Speaker 1: Get in touch with technology with tech Stuff from how
Speaker 1: stuff works dot Com. Hei there and welcome to tech Stuff.
Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer and
Speaker 1: I love all things tech and it is time for
Speaker 1: another classic episode of tech Stuff. This episode originally aired
Speaker 1: on November two thousand eleven. And Chris Pallette, my co
Speaker 1: host and editor at the time, and I decided we
Speaker 1: wanted to take a look at something that's kind of
Speaker 1: hard to see, that is when it's actually being used.
Speaker 1: I'm talking about night vision. How does the technology work? Well,
Speaker 1: Chris and I found out and now you will to
Speaker 1: enjoy this classic episode night Vision. The technology dates back
Speaker 1: to the late thirties early forties. It was technology that
Speaker 1: was developed during World War Two and used mainly by
Speaker 1: the American, British, and and Soviet forces during World War Two,
Speaker 1: although other nations began to to develop their own version
Speaker 1: of night vision technology around the same time. Well, yeah,
Speaker 1: the Germans, Uh, A lot of what we had as
Speaker 1: far as our technology in the United States was based
Speaker 1: on some German research that was done in the late thirties. UM.
Speaker 1: And really what it comes down to, UM is the
Speaker 1: spectrum of light that that you're trying to see. Yeah,
Speaker 1: it's it's two different things. It's trying to accept other
Speaker 1: parts of light that human eye is not able to detect,
Speaker 1: and also to uh to amplify whatever little light is there.
Speaker 1: There are two main ways of achieving a night vision
Speaker 1: UH technology. One is called image enhancement, and that's where
Speaker 1: you're taking the little amount of light that's out there
Speaker 1: and UH and trying to amplify it so that you know,
Speaker 1: you're able to see better in that environment. And the
Speaker 1: other is thermal imaging, which is also you know, we
Speaker 1: think of that as being able to see heat. You know,
Speaker 1: the whole idea about like if you've ever seen that
Speaker 1: documentary Predator, Yeah, the Predator actually uses both forms of this,
Speaker 1: but the thermal imaging would be the one where it
Speaker 1: switches and it's that really colorful display where the hotter
Speaker 1: things in the field of vision are a brighter color,
Speaker 1: usually red, uh, and then the cooler things are are
Speaker 1: in the other part of the spectrum of light, so
Speaker 1: they'd be you know, if it's cold, it might be black,
Speaker 1: but if it's cooler, it might be blue or even
Speaker 1: kind of an indigo color. Um. Both of those are
Speaker 1: ways of achieving night vision. The I think the one
Speaker 1: that most people think of when they think of night
Speaker 1: vision is the one where you've got the greenish uh display.
Speaker 1: That's the image enhancement approach, and well, you know that
Speaker 1: that's I think that's the reason people think about it
Speaker 1: is because it's used that way in TV in the movies. Yeah,
Speaker 1: probably so as a visual clue to the viewer that hey,
Speaker 1: we're doing something that you can't normally do, right, Yeah.
Speaker 1: I In fact, I watched a movie just last night
Speaker 1: that involved having a night vision the screen tinged night vision,
Speaker 1: and it was and I'm not going to call it
Speaker 1: the documentary because that's how much of a skeptic I am.
Speaker 1: It was paranormal activity too, and uh, you know in
Speaker 1: paranormal activity those movies, those are done as found footage movies, which,
Speaker 1: in case you're not familiar with the term, that's the
Speaker 1: idea where the film is presented as if it were
Speaker 1: uh collection of clips taken from various cameras. That it
Speaker 1: wasn't meant to be a feature film. It was supposed
Speaker 1: to be actual footage shot of something, right. So clover
Speaker 1: Field is another example, or Blair Witch Project's another example, Yes,
Speaker 1: that's the first time I thought about. Yeah, and that
Speaker 1: it's really popular with the horror crowd. Uh and uh
Speaker 1: so the paranormal activity too. There's one of the cameras
Speaker 1: that is being used in that has a night vision
Speaker 1: setting and it's using the image enhancement approach. By the way,
Speaker 1: in case you're curious about why green, the the answer
Speaker 1: I found through my research was that the reason why
Speaker 1: you get green images is not because of any technological limitation.
Speaker 1: It's because if you're in an environment where you're using
Speaker 1: night vision, you want to be able to switch between
Speaker 1: night vision and your normal vision as quickly as possible.
