WEBVTT - TechStuff Looks at Night Vision 0:00:00.280 --> 0:00:02.960 Brought to you by the reinvented two thousand twelve Camray. 0:00:03.160 --> 0:00:08.920 It's ready. Are you get in touch with technology with 0:00:09.000 --> 0:00:17.560 tech Stuff from how stuff works dot com. Hello everyone, 0:00:17.600 --> 0:00:20.279 welcome to tech Stuff. My name is Chris Poulette, and 0:00:20.320 --> 0:00:22.640 I am an editor at how stuff works dot com. 0:00:22.640 --> 0:00:25.280 Sitting across from me as always, at least as far 0:00:25.320 --> 0:00:27.280 as I can tell, here in the Dark his senior 0:00:27.280 --> 0:00:30.400 writer Jonathan Strickland when the night has come and the 0:00:30.520 --> 0:00:33.120 land is dark and the moon is the only light 0:00:33.200 --> 0:00:38.320 we will see, as an especially good one for today's episode. Yeah, 0:00:38.360 --> 0:00:42.280 I've been trying to theme them a little. Uh. You 0:00:42.320 --> 0:00:44.080 can tell the theme ones because those are the ones 0:00:44.120 --> 0:00:48.000 where I thought about finding the quote before we started recording. 0:00:48.560 --> 0:00:50.560 And most of the time he goes, oh wait, wait, wait, 0:00:50.560 --> 0:00:52.839 I gotta think of a quote. Yeah, exactly, that's that's 0:00:52.840 --> 0:00:56.240 the problem. Usually it's just when we hit record and uh, 0:00:56.320 --> 0:00:59.560 and I strugged. I struggled to find some lyric. But 0:00:59.680 --> 0:01:02.360 any way, let's move on to today's topic, which is 0:01:03.080 --> 0:01:05.760 night vision. And we've had a couple of people asked 0:01:05.880 --> 0:01:09.319 us to cover night vision and people were just curious, 0:01:09.400 --> 0:01:12.440 you know, how does this work? What does how are 0:01:12.480 --> 0:01:15.600 we able to create electronics that allow us to see 0:01:15.760 --> 0:01:19.080 in near perfect darkness, and so we're going to kind 0:01:19.080 --> 0:01:23.880 of cover that. Night vision The technology dates back to 0:01:24.160 --> 0:01:28.120 the late thirties early forties. It was technology that was 0:01:28.160 --> 0:01:32.679 developed during World War Two and used mainly by the American, British, 0:01:32.760 --> 0:01:38.080 and Soviet forces during World War Two, although other nations 0:01:38.200 --> 0:01:42.080 began to to develop their own version of night vision 0:01:42.080 --> 0:01:45.640 technology around the same time. Well, yeah, the Germans, UH. 0:01:45.680 --> 0:01:48.840 A lot of what we had as far as our 0:01:48.880 --> 0:01:52.080 technology in the United States was based on some German 0:01:52.120 --> 0:01:56.160 research that was done in the late thirties. UM. And 0:01:56.240 --> 0:02:01.040 really what it comes down to, UM is the spectrum 0:02:01.040 --> 0:02:04.680 of light that that you're trying to see. Yeah, it's 0:02:04.760 --> 0:02:09.280 it's two different things. It's trying to accept other parts 0:02:09.280 --> 0:02:12.280 of light that human eye is not able to detect, 0:02:12.320 --> 0:02:17.640 and also to uh to amplify whatever little light is there. 0:02:17.680 --> 0:02:22.200 There are two main ways of achieving a night vision 0:02:23.000 --> 0:02:27.960 UH technology. One is called image enhancement, and that's where 0:02:28.000 --> 0:02:31.040 you're taking the little amount of light that's out there 0:02:31.560 --> 0:02:35.000 and UH and trying to amplify it so that you know, 0:02:35.080 --> 0:02:37.840 you're able to see better in that environment. And the 0:02:37.919 --> 0:02:41.480 other is thermal imaging, which is also you know, we 0:02:41.600 --> 0:02:44.640 think of that as being able to see heat. You know, 0:02:44.680 --> 0:02:47.040 the whole idea about like if you've ever seen that 0:02:47.120 --> 0:02:52.679 documentary Predatory, the Predator actually uses both forms of this, 0:02:53.480 --> 0:02:55.840 but the thermal imaging would be the one where it 0:02:55.960 --> 0:02:59.040 switches and it's that really colorful display where the hotter 0:02:59.280 --> 0:03:02.120 things in the field of vision are a brighter color, 0:03:02.280 --> 0:03:06.120 usually red, uh, and then the cooler things are are 0:03:06.520 --> 0:03:08.960 in the other part of the spectrum of light, so 0:03:09.040 --> 0:03:11.640 they'd be you know, if it's cold, it might be black, 0:03:11.720 --> 0:03:14.400 but if it's cooler, it might be blue or even 0:03:14.600 --> 0:03:17.840 kind of an indigo color. Um. Both of those are 0:03:17.919 --> 0:03:21.480 ways of achieving night vision. I think the one that 0:03:21.520 --> 0:03:23.720 most people think of when they think of night vision 0:03:23.800 --> 0:03:27.720 is the one where you've got the greenish uh display. 