1 00:00:04,400 --> 00:00:07,760 Speaker 1: Welcome to Text Stuff, a production from I Heart Radio. 2 00:00:12,240 --> 00:00:15,160 Speaker 1: Hey there, and welcome to Text Stuff. I'm your host, 3 00:00:15,360 --> 00:00:18,960 Speaker 1: Jonathan Strickland. I'm an executive producer with I Heart Radio, 4 00:00:19,000 --> 00:00:22,080 Speaker 1: and I love all things tech. And you know, there 5 00:00:22,120 --> 00:00:25,079 Speaker 1: are times when I sit down to choose a topic 6 00:00:25,280 --> 00:00:28,960 Speaker 1: for Text Stuff and I just come up empty. Either 7 00:00:29,120 --> 00:00:32,600 Speaker 1: I'll only come across stuff that I've already covered in 8 00:00:32,640 --> 00:00:36,080 Speaker 1: the past, or I'll see stuff that just doesn't really 9 00:00:36,120 --> 00:00:40,080 Speaker 1: ignite my curiosity. And honestly, that just makes researching and 10 00:00:40,120 --> 00:00:43,479 Speaker 1: writing and recording these episodes that much more difficult. I 11 00:00:43,800 --> 00:00:47,000 Speaker 1: feel like if I'm jazzed about it, it just comes 12 00:00:47,040 --> 00:00:50,840 Speaker 1: more easily. But once in a while, I'll see either 13 00:00:51,000 --> 00:00:55,080 Speaker 1: an interesting article or a video, or sometimes just a headline, 14 00:00:55,280 --> 00:00:58,800 Speaker 1: and that makes me think I should probably cover that technology. 15 00:00:59,120 --> 00:01:01,120 Speaker 1: And that's what happened to me on the morning of 16 00:01:01,200 --> 00:01:04,920 Speaker 1: April six, twenty twenty, which is the morning that I 17 00:01:04,959 --> 00:01:09,560 Speaker 1: wrote this sentence right here. Now, um, I'm recording this 18 00:01:09,600 --> 00:01:13,759 Speaker 1: on April, so there's a lot of time shifting going 19 00:01:13,800 --> 00:01:16,679 Speaker 1: on here. But the headline I saw was on tech 20 00:01:16,760 --> 00:01:21,600 Speaker 1: Crunch and it read Chinese startup ro kid pitches COVID 21 00:01:21,720 --> 00:01:26,039 Speaker 1: nineteen detection glasses in US, and I know we've had 22 00:01:26,040 --> 00:01:28,760 Speaker 1: a lot of talk about COVID nineteen, but that's not 23 00:01:29,000 --> 00:01:32,920 Speaker 1: what this episode is really going to be about. See, 24 00:01:32,959 --> 00:01:36,959 Speaker 1: those detection glasses don't magically pick up that someone has 25 00:01:37,000 --> 00:01:40,000 Speaker 1: been infected by the coronavirus. It's not like they see 26 00:01:40,040 --> 00:01:43,520 Speaker 1: the coronavirus crawling on the person or anything that would 27 00:01:43,560 --> 00:01:48,360 Speaker 1: really be a trick. No, these are thermal imaging glasses 28 00:01:48,440 --> 00:01:51,280 Speaker 1: with some added bells and whistles, like the ability to 29 00:01:51,320 --> 00:01:55,320 Speaker 1: take photos or record video. That's not necessarily part of 30 00:01:55,440 --> 00:01:59,400 Speaker 1: thermal imaging cameras or sensors. But really, these glasses don't 31 00:01:59,400 --> 00:02:03,080 Speaker 1: tell you if someone has COVID nineteen. They might tell 32 00:02:03,160 --> 00:02:06,800 Speaker 1: you if someone has an elevated body temperature. Now, keeping 33 00:02:06,800 --> 00:02:09,520 Speaker 1: in mind that some folks might be contagious with COVID 34 00:02:09,600 --> 00:02:13,440 Speaker 1: nineteen and not have any symptoms, that means these glasses 35 00:02:13,480 --> 00:02:16,880 Speaker 1: are helpful but not a perfect way to screen people. 36 00:02:17,360 --> 00:02:21,720 Speaker 1: The glasses wouldn't indicate that an asymptomatic person is a threat, 37 00:02:21,960 --> 00:02:25,920 Speaker 1: for example, and other people might have an elevated body temperature. 38 00:02:25,960 --> 00:02:30,520 Speaker 1: You know, people with immuno compromise systems frequently have this problem, 39 00:02:30,560 --> 00:02:33,920 Speaker 1: but they may not necessarily have COVID nineteen. So what 40 00:02:33,960 --> 00:02:37,400 Speaker 1: I'm saying is that critical thinking and a broad spectrum 41 00:02:37,440 --> 00:02:41,320 Speaker 1: approach to taking precautions is necessary, and that putting all 42 00:02:41,400 --> 00:02:44,919 Speaker 1: our eggs in one basket is always a bad idea, 43 00:02:45,080 --> 00:02:47,639 Speaker 1: And I would usually save that stuff for the end, 44 00:02:48,000 --> 00:02:49,920 Speaker 1: but times being what they are, I felt it was 45 00:02:49,960 --> 00:02:53,760 Speaker 1: important to address that first. Anytime anyone claims that they 46 00:02:53,800 --> 00:02:57,919 Speaker 1: have a solution that solves a really complicated problem, it's 47 00:02:57,919 --> 00:03:00,000 Speaker 1: good to take a closer look. But I want to 48 00:03:00,000 --> 00:03:03,760 Speaker 1: talk about thermal imaging technology in general because it does work, 49 00:03:04,080 --> 00:03:08,320 Speaker 1: it's incredibly precise, and it's super awesome stuff. Now, in 50 00:03:08,360 --> 00:03:11,840 Speaker 1: a past episode, I covered how night vision works, and 51 00:03:11,919 --> 00:03:16,120 Speaker 1: that can include normal imaging, but we typically think of 52 00:03:16,160 --> 00:03:19,120 Speaker 1: a different kind of approach with night vision. You know, 53 00:03:19,160 --> 00:03:21,919 Speaker 1: all the television shows and movies tend to show that 54 00:03:22,040 --> 00:03:26,040 Speaker 1: kind of green vision, that green video where stuff is 55 00:03:26,240 --> 00:03:31,320 Speaker 1: super bright. Well, that's really called image enhancement, and that 56 00:03:31,360 --> 00:03:34,800 Speaker 1: method takes all available light that's in an environment and 57 00:03:34,840 --> 00:03:38,600 Speaker 1: then amplifies the signal from that light to create a 58 00:03:38,760 --> 00:03:42,480 Speaker 1: video with an intensity that is easier for us to perceive. 59 00:03:42,960 --> 00:03:47,160 Speaker 1: Thermal imaging is different from that, So thermal imaging has 60 00:03:47,200 --> 00:03:50,680 Speaker 1: to do with infrared light, which in turn, we cannot 61 00:03:50,720 --> 00:03:53,400 Speaker 1: see with our eyeballs. It is invisible to us, but 62 00:03:53,960 --> 00:03:58,360 Speaker 1: we can still sense it because it's heat. All objects 63 00:03:58,440 --> 00:04:02,720 Speaker 1: in the universe omit some level of infrared radiation as 64 00:04:02,760 --> 00:04:06,760 Speaker 1: long as those objects are above absolute zero. Some of 65 00:04:06,800 --> 00:04:09,840 Speaker 1: them do it a lot more than others, you know, 66 00:04:10,280 --> 00:04:14,160 Speaker 1: like stars and stuff. They emit way more infrared radiation. 67 00:04:14,240 --> 00:04:18,800 Speaker 1: But we emit infrared radiation too. We humans were kind 68 00:04:18,800 --> 00:04:22,440 Speaker 1: of like infrared light bulbs. I mean, granted, so is 69 00:04:22,560 --> 00:04:25,880 Speaker 1: a light bulb and every other object to some extent. 70 00:04:26,400 --> 00:04:28,520 Speaker 1: The visible spectrum of light, you know, the stuff that 71 00:04:28,600 --> 00:04:32,159 Speaker 1: we can perceive with our eyes is bordered on either 72 00:04:32,240 --> 00:04:35,800 Speaker 1: side of the electro magnetic spectrum by bands of light 73 00:04:35,880 --> 00:04:39,799 Speaker 1: that are beyond our ability to see. At frequencies higher 74 00:04:39,960 --> 00:04:43,520 Speaker 1: than visible light. So that means the wavelengths of these 75 00:04:43,640 --> 00:04:47,240 Speaker 1: light waves are shorter. That would be ultra violet light 76 00:04:47,440 --> 00:04:52,000 Speaker 1: or UV. At frequencies lower than visible light, or longer 77 00:04:52,080 --> 00:04:56,080 Speaker 1: wavelengths of light, you get infrared. Now there's other stuff 78 00:04:56,120 --> 00:04:59,280 Speaker 1: that goes beyond those bands as well. For example, if 79 00:04:59,279 --> 00:05:02,680 Speaker 1: you keep going to higher frequencies and shorter wavelengths, you 80 00:05:02,760 --> 00:05:05,400 Speaker 1: run into X rays and gamma rays, and if you 81 00:05:05,480 --> 00:05:09,240 Speaker 1: keep going toward the longer wavelengths and lower frequencies, you'll 82 00:05:09,320 --> 00:05:13,880 Speaker 1: hit microwaves and radio waves. The first recorded discovery of 83 00:05:13,920 --> 00:05:18,279 Speaker 1: infrared light comes to us courtesy of smarty pants extraordinaire, 84 00:05:18,480 --> 00:05:22,480 Speaker 1: Sir William Herschel. This guy is what you would call 85 00:05:22,520 --> 00:05:24,920 Speaker 1: of von der Kind. First of all, he was born 86 00:05:24,920 --> 00:05:29,200 Speaker 1: in Germany, so the word I use is linguistically appropriate. Secondly, 87 00:05:29,440 --> 00:05:32,400 Speaker 1: he was a composer, he was an astronomer and just 88 00:05:32,640 --> 00:05:36,400 Speaker 1: generally a scientifically minded guy. And he's the guy who 89 00:05:36,480 --> 00:05:40,400 Speaker 1: discovered uranus the planet. And yes, I'm going to pronounce 90 00:05:40,480 --> 00:05:42,760 Speaker 1: it that way, because to do it the other way 91 00:05:42,839 --> 00:05:46,320 Speaker 1: makes it sound juvenile. He was also the grandfather of 92 00:05:46,400 --> 00:05:50,240 Speaker 1: another William Herschel, who would go on to establish fingerprints 93 00:05:50,279 --> 00:05:54,480 Speaker 1: as a means of authenticating documentation, but I've covered that 94 