Speaker 1: But if you use really intense light and and some
Speaker 1: of the brighter lights, your pupils will constrict as you're
Speaker 1: looking at it, which means when you take the night
Speaker 1: vision glasses off, it's going to take more time for
Speaker 1: your eyes to readjust to the darkness around you. But
Speaker 1: the green that is used is a more subtle light,
Speaker 1: and so your your pupils are remain mostly dilated, so
Speaker 1: when you remove the night vision goggles, you don't of
Speaker 1: as long a time to adjust. It doesn't take as
Speaker 1: long for you to adjust to night regular night vision
Speaker 1: like our natural night vision. Uh when you when you
Speaker 1: go back and forth, and that kind of makes sense
Speaker 1: to me. I mean, if you especially when you consider
Speaker 1: that night vision was really originally used as a military technology,
Speaker 1: you would want to be able to have as much
Speaker 1: versatility and flexibility as possible so that you can adapt
Speaker 1: to whatever the situation calls for. Yeah, that makes absolute
Speaker 1: sense to me. So yeah, so at least according to that,
Speaker 1: we could in theory have night vision where it's any color. Uh.
Speaker 1: You know, it probably still probably be monochromatic, but we'll
Speaker 1: get into that when we get into the you know
Speaker 1: exactly what's happening. So so, all the different kinds of
Speaker 1: night vision lie at least somewhat on the infrared, uh,
Speaker 1: part of the spectrum of light, right, and that infrared
Speaker 1: spectrum of light is outside the range of uh, the
Speaker 1: visible light spectrum. UM. In fact, there are three parts
Speaker 1: to the infrared spectrum, which is near infrared, and that's
Speaker 1: the closest one to the visible spectrum spectrum. Yes, I
Speaker 1: can say that word mid infrared um and that has uh.
Speaker 1: I didn't mention the wavelengths. The wavelengths for near infrared
Speaker 1: are from point seven to one point three microns um.
Speaker 1: Mid infrared has wavelengths from one point three to three
Speaker 1: microns um, and then thermal infrared, which is the biggest
Speaker 1: part of the infrared spectrum, and that's from three to
Speaker 1: more than thirty microns. Yeah, and so the the thermal
Speaker 1: infrared you're talking at that point about infrared radiation really yeah, heat,
Speaker 1: in other words, is what's kind of how we perceive
Speaker 1: it usually. But uh, that's something that's actually given off
Speaker 1: by an object itself, Whereas when we're talking about visible light,
Speaker 1: that's something that's reflected off of an object. Right. So
Speaker 1: if if I'm looking at a tree in sunlight, what
Speaker 1: I'm seeing is the light being reflected off of that tree,
Speaker 1: it's that lights hitting my eyes then going through the
Speaker 1: whole focal point getting into my brain and somewhere up
Speaker 1: there in yeah, somewhere up there in the gray matter,
Speaker 1: my brain says, Hello, there's a tree, possibly a large
Speaker 1: a large. Um. I recognize that from very far away. Yes,
Speaker 1: that's how to recognize trees from very far away, quite
Speaker 1: a long way away. Yeah, So that's how that would
Speaker 1: normally work with thermal infrared. If I were to see
Speaker 1: an object using thermal infrared. Let's say that somehow I
Speaker 1: have that ability. You know, we're not talking about technology here,
Speaker 1: but I somehow have the the the natural ability to
Speaker 1: see the thermal infrared. It happened when they shot him
Speaker 1: into space and he was bombarded by cosmic waves while
Speaker 1: we're really just pop culturing this all to heck and back.
Speaker 1: So yeah, with the thermal infrared ability, I would be
Speaker 1: able to see the energy that is being emitted by
Speaker 1: any particular object. Um it's not necessarily light that's reflecting off.
Speaker 1: In fact, there doesn't have to be any sort of
Speaker 1: light source at all. It just so. And if I
Speaker 1: were in a perfectly dark room and there was another
Speaker 1: object there that's giving off heat, essentially, I would be
Speaker 1: able to see it because I would be seeing in
Speaker 1: that range even though there's no other light source coming in.
Speaker 1: It would just be that I'm actually seeing that that energy.
Speaker 1: Because we'll get into why, it's kind of interesting. Has
Speaker 1: to do with excitation, but not good vibrations. Yeah, although
Speaker 1: perhaps that lady was able. Never mind, So moving on,
Speaker 1: I hope you guys are enjoying this classic episode so far.
