Yeah, you’d need a tank of luminol, LCV, etc., to get blood to show up…
I’ve looked at the videos, and it seems like they’re shooting blue/cyan and maybe another color, which’d get dirt, leaves, grass, etc., to reflect light, but blood wouldn’t, to show more contrast.
“Print” a blank page on a stinkjet printer so that it puts out its requisite yellow dots on the page (to ID the printer). Yellow-on-white doesn’t show up well at all under normal (white) light.
Shine a blue light on it, so that the white will reflect blue brightly (if not even fluoresce somewhat), but the yellow dots will show up almost black.
Think it’s the same principle at work here as far as blood.
Dr Jones RGB / RGBW firmware has a mode where it lights the green & blue emitters and flashes the red emitter at about 1hz. It makes red objects jump out at you. Never tried it with blood but next time I’m leaking and have access to the light I’ll give it a try. It works very well with solid red items regardless of their reflectivity.
Maybe this would be an option with just a pair of red and blue emitters?
That is very interesting, I can see how it might work. Good old Dr. Jones.
A bit tricky to rig something up for myself, but might just try, for next deerstalking outing. Or just to practice when training the next dog, on a trail.
Have done some reading. You need a light source with appr. 465nm wavelength.
That would be violet(blue). Some grow lights are 465nm. NB Royal Blue is 440nm-450nm.
I have no idea how well they work (never had a reason to track a blood trail) but Bushnell makes the TRKR (short for tracker) series of lights. I bought one when Walmart was selling them cheap, I think mine is the 250 lumen model. There is a white LED in the center and I think three red and three blue LED’s in a ring next to the benzel. Only one color can be lit at a time. I only use mine for walks at a local nature preserve that requires a red light if you carry a flashlight.
I’m looking at the Bushnell, Gerber, Rayovac, and Primos blood lights. Amazon has a add on item light for $6.52 I will try, along with one of the Walmart lights.
Looks like very recently they got a reel of highest flux bin units, right now I see 1000 units of XPGDRY-L1-0000-00601 in stock and selling 'em by the piece. (^̮^)
Obviously quoted the wrong source when I wrote that 465nm is violet(blue).
But then again: I’m colorblind. Awkward.
A bit like Mendel, the founder of genetic’s and very reluctant sharing his own gene pool.
Did a bit more reading: the words Coleman light keep popping up.
Probably a good guess, maybe a little higher on DTP with a good lens. The lowest current I run one at is 700mAh and it’s behind the wide ledil CUTE pebble finish that Dale estimates to cause a ~33% optical loss and it measures 97lm in my light box.
Do keep in mind it will actually be much more power output than 97lm of white light, it can give you a headache pretty quickly. The cheap meters probably read narrow band color light lower than reality as well.
Might I suggest the royal blue XT-E. Same target wavelength as the XP-E2 but they’re designed to be extremely true to their binning. Binned into 2.5nm groups (so you can be sure that 465nm led you purchase will be almost exactly 465nm). Max drive current is spec’d at 1.5A (vs 1.0A spec for the XP-E2)!
Also the XT-E will throw better if you’re not planning to dedomed the XP-E2 (the XT-E can’t be dedomed and if you did dedome the XP-E2 it would then beat the XT-E in throw).
