question for telphony, others may help!

I work in medicine and am trying to find specific leds that give the best color rendition for human skin/mucosa ie. throat. most of the medical light bulbs are made by welch allyn and i don't have any specs on the tempature of the bulbs that they supply
i do have one office operating light that has three ?xenon bulbs in it running 12 volts and 3 amps with a three separate faceted reflectors. light is still too yellow for my tastes. when i illuminate throats with my new 4AAA db mod (thanks lambda for the tips) driving one of the good luxeons (White/blue) every thing looks pretty and all but i am wondering if i am missing some of the erythema in the back of throat for all of you non medical people erythema is just a fancy name for redness due to increased capillary dilation and inflammation of the tissue.

any suggestions would be helpful...

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Bushman:
driving one of the good luxeons (White/blue) every thing looks pretty and all but i am wondering if i am missing some of the erythema in the back of the throat.<HR></BLOCKQUOTE>

Most white LEDs tend to spike strongly in the blue, and the Luxeon is no exception. Blood and other red material tends to look darker and less red when there's too much blue light and not enough output in the red.

The Luxeon does seem to have a bit stronger output in the red than any 5mm lamp though, so it has a lower (warmer) color temperature overall than other white LEDs. Best thing I can suggest is to TRY a Luxeon (get a good one, not one of those violet or pee-green ones that seem to have surfaced lately), but also use your halogen setup during the trial. That way you can determine, from a direct comparison, if you're missing any erythemous tissue with the Luxeon.

Once you've determined you're not (hopefully that will be the case anyway), you can set your halogen setup aside and use it only if there's some doubt with some particular patient.

Mike,

Yes I have the solution; actually a DB AAA with, as far as I can tell, the only true white Luxeon on the planet. Out of all the Luxeons I've handled, it is by far the whitest, hands down. Both the spot and corona are almost pure white. If it could be put to medical use, that would seem a very fitting application for such a rare light.

I'll send it with the 3D mag and you tell me if it's white enough compared to what you have now to make a difference. We can work out the details later.........

True, I would add that we need more full spectrum lights in the hospital. We keep needing to bring babies out to the window to see if they are jaundiced or not...It gets tough when it is foggy or dark.

We had a discussion a while back regarding this same topic, and I think that we came to the conclusion that white leds are very white, but not a true full spectrum. The full spectrum fluorescent bulbs are often tri-phosphor bulbs, and this is what we may need in terms of leds.

The newer head mounted fiber-optic lights are looking better with the new xenon bulbs. They have a pretty good CRI, but then you realize how bad everything is outside that spotlight. I've worked with some headlamps that don't add more light to the field than a AA maglite. I think the attendings just like making the residents where those things.

I've had some good experiences with using my photon II for those quick checks when not in the office. The streamlight is what I have been looking at for a good medical penlight, but the diffuse focus doesn't work that well for looking in corners, or just testing one eye at a time.

Alexis,

You work in Med too? I guess I should start reading bios and see who's who.

The Luxeon I'll send Bushman came from a w/optics, from the same order as yours.

When I got the order Lux/o (5), there was one loose, and four still connected together in a strip. The pure white one I'm sending Bushman was the loose one, I put it in a DB AAA mod. I used two of the four from the strip in Sears AA minimag lights with the optics, and they look great. The fourth went into your light, and I just used the last one in another flashlight mod, and it sucks; not as bad as the puke green ones, but not very bright or good color when used with a flashlight reflector. If yours looks like this, I have to appoligize because the other two lights I made at the same time were with these damn pea green Luxeons, and I'm afraid they may have made yours look bright and white compared to those; this last one looks sickly.

When you get the optics, just set it on the Luxeon and check the beam on the ceiling, and see if it impoves, all of these looked good with the optics; I'm just begining to understand flashlight reflectors use different parts of the output light than the optics.

We need to get Lumileds to bin sort these by color, every order is an adventure, when you just want a white LED.

I guess Luxeons are subjet to not only wild variations of color, but orders may have mixed lots when purchased through Future; and if they supply everyone else, does anybody sort them by color? Please......

We are a bit spoiled by some really nicely colored luxeons vs the other ones. They are still better than the Maglite AA beams. I will admit that the welch allyn xenon bulbs in most of the "good" handheld equipment is pretty white and has a decent CRI.

That's what I need to do, get a beam pic of the LS DB AAA compared to my welch allyn pocket otoscope...

Actually, I have another year and a half for my MD.