Speaker 1: We've got more to talk about, but first, let's take
Speaker 1: a quick break to thank our sponsor. Before we get
Speaker 1: into the whole atoms and thermal infrared, let's let's talk
Speaker 1: about the image enhancement approach first, because that's the one
Speaker 1: that's the most familiar and uh and it's kind of interesting. Um.
Speaker 1: The way that it works currently is that you've got
Speaker 1: you've got very basic parts to a particular kind of
Speaker 1: night vision. You've got you've got your lens. That's where
Speaker 1: the light is going through. The objective lens. Just a
Speaker 1: lens that catches it's a lens. Yeah, it catches ambient light,
Speaker 1: catches near infrared light. So this is the near infrared spectrum,
Speaker 1: the light that's closest to the visible spectrum. Now that
Speaker 1: light is sent to a tube, and that tube is
Speaker 1: called the image intensive fire tube intense. Yeah, and the
Speaker 1: drinking energy drinks all day and yeah. So you can
Speaker 1: think of this tube. It's almost like a vacuum tube.
Speaker 1: In fact, there it is, There is a vacuum in
Speaker 1: side of it. So you think of this sort of
Speaker 1: imagine a glass vial all right in the middle of
Speaker 1: this glass vial or on one end of the class file,
Speaker 1: you've got something called a photo cathode. Now, the photo
Speaker 1: cathode takes photons. Those are those individual elements of energy
Speaker 1: for light. Yes, and and those come in the entire
Speaker 1: spectrum of light um so infrared. They're infrared photons, just
Speaker 1: as there are visible light photons. So the photo cathode
Speaker 1: converts photons into electrons. It's it's one of those. Uh
Speaker 1: So it changes light into electricity essentially. Yeah, And if
Speaker 1: you listen to our episode about high speed and low
Speaker 1: speed photography, we talked about how there are certain types
Speaker 1: of materials that when a photon strikes it, it causes
Speaker 1: a reaction. That's the case here a photocathode. It's that's
Speaker 1: the and that's how it behaves when a photon hits it.
Speaker 1: It gives off an electron. Uh So, You've got the
Speaker 1: photo cathode at one end of this tube, and that's
Speaker 1: where the light that's being captured by the lens is
Speaker 1: directed to the photo cathode. The electrons emitted by the
Speaker 1: photo cathode then have to pass through what is called
Speaker 1: a micro channel plate or m c P. That's a
Speaker 1: little glass disc. Yeah, I see. I thought MCP was
Speaker 1: the master control program. End of line. It is. Okay, However,
Speaker 1: two different mcps well it was until Tron got hold
Speaker 1: of it. That's right. So glass disc Tron m c P.
Speaker 1: I'm sensing some convergence here as we Mentionedron again. Ye.
Speaker 1: So anyway, you've got this glass little tiny glass disc
Speaker 1: called a micro channel plate and has lots and lots
Speaker 1: of channels. That's why it's called a micro channel plate.
Speaker 1: Lots of channels that go through this plate. Okay, So
Speaker 1: think of the plate. Think of it like a dish.
Speaker 1: You got a dish, put it up on its side,
Speaker 1: and it has a whole bunch of little holes drilled
Speaker 1: in it. Now, those holes are what allow electrons to
Speaker 1: pass through. But there's also an electrode on either side
Speaker 1: of the dish. So electrons coming from the photo cathodes
Speaker 1: strike one side of this micro channel plate and start
Speaker 1: to go through one of the channels. And they're going
Speaker 1: through in the same direction they came from the the
Speaker 1: from the photo cathode uh section of this this uh
Speaker 1: this image intensive ire tube. So the photon converts to electron.
Speaker 1: Electron goes through this channel. As it goes through the channel,
Speaker 1: it starts to actually set off a well a reaction. Yeah,
Speaker 1: and it basically functions as a multiplier for the electrons.
