Speaker 1: Welcome to tech Stuff, a production from iHeartRadio. Hey there,
Speaker 1: and welcome to tech Stuff. I'm your host, Jonathan Strickland.
Speaker 1: I'm an executive producer with iHeart Podcasts and How the
Speaker 1: Tech Are You. It's a Friday. It's time for a
Speaker 1: tech Stuff Classics episode, and that means we go back
Speaker 1: into our archives and pick an episode to play for
Speaker 1: your pleasure. This one originally published way back on June fourteenth,
Speaker 1: twenty seventeen. It has the wonderful title Pew Pew Lasers Enjoy.
Speaker 1: So we're going to talk about some pretty high tech
Speaker 1: stuff today. Actually, I'm going to look at a topic
Speaker 1: that we first addressed way back in twenty eleven with
Speaker 1: the episode how Lasers Work. That's when Chris Palette, my
Speaker 1: original co host, and I sat down and we talked
Speaker 1: about a little bit of the history of lasers and
Speaker 1: how they actually operate. But I thought it'd be better
Speaker 1: to revisit this, explain it again, kind of take a
Speaker 1: different approach to it. So, lasers are awesome and they
Speaker 1: can do tons of different stuff. Right. We can do
Speaker 1: everything from having a little laser pointer to amuse ourselves
Speaker 1: and our pets to having a laser element inside optical
Speaker 1: drive so that we can read information that's been stored
Speaker 1: on a disc. To communications satellites, to propelling spacecraft to
Speaker 1: cutting steel. There's all sorts of things we can do
Speaker 1: with lasers. Oh, we can threaten our enemies. We can
Speaker 1: tie them up and put them on a slab and
Speaker 1: then slowly have a laser creep upward and then laugh
Speaker 1: maniacally as we expect mister Bond to die. We can
Speaker 1: do all that sort of stuff with lasers. So we're
Speaker 1: going to talk about what they are, what they can do,
Speaker 1: their history, and maybe some cool trivia about lasers as well,
Speaker 1: and laser related stuff. So let's get to it now.
Speaker 1: First of all, what is the technical definition of a laser? Well,
Speaker 1: a laser is an acronym that means that it's a
Speaker 1: word that's made up of the initials of other words, right,
Speaker 1: so it stands for light amplification by stimulated emission of radiation.
Speaker 1: But for most of us that doesn't really clear things up.
Speaker 1: That just raises other questions like what do they mean
Speaker 1: by stimulated emission of radiation? And how do you amplify light?
Speaker 1: So I'm going to go in talk about all of
Speaker 1: that kind of stuff because it's really fascinating. It involves
Speaker 1: a lot of science and technology, two things I love
Speaker 1: to talk about. The third thing obviously being Chaucer's Canterbury
Speaker 1: tails one that I plicate with the shoulder asuta, but
Speaker 1: that does not really fit with lasers. They didn't have
Speaker 1: the laser's tail, so we're gonna skip Cannabar retails for
Speaker 1: this episode. Now, a laser is a device that produces
Speaker 1: a very narrow beam of light, and these beams are monochromatic.
Speaker 1: That means they are single color see single wavelength. That's
Speaker 1: a very specific wavelength of light for each laser and
Speaker 1: thus a specific color. So we perceive different wavelengths of
Speaker 1: light as different colors of light. So if you think
Speaker 1: of your roy GVIV, that is actually a spectrum literally
Speaker 1: a spectrum of colors. That's also a spectrum of wavelengths,
Speaker 1: with red being the longest wavelength and violet being the
Speaker 1: shortest wavelength. In the visible spectrum. The wavelength of light
Speaker 1: depends entirely on the amount of energy electrons release within
Speaker 1: the laser itself. So electrons release energy and in the
Speaker 1: form of photons or light particles, and the color of
Speaker 1: laser you get depends upon the amount of energy those
Speaker 1: electrons are releasing, and the amount of energy they release
Speaker 1: is dependent upon the type of atoms that they are
Speaker 1: connected to, because it all has to do with orbits
Speaker 1: of electrons around nuclei. More on that in a second.
Speaker 1: So the light is also coherent. Now, that does not
Speaker 1: mean it is able to hold a conversation and make
Speaker 1: salient points. It's not that kind of co parent. It
Speaker 1: means that the light is made up of organized photons.
Speaker 1: Organized photons in this case means that they're all traveling
Speaker 1: the same pattern of wavelength that are all in the
Speaker 1: same page as it were. If you look at wavelength,
Speaker 1: if you were to draw a series of waves, they
Speaker 1: would all be lined up exactly, so all the crests
Speaker 1: and the troughs would be lined up along the same points.
Speaker 1: At any point along the wavelength, they would match entirely.
Speaker 1: So that is what we mean by coherent. It's what
Speaker 1: helps keep the light organized and moving in that specific
Speaker 1: direction you want it to. And the light is also directional.
Speaker 1: That means the beam is tight and concentrated and remains
Speaker 1: so over great distances. You don't get a lot of
Speaker 1: light diverging from that pathway, and some lasers are able
Speaker 1: to project for miles in miles, like hundreds of thousands
Speaker 1: of miles in some cases, or without having any kind
Speaker 1: of degradation of the beam, which is kind of cool.
Speaker 1: I mean, it's amazingly cool. Now you can trast that
Speaker 1: with something like a flashlight. Flashlights have a beam that
Speaker 1: spreads out as it travels out we're from its source,
Speaker 1: it diffuses, so it's different from a laser. It doesn't
Speaker 1: have the coherence that a laser would have. This is
Speaker 1: typical of most light sources. You don't find lasers in nature.
Speaker 1: Lasers are something that we have caused to happen because
Speaker 1: of the natural laws. If it weren't for the natural laws,
Speaker 1: lasers wouldn't work. Obviously we didn't create that out of
Speaker 1: whole cloth. But it doesn't spontaneously happen in nature because
Speaker 1: you have to have very specific parameters set up in
Speaker 1: order to generate a laser beam. Now, to understand why
Speaker 1: it works the way it does, it helps to know
Speaker 1: how light works. Now, light behaves both as a wave
Speaker 1: and a particle, but for this bit of the explanation,
Speaker 1: we're mostly concerned with wave physics, even though we'll be
Speaker 1: talking about photons, the basic unit of light, the basic
Speaker 1: particle of light a lot in this episode. So a
Speaker 1: light source gives off waves of light, and different colors
Speaker 1: of light have different wavelengths. Like I said, you know,
Speaker 1: those red wavelengths are longer than the orange ones, Infrared
Speaker 1: waves are even longer, Ultraviolet are even shorter than violet,
Speaker 1: So you've got that different spectrum of wavelengths there. When
Speaker 1: you get down to that violet, you're really looking at
Speaker 1: the shortest wavelengths that we can perceive before it just
Speaker 1: becomes invisible to us. So again ultraviolet, we can't see that.
Speaker 1: Certain classes in dungeons and dragons different They can see ultravioletlight,
Speaker 1: not the rest of us. So these waves travel typically
Speaker 1: out of phase from each other from normal light sources.
