In article <77d74$457d8724$44a4a10d$13623@msgid.meganewsservers.com>
rokigawaATtristarassociatesDOTcom "Ray O" writes:
[color=blue]
> I don't know how blue light makes blood more visible, I just
> read that claim in a SureFire flashlight ad. My guess is that
> it has something to do with light wavelengths.[/color]
AFAIK, it concerns how red objects, in this case the blood, tend
to absorb non-red colours more than red (else they wouldn't look
red <g>). Human skin (even that of dark-skinned people) gets an
appreciable amount of its colour from blood flowing just beneath
its surface. A truly "white" person is bloodless. Some of this
runs in visible large vessels, some in capillaries. The clearly
defined vessels tend to look dark beside bluer (due to reflected
blue light) skin elsewhere.
--
Andrew Stephenson