Speaker 1: It's called a cascaded secondary emission. So this is where
Speaker 1: when electron collide collides with something inside that that channel,
Speaker 1: it starts to set off other electrons, uh, down that
Speaker 1: same pathway, And there's a voltage applied to those electrodes
Speaker 1: that's channeling the electrons through that pathway, like that's why
Speaker 1: they're going in that direction. So you've got more and
Speaker 1: more electrons bouncing off of each other through these channels,
Speaker 1: which means that you've you've created an amplifier. And uh,
Speaker 1: if you guys want to know kind of like a
Speaker 1: big picture way of what this might look like, imagine
Speaker 1: having a h and you can see play of videos
Speaker 1: of this on YouTube, But imagine having a big glass
Speaker 1: container filled with mouse traps, and each mouse trap has
Speaker 1: a ping pong ball set on it, and then you
Speaker 1: drop a ping pong ball into the glass chamber and
Speaker 1: that will set off a mouse trap, and as the
Speaker 1: ping pong balls bounce around, they set off more and
Speaker 1: more mouse traps, so soon the glass case, like within
Speaker 1: a fraction of a second ball, the balls are bouncing everywhere. Right,
Speaker 1: same sort of idea here with the micro channel plate,
Speaker 1: except that we're talking on a sub atomic level, and
Speaker 1: we're talking about something that's really channeled, really has a
Speaker 1: firm direction. So instead of the electrons bouncing everywhere, they're
Speaker 1: going in a very specific direction. Right now, when they
Speaker 1: get to the other side of that micro channel plate,
Speaker 1: you've got the electrons still traveling in this ame direction
Speaker 1: they were when they came in on the front side,
Speaker 1: but now there are way more electrons, right, just amplified
Speaker 1: the number. The electrons then hit a screen that's coated
Speaker 1: with phosphors. Now phosphors pos phosphors do the they're kind
Speaker 1: of like the opposite of the photo cathode, right. They
Speaker 1: take When the electron strikes the phosphor, they give off light.
Speaker 1: So you're changing the electron back to a photo photon. Right.
Speaker 1: But now, because there are more electrons coming through hitting
Speaker 1: that phosphoor than they were coming in, the light that's
Speaker 1: generated is much greater in intensity than the light that
Speaker 1: was coming in. So you've amplified the light. Now that
Speaker 1: information that light is sent to a viewer of some type.
Speaker 1: It could just be a regular lens, which is usually
Speaker 1: called the ocular lens, or it could be sent to
Speaker 1: a monitor. So if you have a pair of night
Speaker 1: vision goggles or a night vision scope. That's what you're seeing.
Speaker 1: You're seeing that amplified light hitting the lens or the
Speaker 1: Monitor's cool, it's pretty awesome, right, And again, this isn't
Speaker 1: just the the visible light, the ambient visible light that's
Speaker 1: out there, but also the infrared light. So um, because
Speaker 1: those photons, you know it doesn't you know, the photons,
Speaker 1: It doesn't matter if it's visible or not. UM. And uh,
Speaker 1: the more light that's hitting certain areas, that the brighter
Speaker 1: it's going to be for whatever it is you're looking at.
Speaker 1: So if you're looking at something that's that's fairly reflective, um,
Speaker 1: you're gonna be able to see it in higher definition
Speaker 1: than you could with something that is not as reflective. Now,
Speaker 1: there are different ways of actually achieving this too. You
Speaker 1: can have a various they're various generations of this technology,
Speaker 1: all right. So the earliest generation of this technology actually
Speaker 1: involved shining infrared light at the objects you're looking at
Speaker 1: through the through the night vision goggles, right, So when
Speaker 1: that that infrared light was reflected, then you would be
Speaker 1: able to see it, right, because these goggles were not
Speaker 1: so sensitive as to be able to take just the
Speaker 1: ambient light. Right, if you did that, you would probably
Speaker 1: get you you might be able to see marginally better
Speaker 1: than you would if you had just use your regular vision.
Speaker 1: But using this infrared flashlight, essentially you could illuminate the
Speaker 1: scene and be able to see it through the night
Speaker 1: vision goggles. But if you did not have the goggles,
Speaker 1: because infrared light falls outside the visible spectrum, any independent
Speaker 1: observer wouldn't be able to tell what you were doing. Yeah, now,
Speaker 1: I UM I did some research on the the US
Speaker 1: military website about the history of of night vision and apparently,
Speaker 1: um they sent about three hundred sniper scopes over to
Speaker 1: be used in the Pacific theater during World War Two,
Speaker 1: but they didn't get used very much because of the
Speaker 1: way that the technology worked. Um they really could see
Speaker 1: less than a hundred yards. Yeah, they weren't very effective, right,
Speaker 1: because again, since it's dependent upon a reflected ray of
Speaker 1: infrared light, if it's you know, the rays starting to
Speaker 1: dispersees as it goes out, Right, it's not not a
Speaker 1: not a concentrated like a laser beam. Yeah, it's not
Speaker 1: a beam. It does disperse and diffuse as it goes out.