0:03:27.840 --> 0:03:32.560 That's the image enhancement approach, And well, you know that 0:03:32.560 --> 0:03:35.440 that's I think that's the reason people think about it 0:03:35.480 --> 0:03:39.600 is because it's used that way in TV and the movies. Yeah, 0:03:39.680 --> 0:03:44.800 probably so as a visual clue to the viewer that hey, 0:03:44.840 --> 0:03:48.360 we're doing something that you can't normally do, right. Yeah. 0:03:48.400 --> 0:03:51.200 I In fact, I watched a movie just last night 0:03:51.360 --> 0:03:55.680 that involved having a night vision the screen tinged night 0:03:55.760 --> 0:03:58.120 vision and it was and I'm not going to call 0:03:58.160 --> 0:04:01.200 it a documentary because that's how much of a skeptic 0:04:01.240 --> 0:04:04.640 I am. It was paranormal activity too. And uh, you 0:04:04.640 --> 0:04:08.200 know in paranormal activity those movies, those are done as 0:04:08.280 --> 0:04:11.200 found footage movies, which, in case you're not familiar with 0:04:11.240 --> 0:04:13.840 the term, that's the idea where the film is presented 0:04:13.920 --> 0:04:18.520 as if it were uh collection of clips taken from 0:04:18.839 --> 0:04:22.560 various cameras that it wasn't meant to be a feature 0:04:22.600 --> 0:04:26.680 film is supposed to be actual footage shot of something, right, 0:04:27.040 --> 0:04:30.720 So clover Field is another example, or Blair Witch Project. 0:04:30.800 --> 0:04:33.040 There's another example. The first time I thought about yeah, 0:04:33.040 --> 0:04:35.840 and that it's really popular with the horror crowd. Uh 0:04:35.880 --> 0:04:39.719 and uh so the paranormal activity too. There's one of 0:04:39.760 --> 0:04:42.159 the cameras that is being used in that has a 0:04:42.240 --> 0:04:46.120 night vision setting and it's using the image enhancement approach. 0:04:46.279 --> 0:04:49.120 By the way, in case you're curious about why green, 0:04:50.000 --> 0:04:53.160 the the answer I found through my research was that 0:04:53.200 --> 0:04:56.600 the reason why you get green images is not because 0:04:56.600 --> 0:05:00.920 of any technological limitation. It's because does if you're in 0:05:00.960 --> 0:05:03.760 an environment where you're using night vision. You want to 0:05:03.800 --> 0:05:06.280 be able to switch between night vision and your normal 0:05:06.360 --> 0:05:10.119 vision as quickly as possible. But if you use really 0:05:10.160 --> 0:05:13.400 intense light, and in some of the brighter lights, your 0:05:13.920 --> 0:05:17.320 pupils will constrict as you're looking at it, which means 0:05:17.320 --> 0:05:19.120 when you take the night vision glasses off, it's going 0:05:19.160 --> 0:05:21.359 to take more time for your eyes to readjust to 0:05:21.400 --> 0:05:24.600 the darkness around you. But the green that is used 0:05:24.680 --> 0:05:27.719 is a more subtle light, and so your your pupils 0:05:27.960 --> 0:05:31.640 are remain mostly dilated. So when you remove the night 0:05:31.720 --> 0:05:34.760 vision goggles, you don't have as long a time to adjust. 0:05:34.800 --> 0:05:36.360 It doesn't take as long for you to adjust to 0:05:36.480 --> 0:05:41.800 night regular night vision like our natural night vision. Uh, 0:05:41.920 --> 0:05:43.960 when you when you go back and forth, And that 0:05:44.040 --> 0:05:45.480 kind of makes sense to me, I mean, if you 0:05:45.600 --> 0:05:48.600 especially when you consider that night vision was really originally 0:05:49.000 --> 0:05:52.600 used as a military technology, you would want to be 0:05:52.680 --> 0:05:55.440 able to have as much versatility and flexibility as possible 0:05:55.480 --> 0:05:59.240 so that you can adapt to whatever the situation calls for. Yeah, 0:05:59.400 --> 0:06:01.560 that makes sense, Its sense to me. So Yeah, so 0:06:01.920 --> 0:06:04.520 at least according to that, we could in theory have 0:06:04.760 --> 0:06:08.240 night vision where it's any color. Uh, you know, it 0:06:08.480 --> 0:06:12.800 probably still probably be monochromatic, but we'll get into that 0:06:12.839 --> 0:06:14.960 when we get into the you know exactly what's happening. 