00:05:54,600 --> 00:05:58,479 Speaker 1: in a different episode. So Billy Herschel the first was 95 00:05:58,520 --> 00:06:02,120 Speaker 1: pontificating about the nature of light, and it was obvious 96 00:06:02,200 --> 00:06:05,000 Speaker 1: that light carried heat with it. When you step out 97 00:06:05,040 --> 00:06:08,240 Speaker 1: of the shade into the sunlight, you feel it. So 98 00:06:08,320 --> 00:06:11,960 Speaker 1: Herschel was working with different types of colored glass. He 99 00:06:12,000 --> 00:06:14,960 Speaker 1: was experimenting with different telescopes that he might be able 100 00:06:14,960 --> 00:06:18,159 Speaker 1: to use to observe the Sun, because the Sun's rays 101 00:06:18,240 --> 00:06:20,719 Speaker 1: are far too bright to stare at without the risk 102 00:06:20,760 --> 00:06:23,040 Speaker 1: of injury. We all know this. You don't stare at 103 00:06:23,080 --> 00:06:26,960 Speaker 1: the sun. So by using glass of different colors, he 104 00:06:27,000 --> 00:06:29,640 Speaker 1: was hoping to reduce the amount of light coming in 105 00:06:29,680 --> 00:06:32,320 Speaker 1: through the telescope so that he could still take a 106 00:06:32,360 --> 00:06:36,240 Speaker 1: closer look at the Sun and make observations safely. But 107 00:06:36,279 --> 00:06:39,440 Speaker 1: you discovered that some colors of glass seemed to reduce 108 00:06:39,560 --> 00:06:42,240 Speaker 1: the amount of heat that was passing through his telescope, 109 00:06:42,600 --> 00:06:45,480 Speaker 1: and others seemed to allow a great deal of heat 110 00:06:45,520 --> 00:06:50,600 Speaker 1: to come through, including enough heat to potentially cause an injury, 111 00:06:50,680 --> 00:06:52,919 Speaker 1: but this time due to heat rather than to the 112 00:06:52,960 --> 00:06:57,000 Speaker 1: intensity of light damaging his eye. And he knew about 113 00:06:57,120 --> 00:07:00,480 Speaker 1: how light could pass through a prism and would break 114 00:07:00,480 --> 00:07:04,560 Speaker 1: apart into the different colors of light, and collectively those 115 00:07:04,600 --> 00:07:08,320 Speaker 1: colors make up white light. What he wondered was if 116 00:07:08,360 --> 00:07:12,200 Speaker 1: those colors carried different amounts of heat. So he set 117 00:07:12,280 --> 00:07:15,800 Speaker 1: up an experiment and he used a prism to break 118 00:07:15,920 --> 00:07:18,800 Speaker 1: light into the different bands of colors, and then he 119 00:07:18,880 --> 00:07:22,679 Speaker 1: used a thermometer with the bulb end blackened by ink, 120 00:07:23,280 --> 00:07:26,119 Speaker 1: and he used that to measure the temperature within each 121 00:07:26,240 --> 00:07:28,800 Speaker 1: band of color. And he noticed as he measured the 122 00:07:28,880 --> 00:07:32,440 Speaker 1: violet end of the spectrum, the temperature readings were lower, 123 00:07:32,720 --> 00:07:35,320 Speaker 1: and towards the red end they were higher, and he 124 00:07:35,400 --> 00:07:38,840 Speaker 1: decided to also test the area just beyond the red end. 125 00:07:39,360 --> 00:07:42,280 Speaker 1: There was no visible light at that section, but he 126 00:07:42,320 --> 00:07:45,760 Speaker 1: observed that it was at that area where the thermometer 127 00:07:45,920 --> 00:07:49,240 Speaker 1: was registering the highest temperature. And this is the earliest 128 00:07:49,320 --> 00:07:52,400 Speaker 1: recording of someone figuring out that there was something beyond 129 00:07:52,440 --> 00:07:54,840 Speaker 1: the rainbow, so to speak. And yeah, I know, I 130 00:07:54,960 --> 00:07:58,520 Speaker 1: misquoted a song just to make that reference. Herschel referred 131 00:07:58,560 --> 00:08:03,480 Speaker 1: to this area beyond visible light as the thermometric spectrum. 132 00:08:03,520 --> 00:08:06,280 Speaker 1: In early days, some would refer to it as dark 133 00:08:06,360 --> 00:08:10,600 Speaker 1: heat or invisible rays. The term infrared wouldn't really come 134 00:08:10,600 --> 00:08:14,360 Speaker 1: around until the other end of the nineteenth century, and 135 00:08:14,480 --> 00:08:18,040 Speaker 1: there are no reliable records that indicate who actually coined 136 00:08:18,160 --> 00:08:22,080 Speaker 1: the term, but whomever was responsible, it became the standard 137 00:08:22,080 --> 00:08:26,080 Speaker 1: way to refer to this specific band of radiation. So 138 00:08:26,400 --> 00:08:29,440 Speaker 1: I've used the term thermal imaging in this episode, and 139 00:08:29,480 --> 00:08:32,600 Speaker 1: the reason I have is that it implies when we 140 00:08:32,679 --> 00:08:39,120 Speaker 1: use these technologies that were not somehow magically seeing infrared radiation. Right, 141 00:08:39,400 --> 00:08:44,280 Speaker 1: We're not able to suddenly see infrared light through this tech. Instead, 142 00:08:44,320 --> 00:08:47,839 Speaker 1: what we're doing is we're using technology to detect infrared 143 00:08:48,080 --> 00:08:51,880 Speaker 1: radiation or heat, and then using some sort of process 144 00:08:52,200 --> 00:08:56,560 Speaker 1: to convert that data into a visual representation. For example, 145 00:08:56,720 --> 00:09:01,120 Speaker 1: with thermal glasses, we'd see different colors that different intensities 146 00:09:01,280 --> 00:09:05,800 Speaker 1: to indicate varying degrees of heat between objects. Typically we 147 00:09:05,920 --> 00:09:09,120 Speaker 1: use colors like bright yellows, oranges, and reds to indicate 148 00:09:09,160 --> 00:09:13,760 Speaker 1: hot surfaces, and greens and blues to indicate cooler surfaces, 149 00:09:13,920 --> 00:09:16,520 Speaker 1: which is nice because that also corresponds to how much 150 00:09:16,559 --> 00:09:19,880 Speaker 1: heat energy those bands of light carry. Not in a 151 00:09:19,960 --> 00:09:24,079 Speaker 1: one to one scale, mind you, but the general principle remains, 152 00:09:24,160 --> 00:09:27,319 Speaker 1: and we kind of grasp it, right, We say, Okay, 153 00:09:27,360 --> 00:09:31,240 Speaker 1: this red thing is definitely hotter than that blue thing. 154 00:09:32,000 --> 00:09:33,840 Speaker 1: But to be able to do all this, we first 155 00:09:33,880 --> 00:09:36,560 Speaker 1: have to be able to detect and measure the heat 156 00:09:36,679 --> 00:09:39,120 Speaker 1: coming from an object in a reliable way in the 157 00:09:39,160 --> 00:09:42,640 Speaker 1: first place. Right. So, one of the cool things about 158 00:09:42,760 --> 00:09:48,160 Speaker 1: physics is how seemingly unrelated factors are actually tied together. 159 00:09:48,880 --> 00:09:51,680 Speaker 1: From the macro scale. That being the world that you 160 00:09:51,760 --> 00:09:54,720 Speaker 1: and I live in most of the time. Anyway, some 161 00:09:54,800 --> 00:09:56,520 Speaker 1: of you may have been having Honey I Shrunk the 162 00:09:56,559 --> 00:09:59,880 Speaker 1: Kid's Adventures, and I'm all for it. But on the 163 00:10:00,080 --> 00:10:04,400 Speaker 1: rand scale, it's not necessarily intuitive. But temperature can have 164 00:10:04,440 --> 00:10:08,240 Speaker 1: a big impact on other stuff, such as electrical properties 165 00:10:08,280 --> 00:10:13,320 Speaker 1: like conductivity and resistance. So just a reminder, conductivity describes 166 00:10:13,360 --> 00:10:16,640 Speaker 1: a material's ability to act as a conduit for an 167 00:10:16,640 --> 00:10:20,280 Speaker 1: electric charge, to allow an electric charge to pass through it. 168 00:10:20,640 --> 00:10:23,440 Speaker 1: Resistance is the flip side of that coin. It's a 169 00:10:23,440 --> 00:10:27,440 Speaker 1: material's tendency to resist an electrical charge. We can think 170 00:10:27,440 --> 00:10:30,040 Speaker 1: of it kind of in terms of friction. If you 171 00:10:30,080 --> 00:10:33,840 Speaker 1: have a very smooth floor that's been recently waxed, there's 172 00:10:33,920 --> 00:10:36,679 Speaker 1: very little friction there, and you might slide all over it, 173 00:10:36,760 --> 00:10:40,120 Speaker 1: perhaps without even intending to do so. But if you're 174 00:10:40,160 --> 00:10:43,160 Speaker 1: on something like a rough concrete surface, there's a lot 175 00:10:43,200 --> 00:10:46,080 Speaker 1: of friction and your attempts to slide would be met 176 00:10:46,120 --> 00:10:49,880 Speaker 1: with a lot of resistance. Well, the electrical world, that's 177 00:10:50,400 --> 00:10:54,880 Speaker 1: kind of analogous to conductivity and electrical resistance. Heat can 178 00:10:55,000 --> 00:10:59,480 Speaker 1: change these properties. For example, even a good conductor has 179 00:10:59,679 --> 00:11:04,440 Speaker 1: saw electrical resistance just like we can't entirely negate friction, 180 00:11:04,760 --> 00:11:08,800 Speaker 1: even with our smoothest materials. But if you cool that 181 00:11:08,880 --> 00:11:14,079 Speaker 1: conductor down, like way down, like colder than the depths 182 00:11:14,120 --> 00:11:18,480 Speaker 1: of space, you can reduce its resistance, and depending on 183 00:11:18,480 --> 00:11:21,040 Speaker 1: the material, you can reduce it all the way down 184 00:11:21,080 --> 00:11:23,840 Speaker 1: to nothing. At that point you've got what's called a 185 00:11:23,920 --> 00:11:29,200 Speaker 1: super conductor. Likewise, a conductive material will increase in resistance 186 00:11:29,360 --> 00:11:33,200 Speaker 1: as it heats up, so temperature and electrical resistance have 187 00:11:33,400 --> 00:11:36,720 Speaker 1: this kind of relationship. Now, the whole reason I went 188 00:11:36,760 --> 00:11:39,720 Speaker 1: down that apparent bunny trail is that it brings us 189 00:11:39,720 --> 00:11:42,760 Speaker 1: to an important component that would play a huge role 190 00:11:42,920 --> 00:11:47,360 Speaker 1: in thermal sensors, and that's the bolometer. Now, when I 191 00:11:47,480 --> 00:11:51,240 Speaker 1: first read this word, which is spelled b O l 192 00:11:51,400 --> 00:11:55,040 Speaker 1: O m e t e R, I had not heard 193 00:11:55,080 --> 00:11:59,760 Speaker 1: anyone pronounce it, and as many of us know, sometimes 194 00:11:59,760 --> 00:12:03,040 Speaker 1: that means in our heads we have a very different pronunciation. 