# UV LED lights for tracking blood?



## randman (Sep 7, 2005)

Before reading the UV post below, I never connected lights with finding blood. I am a hunter. I especially enjoy big game bow hunting. Shooting an animal just before dark is always a tough decision. If the blood trail is small, it sucks and I don't stop looking. 

But, if a UV light would pick up the blood drops on leaves then life would be much easier. Man, I feel ignorant. What kind of lights would be best and/or strong enough to pick up a blood trail on leaves on the forest floor ??? Do they make a focusable beam? 

This is cool. 

--------------------
Blaster JR.
SF E2E
ARC AAA
Streamlight Super Stinger RC


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## xpitxbullx (Sep 7, 2005)

I don't think UV is what you are looking for. Blue LEDs make blood stand out more at night. With UV, I think you need some kind of spray like they use on CSI.


Jeff


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## Icebreak (Sep 8, 2005)

xpitxbullx -

That's my understanding also. And that it stands out because it turns it black looking. But when I shine a blue at a bloody steak it just seems to take the red out.

I wonder what zenopus is using in this light? http://www.xenopuselectronix.com/XeLED_BT.html


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## HarryN (Sep 8, 2005)

To find red blood on vegetation you need cyan or a blue green as close as possible to 485 - 490nm. In Lumileds lingo, this is blue, color bin 6. This will provide substantial contrast to the vegetation.


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## Lunal_Tic (Sep 8, 2005)

A Google search  turns up an awful lot of links for UV, blood and hunting. Most that I have read say that blood, like other body fluids, fluoresces under UV. I'm not brave enough to cut myself and leave little drops around to check to see if it's true. 

IIRC the flu/spray or whatever is to intensify the UV results .

-LT


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## elgarak (Sep 8, 2005)

Blood, especially dried, does not fluoresce with UV (self experiment, after a rather nasty and stupid accident with a Spyderco Endura, but besides that, that's axactly what the professionals say). Blood appears black with UV and blue illumination. With blue you'll get some light back from the non-blood, providing contrast.

Urine and semen fluoresces, even dried, blood doesn't.


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## Lunal_Tic (Sep 8, 2005)

Is it possible that deer blood is different?

-LT


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## elgarak (Sep 8, 2005)

This site has some information and looks qualified. It says:


> Although blood does not glow in the visible range, it has a unique color band (wavelength) under which the blood stain will darken to enhance its contrast by approximately 4 times.


As I said, blood is pretty much a UV absorber and is black. To get contrast, you need to get enough light back from the surroundings. True UV shouldn't give you enough ambient light. Near UV sources, like the UV Inova X5 (400-405 nm) work a little bit better, true blue works best, especially with orange filter eyeglasses, for blood detection. AFAIK, the same applies for deer blood as for human blood. This of course assumes you want to track a blood trail in the wild. For detecting blood stains on a bed sheet, I would take UV, since the bleach in the sheet will fluoresce, while the blood will not. Presto, blood contrast anhancement.

I guess the myth of blood fluorescing comes from CSI errors. On the show, they expose blood stains with lights, but before they spray something. I don't know what. In real life, they spray Luminol, which _luminesces_ with blood, so you dont' need a light, just a darkened room (http://www.tritechusa.com/evidence/LC-LUM.htm). Why spray _and_ use a light, if you only need to do one? (I know, because it looks cool, that's why.)


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## lrp (Sep 8, 2005)

A blue filter is all you need for tracking blood at nite, I've used them for several years and they work well. You can buy a blue filter for you E2E and that is all you will need.


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## mahoney (Sep 8, 2005)

Blue filters for incandescent lights are designed to pass a suprising amount of red light wavelenghts. It helps keep the filter and the light from overheating. So blood will stand out nicely in the "blue" light as a reddish drop. Pure blue light from an LED is not as good for tracking because it lacks those red wavelenghts.


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## Gander_Man (Sep 10, 2005)

randman,
I think I started the post you referenced. I've always had a hard time getting blue filters, etc. to help in locating blood drops. I've heard the following several times each..."You have to drive at least 200 lumens", "The blood has to be dried first", The filter providing the blue coloration has to be pyrex, not lexan", ETC.. The only thing I know is the expensive sprays I sell at work to help hunters see blood specks by making them foam up when the spray hits them is primarily Hydrogen Peroxyde. Next time you have access to wet blood try putting some in a spray bottle and hit a drop with a squirt. It's pretty impressive. I still need to experiment with various (including foaming) blood sample to see what contrasts best.
- Russ


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## NikolaTesla (Sep 10, 2005)

I have a green output NightCutter "Blood Tracker" that is suposed to do the trick. I am not sure of the exact wavelength but it is a small 2 -123 flashlight designed for that pupose. Definitely NOT a UV light.


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