Speaker 1: So again, if you were to chart those wavelengths, the
Speaker 1: crests and valleys would of each individual photon wouldn't match
Speaker 1: up right, like the crest of one might be matched
Speaker 1: with the valley of another or somewhere else along its waylength.
Speaker 1: They wouldn't be moving in phase, they'd be out of phase.
Speaker 1: So lasers all line up those light waves at the
Speaker 1: same way. So that they are in phase. And that's
Speaker 1: what we mean when we say coherent, that the various
Speaker 1: photons are all in phase with one another. And the
Speaker 1: way you generate lasers makes this happen. It's kind of cool.
Speaker 1: We'll talk about that again a little bit later. But
Speaker 1: all of the photons in the beam have unified wave fronts,
Speaker 1: so they're all moving in exactly the same wavelength at
Speaker 1: exactly the same time. Now, to understand how all of
Speaker 1: this works, it takes a looking at atoms. We have
Speaker 1: to go back to basic science. So let's take a
Speaker 1: look at an atom. Now. Back in the day when
Speaker 1: I was in school, atoms were depicted as being kind
Speaker 1: of like the orbits of planets, where you would have
Speaker 1: a nucleus in the center, kind of like the Sun,
Speaker 1: and electrons would orbit in neat little circles around at
Speaker 1: specific distances from the nucleus. As it turns out, things
Speaker 1: aren't quite so neat, and simple electrons are in an
Speaker 1: electron cloud that are around the nucleus. It is impossible
Speaker 1: to say with complete certainty where an electron is at
Speaker 1: any given moment. You know, you can know a position
Speaker 1: of an electron, but not it's direction. Or vice versa
Speaker 1: with complete certainty. Heisenberg's n certainty principle is a fun thing.
Speaker 1: But you know, when you have a basic atom and
Speaker 1: you haven't added any energy to the atom in its
Speaker 1: ground state energy level, that's when it's just, you know,
Speaker 1: kind of chilling. Atoms are always in motion. You only
Speaker 1: get atoms in no motion at all at absolute zero,
Speaker 1: when you're at zero kelvin. That is when you have
Speaker 1: zero atomic movement. But otherwise, atoms are always in motion.
Speaker 1: Even in solid objects, they're just not moving a lot.
Speaker 1: When you add energy to atoms, they move more. They
Speaker 1: start to get energized. When you energize atoms enough, you
Speaker 1: can boost them to an excited level. Now, typically you
Speaker 1: do this by applying energy like heat, light or electricity
Speaker 1: to the atom, Whereas if you want to excite me,
Speaker 1: you just say, hey, they might be giants's coming to town.
Speaker 1: You want to go see them? And I'm like, yeah, totally.
Speaker 1: So you've got atom which consists of that nucleus, and
Speaker 1: you've got the electron cloud around it. When you apply energy,
Speaker 1: it causes the electrons to move to a higher orbit
Speaker 1: around that nucleus. Again, since we're talking about a cloud,
Speaker 1: and not just a simple orbit circle. You can think
Speaker 1: of it as meaning the electrons move a little further
Speaker 1: away from the nucleus. If you add enough energy, you
Speaker 1: can strip electrons away from the atom entirely. This will
Speaker 1: create a charged atom because you will now have an ion.
Speaker 1: It's going to have a net positive charge because you're
Speaker 1: going to have protons there and you've pulled away some
Speaker 1: of the electrons, so you've taken some of that balance out.
Speaker 1: If you add enough electric enough energy, I was about
Speaker 1: to say electricity, but really energy. Electricity is one form
Speaker 1: of energy you could add to the atom in order
Speaker 1: to do this. But if you didn't add that much,
Speaker 1: like if you added enough to excite the electrons but
Speaker 1: not strip them away from the nucleus. When you remove
Speaker 1: that source of energy, the electrons will move back down
Speaker 1: to their ground state. They do not quote unquote want
Speaker 1: to be at that excited level. They have a ground
Speaker 1: state that they are naturally inclined to be at. But
Speaker 1: they've absorbed energy. So in order to move back down
Speaker 1: to their normal energy level, they have to give up
Speaker 1: some of the energy that they've absorbed, and they do
Speaker 1: this through emitting a photon. That basic unit of light,
Speaker 1: and once they emit that photon, that's what allows them
Speaker 1: to move back to their ground energy state because they
Speaker 1: no longer have that excess energy inside of themselves. So
Speaker 1: you can think of it as almost being like the
Speaker 1: electron is too full, like it's eaten too much, and
Speaker 1: then it has a little belchi belch or something it
Speaker 1: manages to emit some part of that energy. It is absorbed,
Speaker 1: and now it's feeling more like its old self again,
Speaker 1: and then you can just boost it back up again
Speaker 1: if you want to. So photons are emitted this way
Speaker 1: through in lasers, but that's not the only way we
Speaker 1: generate photons, like there are very specific ways of doing
Speaker 1: this in all sorts of applications, and many of them
Speaker 1: are pretty basic. Like your incandescent light bulb uses the
Speaker 1: same principle. You run an electric current through some wire
Speaker 1: a filament, typically in a vacuum sealed tube a bulb,
Speaker 1: and running the electric current causes the filament to heat
Speaker 1: up because as resistance to electrical current, so some of
Speaker 1: that electricity gets converted over into heat. As this heats up,
Speaker 1: it excites the atoms within that filament, and as that
Speaker 1: energy source moves through it allows those electrons to come
Speaker 1: back down, the atoms begin to emit photons, and then
Speaker 1: you get this glow. In the case of light bulbs,
Speaker 1: the glow creates the light you would have from an
Speaker 1: incandescent bulb. You could also see the same thing with
Speaker 1: heating elements, Like if you were to look inside a
Speaker 1: toaster and you see that orange glow, Well, that orange
Speaker 1: glow is coming from the heating elements that have had
Speaker 1: their atoms excited. The electrons got boosted to a higher
Speaker 1: energy level and then they came down and started releasing photons.
Speaker 1: So it's not just lasers that do this, but lasers
Speaker 1: take advantage of it in a very specific way. That's
Speaker 1: pretty cool. I am interrupting this laser focused episode, uh
Speaker 1: huh unintended in order for us to take a quick
Speaker 1: break to think our sponsors. So, a laser uses this
Speaker 1: principle to create those narrow beams of light. And here's
Speaker 1: how they do it. First, you need what is called
Speaker 1: a lasing medium. A laser medium, this is the stuff
Speaker 1: that you're going to use to excite. You know, you're
Speaker 1: gonna excite the atoms in this stuff so that it
Speaker 1: generates the wavelength of light that you want, and so
Speaker 1: the type of stuff you use that's going to determine
Speaker 1: the type of atoms that are present, which in turn
Speaker 1: determines the energy levels of the electrons, which in turn
Speaker 1: determines what color light you're gonna get through the lasing medium.