195 00:12:03,160 --> 00:12:05,040 Speaker 1: So when I first read it, I thought it might 196 00:12:05,040 --> 00:12:08,080 Speaker 1: be a bolo meter, and then I immediately second guess 197 00:12:08,120 --> 00:12:11,080 Speaker 1: myself because I'm pretty sure a bolometer would be a 198 00:12:11,120 --> 00:12:16,040 Speaker 1: device for measuring Texas neckties. So no, it's a bolometer. Now, 199 00:12:16,040 --> 00:12:20,280 Speaker 1: to understand a bolometer. It helps if we also understand 200 00:12:20,480 --> 00:12:23,959 Speaker 1: what a wheat Stone bridge is, and it's not an 201 00:12:24,040 --> 00:12:27,360 Speaker 1: architectural thing. This is a type of circuit and its 202 00:12:27,400 --> 00:12:31,480 Speaker 1: purpose is to measure the unknown electrical resistance of a material. 203 00:12:32,000 --> 00:12:35,880 Speaker 1: It was first implemented in eighteen thirty three by Samuel 204 00:12:35,960 --> 00:12:39,720 Speaker 1: Hunter Christie and later refined by Sir Charles Wheatstone in 205 00:12:39,760 --> 00:12:43,080 Speaker 1: the eighteen forties. This is a little tricky to describe 206 00:12:43,080 --> 00:12:45,400 Speaker 1: without the use of visual aids, but I'm going to 207 00:12:45,440 --> 00:12:48,200 Speaker 1: give it a shot. All right, Imagine you have a 208 00:12:48,200 --> 00:12:52,280 Speaker 1: perfect square. Now turn that perfect square forty five degrees 209 00:12:52,320 --> 00:12:55,080 Speaker 1: so that it's a Diamond's got a top, left, right, 210 00:12:55,160 --> 00:12:59,840 Speaker 1: and bottom point. And those four corners of this diamond 211 00:13:00,080 --> 00:13:04,120 Speaker 1: present points of electric potential. And let's let's name the 212 00:13:04,160 --> 00:13:06,960 Speaker 1: top point is A, the bottom point is B, so 213 00:13:07,000 --> 00:13:09,840 Speaker 1: they're opposite each other. The left point is C, the 214 00:13:09,960 --> 00:13:12,679 Speaker 1: right point is D, so they're opposite each other. Now, 215 00:13:12,760 --> 00:13:16,080 Speaker 1: let's also imagine that C and D connect to each 216 00:13:16,120 --> 00:13:18,319 Speaker 1: other with a horizontal line that cuts right through the 217 00:13:18,360 --> 00:13:20,080 Speaker 1: middle of this diamond. So you've got a path going 218 00:13:20,120 --> 00:13:22,920 Speaker 1: from C to D, as well as the uh the 219 00:13:23,040 --> 00:13:26,360 Speaker 1: straight lines of the diamond from A to c A 220 00:13:26,600 --> 00:13:29,320 Speaker 1: to D and then C two B and D two 221 00:13:29,360 --> 00:13:32,520 Speaker 1: B the sides of the diamond. Those lines that I 222 00:13:32,679 --> 00:13:37,360 Speaker 1: just mentioned connecting the points represent resistors. And here's the 223 00:13:37,440 --> 00:13:41,280 Speaker 1: key when using a wheat stone bridge. You know the 224 00:13:41,360 --> 00:13:45,520 Speaker 1: electrical resistance for three of those resistors. Those are ones 225 00:13:45,559 --> 00:13:49,360 Speaker 1: that you have put in place. So you've got three 226 00:13:49,400 --> 00:13:53,080 Speaker 1: resistors where you know the electrical resistance. The fourth resistor 227 00:13:53,280 --> 00:13:56,600 Speaker 1: represents the material you're actually testing. You don't know its 228 00:13:56,640 --> 00:14:01,520 Speaker 1: electrical resistance. So in our little amount engineering wheat stone bridge, 229 00:14:01,679 --> 00:14:04,720 Speaker 1: let's say that the line between point D, which is 230 00:14:04,720 --> 00:14:06,520 Speaker 1: the one that's on the right side of the diamond, 231 00:14:06,800 --> 00:14:09,000 Speaker 1: and point B, which is on the bottom side of 232 00:14:09,000 --> 00:14:12,360 Speaker 1: the diamond, that represents the resistor we're interested in. We're 233 00:14:12,400 --> 00:14:16,280 Speaker 1: trying to figure out what is its electrical resistance. Now, 234 00:14:16,280 --> 00:14:18,680 Speaker 1: another important point is that on the opposite side of 235 00:14:18,679 --> 00:14:22,360 Speaker 1: the circuit, the line that's representing C the point on 236 00:14:22,400 --> 00:14:24,720 Speaker 1: the left, and B on the bottom. So the other 237 00:14:25,200 --> 00:14:28,400 Speaker 1: bottom leg that one is a resistor that we can 238 00:14:28,440 --> 00:14:32,000 Speaker 1: actually adjust the electrical resistance. We can fine tune it. 239 00:14:32,000 --> 00:14:34,760 Speaker 1: It's like a radio dial. You can just fine tune 240 00:14:34,800 --> 00:14:39,400 Speaker 1: that electrical resistance by applying a difference of voltage between 241 00:14:39,480 --> 00:14:41,960 Speaker 1: A at the top and BE at the bottom. We 242 00:14:42,040 --> 00:14:45,360 Speaker 1: allow current to flow through this circuit, and if current 243 00:14:45,400 --> 00:14:48,080 Speaker 1: can flow from point C on the left to point 244 00:14:48,160 --> 00:14:50,960 Speaker 1: D on the right, or vice versa, it means the 245 00:14:51,000 --> 00:14:55,360 Speaker 1: bridge is unbalanced. That means there's more resistance on one 246 00:14:55,440 --> 00:14:58,960 Speaker 1: side of the circuit than the other. So we slowly 247 00:14:59,000 --> 00:15:03,600 Speaker 1: start to find t that one leg that C B resistor, 248 00:15:04,200 --> 00:15:07,280 Speaker 1: and we continue to fine tune it until no current 249 00:15:07,480 --> 00:15:10,880 Speaker 1: is passing between points C and D. That would mean 250 00:15:10,920 --> 00:15:13,880 Speaker 1: that the wheat stone bridge is in balance. It also 251 00:15:13,960 --> 00:15:17,800 Speaker 1: means the ratio of resistance represented by the left side 252 00:15:17,800 --> 00:15:20,360 Speaker 1: of the circuit has to be equal to the ratio 253 00:15:20,480 --> 00:15:23,240 Speaker 1: of resistance on the right side. And we know the 254 00:15:23,240 --> 00:15:28,040 Speaker 1: electrical resistance of three of those four resistors. So by 255 00:15:28,080 --> 00:15:32,360 Speaker 1: knowing the ratio on one side and knowing half of 256 00:15:32,400 --> 00:15:34,280 Speaker 1: the ratio on the other side, we can figure out 257 00:15:34,320 --> 00:15:37,760 Speaker 1: the variable. Right. It's just a simple algebra problem. So 258 00:15:37,840 --> 00:15:40,600 Speaker 1: you just solve for X and boom, you found the 259 00:15:40,600 --> 00:15:45,280 Speaker 1: electrical resistance of that material you were testing. Why is 260 00:15:45,320 --> 00:15:48,600 Speaker 1: all of that important, Well, it's because the bolometer is 261 00:15:48,640 --> 00:15:52,280 Speaker 1: built upon the premise of the wheat stone bridge. In 262 00:15:52,360 --> 00:15:56,080 Speaker 1: Pokemon terms. It would be an evolution. I'll explain in 263 00:15:56,120 --> 00:15:58,880 Speaker 1: just a moment, but first let's take a quick break. 264 00:16:06,440 --> 00:16:09,640 Speaker 1: Before the break, I described the wheat stone bridge circuit 265 00:16:09,760 --> 00:16:13,040 Speaker 1: and how it allows researchers to determine the electrical resistance 266 00:16:13,080 --> 00:16:16,440 Speaker 1: of a material. Now it's time to talk about bolometers 267 00:16:16,440 --> 00:16:21,040 Speaker 1: and Samuel Pierre Pont Langley what a name. It's sp 268 00:16:21,240 --> 00:16:25,640 Speaker 1: Langley's how he was typically referred to, Professor S. P. Langley. 269 00:16:25,920 --> 00:16:28,280 Speaker 1: Langley was a lot of things. He wasn't just a professor. 