Speaker 1: So the further away your target the less likely you're
Speaker 1: going to be able to see it, and even with
Speaker 1: a really really advanced version. That's, by the way, it's
Speaker 1: called active infrared because you're actively beaming infrared radiation out
Speaker 1: in order to try and see stuff coming back through
Speaker 1: the monitors. Um if because because you're relying on that reflection,
Speaker 1: if it's too far away, you're not gonna be all
Speaker 1: se very well. So obviously a sniper rifle, where at
Speaker 1: least in theory, you want to be able to put
Speaker 1: your snipers at a good distance away from the targets
Speaker 1: to maximize their effectiveness and minimize the chance that they
Speaker 1: will be targeted. Um it doesn't. It's not so effective
Speaker 1: if you know your your distance is cut down that dramatically. Yeah. Plus,
Speaker 1: the first generation wasn't exactly um useful for someone like
Speaker 1: a sniper, considering the batteries were huge and the i
Speaker 1: R emitters had to be carried on flatbed trucks. It's
Speaker 1: hard to put one of those up in a tree. Yeah. Yeah,
Speaker 1: it turns out that also all of these are going
Speaker 1: to involve having a power supply of some sort. But
Speaker 1: for the active infrared it requires either more more energy
Speaker 1: because you're not you're not just for your your actual
Speaker 1: night vision device, whether it's a scope or goggles or whatever,
Speaker 1: but also for the emitter. By the way, that generation
Speaker 1: is normally referred to as generation zero for a night vision.
Speaker 1: Generation one was the first generation using passive infrared system. Now,
Speaker 1: this was the kind of of night vision goggles or
Speaker 1: scope that could just use the ambient light in the area,
Speaker 1: although it needed a good amount of the ambient light.
Speaker 1: So moonlight or starlight. It's funny you should say starlight. Yeah,
Speaker 1: that's what it was called. Yea in the U. S.
Speaker 1: Army they called it starlight. Uh, the without the moon
Speaker 1: or stars, you wouldn't be able to see very much.
Speaker 1: So on an overcast night it would not be terribly useful. Yeah,
Speaker 1: but on a clear day you could see forever. You
Speaker 1: got a clear day, you don't need night vision. Okay,
Speaker 1: starlight first star I see tonight. Um, so yeah, it
Speaker 1: was better than Generation zero. Still still pretty far acry
Speaker 1: from what we have today. Although interestingly, if you were
Speaker 1: to go out and buy a pair of night vision goggles,
Speaker 1: you know, a consumer brand version would probably be Generation one,
Speaker 1: I would guess, you know that's the military tends to
Speaker 1: reserve the more the more advanced forms generations. It's they
Speaker 1: could be generation two as well. Generation two where they
Speaker 1: had better UH image intensive fire tubes, which meant that
Speaker 1: they could use them in extreme low light conditions. So
Speaker 1: on a moonless night, you could use these and it
Speaker 1: would be strong enough to be able to to amplify
Speaker 1: that light. So you can see. Generation three is what
Speaker 1: you can find in the U. S Military now, UM,
Speaker 1: and that is they used a new kind of photo
Speaker 1: cathode called gallium arsenide, so it's even more sensitive than
Speaker 1: the previous ones, which means that you know, it's it's
Speaker 1: not that the UH they've really advanced the technology that much.
Speaker 1: They just found a material that that emits electrons much
Speaker 1: more readily than others. Yeah. As a matter of fact,
Speaker 1: I believe we talked about gallium arsenid when we talked
Speaker 1: about transistors. I believe we did some months back. Yeah,
Speaker 1: and then we have generation four, which is yet more
Speaker 1: improvements UH and it works both in UH in low
Speaker 1: and high level light environments, which that's important too, because
Speaker 1: some sometimes you're in an environment where you're gonna have
Speaker 1: more light than UH than well, let's take two separate
Speaker 1: nights Okay, we have one night where let's say there's
Speaker 1: a lot of moonlight, Uh, there's starlight. There might even
Speaker 1: be some some lights set up in whatever it is
Speaker 1: you're looking at, Like let's say it's an enemy encampment.