Speaker 1: All of this is dependent upon, ultimately the source of
Speaker 1: the lasing medium, like what is that material? The lasing
Speaker 1: medium acts like an amplifier, only this is for optics
Speaker 1: rather than for acoustics. So some people call the lasing
Speaker 1: medium the game medium or the source of optical gain
Speaker 1: because it's like a microphone gain setting. It is amplifying
Speaker 1: a signal, but in this case it's amplifying light, not
Speaker 1: amplifying sound. The gain in this case is that stimulated
Speaker 1: emission of photons I was talking about, and the emission
Speaker 1: is stimulated through an interesting series of events. You start
Speaker 1: by initially adding energy to the lasing medium, and then
Speaker 1: the photons it emits end up stimulating other atoms inside
Speaker 1: the lasing medium that have already been excited, and then
Speaker 1: you get a steady stream of photons that create your
Speaker 1: laser beam. But first you have to add energy into
Speaker 1: the system. You do this from what is called a
Speaker 1: pump source because you are pumping energy into the lasing medium.
Speaker 1: So basically, you pump energy into this medium, you excite
Speaker 1: some atoms. Those excited atoms start to emit photons. Those
Speaker 1: photons will start to hit other stimulated atoms and that's
Speaker 1: where you get this stimulated emission. So there are lots
Speaker 1: of different types of lasing media. So, for example, there
Speaker 1: are certain crystals that can serve as a medium. The
Speaker 1: earliest lasers were ruby lasers, so you would get a
Speaker 1: ruby crystal and that would be your lasing medium. You
Speaker 1: would usually introduce some impurities. It's called doping. You add
Speaker 1: some impurities to the material in order to make this
Speaker 1: a more efficient lasing medium. Usually it's some ions of
Speaker 1: some sort and that helps when you are actually getting
Speaker 1: to the part of generating a laser. Those are specifically
Speaker 1: solid state lasers, the ones that use crystals. You're using
Speaker 1: a solid lasing medium. But there are other ones as well.
Speaker 1: There's some that use glasses. Some that you gases, including
Speaker 1: reactive gases like chlorine and fluorine. Those are specific types
Speaker 1: of gas lasers that are called exemer lasers. You have
Speaker 1: semiconductor lasers, which produce in the grand scheme of things.
Speaker 1: Fairly weak lasers, but they also are fairly inexpensive to produce,
Speaker 1: and those are the ones that we use in things
Speaker 1: like CD players, DVD players, blu ray players, that kind
Speaker 1: of stuff. They tend to be semiconductor lasers. They're easy
Speaker 1: to mass produce, they're less expensive, and they aren't so
Speaker 1: powerful as to cause problems. You don't need a CD
Speaker 1: player laser that could burn a hole through the surface
Speaker 1: of the Earth. That would be ridiculous. You can also
Speaker 1: get liquid medium lasers. These are liquids that have various
Speaker 1: organic dyes, special organic dyes, dyes that will allow for
Speaker 1: this stimulated emission of light amplified light. Now, the pump
Speaker 1: is some sort of energy transfer that you use to
Speaker 1: excite those atoms in the first place, so that they'll
Speaker 1: emit those initial photons when the electrons calm the heck down.
Speaker 1: Laser pumps are some form of external source of energy. Typically,
Speaker 1: they supply energy in the form of either electricity or light,
Speaker 1: but there are other means of pumping a lasing medium
Speaker 1: with energy to create lasers. Light and electricity are the
Speaker 1: two most common ones, but they are not the only kinds.
Speaker 1: There are some that use chemical reactions. There are some
Speaker 1: that even use nuclear reactions, which I think is taking
Speaker 1: it a little far if you're asking me, that's me
Speaker 1: mostly being tongue in cheek. But again, most of the
Speaker 1: lasers that we would encounter throughout our day, those are
Speaker 1: generated either through light or through electricity stimulating the lasing medium. So,
Speaker 1: for example, most early lasers were using some form of
Speaker 1: arc or flash lamp to stack emulate that initial reaction
Speaker 1: within the atoms of the lasing medium, like a crystal rod.
Speaker 1: So you got your crystal rod with a few impurities
Speaker 1: in it that you have specifically placed in there. You
Speaker 1: have doped this crystal rod. You would wrap a light
Speaker 1: source around this thing, usually within some sort of mirrored chamber,
Speaker 1: and you would flash light in pulses against the lasing medium,
Speaker 1: and this would actually excite atoms within the medium, which
Speaker 1: would then give off photons. Now, if there were no
Speaker 1: way for you to keep this reaction going, it would
Speaker 1: be such a small emission of photons that you probably
Speaker 1: wouldn't even be able to tell you wouldn't it wouldn't
Speaker 1: be visible to you. However, by tricking it, you can
Speaker 1: totally make it visible. So you typically would use these
Speaker 1: mirrors to reflect light back into the lasing medium. That
Speaker 1: includes photons that were emitted during that initial flash, and
Speaker 1: that's what allows you to create a cascade effect and
Speaker 1: create a laser. Generally speaking, you would probably use mirrors
Speaker 1: that would allow the reflection of any wavelengths of light
Speaker 1: that were shorter than the laser's wavelength would be, and
Speaker 1: allow the transference of light that is longer wavelengths longer
Speaker 1: than the laser's wavelength that you want. The reason for
Speaker 1: that is that if you were to trap all the
Speaker 1: light within the chamber, you could cause things to heat
Speaker 1: up and create what's called thermal lensing. The actual change
Speaker 1: in temperature would create a lens effect that would end
Speaker 1: up affecting the ability of a laser to be directional
Speaker 1: and coherent. And obviously, if that's your intent, you don't
Speaker 1: want that to happen. So, yeah, Thermal lensing occurs when
Speaker 1: a sample absorbs energy from a laser beam, it heats up,
Speaker 1: it creates this refractive lens that causes beam divergence. That's
Speaker 1: not what you want with a laser typically, I mean
Speaker 1: you might want to design a system that creates that
Speaker 1: splits a beam but that's different from beam divergence. You
Speaker 1: want that beam to be nice and tight, typically or
Speaker 1: your average laser applications. So let's imagine that we're building
Speaker 1: a laser and we start with a rod made out
Speaker 1: of ruby. I was gonna say that you could have
Speaker 1: a ruby rod, but we all know that he is
Speaker 1: busy with Corbyn Dallas trying to save the universe. A
Speaker 1: shout out to any of you guys out there who
Speaker 1: understand what that reference means. So you've got ruby rod,
Speaker 1: and you've got a flash tube that is probably wrapped
Speaker 1: around the ruby rod, but at least is shining can
Speaker 1: shine on the ruby rod, and you can use the
Speaker 1: flash tube out of like a camera. In fact, the
Speaker 1: earliest lasers we're using camera flash bulbs as the source
Speaker 1: of light to start this reaction. It's not like it's
Speaker 1: something super high tech. It's actually pretty cool. And you've
Speaker 1: got a mirrored chamber that surrounds the whole thing on
Speaker 1: the on either end of the rod. So think of
Speaker 1: the rod as like a cylinder. You have put a
Speaker 1: silvered mirror on either end. One side is a pure
Speaker 1: silvered mirror, so it just reflects light. The other one
Speaker 1: is a partially silvered mirror, meaning that it can allow
Speaker 1: some light to pass through. Specifically, you want to design
Speaker 1: it so it allows the wavelength of the laser light
Speaker 1: to pass through, but doesn't allow any other light to
Speaker 1: pass through. You turn on the flash tube. This shines
Speaker 1: bright light onto the rod, which causes some of the
Speaker 1: atoms in the rod to excite. Then, as those electrons
Speaker 1: move back down from their excited stage back to the
Speaker 1: ground level stage, they release photons, and with enough energy
Speaker 1: pumped into the medium, you end up with a larger
Speaker 1: population of atoms that are in an excited state than
Speaker 1: there are atoms in the ground state. When you reach
Speaker 1: that point, it is called a population inversion because you've
Speaker 1: inverted the relationship between excited atoms and ground state atoms.