270 00:16:28,640 --> 00:16:31,520 Speaker 1: He was almost the inventor of the airplane. A couple 271 00:16:31,560 --> 00:16:33,800 Speaker 1: of upstarts called the Right Brothers beat him to it. 272 00:16:34,200 --> 00:16:37,320 Speaker 1: He was also an astronomer, and like Sir William Herschel 273 00:16:37,480 --> 00:16:40,560 Speaker 1: nearly a century earlier, he wanted to find ways to 274 00:16:40,640 --> 00:16:43,680 Speaker 1: study the solar energy that made it from the Sun 275 00:16:43,920 --> 00:16:47,440 Speaker 1: to the Earth, And in eight seventy eight he invented 276 00:16:47,480 --> 00:16:50,400 Speaker 1: an apparatus that could be used to measure the amount 277 00:16:50,480 --> 00:16:54,000 Speaker 1: of infrared energy hitting a specific point. And this was 278 00:16:54,080 --> 00:16:58,400 Speaker 1: the bolometer. So remember the wheat stone bridge I described earlier, Well, 279 00:16:58,440 --> 00:17:01,200 Speaker 1: now imagine you've got the same sort of layout, except 280 00:17:01,240 --> 00:17:04,440 Speaker 1: this time you know the electrical resistance of every leg 281 00:17:04,760 --> 00:17:07,040 Speaker 1: in this circuit, so you're not you're not trying to 282 00:17:07,080 --> 00:17:09,800 Speaker 1: figure out the electrical resistance You already know what it's 283 00:17:09,840 --> 00:17:13,280 Speaker 1: supposed to be for all parts of this wheat stone 284 00:17:13,320 --> 00:17:19,080 Speaker 1: bridge style circuit. However, the material you're using is very 285 00:17:19,119 --> 00:17:23,159 Speaker 1: sensitive to changes in heat, which in turn changes the 286 00:17:23,200 --> 00:17:28,440 Speaker 1: electrical resistance of those resistors like super super sensitive, even 287 00:17:28,520 --> 00:17:31,920 Speaker 1: the shift of just one thousand of a degree celsius 288 00:17:31,960 --> 00:17:36,879 Speaker 1: will make a change in its electrical resistance, So the 289 00:17:36,920 --> 00:17:41,399 Speaker 1: electrical resistance of the materials changes. So rather than tuning 290 00:17:41,440 --> 00:17:44,920 Speaker 1: in to find a specific electrical resistance as you would 291 00:17:44,960 --> 00:17:48,800 Speaker 1: with a traditional wheat stone bridge, a volometer monitors the 292 00:17:48,800 --> 00:17:52,800 Speaker 1: electrical resistance of a circuit, and the changes in resistance 293 00:17:52,920 --> 00:17:57,280 Speaker 1: indicate a change in temperature. A bigger change in electrical 294 00:17:57,320 --> 00:18:03,000 Speaker 1: resistance indicates a higher intensive of infrared radiation, meaning a 295 00:18:03,040 --> 00:18:09,600 Speaker 1: bigger change in temperature. Langley invented an incredibly sensitive thermal detector. 296 00:18:10,440 --> 00:18:13,480 Speaker 1: It was able to pick up incredibly small changes in 297 00:18:13,560 --> 00:18:17,359 Speaker 1: heat from an enormous distance. Reportedly, with one of his 298 00:18:17,480 --> 00:18:21,719 Speaker 1: refined thermal sensors using a bolometer, he could detect the 299 00:18:21,760 --> 00:18:25,800 Speaker 1: body heat of a cow from four hundred meters away. 300 00:18:26,240 --> 00:18:29,159 Speaker 1: The bolometer was that sensitive and would pick up the 301 00:18:29,200 --> 00:18:32,399 Speaker 1: infrared energy coming off that cow, indicating that there was 302 00:18:32,440 --> 00:18:35,200 Speaker 1: something in that spot that was generating more heat than 303 00:18:35,400 --> 00:18:39,639 Speaker 1: the surrounding objects in that environment. So by measuring the 304 00:18:39,720 --> 00:18:43,440 Speaker 1: changes in electrical resistance, you could work back to understand 305 00:18:43,480 --> 00:18:48,520 Speaker 1: the intensity of the infrared radiation hitting that sensor. And 306 00:18:48,600 --> 00:18:52,600 Speaker 1: this was really good for detecting differences in temperature, right, 307 00:18:52,720 --> 00:18:56,720 Speaker 1: not necessarily getting an exact read out of the temperature 308 00:18:56,760 --> 00:19:00,360 Speaker 1: of an object, but rather getting the difference between one 309 00:19:00,400 --> 00:19:04,639 Speaker 1: object and say it's environment or another object, and hotter 310 00:19:04,760 --> 00:19:08,040 Speaker 1: things give off more intense infra red radiation, so you 311 00:19:08,040 --> 00:19:11,080 Speaker 1: can build up your knowledge base this way. There's a 312 00:19:11,119 --> 00:19:12,960 Speaker 1: bit more to it than that. When we talk about 313 00:19:13,080 --> 00:19:17,000 Speaker 1: modern bolometers, those get pretty complicated, and honestly, it gets 314 00:19:17,040 --> 00:19:18,600 Speaker 1: to a point where I don't think I can really 315 00:19:18,640 --> 00:19:22,120 Speaker 1: tackle an explanation that will mean anything without the use 316 00:19:22,160 --> 00:19:26,600 Speaker 1: of visual aids. But the basic principle measuring infrared radiation 317 00:19:26,720 --> 00:19:31,120 Speaker 1: through monitoring electrical changes remains the same. So again, this 318 00:19:31,160 --> 00:19:34,280 Speaker 1: was sort of an indirect way to detect heat, right. 319 00:19:34,320 --> 00:19:37,040 Speaker 1: I mean, the changes in temperature would affect the electrical 320 00:19:37,080 --> 00:19:40,560 Speaker 1: resistance in the bolometer, and that's what we were actually measuring. 321 00:19:41,040 --> 00:19:45,400 Speaker 1: We're not measuring heat, We're measuring electrical resistance that changes 322 00:19:45,560 --> 00:19:50,080 Speaker 1: as a result of infrared radiation or heat, and then 323 00:19:50,119 --> 00:19:53,400 Speaker 1: a meter measuring that resistance would indicate what was going on. 324 00:19:53,840 --> 00:19:56,360 Speaker 1: But this meant researchers had to spend time to refine 325 00:19:56,440 --> 00:19:59,360 Speaker 1: what that actually meant. They had to match the changes 326 00:19:59,400 --> 00:20:03,120 Speaker 1: in electrical resistance to the differences in temperature. And this 327 00:20:03,200 --> 00:20:05,760 Speaker 1: is a part of science and engineering that just blows 328 00:20:05,800 --> 00:20:08,240 Speaker 1: my mind, not just that super smart people had to 329 00:20:08,760 --> 00:20:12,240 Speaker 1: take some known phenomena and then make use of it, 330 00:20:12,280 --> 00:20:14,960 Speaker 1: but then later refine that so that the use is 331 00:20:14,960 --> 00:20:18,199 Speaker 1: more practical. We'd see a lot of further steps build 332 00:20:18,359 --> 00:20:22,080 Speaker 1: upon this foundation. Bilometers could indicate changes in temperature, but 333 00:20:22,119 --> 00:20:24,359 Speaker 1: it would take a lot more work and technology to 334 00:20:24,440 --> 00:20:27,080 Speaker 1: use that data and then convert it again into something 335 00:20:27,119 --> 00:20:30,160 Speaker 1: that could be presented visually as a thermal image or 336 00:20:30,440 --> 00:20:35,960 Speaker 1: thermographic display. So with a bolometer based thermal imager, you've 337 00:20:35,960 --> 00:20:40,280 Speaker 1: got infrared radiation which hits a thermal sensor, which changes 338 00:20:40,320 --> 00:20:43,960 Speaker 1: its electrical resistance as a result, which a meter detects, 339 00:20:44,000 --> 00:20:47,720 Speaker 1: which sends this metric to a processor which interprets that 340 00:20:47,840 --> 00:20:50,359 Speaker 1: data and then converts it into a different type of 341 00:20:50,400 --> 00:20:52,919 Speaker 1: information that can be displayed on a screen. This is 342 00:20:52,960 --> 00:20:56,000 Speaker 1: what amazes me. So the bolometer would become a really 343 00:20:56,040 --> 00:20:58,800 Speaker 1: important tool for astronomers, but it would take a bit 344 00:20:58,840 --> 00:21:02,520 Speaker 1: longer to play a role in thermal imagers, though not 345 00:21:02,680 --> 00:21:08,000 Speaker 1: too much longer. According to multiple sources, the first person 346 00:21:08,119 --> 00:21:12,119 Speaker 1: to create a thermal television camera was the Hungarian born 347 00:21:12,440 --> 00:21:16,720 Speaker 1: Kalman to Hanji in nineteen nine. He built it for 348 00:21:16,760 --> 00:21:21,119 Speaker 1: Britain to use as part of their anti aircraft technologies 349 00:21:21,320 --> 00:21:24,359 Speaker 1: after World War One. I wish I could tell you 350 00:21:24,400 --> 00:21:28,560 Speaker 1: more about the technology of his device, but honestly, there's 351 00:21:28,600 --> 00:21:32,320 Speaker 1: not much information I could find about how it actually worked. 352 00:21:32,680 --> 00:21:35,560 Speaker 1: There's a general agreement that this is the first thermal 353 00:21:35,640 --> 00:21:39,080 Speaker 1: imaging camera, though all of that could ultimately be pulling 354 00:21:39,160 --> 00:21:42,399 Speaker 1: the information from a single source, which makes it less reliable. 355 00:21:42,760 --> 00:21:45,600 Speaker 1: But I couldn't find much information on what the actual 356 00:21:45,640 --> 00:21:49,560 Speaker 1: implementation to Hanyi used in his invention, and in a 357 00:21:49,600 --> 00:21:53,280 Speaker 1: few sources, I found his device confused with a later 358 00:21:53,440 --> 00:21:57,520 Speaker 1: thermographic camera that would be reportedly based off his invention, 359 00:21:57,640 --> 00:22:01,240 Speaker 1: but was its own distinct thing. So while it appears 360 00:22:01,280 --> 00:22:05,800 Speaker 1: The first thermal imaging camera dates to nine nine, and 361 00:22:05,880 --> 00:22:09,119 Speaker 1: it was all about live images. I can't tell you 362 00:22:09,160 --> 00:22:11,120 Speaker 1: a whole lot about it, and I'm sure there are 363 00:22:11,119 --> 00:22:13,880 Speaker 1: patents out there for it, but my patent searches were 364 00:22:13,880 --> 00:22:16,760 Speaker 1: not terribly fruitful. I couldn't find anything all the way 365 00:22:16,800 --> 00:22:21,600 Speaker 1: back at nine that match the description. However, one thing 366 00:22:21,640 --> 00:22:25,240 Speaker 1: I can say is that for the first few decades 367 00:22:25,320 --> 00:22:29,280 Speaker 1: of thermal imaging, almost all the research and development for 368 00:22:29,320 --> 00:22:33,720 Speaker 1: that technology fell to militaries around the world. Thermal detection 369 00:22:33,760 --> 00:22:36,880 Speaker 1: in general was a big area of research, and engineers 370 00:22:36,920 --> 00:22:40,760 Speaker 1: were trying to incorporate thermal sensors and stuff like missiles 371 00:22:40,800 --> 00:22:45,520 Speaker 1: and torpedoes, and later on in rifle scopes and headsets, 372 00:22:45,960 --> 00:22:48,560 Speaker 1: the idea being that this could be part of a 373 00:22:48,600 --> 00:22:51,959 Speaker 1: guidance system to help an explosive projectile lock into a target. 