0:06:15.480 --> 0:06:19.159 So so all the different kinds of night vision lie 0:06:19.240 --> 0:06:22.839 at least somewhat on the infrared, uh, part of the 0:06:22.920 --> 0:06:26.039 spectrum of light, right, and that infrared spectrum of light 0:06:26.200 --> 0:06:32.640 is outside the range of uh, the visible light spectrum. UM. 0:06:32.680 --> 0:06:36.000 In fact, there are three parts to the infrared spectrum, 0:06:36.040 --> 0:06:39.200 which is near infrared, and that's the closest one to 0:06:39.560 --> 0:06:43.440 the visible spectrum spectrum. Yes, I can say that word 0:06:43.960 --> 0:06:47.800 mid infrared um and that has uh oh, I didn't 0:06:47.800 --> 0:06:50.960 mention the wavelengths. The wavelengths for near infrared are from 0:06:51.200 --> 0:06:55.520 point seven to one point three microns um. Mid infrared 0:06:55.640 --> 0:07:00.160 has wavelengths from one point three to three microns um. 0:07:00.240 --> 0:07:04.919 And then thermal infrared, which is the biggest part of 0:07:05.000 --> 0:07:08.800 the infrared spectrum, and that's from three to more than 0:07:08.960 --> 0:07:12.960 thirty microfs. Yeah, and so the the thermal infrared you're 0:07:12.960 --> 0:07:19.960 talking at that point about infrared radiation really heat in 0:07:20.000 --> 0:07:22.960 other words, is what's kind of how we perceive it usually, 0:07:23.400 --> 0:07:26.760 but uh, that's something that's actually given off by an 0:07:26.800 --> 0:07:30.920 object itself, whereas when we're talking about visible light. That's 0:07:30.960 --> 0:07:34.480 something that's reflected off of an object. Right, So if 0:07:34.600 --> 0:07:37.680 if I'm looking at a tree in sunlight, what I'm 0:07:37.680 --> 0:07:40.320 seeing is the light being reflected off of that tree. 0:07:40.520 --> 0:07:43.480 It's that light's hitting my eyes then going through the 0:07:43.480 --> 0:07:46.720 whole focal point, getting into my brain and somewhere up 0:07:46.760 --> 0:07:49.520 there in that Yeah, somewhere up there in the gray matter, 0:07:49.840 --> 0:07:54.400 my brain says, Hello, that's a tree, possibly a large 0:07:55.800 --> 0:08:00.600 a large. Um, I recognize that from very far away. Yes, 0:08:01.160 --> 0:08:03.800 that's how to recognize treats from very far away, quite 0:08:03.800 --> 0:08:06.840 a long way away. Uh. Yeah, So that's how that 0:08:07.000 --> 0:08:10.240 would normally work with thermal infrared. If I were to 0:08:10.440 --> 0:08:13.560 see an object using thermal infrared, Let's say that somehow 0:08:13.600 --> 0:08:15.720 I have that ability. You know, we're not talking about 0:08:15.720 --> 0:08:19.640 technology here, but I somehow have the the the natural 0:08:19.680 --> 0:08:22.600 ability to see the thermal infrared. It happened when they 0:08:22.600 --> 0:08:25.240 shot him into space and he was bombarded by cosmic 0:08:25.280 --> 0:08:28.600 waves while we're really just pop culturing this all to 0:08:28.720 --> 0:08:31.800 heck and back. So yeah, with the thermal infrared ability, 0:08:31.840 --> 0:08:34.200 I would be able to see the energy that is 0:08:34.240 --> 0:08:39.000 being emitted by any particular object. Uh. It's not necessarily light. 