Speaker 1: Typically you would have more ground state atoms than excited ones.
Speaker 1: Once you're able to flip that balance, you can create
Speaker 1: this cascading effect that I've been talking about. So you've
Speaker 1: got more excited atoms than you have ground energy level
Speaker 1: atoms inside of this lazing medium. At that point they
Speaker 1: start giving off photons, and this is pretty cool. What
Speaker 1: happens next is photons from some of those first atoms
Speaker 1: that had been excited and then were calming down. If
Speaker 1: you like, they'll go out and they'll hit other excited atoms.
Speaker 1: So these are atoms that I've already had their energy
Speaker 1: levels boosted by that flash bulb. The photon from the
Speaker 1: first atom, the one that excited and calmed down, has
Speaker 1: just the right amount of energy to cause the electron
Speaker 1: in an excited atom to come back down to its
Speaker 1: ground state and release another photon. So what happens is
Speaker 1: the atom that it it connects with will absorb the photon,
Speaker 1: then it will emit the photon and emit a second
Speaker 1: photon as its own electron comes down an energy level.
Speaker 1: So you get two photons emitted, the initial one that
Speaker 1: you shot the atom with and then the one that
Speaker 1: that atom produced itself. So this is what is called
Speaker 1: light amplification. Right, you have amplified the light. You started
Speaker 1: with one photon. Now you have two photons and they're
Speaker 1: moving in phase with one another because well, because of
Speaker 1: quantum physics, but I don't want to get into that
Speaker 1: too much. So you get this light amplification through that process.
Speaker 1: Now that you have the light amplification, you might as
Speaker 1: well say, like, well, what are we calling this this
Speaker 1: whole process where a photon can cause another atom to
Speaker 1: emit a photon. That's the stimulated emission. You might think
Speaker 1: stimulated emission was when you turned on the flash bulb.
Speaker 1: That's not technically correct. The stimulated emission part technically comes
Speaker 1: from these initial atoms that release photons, and those cause
Speaker 1: this chain reaction in the lasing medium. So this can
Speaker 1: happen over and over and over again. Right, you're not
Speaker 1: really the atoms aren't losing any matter in this. It's
Speaker 1: just a process of electrons being boosted up to an
Speaker 1: energy level and then coming back down again, so they're
Speaker 1: releasing energy. They're not losing anything in this. It's just
Speaker 1: a transfer of energy and really a transformation of it
Speaker 1: from one form of light to another. So it's fascinating
Speaker 1: to me that this is something that not only works,
Speaker 1: but that people were able to figure out would work.
Speaker 1: It's so far into quantum physics and optics and photonics
Speaker 1: that I am amazed that people figured this out. In fact,
Speaker 1: they figured it out way back at the beginning of
Speaker 1: the twentieth century. It would take the middle of the
Speaker 1: twentieth century before anyone built a working laser, but they
Speaker 1: figured out the physics of it decades ahead of time,
Speaker 1: and that still blows my mind to this day. Then again,
Speaker 1: I'm also the guy who can't figure out which remote
Speaker 1: control controls the TV versus the audio system. So what
Speaker 1: do I know? You get this series of photons being
Speaker 1: omitted that are all in phase with one another, and
Speaker 1: they bounce back and forth between these two mirrored ends
Speaker 1: of this ruby rod, but some of them can pass
Speaker 1: through the half silvered or partially silvered end because that
Speaker 1: it allows for that, and this is the source of
Speaker 1: the laser beam. The photons that get out through that
Speaker 1: end become the laser beam, and it's just a steady
Speaker 1: beam of light that will continue to fire as long
Speaker 1: as this reaction is allowed to continue. If you remove
Speaker 1: that source of energy, the pump energy that is allowing
Speaker 1: this to happen in the first place, it will stop,
Speaker 1: right will. The reaction is not sustaining. It can't just
Speaker 1: keep on going. You have to have that external source
Speaker 1: of energy to maintain it throughout the whole process, otherwise
Speaker 1: it just goes dark. So that's basically how your standard
Speaker 1: laser works now if you're using that ruby based laser.
Speaker 1: I was talking about the wavelength of the laser. Light
Speaker 1: could be measured at six hundred and ninety four nanometers.
Speaker 1: That's how long. A wavelength of UBI laser is. Six
Speaker 1: hundred ninety four nanimeters, which is incredibly tiny. The visible
Speaker 1: spectrum of light is between four hundred nanimeters, which would
Speaker 1: be the violet side, up to seven hundred nanometers, which
Speaker 1: is the red side. So this ruby one is right
Speaker 1: up there at the top level of what we can
Speaker 1: see as human beings. Now, you can also have infrared
Speaker 1: or ultraviolet lasers. Obviously those would be invisible to us,
Speaker 1: but they would still exist and you can still do
Speaker 1: some pretty cool stuff with it. In fact, infrared lasers
Speaker 1: are often used to cut steel, for example, which pretty
Speaker 1: serious stuff when you think about it. But we'll talk
Speaker 1: about that more in a little bit. Before we get
Speaker 1: into more about PEWPW lasers, let's take a quick break
Speaker 1: to thank our sponsor. Now. According to the company Wicked Lasers,
Speaker 1: which makes range of laser products, including ones that are
Speaker 1: capable of actually burning stuff if you use them, they
Speaker 1: say that the wavelength of five hundred and fifty five
Speaker 1: nanometers is ideal for brightness compared to other colors that
Speaker 1: are produced at that same amount of power. So lasers
Speaker 1: have a couple of different elements to them. There's the
Speaker 1: wavelength of the laser itself, and then there's the amount
Speaker 1: of power that you are able to generate. You measure
Speaker 1: laser power in milliwatts. Typically for the ones that we
Speaker 1: use day to day as consumers, they can go higher
Speaker 1: than millawatts, but typically the ones we consumers use are
Speaker 1: in the milliwat lange range rather. But you would measure
Speaker 1: them in watts the same way you would with light bulbs.