Here are some beam pics

http://home.mindspring.com/~alexis.dang/leds.html

The welch allyn is their pocket model otoscope and is using 2 NiMh. Their brighter scopes use 3.6 volts I also used my Brinkmann Legend AA which has a virtually identical beam pattern and bulb as the Maglite AA. This was using a set of relatively new alkalines.

The diffuse, even beam of the welch allyn, without a hot spot is perfect for medical use. Something that is very bright without a hot spot, and with good focus would be the ideal light. I've seen some focused nichias that have a pretty nice and even beam pattern.

Even with all this, the ideal medical penlight needs to be small. A AA maglite is still a bit bulky for everyday use. The AAA maglite and the streamlight stylus are the ideal size.

thanks lambda and alexis. all input appreciated, thanks lambda for considering sending the aaa db mod to me i know that this is probably one of your last ones and that is a sacrifice. I will work out the details with you as of yet i still have not gotten the luxeons from the place we discussed. i will make a post later about the potential availability of good color luxeons if the ones that i get look worthwile. have you been able to contact him?

Alexis it is good to know that there is someone else in the medical field out there. I am a nurse practitoner in internal medicine. Thanks for the great beam pics. they are helpful i am using my own aaa DB in "trials" right now vs welch allyn equipment in my office.

Lambda I will send you a few spare welch allyn xenon bulbs with specs (if i can find the specs) for you to play with and use as a "standard against some other luxeons.

talk to you later

Bushman,

Do you have a source for other welch allyn bulbs? There was a thread on the regular light forum about a 90 lumen replacement for the 8AA DB, but the min order for bare bulbs was pretty high.

It's funny how the welch allyn has as one of its feature "throat illuminator" which is just a flashlight!

alexis, i can probably order any welch allyn bulb you want through my clinic, if you can get me part numbers etc iwill look in to it email meat
[email protected]
i have a 8aa db too and would be interested in this bulb. hope it dosent melt the reflector!!!

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Bushman:
alexis, i can probably order any welch allyn bulb you want through my clinic, if you can get me part numbers etc iwill look in to it email meat
[email protected]
i have a 8aa db too and would be interested in this bulb. hope it dosent melt the reflector!!!<HR></BLOCKQUOTE>

Ditto to what alexis says (I've also got an 8AA DB that needs that powerful bulb). I don't have the part # though...

That bulb definitely won't melt the refector, because the flashlight originally came with that lamp.

So, is 4500K blue or green?

Did some looking for color temperature and found this chart:

Temperature Typical Sources
1000K Candles; oil lamps
2000K Very early sunrise; tungsten lamps
2500K Household light bulbs
3000K Studio lights, photo floods
4000K Clear flashbulbs
5000K Typical daylight; electronic flash
5500K The sun at noon near Kodak's offices
6000K Bright sunshine with clear sky
7000K Slightly overcast sky
8000K Hazy sky
9000K Open shade on clear day
10,000K Heavily overcast sky
11,000K Sunless blue skies
20,000+K Open shade in mountains on a really clear day

So a Luxeon is supposed to be between a flash bulb and electronic xenon flash tube in color.....How come all Future is shipping for loose emitters is pea green?

By the chart, pea green would be below candles in 'color temperature', like 450-500K or something. I would call these Luxeons reject seconds by definition.............

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by lambda:
So, is 4500K blue or green?<HR></BLOCKQUOTE>

good question i will email telphony and ask. i think it leans more towards blue.

Found this chart at http://www.konica.co.jp/english/how_to/nar/nar_15.html that shows 4500K as pea green!

Could it be the wht/blu Luxeons are actually the rejects?????????? And the pea green ones the good ones (according to Lumileds)????

If so, I'll buy every reject they have!

To add, 10k is the color of sunlight at about 10 feet below the ocean surface. Lights for saltwater tanks are generally full spectrum and are often rated from 5000 to 20000 depending on how blue you prefer your light.

Here is the thread for the upgraded welch allyn bulbs
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=1&t=001121

i have understood that energizer is really good about warranty for this flashlight and i believe that one of our european forum members (reumen i believe) said that he simlply called energizer and they sent him a replacement bulb for free1 even though the bulb is specifically excluded in the warranty...

i just checked the welch allyn website and they say thier solarc system xenon bulb puts out 5500k color for best tissue color redering this is what i use for flexible sigmoidoscopy... thier main exam light is 3200K which is yellowish halogen. closer to ordinary flashlight output now off to find what K the luxeon whites are rated at.

lumileds says that the luxeon is at 4500K (i wonder about all of the different color variations on the luxeon white have any change in this anybody got a photometer that measures color rendering??