watt. Therefore You had to select every individual emitter and adjust the driver of every individual light to its individual emitter. That is very expensive.

gcbryan · Oct 8, 2011

Erzengel said:
Only very few people need colored light to illuminate objects and they are usually satisfied with one additional color. Most users need the colors only for marking or signalling and are satisfied with colored 5mm LEDs.
Mixing light from RGB LEDs is difficult because every color has a different Vf and delivers a different amount of lumen per watt. Therefore You had to select every individual emitter and adjust the driver of every individual light to its individual emitter. That is very expensive.

http://www.thinkgeek.com/gadgets/lights/8db4/?srp=20

carrot · Oct 8, 2011

I'll bet Peak would be very happy to make one for you.

B0wz3r · Oct 8, 2011

Th232 said:
The issue I have with mixing RGB is due to the difference between shining red + green into your eyes vs shining red + green onto a yellow object. In the former you'll see yellow light since the right receptors will be stimulated, but in the latter, since an actual yellow object reflects yellow light (and not red or green light), it won't be illuminated well since the majority of the power will be at the wrong wavelengths.

I believe lux-rc had an RGB setup (3 separate LEDs though), and the results looked quite vivid, but not natural compared to when the objects were photographed under sunlight. If you analyse the spectrum you'll see that it's very spiky, centred over red green and blue (surprise surprise!). In a similar way to why regular blue die + phosphor LEDs have a relatively low CRI due to the huge trough around the 475 nm area, the output of such an RGB setup is likely to suffer in a similar way.

This isn't just applicable to white light, if we mix RGB to get, say, a purple light for whatever purposes, if you shine it on something with purple pigment, again it'll be quite dark since neither red nor blue will be reflected from the pigment.

Edit: I'm aware of the debate on how useful CRI is, but I hope we can agree that having huge troughs in a light's spectrum is probably not a good thing to have.

Th232; thanks for your nice summary. I was trying to say something similar in my post above, but you've put it much more succinctly than I. I think GCbryan didn't understand what I meant because I was unintentionally unclear about it. Thanks.

mmace1 · Oct 8, 2011

I'm a finance type, but - I think the issue isn't the R&D needed to produce such a light (possibly copyable - and anyway, should be miniscule in the total costs of a serious production run). As the first response stated far better than I could- difficult technically, sure. But a company doesn't care how "hard" the problem is, just the cost to solve it - and it could not possibly be much % wise compared to the cost of production/etc. Development is, cost wise, pretty much OK.

The issue is just demand - very few people want a RGB flashlight. There's the...essentially no large market I can think of, that wants one. Even most flashaholics have little use for one! I mean...a legitimately good flashlight is almost a niche product at the moment! Consumers don't appreciate the value of an LED to a large extent, think about multiple output levels, or even know what "regulated" means! And certainly are not up for buying nimh batteries to properly use their lights...now we throw in a RBG light which even most flashaholics do not have a use for...

Why no RGB flashlights?

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