Speaker 1: Let's say you're sniper looking at an enemy encampment. Uh.
Speaker 1: If you're using a device that's meant for low light environments,
Speaker 1: you might not be able to see anything anyway, because
Speaker 1: all of that light just overwhelms the device, and so
Speaker 1: you all you see is just a big, you know,
Speaker 1: green screen. Uh. So you need to have one that
Speaker 1: can work in both kinds of situations. Um. So yeah,
Speaker 1: that's your basic that's your basic. Uh. Image enhancement style
Speaker 1: night vision. Chris and I are about to wrap up
Speaker 1: this discussion about night vision, but before we get to that,
Speaker 1: let's take another quick break to thank our sponsor. Now,
Speaker 1: I guess we can move on to the the thermal devices,
Speaker 1: which again can look at you can look at stuff
Speaker 1: and see the energy it's giving off, the light it's
Speaker 1: giving off even though light uh, an outside source of
Speaker 1: light isn't necessarily present. M And this has to this
Speaker 1: involves the whole concept of excitation. Yeah, yeah, Now, you
Speaker 1: have to have a special type of lens to use
Speaker 1: when you're working with thermal imaging basically to identify the
Speaker 1: infrared light. And you've got to what happens is once
Speaker 1: the light is focused through the lens, UM I phased
Speaker 1: array of infrared detector elements scans it UM basically trying
Speaker 1: to create a pattern called a thermogram, which shows you
Speaker 1: the different ranges in temperature UM. And this can be
Speaker 1: done pretty quickly, about one of a second. Yeah, so
Speaker 1: like okay, thirty frames a second essentially, so yeah, and
Speaker 1: considering that film is twenty four frames a second, that
Speaker 1: is that's Yeah, it's fast enough so that you can
Speaker 1: get a good view. So even if something's in motion,
Speaker 1: you should be able to get a pretty good view
Speaker 1: of it. Yeah. And then and then, very much like
Speaker 1: the other style, it creates a thermogram UH and then
Speaker 1: translates it into an electric impulse UM just like that,
Speaker 1: and then it's sent to a signal processing unit which
Speaker 1: is basically UH electronic circuit board UM and UH. Instead
Speaker 1: of converting electrons to photons, it actually creates a display
Speaker 1: of information UM. So it's more like a computer than
Speaker 1: it is an ocular system with the other one. Yeah,
Speaker 1: you wouldn't have a lens. You would have a monitor
Speaker 1: of some site, some type. Now that motor might be small, Yeah,
Speaker 1: so it could be a motor they then probably Yeah,
Speaker 1: it could even fit into a headset or or binoculars
Speaker 1: or whatever. Um. Yeah, this is the what I was
Speaker 1: talking about with the the documentary Predator, where you've got
Speaker 1: the different colors representing different temperatures. So if you've ever
Speaker 1: watched any ghost hunting shows where they use thermal detectors
Speaker 1: to try and see if there are cold or warm spots,
Speaker 1: that's what they're using. By the way, just so just
Speaker 1: side note, the air can actually retain heat for a
Speaker 1: good amount of time. So let's say that you're with
Speaker 1: a big crew of people down in a cold basement
Speaker 1: and you've set up a bunch of lights and stuff,
Speaker 1: and you're filming some things, and then you turn the
Speaker 1: lights off and you go and you turn on the
Speaker 1: thermal imaging detector and you see this hot spot in
Speaker 1: the air that could possibly be generated by someone who
Speaker 1: had been standing there for about five or ten minutes,
Speaker 1: or even a light that had been turned on. Not
Speaker 1: necessarily a paranormal, uh ghostly presence Okay, rant Over, I
Speaker 1: was actually going to use blue Thunder as an example.
Speaker 1: Like they used to they would fly outside and hover
Speaker 1: outside the window and they could see the shapes where
Speaker 1: people were. Which is funny because when you when you
Speaker 1: mentioned it like that and the movies and tv uh,
Speaker 1: when a person moves across the room, the heat stay,
Speaker 1: you know, stays with the person. It's identifiable human shape.
Speaker 1: It's very very much defined to that particular shape. It
Speaker 1: seems like in the case of since the air can
Speaker 1: retain heat, it seems like they would leave a trail
Speaker 1: of some Yeah, depending on how where residual pattern as
Speaker 1: much as the roadrunner does with a little cloud of dust.
