In daytime this emission component is overpowered out by reflected
sunlight. That, at least is how I think it works.
Hi John, I am not sure that last statement is totally correct,
seems if that were the complete case, we would not need ir goggles
to see heat at night. You see what I mean?? Or did you mean
something else??
Parker,
All warm bodies emit infrared light. Try taking a photo of your
clothes iron in the dark with an ifrared sensitive film or digital
image sensor. It should come out white. As someone said, that's
how the cops track fugitives at night from the helicopter. The
infrared emitted by their bodies is sensed by highly sensitive
cameras. If the fugitive wore enough insulation (winter parkers),
they would be much harder to dedect.
Actually, we are just talking wavelengths, I studied them a lot
when I was an radio frequency tech, and then in nuclear power
school, you may have missed my later posts referring to the heat,
anyway, it is just all relative to sensitivity of the sensor, freq
range of the sensors systems, and how small amount of heat (thermal
radiation I believe?).
The thing that freaks me out is in the radar range, where you need
a square hollow pipe and bends at half and quarter wavelengths to
make the electrons keep flowing. And then you have to track the
hole flow backwards, which is actually forwards.
What surprised me about Daniella's original post is that she
claimed to see infrared emitters as white. The reason film and
digi-cams see it as white is that the exposure is such that the
infrared light saturates the film or image sensor and it appears
white. I would expect the human eye to adjust and see the infrared
as a deep red color. In my iron example, if you ran the iron very
hot and turned out the lights, you might see the higher end of it's
spectrum as a dull red glow. With an electic stove, you can keep
cranking up the power and eventually the stove coils will appear
orange. If you could go further, they would eventually emit white
light. However, they'd probably burn out or melt before that
point. There are lots of such examples, but these illustrate where
I'm coming from
I am not sure on the exact frequencies and colors and rendering
oddities the eye performs. I do know, when camcorders first came
out and were 2500 bucks, I used to test suspect remotes by beaming
them into the lens,
worked great, cant rember if it was red or white because the
viewfinders were b/w and I can't remember what shades the dots
were. I never did record the beams to find out.
Oh yeah, the primary colors combined make white, correct??
Parker