0:08:39.040 --> 0:08:40.719 That's reflecting off. In fact, there doesn't have to be 0:08:40.800 --> 0:08:43.560 any sort of light source at all. It just so. 0:08:43.679 --> 0:08:46.160 And if I were in a perfectly dark room and 0:08:46.160 --> 0:08:51.360 there was another object there that's giving off heat, essentially, 0:08:51.840 --> 0:08:53.920 I would be able to see it because I would 0:08:53.960 --> 0:08:56.200 be seeing in that range even though there's no other 0:08:56.559 --> 0:08:59.320 light source coming in. It would just be that I've 0:08:59.320 --> 0:09:04.240 actually seeing that that energy. Because we'll get into why 0:09:04.559 --> 0:09:08.680 it's kind of interesting. Has to do with excitation, but 0:09:08.800 --> 0:09:13.800 not good vibrations. Yeah, although perhaps that lady was a 0:09:13.920 --> 0:09:18.240 will never mind, so moving on. She was made up 0:09:18.280 --> 0:09:21.160 of atoms, that's true. But before we get into the 0:09:21.160 --> 0:09:24.160 whole atoms and thermal infrared, let's let's talk about the 0:09:24.160 --> 0:09:28.600 image enhancement approach first because that's the one that's the 0:09:28.600 --> 0:09:33.240 most familiar and uh, it's kind of uh interesting. Um. 0:09:33.280 --> 0:09:37.160 The way that it works currently is that you've got 0:09:37.200 --> 0:09:40.640 you've got very basic parts to a particular kind of 0:09:40.760 --> 0:09:43.040 night vision. You've got you've got your lens. That's where 0:09:43.080 --> 0:09:47.079 the light is going through. The objective lens. Just a 0:09:47.679 --> 0:09:50.560 lens that catches a lens. Yeah, it catches ambient light, 0:09:50.600 --> 0:09:53.480 it catches near infrared light. So this is the near 0:09:53.600 --> 0:09:58.200 infrared spectrum, the light that's closest to the visible spectrum. 0:09:58.480 --> 0:10:02.560 Now that light is sent to a tube, and that 0:10:02.600 --> 0:10:07.239 tube is called the image intensive fire tube tense. Yeah, 0:10:07.320 --> 0:10:10.480 and the drinking energy drinks all day and yeah. So 0:10:10.520 --> 0:10:11.839 you can think of this tube. It's almost like a 0:10:11.920 --> 0:10:13.880 vacuum tube. In fact, there it is, There is a 0:10:13.960 --> 0:10:16.000 vacuum in side of it. So you think of this 0:10:16.120 --> 0:10:19.880 sort of a imagine a glass vial all right. In 0:10:19.960 --> 0:10:22.240 the middle of this glass vial or on one end 0:10:22.280 --> 0:10:25.679 of the glass vile, you've got something called a photo cathode. Now, 0:10:25.720 --> 0:10:30.280 the photo cathode takes photons. Those are those individual elements 0:10:30.400 --> 0:10:33.320 of energy for light, yes, and and those come in 0:10:33.480 --> 0:10:37.440 the entire spectrum of light um, so infrared. There are 0:10:37.480 --> 0:10:41.440 infrared photons just as there are visible light photons. So 0:10:42.400 --> 0:10:47.840 the photo cathode converts photons into electrons. It's it's one 0:10:47.880 --> 0:10:51.520 of those, uh so it changes light into electricity essentially. Yeah. 0:10:51.679 --> 0:10:54.400 And if you listen to our episode about high speed 0:10:54.400 --> 0:10:58.679 and low speed photography, we talked about how there are 0:10:58.840 --> 0:11:05.120 certain types of materials that when a photon strikes it, 0:11:05.120 --> 0:11:09.120 it causes a reaction. That's the case here a photocathode. 0:11:09.200 --> 0:11:11.280 It's that's the and that's how it behaves. When a 0:11:11.320 --> 0:11:14.760 photon hits it, it gives off an electron. Uh. So 0:11:14.840 --> 0:11:17.240 you've got the photocathode at one end of this tube, 0:11:17.240 --> 0:11:19.439 and that's where the light that's being captured by the 0:11:19.520 --> 0:11:23.200 lens is directed to the photo cathode. The electrons emitted 0:11:23.200 --> 0:11:25.440 by the photo cathode then have to pass through what 0:11:25.679 --> 0:11:30.360 is called a micro channel plate or or m c P. 0:11:30.840 --> 0:11:33.600 That's a little glass disc. Yeah, I see, I thought 0:11:33.720 --> 0:11:39.680 MCP was the master control program end of line is Okay, However, 0:11:39.840 --> 0:11:42.520 two different mcps. Well, it was until Tron got a 0:11:42.520 --> 0:11:46.120 hold of it, that's right. So glass disc Tron, m 0:11:46.160 --> 0:11:51.360 c P. I'm sensing some convergence here again. Ye. So anyway, 0:11:51.400 --> 0:11:53.840 you've got this glass, little tiny glass disc called a 0:11:53.880 --> 0:11:57.600 micro channel plate and has lots and lots of channels. 