(classical music)
- So, night vision seems like
a pretty cool idea, right?
I mean, you see it all the time in movies.
Some secret agent type
straps on a pair of goggles,
sneaks into a luxurious
supervillain compound
and mows down enemies under
the cover of darkness.
Or a predator stalks
Arnold Schwartzenegger,
killing his platoon one by one by one.
And as you're watching all this,
you may occasionally ask yourself,
"Hey, do those goofy looking
goggles really work?"
The answer is yes, absolutely.
With a good Night Vision Device, or N-V-D,
you can see a person standing over
200 yards away on a
moonless, cloudy night.
And whether we're talking
goggles, scopes, or cameras,
most of these devices rely on one
of two types of night vision.
Image enhancement, that's
the green-looking one.
And thermal imaging, which
is the bluish-grey stuff.
They both produce results
but work in different ways.
Thermal imaging captures the upper portion
of the infrared light spectrum.
Objects emit this as heat
rather than reflecting it as light.
Hotter objects, such as the
bodies of secret agents,
emit more of this light
than cooler objects,
like buildings, trees, or dead bodies.
And that's what you're seeing
when you use thermal imaging.
A measure of temperature from
negative 4 degrees Fahrenheit
to 3,600 degrees Fahrenheit.
The magic, or the science,
starts at the lens,
which focuses the infrared light emitted
by all the objects in view and uses a
phased array of infrared detector elements
to create a temperature
pattern called a thermogram,
which is translated first
into electric impulses,
and then into data for the display.
Or it appears as various colors
depending on the
intensity of the infrared.
Then there's image enhancement.
This collects tiny amounts of light,
including the lower portion of
the infrared light spectrum,
and amplifies it.
Image enhancers use a photocathode
to convert photons into electrons,
and high-voltage to
amplify those electrons
in a microchannel plate, or M-C-P,
before they hit a screen
coated with phosphors.
Here's the crazy part.
These electrons maintain their position
in relation to the microchannel
they passed through,
which provides a perfect image
since the electrons stay in the
same alignment as the original photons.
When they hit the screen,
their energy excites the
phosphors, releasing photons.
Those phosphors create
that green image you see
when you look though a night vision scope.
Night Vision Devices have
been around for more than
40 years and they've gone
through multiple improvements.
Today they're used for everything
from military applications
to navigation and wildlife observation.
Thanks for watching.
And, hey, here's a question for you.
What should I cover next?
Let me know in the comments,
and stay tuned for more Brain Stuff.