Speaker 1: But a ten watt laser or a fifty watt laser
Speaker 1: would be much more much brighter than a fifty watt
Speaker 1: light bulb because remember a fifty what light bulb is
Speaker 1: giving out fifty watts of light, but it's emitting that
Speaker 1: in practically all directions, whereas a laser has it very
Speaker 1: much concentrated in a coherent beam. So a fifty watt
Speaker 1: laser would be incredibly bright compared to a fifty watt
Speaker 1: light bulb. And we're mostly talking about millawats. So if
Speaker 1: you have a certain laser pointer of let's say, let's
Speaker 1: just say twenty milawatts, I mean it's incredibly small, but
Speaker 1: this is just for the purposes of an example, twenty
Speaker 1: melawat laser pointer, and it's green, which is closer to
Speaker 1: that five hundred and fifty five nanometers in wavelength, and
Speaker 1: then you've got another one that's red. The green one's
Speaker 1: gonna appear brighter than the red one, even if they're
Speaker 1: both emitting the same wattage of laser light, because our
Speaker 1: visual acuity is closer to that five hundred and fifty
Speaker 1: five nano wavelength range. So violet and blue lasers are
Speaker 1: slightly less powerful than that, but the greens are the
Speaker 1: ones that are gonna show up the best for their
Speaker 1: respective amount of power. Obviously, you can pour more power
Speaker 1: into a laser, and in some cases you can end
Speaker 1: up with a brighter laser because of it, of course,
Speaker 1: depending upon whether or not the laser is within the
Speaker 1: visible spectrum in the first place. It doesn't matter how
Speaker 1: much power you pour into an infrared laser. You're never
Speaker 1: gonna see it. You'll see the results because it'll burn
Speaker 1: through stuff, but you won't see the laser itself. But yeah,
Speaker 1: it's all about those extra things as well, not just
Speaker 1: the wavelength but also the power. So that's really what
Speaker 1: helps determine a laser strength is the wavelength and the
Speaker 1: amount of power that it's putting out. Really, how much
Speaker 1: power are you putting in and getting out of it?
Speaker 1: So if I want to use a death laser in
Speaker 1: order to defeat my arch nemesis who happens to be
Speaker 1: a British secret spy, and I want to also use
Speaker 1: another laser to amuse my cat but not turn it
Speaker 1: into kittycatflombai, what do I need to do to make
Speaker 1: sure about that? Well, one is again that wavelength of light.
Speaker 1: Certain wavelengths are absorbed more readily by a broader variety
Speaker 1: of substances than other wavelengths. So if you pick a
Speaker 1: wavelength that is easily absorbed by lots of different stuff,
Speaker 1: that is going to transfer energy more readily to your target. So,
Speaker 1: as it turns out, infra red lasers can really transfer
Speaker 1: a lot of energy to a broad array of stuff,
Speaker 1: including steel. That's why carbon dioxide megawatt lasers are used
Speaker 1: to cut through stuff like sheets of steel. But other
Speaker 1: colors are not as easily absorbed by as wide a
Speaker 1: variety of materials, and so you would really have to
Speaker 1: pour more energy into the laser in order to get
Speaker 1: a beam strong enough to start cutting through stuff. So
Speaker 1: it depends on both how much power you're putting into
Speaker 1: the laser and the wavelength of the light. Both of
Speaker 1: those together will determine how strong, quote unquote your laser is. Strong.
Speaker 1: Isn't really a meaningful term because there are different ways
Speaker 1: of measuring laser. It's by how much light it gives
Speaker 1: off and also how much energy does it transfer to
Speaker 1: a target. But if you're talking about that energy transfer
Speaker 1: to a target, those are the two things you have
Speaker 1: to worry about, the wavelength and the amount of power
Speaker 1: that it generates. You can use other stuff to help
Speaker 1: with that too, like lenses. You can use lenses to
Speaker 1: help maintain a tighter laser for further distances, but ultimately
Speaker 1: it's power and wavelength that you're really concerned with. Lasers
Speaker 1: can be used for all sorts of things, from optical
Speaker 1: media like DVDs, blu rays, and CD players, to communication
Speaker 1: systems to massive industrial lasers that can cut through steel
Speaker 1: like warm butter and they're really nifty. But I thought
Speaker 1: it might be interesting to learn a little bit more
Speaker 1: about not just how lasers work, but sort of the
Speaker 1: history of lasers as well. Right, because there's a ton
Speaker 1: of different stuff to talk about. I mean, who figured
Speaker 1: out how lasers would even be a thing? Like? Where
Speaker 1: did that come from? So to trace the history of
Speaker 1: the laser, you have to look at the scientists whose
Speaker 1: work provided the foundation for all the people who followed.
Speaker 1: So all the scientists and engineers who actually started building
Speaker 1: lasers in the nineteen fifties, they did this working off
Speaker 1: of the theoretical work of people who came before them.
Speaker 1: So one of those people was Max Planck. So Plank
Speaker 1: was born in eighteen fifty eight in Germany and his
Speaker 1: father was a law professor. And when he was a kid,
Speaker 1: he was really good at studying and stuff. He was
Speaker 1: really interested in tons of different things. He was a
Speaker 1: bit of a polymath, really intelligent, very and very accomplished
Speaker 1: in several fields, including music. And in fact, when he
Speaker 1: turned seventeen, he had to make the tough decision what
Speaker 1: was he going to pursue as a career. Was he
Speaker 1: going to continue to study science or was he going
Speaker 1: to become a musician. And somewhere there's an alternate universe
Speaker 1: where Plank decided to become a musician instead of a physicist.
Speaker 1: And in that alternate universe we had totally different types
Speaker 1: of piano music that Plank would have written. It would
Speaker 1: have been amazing. But I think we're pretty thankful for
Speaker 1: his contributions to science. So ultimately, if we were to
Speaker 1: measure us versus them, I think we get the better
Speaker 1: end of the deal. But still, it's really interesting to
Speaker 1: think that he could have become a musician instead of
Speaker 1: a physicist. And he's sort of the father of quantum physics,
Speaker 1: so if he had not gone and to study physics,
Speaker 1: it might have delayed our study of quantum physics as
Speaker 1: a discipline by at least a decade, potentially more because
Speaker 1: his work would go on to inspire lots of other
Speaker 1: heavy thinkers, including a mister Albert Einstein. So Plank earned
Speaker 1: his doctorate the same year as Einstein's birth, so Plank's
Speaker 1: predecessor to Albert Einstein, obviously, and Einstein would take inspiration
Speaker 1: from several of Plank's ideas, and one of those was
Speaker 1: Plank's idea that energy could only be emitted and absorbed
Speaker 1: in discrete amounts. So if you think about it, it's
Speaker 1: almost more like digital versus analog. If you've listened to
Speaker 1: me talk about digital audio. You know how digital audio
Speaker 1: is made up of tiny little steps of pitch and volume,
Speaker 1: whereas analog is a continuous wave, right is a bunch
Speaker 1: of discrete little moments in time, And the number of
Speaker 1: those moments in time that's your sample rate. The more
Speaker 1: the higher your sample rate is, the closer this looks
Speaker 1: to be a continuous line, but it's not really a
Speaker 1: continuous line, tiny little steps in pitch and volume. Well,
Speaker 1: Plank's point was that energy is sort of similar it. Ultimately,
Speaker 1: when you get down to the very very very tiny
Speaker 1: amounts could only be emitted or absorbed in discrete chunks.
Speaker 1: It's not continuous, not analog, And this was a revolutionary idea.
Speaker 1: Einstein would end up looking at this idea and saying
Speaker 1: this is pretty cool. I'm gonna use this and add
Speaker 1: on to it, and he created his theory about the
Speaker 1: photoelectric effect. Plank, meanwhile, would end up being awarded the
Speaker 1: Nobel Prize in Physics in nineteen eighteen for his his
Speaker 1: working quantum mechanics. Einstein would similarly be honored several times.