374 00:22:52,000 --> 00:22:54,560 Speaker 1: I mean a lot of military targets are also sources 375 00:22:54,640 --> 00:22:59,240 Speaker 1: of considerable amounts of heat, such as warships, submarines, tanks, 376 00:22:59,320 --> 00:23:02,919 Speaker 1: or aircraft. So a missile or torpedo that has a 377 00:23:02,960 --> 00:23:05,560 Speaker 1: thermal sensor on it would be able to hone in 378 00:23:05,680 --> 00:23:09,480 Speaker 1: on the heat source pretty easily. But by the nineteen fifties, 379 00:23:10,040 --> 00:23:13,520 Speaker 1: other disciplines were also interested in making use of this technology, 380 00:23:13,720 --> 00:23:16,800 Speaker 1: such as in medicine. There were some doctors who were 381 00:23:16,840 --> 00:23:19,919 Speaker 1: hoping to use thermal imaging to help them do stuff 382 00:23:19,960 --> 00:23:23,760 Speaker 1: like identify potentially cancerous tumors. The idea being that a 383 00:23:23,800 --> 00:23:27,159 Speaker 1: cancerous tumor would likely consist of cells replicating at a 384 00:23:27,200 --> 00:23:29,920 Speaker 1: faster rate than normal cells. Thus they would have a 385 00:23:29,960 --> 00:23:33,880 Speaker 1: higher metabolic rate, and you would think that that would 386 00:23:33,920 --> 00:23:37,160 Speaker 1: mean they would be generating more heat than healthy tissue. 387 00:23:37,640 --> 00:23:41,520 Speaker 1: A device sensitive to minute differences in temperature and capable 388 00:23:41,520 --> 00:23:44,480 Speaker 1: of displaying that information on a screen, particularly if you 389 00:23:44,480 --> 00:23:47,639 Speaker 1: could do it in real time, would be handy if 390 00:23:47,720 --> 00:23:50,919 Speaker 1: that hypothesis were to hold true. Now, I want to 391 00:23:50,960 --> 00:23:53,960 Speaker 1: add that this particular approach isn't proven to be the 392 00:23:53,960 --> 00:23:56,880 Speaker 1: most effective means for detecting a tumor, and that other 393 00:23:56,960 --> 00:24:01,000 Speaker 1: methods such as mammograms are far moral liable and likely 394 00:24:01,040 --> 00:24:04,439 Speaker 1: to catch cancer at earlier stages. But at the time 395 00:24:04,600 --> 00:24:08,360 Speaker 1: there were doctors hoping that it might be a helpful technology. However, 396 00:24:08,400 --> 00:24:11,359 Speaker 1: for most part, thermal imaging remained in the domain of 397 00:24:11,440 --> 00:24:14,600 Speaker 1: the military around this time. So we're going to skip 398 00:24:14,640 --> 00:24:17,480 Speaker 1: forward a bit to the development of a different kind 399 00:24:17,640 --> 00:24:22,080 Speaker 1: of heat sensor. This one is based off pyroelectric materials. 400 00:24:22,520 --> 00:24:26,359 Speaker 1: Pyro Electricity refers to a certain set of crystals that 401 00:24:26,480 --> 00:24:30,480 Speaker 1: have large electric fields and that generate a voltage when 402 00:24:30,520 --> 00:24:34,639 Speaker 1: they undergo changes in temperatures. This is similar to, but 403 00:24:34,760 --> 00:24:39,240 Speaker 1: distinct from piezo electricity or piezo electricity if you prefer. 404 00:24:39,520 --> 00:24:42,720 Speaker 1: Those are crystals that accumulate an electric charge after those 405 00:24:42,720 --> 00:24:46,639 Speaker 1: crystals have been subjected to a mechanical stress. They also 406 00:24:46,800 --> 00:24:49,959 Speaker 1: will vibrate if they are subjected to an electric charge. 407 00:24:50,160 --> 00:24:54,080 Speaker 1: So the quartz crystal in a you know, classic watch 408 00:24:54,600 --> 00:25:00,080 Speaker 1: is a piezoelectric crystal. Pyro electric is slightly different. This 409 00:25:00,280 --> 00:25:03,400 Speaker 1: is in changes in temperature. That's where you get the voltage. 410 00:25:03,880 --> 00:25:07,560 Speaker 1: Pyro Electric crystals generate voltages upon those temperature changes, but 411 00:25:07,600 --> 00:25:11,160 Speaker 1: after a while, if the temperature remains constant, the voltage 412 00:25:11,280 --> 00:25:15,480 Speaker 1: will decrease and eventually disappear. These aren't typically used in 413 00:25:15,560 --> 00:25:19,560 Speaker 1: thermal sensors for cameras. They can be, but they're not 414 00:25:19,920 --> 00:25:22,840 Speaker 1: typically used that way. They're commonly found in stuff like 415 00:25:22,960 --> 00:25:26,080 Speaker 1: light switches that automate lights when they detect someone's in 416 00:25:26,080 --> 00:25:29,280 Speaker 1: the area. We often think of these as motion sensors 417 00:25:29,320 --> 00:25:31,400 Speaker 1: and I'm sure some of you out there have stories 418 00:25:31,440 --> 00:25:35,200 Speaker 1: of being in, say I don't know, a bathroom when 419 00:25:35,200 --> 00:25:37,320 Speaker 1: the lights automatically go out, and then you have to 420 00:25:37,359 --> 00:25:39,480 Speaker 1: find creative ways to get the sensors to pick up 421 00:25:39,480 --> 00:25:41,280 Speaker 1: on the fact that you're still in there and you're 422 00:25:42,000 --> 00:25:47,480 Speaker 1: still attending to your dark business. Typically these aren't motion sensors. 423 00:25:47,520 --> 00:25:50,280 Speaker 1: They can be, but they're not always. They often are 424 00:25:50,400 --> 00:25:53,920 Speaker 1: heat sensors. So moving around isn't getting picked up by 425 00:25:53,960 --> 00:25:56,639 Speaker 1: some sort of optical element, at least not in the 426 00:25:56,720 --> 00:26:00,400 Speaker 1: visible spectrum, but rather you are generating a lot more 427 00:26:00,520 --> 00:26:05,800 Speaker 1: infrared radiation as you're moving around, getting head up, and 428 00:26:05,880 --> 00:26:09,040 Speaker 1: thus the sensor picks up this infrared radiation says, whoops, 429 00:26:09,040 --> 00:26:11,960 Speaker 1: somebody's still in here, and then the light cell come 430 00:26:11,960 --> 00:26:14,920 Speaker 1: on so that that warm body inside that bathroom can 431 00:26:14,920 --> 00:26:19,520 Speaker 1: get down to business. Then there are thermo couples. Breaking 432 00:26:19,520 --> 00:26:22,080 Speaker 1: down the name, we can figure out this has something 433 00:26:22,080 --> 00:26:25,800 Speaker 1: to do with heat and it has to something or others, right, 434 00:26:25,880 --> 00:26:29,280 Speaker 1: a couple. So in this case, the couple the something 435 00:26:29,359 --> 00:26:32,280 Speaker 1: or others are strips of two different types of metal. 436 00:26:33,119 --> 00:26:36,040 Speaker 1: The metals have to be specific types that will generate 437 00:26:36,080 --> 00:26:39,919 Speaker 1: a voltage when the temperature of the two metals doesn't match, 438 00:26:40,240 --> 00:26:43,000 Speaker 1: so the temperature of one metal is higher than the 439 00:26:43,000 --> 00:26:46,320 Speaker 1: temperature of the other metal. So when infrared energy hits 440 00:26:46,359 --> 00:26:49,439 Speaker 1: the strips of metal, the strip one of them is 441 00:26:49,440 --> 00:26:52,240 Speaker 1: painted black that one will absorb more energy it heats 442 00:26:52,320 --> 00:26:55,159 Speaker 1: up faster. The change in temperature causes a voltage to 443 00:26:55,200 --> 00:26:59,320 Speaker 1: apply across the circuit and current flows. Typically you create 444 00:26:59,680 --> 00:27:03,160 Speaker 1: a big collection of thermo couples into what is called 445 00:27:03,200 --> 00:27:06,399 Speaker 1: a thermopile to do anything useful with it. All of 446 00:27:06,440 --> 00:27:09,919 Speaker 1: these approaches rely on physical materials generating some sort of 447 00:27:09,960 --> 00:27:14,160 Speaker 1: detectable and measurable response to changes in temperature, and over 448 00:27:14,200 --> 00:27:17,160 Speaker 1: the decades, these sort of components would play a part 449 00:27:17,280 --> 00:27:21,080 Speaker 1: in sensors in general and thermal imaging in particular. In 450 00:27:21,200 --> 00:27:25,399 Speaker 1: nineteen sixty three, an engineer at the company Texas Instruments 451 00:27:25,520 --> 00:27:30,359 Speaker 1: named Kirby Taylor invented a technology called forward looking Infrared 452 00:27:30,760 --> 00:27:35,240 Speaker 1: or f l I R. FLEAR. Okay, so before f 453 00:27:35,560 --> 00:27:39,560 Speaker 1: l I R, most thermal imaging systems used a single 454 00:27:39,680 --> 00:27:43,080 Speaker 1: line of sensors. So just think of a line of 455 00:27:43,119 --> 00:27:46,480 Speaker 1: these things, a vertical line or a horizontal line, and 456 00:27:46,520 --> 00:27:50,800 Speaker 1: you would sweep that line of sensors across an area 457 00:27:50,840 --> 00:27:53,879 Speaker 1: to pick up differences of temperatures, you would physically move 458 00:27:54,359 --> 00:27:58,160 Speaker 1: the sensors across this area. The military would use these 459 00:27:58,240 --> 00:28:01,320 Speaker 1: kind of sensors mounted on planes to do this. The 460 00:28:01,320 --> 00:28:04,919 Speaker 1: planes could fly over an area and scan the area below. 