0:11:57.679 --> 0:11:59.599 That's why it's called a micro channel plate. Lots of 0:11:59.679 --> 0:12:02.520 channels that go through this plate. Okay, So think of 0:12:02.520 --> 0:12:05.440 the plate. Think of it like a dish. You got 0:12:05.440 --> 0:12:07.960 a dish, put it up on its side, and it 0:12:08.000 --> 0:12:10.679 has a whole bunch of holes drilled in it. Now, 0:12:10.679 --> 0:12:13.760 those holes are what allow electrons to pass through. But 0:12:13.800 --> 0:12:18.240 there's also an electrode on either side of the dish. 0:12:18.640 --> 0:12:23.160 So electrons coming from the photo cathode strike one side 0:12:23.240 --> 0:12:26.319 of this micro channel plate and start to go through 0:12:26.520 --> 0:12:29.200 one of the channels, and they're going through in the 0:12:29.240 --> 0:12:32.680 same direction they came from the the from the photo 0:12:32.720 --> 0:12:38.520 cathode UH section of this this UH this image intensive 0:12:38.559 --> 0:12:43.600 ire tube. So the photon converts to electron. Electron goes 0:12:43.640 --> 0:12:45.800 through this channel. As it goes to the channel, it 0:12:45.880 --> 0:12:52.680 starts to actually set off a well a reaction and 0:12:53.120 --> 0:12:56.560 it basically functions as a multiplier for the electrons. It's 0:12:56.600 --> 0:13:00.840 called a cascaded secondary emission. So this is where when 0:13:00.920 --> 0:13:04.640 electron collie collides with something inside that that channel, it 0:13:04.720 --> 0:13:08.640 starts to set off other electrons uh down that same pathway. 0:13:08.840 --> 0:13:12.040 And there's a voltage applied to those electrodes that's channeling 0:13:12.080 --> 0:13:14.800 the electrons through that pathway, like that's why they're going 0:13:14.920 --> 0:13:19.240 in that direction. So you've got more and more electrons 0:13:19.280 --> 0:13:22.760 bouncing off of each other through these channels, which means 0:13:22.800 --> 0:13:26.800 that you've you've created an amplifier and UH, if you 0:13:26.840 --> 0:13:29.320 guys want to know kind of like a big picture 0:13:29.360 --> 0:13:33.720 way of what this might look like. Imagine having a 0:13:32.960 --> 0:13:35.720 h and you can see play of videos of this 0:13:35.800 --> 0:13:39.800 on YouTube. But imagine having a big glass container filled 0:13:39.800 --> 0:13:43.000 with mouse traps, and each mouse trap has a ping 0:13:43.080 --> 0:13:45.640 pong ball set on it, and then you drop a 0:13:45.679 --> 0:13:49.560 ping pong ball into the the glass chamber and that 0:13:49.600 --> 0:13:52.000 will set off a mouse trap, And as the ping 0:13:52.040 --> 0:13:54.200 pong balls bounce around, they set off more and more 0:13:54.280 --> 0:13:57.440 mouse traps, so soon the glass case like within a 0:13:57.480 --> 0:14:00.880 fraction of the second ball. The balls are bouncing everywhere, right, 0:14:01.440 --> 0:14:04.160 same sort of idea here with the microchannel plate, except 0:14:04.160 --> 0:14:07.120 that we're talking on a sub atomic level, and we're 0:14:07.120 --> 0:14:11.439 talking about something that's really channeled, really has a firm direction. 0:14:11.480 --> 0:14:14.080 So instead of the electrons bouncing everywhere, they're going in 0:14:14.080 --> 0:14:17.319 a very specific direction. Right now, when they get to 0:14:17.400 --> 0:14:20.120 the other side of that micro channel plate, you've got 0:14:20.120 --> 0:14:22.720 the electron still traveling in the same direction they were 0:14:22.760 --> 0:14:25.200 when they came in on the front side, but now 0:14:25.200 --> 0:14:28.560 there are way more electrons, right, just amplified the number. 0:14:29.040 --> 0:14:34.760 The electrons then hit a screen that's coated with phosphors. Now, 0:14:34.840 --> 0:14:39.440 phosphors phosphors do there, they're kind of like the opposite 0:14:39.480 --> 0:14:42.520 of the photo cathode. Right, they take when the electron 0:14:42.560 --> 0:14:45.800 strikes the phosphoor, they give off light, So you're changing 0:14:45.800 --> 0:14:48.440 the electron back to a pot photon. Right. But now, 0:14:48.480 --> 0:14:51.920 because there are more electrons coming through hitting that phosphoor 0:14:51.960 --> 0:14:55.120 than they were coming in, the light that's generated is 0:14:55.240 --> 0:14:58.440 much greater in intensity than the light that was coming in. 0:14:59.160 --> 0:15:03.400 So you've ample vide the light. Now that information that 0:15:03.520 --> 0:15:06.640 light is sent to a viewer of some type. It 0:15:06.640 --> 0:15:09.280 could just be a regular lens, which is usually called 0:15:09.320 --> 0:15:12.520 the ocular lens, or it could be sent to a monitor. 