Speaker 1: It was Einstein who first suggested that atoms might be
Speaker 1: able to produce photons through stimulated emission so lasers are
Speaker 1: somewhat built upon the theories of Einstein himself. He stated
Speaker 1: that electrons could be stimulated to emit light of a
Speaker 1: specific wavelength, which of course is the very basis of lasers.
Speaker 1: And Einstein published that theory in nineteen seventeen, so it
Speaker 1: would be nearly forty years before anyone could actually build
Speaker 1: something to test out and see if Einstein's theory was
Speaker 1: of practical application. But it turns out he was right,
Speaker 1: which again blows my mind. Forty years before anyone could
Speaker 1: build something, and he's saying, hey, you know what probably
Speaker 1: would work. I'm oversimplifying it and making light of it.
Speaker 1: But I am in awe of people who are able
Speaker 1: to think in these terms, where they're able to work
Speaker 1: out the basic laws of the universe well before we
Speaker 1: could ever make any sort of practical attempt to test
Speaker 1: those ideas. It is phenomenal to me. Now, granted, I
Speaker 1: could make up laws of the universe, but they would
Speaker 1: be completely unsubstantiated and would fail to hold up to
Speaker 1: any testing in the future. I lack the ability to
Speaker 1: have that level of insight into how our universe works,
Speaker 1: but I do appreciate it in others. So let's flash
Speaker 1: forward to nineteen fifty one. So we go from nineteen
Speaker 1: seventeen to nineteen fifty one. That's when a guy named
Speaker 1: Charles H. Towns, who worked at Columbia University in New York,
Speaker 1: was sitting on a park bench, which in itself is
Speaker 1: not that remarkable, but he came up with an idea
Speaker 1: of creating a device that could produce microwaves through stimulated
Speaker 1: emission of radiation, and this idea became the basis of
Speaker 1: the maser maser, which is similar to the laser, but
Speaker 1: obvious amidst microwaves rather than light. Three years later, Towns
Speaker 1: would demonstrate a working maser, So this is nineteen fifty four,
Speaker 1: not a laser, yet still a mazer. So microwaves are
Speaker 1: part of the electromagnetic spectrum, but are not considered part
Speaker 1: of light. Right, you've gone beyond infrared at this point.
Speaker 1: The wavelengths of microwaves are much, much, much longer than
Speaker 1: the wavelengths of light. Towns had actually partnered with a
Speaker 1: couple of people in order to create this working maser
Speaker 1: that included Herbert J. Zeiger and a graduate student named
Speaker 1: James P. Gordon. They used ammonia as their medium for
Speaker 1: the mazer, and the wavelength of the microwave was one centimeter.
Speaker 1: A centimeter is it's almost impossible for me to describe
Speaker 1: how big that is compared to the waves that are
Speaker 1: in the nanometer range, the hundreds of nanometers, but it
Speaker 1: is while centimeter is small to us, it is enormous
Speaker 1: in the quantum world. So they were able to create this,
Speaker 1: They were able to build a working mazer using ammonia
Speaker 1: as their medium. Now in Moscow at around the same time,
Speaker 1: there were a couple of engineers, Nikolai g. Basov and
Speaker 1: Alexander M. Prokhorov, who were working on building oscillators at
Speaker 1: the time, and while they were building oscillators, they came
Speaker 1: up with a method that they thought would work for
Speaker 1: negative absorption while building these things, and they called it
Speaker 1: the pumping method, which would become important for future mazers
Speaker 1: and lasers. In nineteen fifty six, Nicholas Bloembergen at Harvard
Speaker 1: develops the first solid state maser. In September nineteen fifty seven,
Speaker 1: Towns would sketch out an optical mazer design in a
Speaker 1: lab notebook. Also in nineteen fifty seven, there was a
Speaker 1: guy named Gordon Gould, who was a grad student at Columbia,
Speaker 1: who wrote down his own ideas for a device that
Speaker 1: would be similar to a maser, but he called this
Speaker 1: one a laser. So this appears to be the first
Speaker 1: use of the word lasers, the first recorded instance of
Speaker 1: laser as a word. And Gould thought ahead and even
Speaker 1: had his notes notarized. So he had them notarized by
Speaker 1: a notary, where as a date on it and everything,
Speaker 1: so that he could prove that he had come up
Speaker 1: with this notion. He tracked down a notary at a
Speaker 1: candy shop in the Bronx, which is a phenomenal story
Speaker 1: in my mind. I love the idea that this is
Speaker 1: non a joke, This really happened. You had a guy
Speaker 1: come up with what would become a transformative technology, a laser,
Speaker 1: like the idea of creating a light version of what
Speaker 1: had already happened, And so he needs it notarized, so
Speaker 1: he goes to a candy store. It's pretty sweet when
Speaker 1: you think about it. By nineteen fifty eight, Towns was
Speaker 1: working with his brother in law Arthur L. Shallow or Shawlow.
Speaker 1: I guess is the way you would pronounce it Scchawlow
Speaker 1: Shawlow he was a researcher for Bell Labs, which obviously
Speaker 1: has played an enormously important role in the development of
Speaker 1: electronics in general. Together, they proposed developing masers that could
Speaker 1: operate in the infrared and optical parts of the electro
Speaker 1: magnetic spectrum. And meanwhile, over in Russia, Prokhorov and Besov
Speaker 1: were also investigating the possibility of developing optical mazers. So
Speaker 1: the race was on a lot of different people, all
Speaker 1: trying to create an optical maser or laser. In April
Speaker 1: nineteen fifty nine, Gould would apply for patents relating to lasers,
Speaker 1: and in nineteen sixty Towns and Shawlow received a patent
Speaker 1: for the optical mazer, which they now were calling a laser,
Speaker 1: and thus the Great Laser Battle began. Only this laser
Speaker 1: battle wasn't fought with lasers. It was fought over the
Speaker 1: intellectual property represent resented by lasers. And this was a
Speaker 1: legal battle that would stretch for three decades. So an
Speaker 1: incredible laser battle really. But the first working laser was
Speaker 1: built in Malibu, California, in nineteen sixty and almost certainly
Speaker 1: had nothing to do with plastic surgery. Unlike everything else
Speaker 1: in Malibu, California. Theodore H. Mahmon, who worked at Hughes
Speaker 1: Research Labs in Malibu, built this first laser. He used
Speaker 1: a synthetic ruby that was two centimeters long and one
Speaker 1: centimeter in diameter, and he coated the ends in silver
Speaker 1: to make them reflective. He used a photographic flash lamp
Speaker 1: to pump the lasing materials, so he used the exact
Speaker 1: same sort of flash bulbs you would find in a
Speaker 1: cameras flash, which was pretty incredible, and a couple of
Speaker 1: months later, Hughes's Research would hold a press conference to
Speaker 1: announce that they had developed the first working laser. A
Speaker 1: few months after that, scientists at IBM's Thomas J. Watson
Speaker 1: Research Center demonstrated a working uranium laser, which seems like
Speaker 1: a massive show of escalation in my mind. Now at
Speaker 1: this point the developments would come really fast and furious,
Speaker 1: not like the film series within Diesel, but I mean,
Speaker 1: they were just laser development after laser development, tons of advances.
Speaker 1: I'm not going to cover all of them because they're
Speaker 1: way too many, but I'll cover some of the big ones.