461 00:28:05,359 --> 00:28:09,080 Speaker 1: The line of sensors were perpendicular to the planes travel, 462 00:28:09,280 --> 00:28:13,439 Speaker 1: so the planes flying forward, the line is perpendicular to 463 00:28:13,600 --> 00:28:18,120 Speaker 1: that forward uh direction, and this allowed it to scan 464 00:28:18,200 --> 00:28:22,520 Speaker 1: across the ground underneath. This approach was incapable of producing 465 00:28:22,600 --> 00:28:26,520 Speaker 1: real time two dimensional images. You were getting slices essentially, 466 00:28:26,760 --> 00:28:29,520 Speaker 1: and it would be useful for reconnaissance, such as if 467 00:28:29,520 --> 00:28:32,520 Speaker 1: you wanted to identify, I don't know, a possible Soviet 468 00:28:32,560 --> 00:28:37,160 Speaker 1: missile silo in Siberia or something, but you weren't getting 469 00:28:37,200 --> 00:28:40,720 Speaker 1: a real time image of a heat map. Taylor worked 470 00:28:40,720 --> 00:28:44,080 Speaker 1: on creating a forward looking thermal sensor, one that would 471 00:28:44,160 --> 00:28:48,400 Speaker 1: use a scanning mirror to steer the sensors. So technically, 472 00:28:48,440 --> 00:28:51,520 Speaker 1: what this mirror was doing was sweeping back and forth 473 00:28:51,600 --> 00:28:55,800 Speaker 1: across the sensors, directing the infrared radiation coming in through 474 00:28:55,840 --> 00:29:00,400 Speaker 1: the camera and in a coordinated way so that the 475 00:29:00,480 --> 00:29:02,520 Speaker 1: processor on the other side of this could take the 476 00:29:02,640 --> 00:29:06,800 Speaker 1: information and make a two dimensional image from it. The 477 00:29:06,840 --> 00:29:10,840 Speaker 1: scanning mirror achieved the same effect as moving a line 478 00:29:10,960 --> 00:29:13,600 Speaker 1: of sensors across an area, but you didn't have to 479 00:29:13,640 --> 00:29:16,440 Speaker 1: move the sensors because the mirror was doing the moving 480 00:29:16,640 --> 00:29:20,040 Speaker 1: for them. Now, there are two branching forms of thermal 481 00:29:20,160 --> 00:29:23,640 Speaker 1: imaging sensors that I should mention from this point. There 482 00:29:23,680 --> 00:29:27,840 Speaker 1: are uncooled detectors which can operate at normal temperatures. They 483 00:29:27,840 --> 00:29:30,480 Speaker 1: don't require any special conditions apart from you know, the 484 00:29:30,520 --> 00:29:33,720 Speaker 1: typical stuff like a source of power like a battery. 485 00:29:33,880 --> 00:29:38,080 Speaker 1: Then there are cooled systems which require special cooling systems 486 00:29:38,520 --> 00:29:41,040 Speaker 1: no big shock there to keep the sensors at a 487 00:29:41,200 --> 00:29:44,840 Speaker 1: very low temperature. And these systems work with different types 488 00:29:44,840 --> 00:29:48,920 Speaker 1: of infrared radiation. See, just like the visible light spectrum, 489 00:29:49,120 --> 00:29:52,720 Speaker 1: infrared itself is a spectrum, but it's not just one 490 00:29:52,840 --> 00:29:57,120 Speaker 1: band of frequencies. Right, You've got near infrared on one side. 491 00:29:57,320 --> 00:30:00,040 Speaker 1: That's the side of the band that's best buds of 492 00:30:00,080 --> 00:30:03,280 Speaker 1: the visible spectrum. Right, you've got red light. The red 493 00:30:03,360 --> 00:30:07,160 Speaker 1: light then gradually gives way to near infrared, which is 494 00:30:07,200 --> 00:30:10,920 Speaker 1: invisible to us, but it is much closer to the 495 00:30:10,960 --> 00:30:13,680 Speaker 1: wavelength of red light. Then on the other end of 496 00:30:13,720 --> 00:30:17,800 Speaker 1: the infrared spectrum is what's called long wave infrared, in 497 00:30:17,840 --> 00:30:22,280 Speaker 1: between his midwave infrared. In general, uncooled detectors tend to 498 00:30:22,320 --> 00:30:27,240 Speaker 1: work on the long wave infrared spectrum, while cooled detectors 499 00:30:27,280 --> 00:30:31,240 Speaker 1: focus har har harror on the midwave spectrum. One thing 500 00:30:31,280 --> 00:30:34,400 Speaker 1: that helped bring thermal imaging cameras out of the realm 501 00:30:34,440 --> 00:30:37,240 Speaker 1: of the military, meaning it helped bring the cost down, 502 00:30:37,920 --> 00:30:41,560 Speaker 1: was the development of micro bolometers. Now, a camera could 503 00:30:41,600 --> 00:30:45,600 Speaker 1: have an array of micro bolometers acting like the pixels 504 00:30:45,680 --> 00:30:49,400 Speaker 1: in a digital camera. The camera would bring in infrared 505 00:30:49,520 --> 00:30:53,240 Speaker 1: light just as it would light in a visible spectrum, 506 00:30:53,280 --> 00:30:55,280 Speaker 1: and it would aim that light to an array of 507 00:30:55,360 --> 00:30:59,200 Speaker 1: micro bilometers, just like it would an image sensor in 508 00:30:59,240 --> 00:31:03,520 Speaker 1: a digital camera, and the microprocessor would take the information 509 00:31:03,600 --> 00:31:07,560 Speaker 1: coming from these micro bolometers and interpret it as differences 510 00:31:07,640 --> 00:31:10,560 Speaker 1: in temperature, which in turn could be communicated to the 511 00:31:10,640 --> 00:31:14,040 Speaker 1: user as different colors and levels of brightness to indicate 512 00:31:14,040 --> 00:31:16,760 Speaker 1: which parts of an image were the warmest or coolest. 513 00:31:17,400 --> 00:31:21,000 Speaker 1: I'll talk a bit more about cooled thermal detectors after 514 00:31:21,040 --> 00:31:31,720 Speaker 1: the break. Cooled thermal cameras work on a different principle 515 00:31:31,920 --> 00:31:36,280 Speaker 1: from the micro bilometers. Remember a bolometer describes the technology 516 00:31:36,320 --> 00:31:39,880 Speaker 1: in which a component changes its electrical resistance in response 517 00:31:39,920 --> 00:31:43,200 Speaker 1: to a change in temperature. Measuring that change in electrical 518 00:31:43,240 --> 00:31:47,280 Speaker 1: resistance tells you how much infrared radiation the sensor has encountered. 519 00:31:47,880 --> 00:31:54,360 Speaker 1: Cooled thermal sensors respond to individual photons of infrared light. Yeah, 520 00:31:54,440 --> 00:31:56,800 Speaker 1: just because we can't see it doesn't mean that the 521 00:31:56,840 --> 00:32:00,840 Speaker 1: photons aren't there. So these sensors are sometimes referred to 522 00:32:00,960 --> 00:32:06,040 Speaker 1: as photon counters. These are incredibly precise sensors that can 523 00:32:06,040 --> 00:32:10,400 Speaker 1: detect single photons colliding with them. They might then generate 524 00:32:10,440 --> 00:32:12,920 Speaker 1: what's called a t t L pulse. T t L 525 00:32:12,960 --> 00:32:16,240 Speaker 1: stands for transistor to transistor logic. You can think of 526 00:32:16,280 --> 00:32:19,720 Speaker 1: it as a little digit counter clicker. The sensor picks 527 00:32:19,800 --> 00:32:22,920 Speaker 1: up on a photon collision. There's a clique. It has 528 00:32:23,200 --> 00:32:26,600 Speaker 1: a register to hit. In other words, if it registers 529 00:32:26,600 --> 00:32:29,080 Speaker 1: many hits in a short amount of time, that can 530 00:32:29,120 --> 00:32:33,600 Speaker 1: relate back to intensity, meaning you've found something pretty hot. 531 00:32:34,120 --> 00:32:37,800 Speaker 1: It's super nifty stuff. Others might take a photon and 532 00:32:37,840 --> 00:32:41,840 Speaker 1: generate an electron As a result, that electron would get 533 00:32:41,880 --> 00:32:45,479 Speaker 1: stored in a capacitor and it honestly gets super duper 534 00:32:45,520 --> 00:32:49,840 Speaker 1: technical and also gets beyond my level of familiarity pretty quickly. 535 00:32:50,120 --> 00:32:52,680 Speaker 1: Suffice it to say that this approach is not quite 536 00:32:52,720 --> 00:32:55,880 Speaker 1: the same thing as using a bolometer. There are photon 537 00:32:56,000 --> 00:32:58,800 Speaker 1: counters for all sorts of frequencies of light, not just 538 00:32:58,880 --> 00:33:03,000 Speaker 1: the infrared spectrum, but obviously I are or infrared, that's 539 00:33:03,000 --> 00:33:05,320 Speaker 1: what we're interested in for our topic, So let's get 540 00:33:05,320 --> 00:33:09,320 Speaker 1: back to these cooled thermal sensors. Cameras using the photon 541 00:33:09,520 --> 00:33:13,840 Speaker 1: counting methodology have very short response times, which in turn 542 00:33:13,880 --> 00:33:17,320 Speaker 1: allows for faster frame rates of video, so you get 543 00:33:17,400 --> 00:33:21,600 Speaker 1: better video output than you would with an uncooled system. 544 00:33:21,680 --> 00:33:24,840 Speaker 1: These cameras also have a greater level of sensitivity and 545 00:33:24,920 --> 00:33:28,360 Speaker 1: can be more easily used to detect small differences in 546 00:33:28,360 --> 00:33:31,560 Speaker 1: temperature within the field of view. They're also better at 547 00:33:31,600 --> 00:33:35,920 Speaker 1: detecting thermal output from small objects and depicting those small 548 00:33:35,920 --> 00:33:39,360 Speaker 1: shapes on camera in an accurate way, as opposed to 549 00:33:39,840 --> 00:33:42,800 Speaker 1: an uncooled system, where if it's a small object that's 550 00:33:42,800 --> 00:33:45,160 Speaker 1: giving out heat, chances are you're just going to see 551 00:33:45,160 --> 00:33:49,400 Speaker 1: an unidentifiable blob of color representing that smaller object. You 552 00:33:49,400 --> 00:33:51,520 Speaker 1: wouldn't be able to see what the thing was. You 553 00:33:51,520 --> 00:33:53,680 Speaker 1: would have a rough idea of how warm or cold 554 00:33:53,720 --> 00:33:55,960 Speaker 1: it was with respect to the other things in the environment. 