0:15:13.280 --> 0:15:15.200 So if you have a night a pair of night 0:15:15.280 --> 0:15:19.400 vision goggles or a night vision scope, that's what you're seeing. 0:15:19.400 --> 0:15:23.720 You're seeing that amplified light hitting the lens or the 0:15:23.760 --> 0:15:28.400 Monitor's pretty cool, it's pretty awesome. Right. And again, this 0:15:28.480 --> 0:15:32.040 isn't just the the visible light, the ambient visible light 0:15:32.080 --> 0:15:35.640 that's out there, but also the infrared light so um 0:15:36.000 --> 0:15:38.560 because those photons, you know, it doesn't you know, the photons, 0:15:38.600 --> 0:15:42.880 It doesn't matter if it's visible or not. Um. And uh, 0:15:43.280 --> 0:15:46.520 the more light that's hitting certain areas, that the brighter 0:15:46.560 --> 0:15:49.640 it's going to be for whatever it is you're looking at. 0:15:49.640 --> 0:15:52.479 So if you're looking at something that's that's fairly reflective. 0:15:53.160 --> 0:15:56.680 Um you're gonna be able to see it in higher 0:15:56.680 --> 0:16:00.920 definition than you could with something that is not as reflective. Uh. Now, 0:16:00.960 --> 0:16:04.240 there are different ways of actually achieving this too. You 0:16:04.320 --> 0:16:10.400 can have a various there are various generations of this technology, 0:16:10.600 --> 0:16:15.480 all right, So the earliest generation of this technology actually 0:16:15.520 --> 0:16:20.960 involved shining infrared light at the objects you're looking at 0:16:21.040 --> 0:16:24.080 through the through the night vision goggles. Right, So when 0:16:24.080 --> 0:16:27.200 that that infrared light was reflected, then you would be 0:16:27.240 --> 0:16:30.720 able to see it, right, because these goggles were not 0:16:30.880 --> 0:16:33.400 so sensitive as to be able to take just the 0:16:33.440 --> 0:16:36.560 ambient light. If you did that, you would probably get 0:16:36.600 --> 0:16:39.200 you you might be able to see marginally better than 0:16:39.240 --> 0:16:42.200 you would if you had just use your regular vision. 0:16:42.600 --> 0:16:47.960 But using this infrared flashlight, essentially you could illuminate the 0:16:48.920 --> 0:16:50.760 scene and be able to see it through the night 0:16:50.840 --> 0:16:53.200 vision goggles. But if you did not have the goggles, 0:16:53.200 --> 0:16:57.640 because infrared light falls outside the visible spectrum, any independent 0:16:57.640 --> 0:17:01.840 observer wouldn't be able to tell you were doing Yeah, now, 0:17:01.960 --> 0:17:04.879 uh I UM I did some research on the the 0:17:04.960 --> 0:17:10.520 US military website about the history of of night vision, 0:17:10.640 --> 0:17:15.560 and apparently UM they sent about three hundred sniper scopes 0:17:15.840 --> 0:17:18.160 over to be used in the Pacific theater during World 0:17:18.160 --> 0:17:21.600 War Two, but they didn't get used very much because 0:17:21.600 --> 0:17:24.680 of the way that the technology worked. Um they really 0:17:24.680 --> 0:17:28.160 could see less than a hundred yards, so they weren't 0:17:28.240 --> 0:17:33.520 very effective, right because again, since it's dependent upon a 0:17:33.680 --> 0:17:38.199 reflected ray of infrared light, if it's you know, the 0:17:38.280 --> 0:17:41.320 rays starting to dispersees as it goes out, Right, it's 0:17:41.320 --> 0:17:44.600 not not a not a concentrated like a laser beam. Yeah, 0:17:44.600 --> 0:17:47.520 it's not a beam. It does disperse and diffuse as 0:17:47.520 --> 0:17:50.840 it goes out. So the further away your target, the 0:17:50.960 --> 0:17:52.840 less likely you're going to be able to see it. 0:17:53.119 --> 0:17:55.879 And even with a really really advanced version. That's