Speaker 1: It takes off well if you're if you're moving, if
Speaker 1: you're moving steadily through the environment, you're probably not leaving
Speaker 1: much of a trail. But if you have been staying
Speaker 1: in a position and then start moving, then it wouldn't
Speaker 1: be so quick as to you wouldn't see like a
Speaker 1: clearly human defined red shape. Um move from h from
Speaker 1: a position that had been standing in for like twenty
Speaker 1: minutes and then move across the room. It wouldn't you know,
Speaker 1: it wouldn't be in an immediate effect you would still
Speaker 1: be able to see at least the residual heat that
Speaker 1: was left behind. Now, it might be enough so that
Speaker 1: you can clearly tell which one is the human and
Speaker 1: which one's just the space that the human was in,
Speaker 1: but it's not gonna be, you know, just totally clear cut. Um.
Speaker 1: So I'm sorry. I was just gonna say. So if
Speaker 1: you're if you're looking at a show and they're showing
Speaker 1: a colored image of you know, night vision, basically that's
Speaker 1: thermal image and if you're looking at the monochromatic green
Speaker 1: screen version, that would be the image ence, So you
Speaker 1: know now which one is which, right, So let's why
Speaker 1: are you able to see the heat? That's the question. Well,
Speaker 1: let me let me talk about some atoms here. Now
Speaker 1: you've probably heard us talk about how atoms are. Uh,
Speaker 1: normally they're moving. Yes, it's really only if you're at
Speaker 1: zero kelvin, when you have no molecular movement, when you
Speaker 1: have no movement on the atomic scale, absolutely, thank you,
Speaker 1: absolute zero. Yes, uh, Because you know, atoms are always moving,
Speaker 1: even in in solid material like a block of marble.
Speaker 1: The atoms within that block of marble are moving. They're
Speaker 1: not moving necessarily at the same speed as say, uh,
Speaker 1: oxygen gas is moving, but they are moving, and atoms
Speaker 1: have a specific state, an energy state that they are
Speaker 1: naturally found in the ground state. No, no, not that
Speaker 1: kind of state. The ground state is what we call it.
Speaker 1: That's the ground state energy level. That's the amount of
Speaker 1: energy and atom has normally if no other outside forces
Speaker 1: or energies are acting upon it. Okay, so you've got
Speaker 1: the ground state energy level. That's when all the electrons
Speaker 1: are at their normal electron shell. This is from the
Speaker 1: nucleus of the atom. When you add energy to an atom,
Speaker 1: then you excite the electrons until they start to have
Speaker 1: so much energy that they'll pop into outer electron shells
Speaker 1: further out from the nucleus, and the more energy you
Speaker 1: pour in, the further out they get. Okay, So when
Speaker 1: you remove that energy, when that energy is when the
Speaker 1: electrons get to a point where the energy is as
Speaker 1: decreased enough so that the the electrons are going to
Speaker 1: go back toward the nucleus. They have to give off
Speaker 1: some kind of energy for that to happen. You all right,
Speaker 1: So you think of it almost like you have a
Speaker 1: a balloon and you over inflate that balloon. When you
Speaker 1: let out the uh, the air, than that balloon is
Speaker 1: gonna deflate some. Right, it's gonna come back down to
Speaker 1: a smaller size, and if you keep it open, it's
Speaker 1: gonna go all the way down to flat. Well, the
Speaker 1: electrons are gonna start moving back towards the nucleus. They
Speaker 1: give off photons when they do this, and depending upon
Speaker 1: the material uh that in question, you'll get different different
Speaker 1: kinds of photons within the spectrum of light. So some
Speaker 1: things are going to give off light that is actually visible,
Speaker 1: especially if you pour enough energy into it. That's why
Speaker 1: Let's say you've got a toaster oven and you've got
Speaker 1: a toaster oven going on full blast, and you look
Speaker 1: in and you see the little toaster oven coils have
Speaker 1: turned red. That's actually photons being given off by these atoms.
Speaker 1: And uh, if you were to pour even more energy
Speaker 1: into it, if you were to crank it up a notch,
Speaker 1: those coils might start to glow even brighter and different colors.