Speaker 1: The first helium neon laser debuted at the end of
Speaker 1: nineteen sixty again at Bell Labs, and it was able
Speaker 1: to create a one point one five micrometer wavelength of
Speaker 1: continuous light, so beyond the range of human vision. It
Speaker 1: wasn't light that was visible, but it was in the
Speaker 1: spectrum of light. And in nineteen sixty one companies began
Speaker 1: to manufacture lasers for the market. This is incredible to me.
Speaker 1: It had been only a year since someone had built
Speaker 1: a working laser, and by the following year people were
Speaker 1: making them for sale. Now, granted, they weren't selling them
Speaker 1: to average consumers. It's not like John Smith or John Q. Public.
Speaker 1: If you prefer I could walk into the closest laser
Speaker 1: store and order a laser. These were meant for research
Speaker 1: and development purposes and not for people who wanted to
Speaker 1: amuse their cats. It was also meant for some early
Speaker 1: industrial uses and as it turns out, some early medical uses.
Speaker 1: So again I'm going to jump over some of the
Speaker 1: incremental developments. It wouldn't make sense for me to cover
Speaker 1: all of them, and a lot of them I would
Speaker 1: have to go into even more description about very specific
Speaker 1: types of lasers which only apply to particular cases and
Speaker 1: not to others, and that would just make this kind
Speaker 1: of muddy and directionless. But I do want to point
Speaker 1: out a few really cool moments in history and explain
Speaker 1: some related topics to lasers as a result, such as
Speaker 1: what happened in December of nineteen sixty one. So keep
Speaker 1: in mind it only been a bit longer than a
Speaker 1: year since someone had demonstrated a working laser at all.
Speaker 1: In December nineteen sixty one, doctor Charles J. Campbell and
Speaker 1: Charles J. Kuster, a lot of Charles Jay's, decided that
Speaker 1: they were going to treat a patient, a medical patient,
Speaker 1: a human medical patient using an optical Ruby laser to
Speaker 1: destroy a retinal tumor. Now that's incredible. It had been
Speaker 1: only eighteen months since someone had built the first working laser,
Speaker 1: and you already had people using it in a medical
Speaker 1: procedure on a human patient. I suspect that today it
Speaker 1: would take a bit longer to prove that the methodology
Speaker 1: being used was safe and efficacious before using it on
Speaker 1: a human, but it shows how quickly things were moving
Speaker 1: back then. I think it's pretty incredible that it took
Speaker 1: less than two years to actually use lasers in a
Speaker 1: medical an actual medical procedure. Now, the mid nineteen sixties
Speaker 1: would see advances in the field of fiber optics, which,
Speaker 1: when paired with lasers, allow for low long distance communication
Speaker 1: using light through glass filaments. Now, I've done episodes about
Speaker 1: fiber optics before, so you can go and look at
Speaker 1: the Tech Stuff archives and learn more about that. But
Speaker 1: this still blows my mind too. Just the fact that
Speaker 1: fiber optics are a thing that work, it is incredible
Speaker 1: to me. Meanwhile, Bell Labs would strike again in nineteen
Speaker 1: seventy two with a laser beam cutter they used to
Speaker 1: form electronic circuit patterns on ceramic and on June twenty sixth,
Speaker 1: nineteen seventy four, which just for trivia's sake, is exactly
Speaker 1: one year to the day before I was born. A
Speaker 1: barcode scanner, which typically uses lasers. Read the very first
Speaker 1: product ever registered for real Z's using a UPC code
Speaker 1: and a barcode scanner. The product, by the way, was
Speaker 1: a pack of Wrigley's chewing gum. So how the heck
Speaker 1: do those barcode scanners work? Because you see them on
Speaker 1: everything these days. And here's where I'm going to go
Speaker 1: on a bit of a tangent to talk about barcodes.
Speaker 1: In just a second, and I also just want to
Speaker 1: mention that I think it's really cool that, now you
Speaker 1: know a trivia question that the first product to ever
Speaker 1: be scanned using a barcode scanner was Wrigley's chewing gum.
Speaker 1: Important to remember in case you ever played bar trivia. Now, next,
Speaker 1: I'm going to talk all about UPC codes and how
Speaker 1: they work. But before I jump into that and go
Speaker 1: way off the rails, let's take another quick break to
Speaker 1: thank our sponsor. All Right, so let's talk about barcodes,
Speaker 1: which are I agree, tangentially related to lasers. But I've
Speaker 1: already talked about how lasers work, and I really love
Speaker 1: how barcodes work because I just think they're kind of cool.
Speaker 1: So these are the good old universal product code or
Speaker 1: UPC code things that you would see on products today
Speaker 1: at your average store. They were designed in order to
Speaker 1: help speed up check out and also make it easier
Speaker 1: to keep a working inventory of a store. And you
Speaker 1: can just scan each item and then you use a
Speaker 1: computer database to match the scan with other information like
Speaker 1: what that product is, how much it costs. So the
Speaker 1: scanner all it needs to do is identify which product
Speaker 1: you are actually scanning at any given time. That's its
Speaker 1: only job. It doesn't really have anything to do with
Speaker 1: how much something costs. That is not necessarily represented in
Speaker 1: the code itself. There are codes that do have the
Speaker 1: information in them, but the basic PC code is really
Speaker 1: just to tell a system what the product is, and
Speaker 1: then you have a separate database that links products to prices.
Speaker 1: So what would you do if you were a manufacturer
Speaker 1: and you wanted to put a UPC code on something
Speaker 1: that you yourself were making, your company was making. Here's
Speaker 1: the process. You have a company called the Uniform Code
Speaker 1: or UCC, and they are in charge of UPC codes.
Speaker 1: And to me, the UCC sounds like it should be
Speaker 1: staffed by shadowy figures in robes. But to be fair,
Speaker 1: I did watch Hot Fuzz again not too long ago,
Speaker 1: and that's probably why I'm thinking that. So let's say
Speaker 1: you're a manufacturing company and you make a very specific
Speaker 1: product and you want to get it into stores around
Speaker 1: the world. And since the earliest implementations of the UPC
Speaker 1: codes were for grocery stores, let's say that it's a
Speaker 1: grocery store product. So let's say you're making a really awesome, tasty,
Speaker 1: sugary breakfast cereal for kids and you're calling them crispydus.
Speaker 1: So you make delicious crispydos that are a nutritional part
Speaker 1: of a balanced breakfast. You want to sell Crispy dues
Speaker 1: in grocery stores, so you want to end up selling
Speaker 1: to grocery stores. Grocery stores will sell the crispydos to
Speaker 1: their customers and everyone benefits, presumably assuming that there's enough
Speaker 1: nutritional value in the Crispy dues to not, you know,
Speaker 1: turn your customers into goo. So grocery stores love the
Speaker 1: idea of UPC codes because again, it makes it much
Speaker 1: easier to ring up products and it makes it very
Speaker 1: easy to keep track of the stock that the grocery
Speaker 1: store has. If they notice that they're selling, you know,
Speaker 1: eight pallets of Crispy dues a week, then they might
Speaker 1: up their order and that's good for you. So it
Speaker 1: benefits you to get a UPC code on your product.