by 0:17:55.880 --> 0:17:59.880 the way, it's called active infrared because you're actively beam 0:18:00.119 --> 0:18:03.719 infrared radiation out in order to try and see uh, 0:18:03.920 --> 0:18:10.320 stuff coming back through the monitors. Um if because because 0:18:10.359 --> 0:18:12.880 you're relying on that reflection, if it's too far away, 0:18:12.920 --> 0:18:14.800 you're not gonna be all se very well. So obviously 0:18:14.920 --> 0:18:18.440 a sniper rifle where at least in theory, you want 0:18:18.440 --> 0:18:20.600 to be able to put your snipers at a good 0:18:20.680 --> 0:18:23.879 distance away from the targets to maximize their effectiveness and 0:18:23.920 --> 0:18:27.720 minimize the chance that they will be targeted. Um, it doesn't. 0:18:27.760 --> 0:18:30.360 It's not so effective if you know your your distance 0:18:30.440 --> 0:18:34.520 is cut down that dramatically. Yeah. Plus, the first generation 0:18:34.680 --> 0:18:38.880 wasn't exactly um useful for someone like a sniper, considering 0:18:38.920 --> 0:18:42.720 the batteries were huge and the I R emitters had 0:18:42.760 --> 0:18:46.080 to be carried on flatbed trucks. It's hard to put 0:18:46.080 --> 0:18:48.000 one of those up in a tree. Yeah. Yeah, it 0:18:48.040 --> 0:18:51.199 turns out that also all of these are going to 0:18:51.480 --> 0:18:54.919 involve having a power supply of some sort. But for 0:18:54.960 --> 0:18:58.240 the active infrared it requires even lot more energy because 0:18:58.240 --> 0:19:01.120 you're not you're not just for your your actual night 0:19:01.240 --> 0:19:03.840 vision device, whether it's a scope or goggles or whatever, 0:19:03.880 --> 0:19:07.240 but also for the emitter. By the way, that generation 0:19:07.400 --> 0:19:11.480 is normally referred to as generation zero for a night vision. 0:19:12.000 --> 0:19:18.080 Generation one was the first generation using passive infrared system. Now, 0:19:18.119 --> 0:19:21.320 this was the kind of of night vision goggles or 0:19:21.640 --> 0:19:25.080 scope that could just use the ambient light in the area, 0:19:25.160 --> 0:19:28.320 although it needed a good amount of the ambient light. 0:19:28.400 --> 0:19:33.280 So moonlight or starlight should say starlight, Yeah, that's what 0:19:33.320 --> 0:19:36.920 it was. Yeah, the U. S Army they called it starlight. Uh, 0:19:37.080 --> 0:19:41.040 the without the moon or stars you wouldn't be able 0:19:41.080 --> 0:19:43.320 to see very much, so on an overcast night it 0:19:43.320 --> 0:19:46.040 would not be terribly useful. But on a clear day, 0:19:46.080 --> 0:19:48.960 you could see forever. You're got a clear day, you 0:19:49.000 --> 0:19:54.960 don't need night vision. Okay, starlight first star I see tonight. Um, 0:19:55.119 --> 0:20:00.240 So yeah, it was better than generation zero. Still still 0:20:00.359 --> 0:20:03.840 pretty far acry from what we have today. Although interestingly, 0:20:04.440 --> 0:20:06.440 if you were to go out and buy a pair 0:20:06.600 --> 0:20:10.320 of night vision goggles, you know, a consumer brand version 0:20:10.480 --> 0:20:14.960 would probably be Generation one. I guess you know. That's 0:20:15.720 --> 0:20:19.440 the military tends to reserve the more the more advanced 0:20:19.480 --> 0:20:22.520 forms UH generation too, it's possible that they could be 0:20:22.560 --> 0:20:26.720 generation two as well. Generation two where they had better 0:20:27.400 --> 0:20:29.800 UH image in tensi fire tubes, which meant that they 0:20:29.800 --> 0:20:34.000 could use them in extreme low light conditions. So on 0:20:34.040 --> 0:20:36.560 a moonless night, you could use these and it would 0:20:36.560 --> 0:20:39.520 be UH strong enough to be able to to amplify 0:20:39.560 --> 0:20:42.320 that light so you can see. Generation three is what 0:20:42.520 --> 0:20:46.160 you can find in the US military now. Um. And 0:20:46.240 --> 0:20:49.960 that is they used a new kind of photo cathode 0:20:50.000 --> 0:20:52.920 called gallium marsonite, so it's even more sensitive than the 0:20:52.960 --> 0:20:55.600 previous ones, which means that you know, it's it's not 0:20:55.680 --> 0:20:59.320 that the Uh, they've really advanced the technology that much. 0:20:59.320 --> 0:21:03.360 They just found them material that that emits electrons much 0:21:03.400 --> 0:21:06.120 more readily than others. Yeah. As a matter of fact, 0:21:06.119 --> 0:21:07.960 I believe we talked about gallium arson and when we 0:21:07.960 --> 0:21:11.480 talked about transistors, I believe we did back. Yeah, and 0:21:11.520 --> 0:21:17.399 then we have generation four, which is yet more improvements. Uh. 0:21:17.440 --> 0:21:20.879 And it works both in in low and high level 0:21:21.560 --> 0:21:25.440 light environments. Which that's important too, because some sometimes you're 0:21:25.440 --> 0:21:27.680 in an environment where you're gonna have more light than 0:21:28.359 --> 0:21:31.560 uh than Well, let's take two separate nights. Okay, we 0:21:31.640 --> 0:21:34.360 have one night where let's say there's a lot of moonlight, Uh, 0:21:34.400 --> 0:21:37.800 there's starlight. There might even be some some lights set 0:21:37.880 --> 0:21:40.640 up in whatever it is you're looking at, Like let's 0:21:40.640 --> 0:21:43.000 say it's an enemy encampment. Let's say you're sniper looking 0:21:43.040 --> 0:21:46.560 at an enemy encampment. Uh. If you're using a device 0:21:46.640 --> 0:21:50.439 that's meant for low light environments, you might not be 0:21:50.480 --> 0:21:53.280 able to see anything anyway because all of that light 0:21:53.359 --> 0:21:56.200 just overwhelms the device, and so you all you see 0:21:56.240 --> 0:22:00.160 is just a big green screen. Uh. So you need 0:22:00.200 --> 0:22:02.640 to have one that can work in both kinds of situations. 0:22:03.200 --> 0:22:09.240 UM So, Yeah, that's your basic that's your basic uh 0:22:09.480 --> 0:22:14.080 image enhancement style night vision. Now, I guess we can 0:22:14.119 --> 0:22:20.440 move on to the the thermal devices, which again can 0:22:20.640 --> 0:22:23.840 look at you can look at stuff and see the 0:22:23.960 --> 0:22:27.120 energy it's giving off, the light it's giving off even 0:22:27.160 --> 0:22:30.800 though light, uh, an outside source of light isn't necessarily 0:22:30.840 --> 0:22:34.679 present m and this has to and this involves the 0:22:34.720 --> 0:22:38.639 whole concept of excitation. Yeah. Yeah, Now you have to 0:22:38.680 --> 0:22:42.880 have a special type of lens to use when you're 0:22:42.880 --> 0:22:47.200 working with thermal imaging, basically to identify the infrared light. 0:22:47.240 --> 0:22:49.920 And you've got to uh, what happens is once the 0:22:50.000 --> 0:22:53.359 light is focused through the lens um, a phased array 0:22:53.440 --> 0:22:58.639 of infrared detector elements scans it um basically trying to 0:22:58.680 --> 0:23:02.159 create a dn called a thermogram, which shows you the 0:23:02.200 --> 0:23:06.600 different ranges in temperature um. And this can be done 0:23:06.640 --> 0:23:13.159 pretty quickly, about on a second, So like okays a 0:23:13.240 --> 0:23:16.480 second essentially, yeah, and concerning that film is twenty four 0:23:16.560 --> 0:23:18.960 frames a second. That is that's fast. Yeah, It's fast 0:23:19.040 --> 0:23:21.119 enough so that you can get a good view. So 0:23:21.160 --> 0:23:23.920 even if something's in motion, you should be able to 0:23:23.960 --> 0:23:26.560 get a pretty good view of it. Yeah. And then 0:23:26.640 --> 0:23:30.320 and then very much like the other style. It creates 0:23:30.600 --> 0:23:34.680 a thermogram UH and then translates it into UH an 0:23:34.680 --> 0:23:38.160 electric impulse UM just like that, and then it's sent 0:23:38.200 --> 0:23:43.280 to a signal processing unit which is basically UH electronic 0:23:43.880 --> 0:23:50.160 circuit board UM, and UH. Instead of converting electrons to photons, 0:23:50.240 --> 0:23:56.160 it actually creates display of information UM. So it's more 0:23:56.200 --> 0:23:59.560 like a computer than it is UH. An ocular system 0:23:59.600 --> 0:24:01.520 with the Yeah, you wouldn't have a lens. You would 0:24:01.520 --> 0:24:03.520 have a monitor of some site, some type. Now that 0:24:03.600 --> 0:24:08.040