Speaker 1: So if they went from red to orange, that would
Speaker 1: mean that you have even more energy that's being given off, right,
Speaker 1: that you've you've poured more into it and it's and
Speaker 1: it's giving off higher energy photons. So, uh, all materials,
Speaker 1: all all things are giving off at least some kind
Speaker 1: of photon energy when the because the whole idea of
Speaker 1: movement and excitation, and the more it gives off, the
Speaker 1: brighter it's going to be. So that's that's what the
Speaker 1: thermal night vision goggles are detecting. When when they're going
Speaker 1: when the lights being pulled through that lens, when the
Speaker 1: lens is directing that light to the the sensors, it's
Speaker 1: detecting the the photons that are given off, the thermal
Speaker 1: infrared photons that are given off by things just because
Speaker 1: of the excitation of atoms. So that's what we're actually
Speaker 1: looking at. That's why you can be in a completely
Speaker 1: isolated room. You could be in a cave deep below
Speaker 1: the Earth's surface where there's there's no ambient light whatsoever,
Speaker 1: and still be able to see based upon the what's
Speaker 1: around you. Now, the less the less stuff gives off heat,
Speaker 1: then the less you're gonna be able to see, the
Speaker 1: less the less excitation is there. So if you're in
Speaker 1: a cave where there's nothing else living in there, it
Speaker 1: may you know, the thermal the thermal gogs may not
Speaker 1: do you any good except to let you see where
Speaker 1: your feet are in relation to the rest of you.
Speaker 1: So that might be more useful to carry, say a flashlight. Yes, yes,
Speaker 1: that might be a good idea to carry a flashlight
Speaker 1: or a headlamp even better. And um, yeah, so that's
Speaker 1: kind of the basics of night vision. It's pretty cool stuff.
Speaker 1: I don't know, have you ever had an opportunity to
Speaker 1: actually look through any sort of night vision stuff? No,
Speaker 1: not really, I just haven't been exposed to it. Um.
Speaker 1: But you can use it for all kinds of different things.
Speaker 1: Of course, the military applications are obvious, um. But you
Speaker 1: can use it for uh, you know, photography, um, for spelunking.
Speaker 1: You know, that was an excellent uh suggestion, you know,
Speaker 1: all kinds of sports and things where you might be
Speaker 1: out on hunting, you know, out in the woods. There
Speaker 1: are a lot of cam quarters out there that have it. Now,
Speaker 1: there's also cars that have displays that include night vision
Speaker 1: uh a night vision elements so that you see better
Speaker 1: when you're driving a night and and they're in fact
Speaker 1: cars that use different versions of it. There's some that
Speaker 1: use the thermal version where they're really detecting the heat
Speaker 1: of things, so that you can get an idea if
Speaker 1: there's something in the road, like a person or an animal,
Speaker 1: but those are only gonna show you things that are
Speaker 1: again active. Really Uh. Then there are other kinds that
Speaker 1: use the the the image enhancement style. Um. And there
Speaker 1: are even some that use the active image enhancement. So
Speaker 1: when you turn on your head lights, you're actually beaming
Speaker 1: not just visible light, but infrared rays as well, infrared radiation.
Speaker 1: So uh, the the system and those cars picks up
Speaker 1: the reflection, just like we were talking about in the
Speaker 1: generation zero image enhancement. Night vision he uses that same principle.
Speaker 1: And now that of course means that the range is limited,
Speaker 1: just as we were talking about earlier. And if it's
Speaker 1: a foggy night, it doesn't work so well because the
Speaker 1: fog will reflect that h that radiation back before it
Speaker 1: can hit something more substantial, so you'll just end up
Speaker 1: It's just like fog, right, It's just like if you
Speaker 1: were to put your high beams on the fog bank there. Yeah,
Speaker 1: and and in that case, the night vision might not
Speaker 1: help you out unless you have well, if you have
Speaker 1: the thermal one it might, but the the the image
Speaker 1: enhancement style not so not so useful in that situation.
Speaker 1: And that's it for another classic episode of tech Stuff.
Speaker 1: I hope you guys enjoyed this. It's always fun to
Speaker 1: look back in the stretches of time and revisit some
Speaker 1: of these topics that I've talked about in the past.
Speaker 1: I occasionally take these and make new episodes out of them,
Speaker 1: so you never know when I might revisit this topic
Speaker 1: and talk about the advances that have been made since
Speaker 1: two thousand eleven. If you have any suggestions for future episodes,
Speaker 1: why not go to tech Stuff podcast dot com. That
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