555 00:33:56,000 --> 00:33:59,600 Speaker 1: But that's about it. The cooled cameras come with some 556 00:33:59,720 --> 00:34:02,520 Speaker 1: this advantages. First of all, they tend to be more 557 00:34:02,560 --> 00:34:08,360 Speaker 1: expensive than uncooled systems, so that's a downside. And also 558 00:34:08,800 --> 00:34:11,440 Speaker 1: that has to do partly with the fact that you've 559 00:34:11,480 --> 00:34:15,560 Speaker 1: got a sensor that has to remain cryogenically cooled, and 560 00:34:15,560 --> 00:34:18,560 Speaker 1: that in term requires special considerations and often a good 561 00:34:18,600 --> 00:34:22,160 Speaker 1: deal of energy. It makes the cooled systems unsuitable for 562 00:34:22,239 --> 00:34:25,480 Speaker 1: certain use cases like normal glasses, because I don't know 563 00:34:25,520 --> 00:34:27,480 Speaker 1: about you, but I'm not too eager to put on 564 00:34:27,520 --> 00:34:34,239 Speaker 1: a cryogenically cooled headset anytime soon. In a little film 565 00:34:34,280 --> 00:34:37,719 Speaker 1: called Predator came out and it taught us that I 566 00:34:37,800 --> 00:34:42,520 Speaker 1: don't got time to bleed, Okay. In that movie, a 567 00:34:42,560 --> 00:34:47,120 Speaker 1: group of mercenaries, including the iconic Arnold Schwarzenegger, although I 568 00:34:47,200 --> 00:34:52,400 Speaker 1: just I just quoted the equally iconic Jesse the body Ventura. Anyway, 569 00:34:52,440 --> 00:34:55,240 Speaker 1: they end up becoming the targets of a planet trotting 570 00:34:55,360 --> 00:34:59,680 Speaker 1: big game hunter alien, the titular Predator, and we get 571 00:34:59,719 --> 00:35:02,880 Speaker 1: treat did to Predator vision a few times where we 572 00:35:02,920 --> 00:35:05,960 Speaker 1: see the world from the perspective of this alien, and 573 00:35:06,000 --> 00:35:09,880 Speaker 1: that includes heat vision. Schwarzenegger helps avoid the predator at 574 00:35:09,920 --> 00:35:12,920 Speaker 1: one point by coating himself in mud to disguise his 575 00:35:12,960 --> 00:35:16,920 Speaker 1: heat signature. That would only work for a short while 576 00:35:17,480 --> 00:35:20,560 Speaker 1: because the thermal sensors initially would just pick up on 577 00:35:20,640 --> 00:35:23,640 Speaker 1: the temperature of the mud, not the person under it, 578 00:35:24,000 --> 00:35:27,319 Speaker 1: but your body heat would gradually raise the temperature of 579 00:35:27,360 --> 00:35:30,200 Speaker 1: the mud to your own temperature, so soon you would 580 00:35:30,239 --> 00:35:33,319 Speaker 1: just be a muddy, warm mess, and then shortly after 581 00:35:33,360 --> 00:35:37,759 Speaker 1: that you'd become predator trophy material. Thermal cameras can see 582 00:35:37,800 --> 00:35:42,360 Speaker 1: through stuff like smoke pretty effectively, and firefighters have used 583 00:35:42,440 --> 00:35:45,760 Speaker 1: thermal cameras when entering smoke filled areas to help rescue 584 00:35:45,800 --> 00:35:50,399 Speaker 1: people from dangerous situations. Uh, thermal cameras don't work so 585 00:35:50,480 --> 00:35:54,080 Speaker 1: well in fog and rain because water droplets can scatter 586 00:35:54,200 --> 00:35:57,520 Speaker 1: infrared radiation makes it harder to get a clear image. 587 00:35:57,760 --> 00:36:00,640 Speaker 1: That being said, in certain rainy can sans they can 588 00:36:00,680 --> 00:36:04,239 Speaker 1: be more effective than visible light sensors, so while it's 589 00:36:04,239 --> 00:36:07,840 Speaker 1: not ideal, it's still an improvement over other methods in 590 00:36:07,880 --> 00:36:12,000 Speaker 1: several cases. On top of that, you've got glass. Glass 591 00:36:12,120 --> 00:36:16,400 Speaker 1: is highly reflective for light in the infrared range. Visible 592 00:36:16,480 --> 00:36:20,000 Speaker 1: light can pass through transparent glass no problem, so you 593 00:36:20,040 --> 00:36:22,320 Speaker 1: can see on the other side of a transparent pane 594 00:36:22,320 --> 00:36:26,560 Speaker 1: of glass, but infrared light bounces off that glass like 595 00:36:26,600 --> 00:36:29,640 Speaker 1: it's a mirror. So if you take a thermal image 596 00:36:29,680 --> 00:36:33,160 Speaker 1: of someone who's wearing glasses, you'll see that the lenses 597 00:36:33,200 --> 00:36:36,120 Speaker 1: are just these solid shapes of color. You can't see 598 00:36:36,160 --> 00:36:38,360 Speaker 1: through them. You will be able to see the person's 599 00:36:38,400 --> 00:36:42,760 Speaker 1: eyes because of that reflectivity. Highly reflective surfaces in general 600 00:36:42,920 --> 00:36:46,759 Speaker 1: are a problem. Shiny metal can reflect infrared radiation, which 601 00:36:46,800 --> 00:36:49,520 Speaker 1: means it can be hard to use thermal sensors if 602 00:36:49,560 --> 00:36:53,080 Speaker 1: you want to monitor, say, machinery for signs of overheating. 603 00:36:53,480 --> 00:36:55,760 Speaker 1: One cool thing you can do, and there are great 604 00:36:55,800 --> 00:36:59,280 Speaker 1: photos of people doing this online, is take a photo 605 00:36:59,360 --> 00:37:03,080 Speaker 1: of something warm, like I don't know, your foot inside 606 00:37:03,160 --> 00:37:05,880 Speaker 1: an opaque plastic bag, I mean still attached to you. 607 00:37:05,960 --> 00:37:09,600 Speaker 1: Don't don't remove your foot, but like put a plastic 608 00:37:09,600 --> 00:37:13,000 Speaker 1: bag like a garbage bag or a bin liner, as 609 00:37:13,120 --> 00:37:16,040 Speaker 1: my buddies across the pond would say, around your foot. 610 00:37:16,120 --> 00:37:19,719 Speaker 1: So this is opaque. You cannot see through it, as 611 00:37:19,760 --> 00:37:23,120 Speaker 1: long as that plastic isn't too thick. However, the infrared 612 00:37:23,200 --> 00:37:26,920 Speaker 1: light will pass right through. Visible light gets blocked so 613 00:37:26,960 --> 00:37:30,240 Speaker 1: you can't see your foot, but that infrared radiation passes 614 00:37:30,280 --> 00:37:33,560 Speaker 1: straight through the bag, and a thermal imaging camera can 615 00:37:33,600 --> 00:37:36,040 Speaker 1: still see your foot just fine. Inside of it. You 616 00:37:36,040 --> 00:37:39,239 Speaker 1: also get this kind of nifty halo effect too. The 617 00:37:39,280 --> 00:37:43,680 Speaker 1: Predator film helped bring thermal imaging cameras into the mainstream consciousness, 618 00:37:43,920 --> 00:37:47,320 Speaker 1: but the equipment was still pretty expensive, so you weren't 619 00:37:47,360 --> 00:37:51,960 Speaker 1: likely to find it outside of some limited commercial uses, 620 00:37:52,040 --> 00:37:55,640 Speaker 1: and in the military, firefighters were using it. Heavy industry 621 00:37:55,680 --> 00:37:57,640 Speaker 1: was starting to use it. It would take a while 622 00:37:57,680 --> 00:38:01,360 Speaker 1: for the price to come down enough for inspectors to 623 00:38:01,440 --> 00:38:04,040 Speaker 1: be able to use it, for example. But these days 624 00:38:04,280 --> 00:38:08,080 Speaker 1: thermal cameras and smartphone thermal camera accessories are far more 625 00:38:08,080 --> 00:38:12,080 Speaker 1: accessible than the early days of thermal imaging. It's still 626 00:38:12,120 --> 00:38:15,799 Speaker 1: a relatively expensive technology. You're typically looking at a few 627 00:38:15,840 --> 00:38:20,560 Speaker 1: hundred dollars for a basic thermal imaging camera, probably more 628 00:38:20,560 --> 00:38:24,400 Speaker 1: than a thousand for something of really decent quality, and 629 00:38:24,520 --> 00:38:27,280 Speaker 1: far more than that if you want something of professional quality. 630 00:38:27,600 --> 00:38:30,359 Speaker 1: But that's still an incredible step down in price from 631 00:38:30,360 --> 00:38:32,880 Speaker 1: what it used to be, and when you think about 632 00:38:32,880 --> 00:38:36,240 Speaker 1: everything that has to happen to make thermal imaging possible, 633 00:38:36,480 --> 00:38:40,040 Speaker 1: from detecting heat to measuring intensity to translating that into 634 00:38:40,080 --> 00:38:43,040 Speaker 1: something we can see, all in real time. It's a 635 00:38:43,040 --> 00:38:45,360 Speaker 1: heck of a thing. One thing I wanted to close 636 00:38:45,440 --> 00:38:48,440 Speaker 1: this with is the concept of active I R sensors. 