WEBVTT - BrainStuff Classics: How Does Night Vision Work?

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<v Speaker 1>Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff,

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<v Speaker 1>I'm Lauren Bokelbaum, and this is a classic episode from

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<v Speaker 1>our erstwhile host, Christian Sagar. This one concerns a favorite

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<v Speaker 1>technological trope of spy and action movies, night vision goggles.

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<v Speaker 1>How do they really work? Hey, brain stuff? This is

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<v Speaker 1>Christian Sager. So night vision seems like a pretty cool idea, right,

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<v Speaker 1>I mean, you see it all the time in movies.

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<v Speaker 1>Some secret agent type straps on a pair of goggles,

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<v Speaker 1>sneaks into a luxurious supervillain compound and mose down enemies

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<v Speaker 1>under the cover of darkness, or the predator stalks Arnold

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<v Speaker 1>Schwarzenegger killing his platoon one by one by one. And

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<v Speaker 1>as you're watching all this, you may occasionally ask yourself, Hey,

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<v Speaker 1>do those goofy looking goggles really work? Well? The answer

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<v Speaker 1>is yes, absolutely. With a good night vision device or

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<v Speaker 1>n v D, you can see a person standing over

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<v Speaker 1>two hundred yards or a hun driden eighty three meters

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<v Speaker 1>away on a moonless, cloudy night. And whether we're talking goggles, scopes,

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<v Speaker 1>or cameras, most of these devices rely on one or

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<v Speaker 1>two types of night vision image enhancement. That's the green

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<v Speaker 1>looking one, and thermal imaging, which is the bluish gray stuff.

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<v Speaker 1>They both produce results, but work in different ways. Thermal

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<v Speaker 1>imaging captures the upper portion of the infrared light spectrum.

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<v Speaker 1>Objects emit this as heat rather than reflecting it as light.

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<v Speaker 1>Hotter objects, such as the bodies of secret agents, emit

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<v Speaker 1>more of this light than cooler objects like buildings, trees,

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<v Speaker 1>or you know, dead bodies, and that's what you're seeing

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<v Speaker 1>when you use thermal imaging, essentially a measure of temperature

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<v Speaker 1>from negative four degrees fahrenheit to three thousand and six

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<v Speaker 1>hundred degrees fahrenheit. The magic or well you know, the

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<v Speaker 1>science starts at the lens, which focuses the infrared light

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<v Speaker 1>emitted by all of the objects in view and uses

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<v Speaker 1>a phased array of infrared detector elements to create a

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<v Speaker 1>temperature pattern called a thermogram, which is translated first into

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<v Speaker 1>electric impulses and then into data for the display, where

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<v Speaker 1>it appears as various colors depending on the intensity of

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<v Speaker 1>the infrared. Then there's image enhancement. This collects tiny amounts

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<v Speaker 1>of light, including the lower portion of the infrared light spectrum,

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<v Speaker 1>and amplifies it devices using this approach rely on an

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<v Speaker 1>image intensifier tube to collect and amplify light, both the

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<v Speaker 1>infrared kind and the visible stuff. Image enhancers use a

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<v Speaker 1>photo cathode to convert photons into electrons and high voltage

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<v Speaker 1>to amplify those electrons in a micro channel plate or

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<v Speaker 1>an m c P before they hit a screen that's

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<v Speaker 1>coated with phosphors. Here's the crazy part. These electrons maintain

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<v Speaker 1>their position in relation to the micro channel they passed through,

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<v Speaker 1>which provides a perfect image, and the electrons stay in

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<v Speaker 1>the same alignment as the original photons. When they hit

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<v Speaker 1>the screen, their energy excites the phosphors, releasing photons. Those

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<v Speaker 1>phosphors create the green image you see when you look

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<v Speaker 1>through a night vision scope. Today's episode was written by

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<v Speaker 1>Ben Bollen and produced by Tyler Clang. For more on

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<v Speaker 1>this and lots of other insightful topics, visit hous toff

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<v Speaker 1>works dot com. Brain Stuff is production of I Heart Radio.

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<v Speaker 1>For more podcasts for my heart Radio, visit the iHeart

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