637 00:38:48,680 --> 00:38:52,600 Speaker 1: I've really been talking about passive I R sensors, which detect, measure, 638 00:38:52,640 --> 00:38:56,319 Speaker 1: and display thermal information from the environment. It's coming from 639 00:38:56,400 --> 00:39:00,400 Speaker 1: the environment itself, but there are also active thermal sensors 640 00:39:00,400 --> 00:39:04,600 Speaker 1: which both detect and project infrared radiation. So why do 641 00:39:04,680 --> 00:39:06,960 Speaker 1: they do that? Well, think of it kind of like 642 00:39:07,080 --> 00:39:10,319 Speaker 1: using a flashlight, except the light you're giving off is 643 00:39:10,360 --> 00:39:13,520 Speaker 1: in the infrared spectrum, so we humans can't see that 644 00:39:13,640 --> 00:39:16,920 Speaker 1: light unaided. So you might use something like this and say, 645 00:39:17,280 --> 00:39:21,279 Speaker 1: I don't know, a nighttime military operation, so that no 646 00:39:21,320 --> 00:39:23,920 Speaker 1: one would be the wiser, and you have people snooping 647 00:39:23,960 --> 00:39:28,400 Speaker 1: around using these infrared flashlights and infrared sensors to be 648 00:39:28,480 --> 00:39:31,719 Speaker 1: able to look at their environments in the dark. You 649 00:39:31,760 --> 00:39:34,600 Speaker 1: would have the thermal sensor system, perhaps mounted in a 650 00:39:34,719 --> 00:39:38,080 Speaker 1: head display. Inside that system would be the projector that 651 00:39:38,160 --> 00:39:41,200 Speaker 1: sends out those infrared rays, and then the detector that 652 00:39:41,320 --> 00:39:45,680 Speaker 1: picks up the reflected incoming infrared rays. It's just like 653 00:39:45,760 --> 00:39:48,600 Speaker 1: visible light. When the infrared rays come out of the projector, 654 00:39:48,719 --> 00:39:51,880 Speaker 1: when they hit something, they reflect off and then the 655 00:39:51,920 --> 00:39:54,960 Speaker 1: sensor can pick up that reflection and then you get 656 00:39:55,000 --> 00:40:00,440 Speaker 1: the redoubt in your display or the visualization in your display. Uh. 657 00:40:00,840 --> 00:40:04,720 Speaker 1: That would work pretty well unless the person you're snooping 658 00:40:04,760 --> 00:40:08,799 Speaker 1: around also happens to have thermal imaging sensors, because then 659 00:40:08,840 --> 00:40:12,719 Speaker 1: they would see that beam coming out from your system 660 00:40:12,719 --> 00:40:14,880 Speaker 1: as if it were a flashlight beam. They would be 661 00:40:14,880 --> 00:40:18,359 Speaker 1: picked up. Active i R systems are used in lots 662 00:40:18,440 --> 00:40:22,440 Speaker 1: of applications, such as in robotics. Many robots have active 663 00:40:22,480 --> 00:40:24,880 Speaker 1: i R sensors in them as a way to avoid 664 00:40:24,920 --> 00:40:29,880 Speaker 1: hitting obstacles. The projector sends out an infrared ray, and 665 00:40:29,960 --> 00:40:32,839 Speaker 1: the sensor is looking out for infrared radiation in that 666 00:40:32,960 --> 00:40:36,520 Speaker 1: same frequency band and above some sort of threshold. So 667 00:40:36,600 --> 00:40:40,320 Speaker 1: not just like a tiny indicator has to hit above 668 00:40:40,400 --> 00:40:43,440 Speaker 1: that for the robot to think, oh, there's something in 669 00:40:43,480 --> 00:40:46,800 Speaker 1: my way. So when the sensor detects radiation at or 670 00:40:46,880 --> 00:40:49,879 Speaker 1: above that threshold, it sends a signal that then gets 671 00:40:49,920 --> 00:40:52,920 Speaker 1: acted upon in some way by the robot. An easy 672 00:40:52,920 --> 00:40:56,360 Speaker 1: example This is a robotic vacuum cleaner that starts to 673 00:40:56,400 --> 00:40:58,880 Speaker 1: approach a wall, and then when it gets to a 674 00:40:58,920 --> 00:41:03,120 Speaker 1: certain distance, it's close enough where the infrared radiation coming 675 00:41:03,160 --> 00:41:05,840 Speaker 1: from its projector bounces off the wall and gets picked 676 00:41:05,840 --> 00:41:08,799 Speaker 1: back up by the sensor that tells the robot to 677 00:41:08,840 --> 00:41:12,680 Speaker 1: stop moving forward, to turn and move in a different direction. 678 00:41:13,560 --> 00:41:18,880 Speaker 1: Tuning stuff to a particular infrared frequency helps avoid interference, 679 00:41:18,920 --> 00:41:22,320 Speaker 1: so not just like any infrared ray, but rather within 680 00:41:22,360 --> 00:41:24,919 Speaker 1: this narrow band that's what it's looking for, so it's 681 00:41:24,920 --> 00:41:30,160 Speaker 1: not likely to uh to misidentify another infrared source as 682 00:41:30,200 --> 00:41:35,000 Speaker 1: being a problem. The Microsoft Connect Xbox per referral also 683 00:41:35,120 --> 00:41:39,840 Speaker 1: uses a similar implementation of infrared active sensors to sense depth. 684 00:41:40,560 --> 00:41:44,240 Speaker 1: This sensor includes a near infrared projector, so it's near 685 00:41:44,280 --> 00:41:47,600 Speaker 1: infrared beams. Those are the beams that are still invisible 686 00:41:47,640 --> 00:41:50,120 Speaker 1: to us but are closer to the red side of 687 00:41:50,160 --> 00:41:53,040 Speaker 1: the visible light spectrum, and they can be detected by 688 00:41:53,040 --> 00:41:57,040 Speaker 1: standard digital camera sensors. So the projector and sensors work 689 00:41:57,080 --> 00:42:00,279 Speaker 1: together to measure the time of flight. That it's the 690 00:42:00,360 --> 00:42:03,799 Speaker 1: moment the light leaves the projector to the moment when 691 00:42:03,800 --> 00:42:07,040 Speaker 1: a sensor picks it up and then working backward by 692 00:42:07,080 --> 00:42:09,319 Speaker 1: knowing how long it took the light to go out 693 00:42:09,360 --> 00:42:12,200 Speaker 1: and come back. You know how far things are because 694 00:42:12,239 --> 00:42:14,640 Speaker 1: you know about the constant of the speed of light. 695 00:42:15,040 --> 00:42:17,799 Speaker 1: So the Microsoft system could determine how far away an 696 00:42:17,880 --> 00:42:21,759 Speaker 1: object is, like the player from from the sensor. So 697 00:42:21,920 --> 00:42:24,840 Speaker 1: this gives developers the option to include depth as a 698 00:42:24,880 --> 00:42:28,560 Speaker 1: factor in games and applications that use the connect. So 699 00:42:28,719 --> 00:42:31,560 Speaker 1: you wouldn't just have stuff that relies on movement within 700 00:42:31,640 --> 00:42:34,279 Speaker 1: the two dimensional plane of up and down and left 701 00:42:34,280 --> 00:42:36,480 Speaker 1: and right. It would also take in the third dimension 702 00:42:36,719 --> 00:42:40,920 Speaker 1: of closer to or further from the connect. Now, I 703 00:42:40,960 --> 00:42:43,800 Speaker 1: want you guys to know there's a lot of super 704 00:42:43,880 --> 00:42:46,799 Speaker 1: technical stuff that I skipped over in this episode. There 705 00:42:46,800 --> 00:42:49,680 Speaker 1: are things we could talk about with focal plane arrays 706 00:42:49,880 --> 00:42:53,520 Speaker 1: and various materials used over the years, and thermal sensors, 707 00:42:53,800 --> 00:42:55,520 Speaker 1: but I felt the important part was to get the 708 00:42:55,560 --> 00:42:59,640 Speaker 1: basic understanding down. I think that's pretty cool or hot. 709 00:43:00,480 --> 00:43:04,520 Speaker 1: I'm not sure which. I've misplaced my thermal glasses. And 710 00:43:04,560 --> 00:43:06,879 Speaker 1: as for using them to screen people, as I said, 711 00:43:06,920 --> 00:43:09,680 Speaker 1: it could be useful as a quick first pass for 712 00:43:09,719 --> 00:43:13,120 Speaker 1: anyone who happens to have an elevated body temperature, but 713 00:43:13,160 --> 00:43:17,399 Speaker 1: again that doesn't necessarily indicate a COVID nineteen infection. It's 714 00:43:17,440 --> 00:43:20,320 Speaker 1: not enough of a precautionary measure all on its own. 715 00:43:20,680 --> 00:43:23,359 Speaker 1: And that's not the fall of the technology. That tech 716 00:43:23,400 --> 00:43:27,719 Speaker 1: can be incredibly precise. It's rather that the risks go 717 00:43:27,880 --> 00:43:31,000 Speaker 1: beyond those who may just have a fever and like 718 00:43:31,160 --> 00:43:33,400 Speaker 1: that might not be someone with COVID nineteen, or you 719 00:43:33,480 --> 00:43:36,240 Speaker 1: might be overlooking people who do have COVID nineteen because 720 00:43:36,280 --> 00:43:39,319 Speaker 1: they don't actually have a fever. Yet that as long 721 00:43:39,360 --> 00:43:43,479 Speaker 1: as you overlook these possible vectors, infection will continue, which 722 00:43:43,480 --> 00:43:47,480 Speaker 1: is why we should never consider any one approach to 723 00:43:47,520 --> 00:43:51,480 Speaker 1: be sufficient. We have to take a combination of approaches 724 00:43:51,800 --> 00:43:56,080 Speaker 1: if we want to put protective measures in place. As always, 725 00:43:56,640 --> 00:43:59,680 Speaker 1: make sure you exercise critical thinking, give it a healthy 726 00:43:59,719 --> 00:44:04,560 Speaker 1: dose of compassion, because without compassion, critical thinking is just 727 00:44:05,040 --> 00:44:08,799 Speaker 1: cold and heartless. You gotta have both, and if you're 728 00:44:08,840 --> 00:44:11,560 Speaker 1: able to apply both of them, then I think things 729 00:44:11,600 --> 00:44:15,240 Speaker 1: will be okay. If you guys have suggestions for future 730 00:44:15,239 --> 00:44:18,640 Speaker 1: episodes of tech stuff, whether it's a technology, a company, 731 00:44:19,120 --> 00:44:22,080 Speaker 1: a trend in tech, anything like that, let me know. 732 00:44:22,320 --> 00:44:24,160 Speaker 1: Reach out to me. You can get in touch with 733 00:44:24,200 --> 00:44:27,080 Speaker 1: me on Twitter or Facebook to handle for both is 734 00:44:27,160 --> 00:44:30,080 Speaker 1: tech Stuff h s W and I'll talk to You 735 00:44:30,120 --> 00:44:39,040 Speaker 1: again really soon. Tex Stuff is an I Heart Radio production. 736 00:44:39,280 --> 00:44:42,120 Speaker 1: For more podcasts from My Heart Radio, visit the i 737 00:44:42,239 --> 00:44:45,440 Speaker 1: Heart Radio app, Apple Podcasts, or wherever you listen to 738 00:44:45,480 --> 00:44:46,440 Speaker 1: your favorite shows.