Speaker 1: To do that, you would first have to apply for
Speaker 1: a manufacturer identification number from the UCC. This is almost
Speaker 1: like a subscription service. You'd have to pay the UCC
Speaker 1: to get this manufacturer identification number. The UCC would then
Speaker 1: issue you this number. It's a six digit number and
Speaker 1: if you look at a UPC code. You'll see that
Speaker 1: there are twelve digits on a UPC code, So those
Speaker 1: are the human readable digits, right, that's the thing that
Speaker 1: you have to type in. If for some reason the
Speaker 1: scanner's not scanning anything, you might type in the code. Well,
Speaker 1: those first six digits refer to the manufacturer identification number,
Speaker 1: So all the products from that specific manufacturer should have
Speaker 1: those first six numbers the same on all of them
Speaker 1: because it's unique to the company itself. It doesn't matter
Speaker 1: what the product is. The next five digits on that
Speaker 1: UPC code represent the item number, so it's unique to
Speaker 1: the product. So if you make fourteen different products, each
Speaker 1: product is going to have its same or its own
Speaker 1: five digit item code, and it'll be different from the
Speaker 1: other thirteen item codes. So if your company also produces, say,
Speaker 1: flea collars for Kiddi cats, the five digits for the
Speaker 1: flea colors are going to be different than the five
Speaker 1: digits for the Chris which is good because you don't
Speaker 1: want to mix up your flea collars with your Crispy Dues.
Speaker 1: That would be a pr nightmare. And this episode really
Speaker 1: isn't meant to go into that sort of thing. So
Speaker 1: that leaves one digit leftover. Right, You've got the first
Speaker 1: six that's the manufacturer ID number, the next five which
Speaker 1: is the item number. But you have a single digit
Speaker 1: leftover of those twelve. So what as that for. That
Speaker 1: is called the check digit, and the check digit is
Speaker 1: meant to give the scanner the opportunity to verify that
Speaker 1: it has scanned the product properly. And the way you
Speaker 1: do this is through some pretty ridiculous math. It's not difficult,
Speaker 1: it's just tedious. So it's again a verification right to
Speaker 1: say that, yes, the scan went through properly, because if
Speaker 1: the math checks out, if you get the answer you're
Speaker 1: supposed to get, you know that you scanned it properly.
Speaker 1: And by you, I mean the scanner system is able
Speaker 1: to verify that a scan went through correctly. So let's
Speaker 1: take a second to talk about how you arrive at
Speaker 1: the check digit so you can understand what I mean
Speaker 1: when you do some ridiculous arithmetic. It's not difficult. Again,
Speaker 1: it's just ridiculous. So you've got eleven other digits in
Speaker 1: the UPC code and those are what you use to
Speaker 1: do the arithmetic. First, you take all the numbers, all
Speaker 1: the digits, and the UPC codes that are at odd positions,
Speaker 1: so not the odd numbers, just in the odd positions.
Speaker 1: So that would be the position number one, position number three, five,
Speaker 1: et cetera, up to eleven. Because you have eleven other numbers.
Speaker 1: You take all of those and you add them together
Speaker 1: and you get a sum. So you've got that sum
Speaker 1: by adding all the odd position numbers together, and you
Speaker 1: then multiply that by three. Now you look at all
Speaker 1: the digits that are in even positions, so two, four, six, eight,
Speaker 1: and ten, you add all of those together. You then
Speaker 1: take the number you got from all the odd positions
Speaker 1: multiplied by three, and all the even positions added together,
Speaker 1: and you add those two numbers together. And then you
Speaker 1: take a look at this new number, this monstrausity of
Speaker 1: a thing. It's not a huge number. It's just weird
Speaker 1: that you've got it. And you say, all right, how
Speaker 1: many more numbers would I have to add to this
Speaker 1: in order to get a multiple of ten? And as
Speaker 1: long as the last digit is the same as the
Speaker 1: number you need to add to your monstrosity to get
Speaker 1: a multiple of ten, you're good to go. So this
Speaker 1: is easier to understand with an example. So here's our
Speaker 1: UPC code. We've got our crispy dues, and our UPC
Speaker 1: code happens to be six three nine three eight two
Speaker 1: zero zero zero three nine three. Well, that last three
Speaker 1: is the check digit. That's the number we're supposed to
Speaker 1: get at the end of all this other nonsense. So
Speaker 1: we put that aside. We say, three is what we're
Speaker 1: hoping is the outcome. How do we get to that.
Speaker 1: We take all those odd positioned digits, which would be
Speaker 1: six and nine and eight, et cetera, et cetera. We
Speaker 1: add them all up technically at six, nine, eight, two
Speaker 1: zero's in a nine. That gets you thirty two. You
Speaker 1: multiply that number by three, you get ninety six. So
Speaker 1: that's your first number. You set that aside. Your ninety
Speaker 1: six is good to go. Then you take a look
Speaker 1: at all the even positioned numbers and you add those up.
Speaker 1: The even position numbers would be a three, A three,
Speaker 1: a two, a zero, and another three. That gives you eleven.
Speaker 1: So now you add the eleven to the ninety six
Speaker 1: that you arrived at earlier. That gives you one hundred
Speaker 1: and seven. You look at one hundred and seven and say,
Speaker 1: how many digits or how much we need to add
Speaker 1: to this to make a multiple of ten answers three,
Speaker 1: because if you add three to one hundred and seven
Speaker 1: you get one hundred and ten. One hundred and ten
Speaker 1: is a multiple of ten. There you go. Three is
Speaker 1: the number you wanted. Three is the number that's on
Speaker 1: the check digit. You know that you got the right answer. Now,
Speaker 1: the way the scanner does this is not by looking
Speaker 1: at the digits. It's looking at the relationship between the
Speaker 1: thin bars, the gaps between the bars, and how thicker
Speaker 1: thin each of those are. Right. So if you look
Speaker 1: at a UPC bar code, you're looking at just the bars.
Speaker 1: You'll see some of the bars are thin, some of
Speaker 1: the bars are a little thicker, some of the gaps
Speaker 1: between the bars are thinner or thicker than the others.
Speaker 1: That relationship of bars to gaps and the thickness of
Speaker 1: them tells you what the value is of each of those.
Speaker 1: And if you really really wanted to, you could decode
Speaker 1: a barcode just by sight, once you know the basic
Speaker 1: system of coding, and if you're able to determine what
Speaker 1: is a narrow versus a wide bar or gap, because
Speaker 1: that's very important. So the scanner is looking at the
Speaker 1: series of bars and gaps and measuring those those widths,
Speaker 1: and by measuring it, it then is able to match
Speaker 1: that to a numeric code and verify whether or not
Speaker 1: it matches that check digit at the end, and if
Speaker 1: it does, the scan goes through, it gets matched to
Speaker 1: a product and your charge however much for your Crispy dues.
Speaker 1: I'm going to say it's five ninety nine for a bucks,
Speaker 1: so that's what would pop up. There are variations on
Speaker 1: these UPC codes, like zero suppressed number UPC codes, which
Speaker 1: is exactly what sounds like. Any number that is a
Speaker 1: zero that would otherwise appear in the code gets emitted omitted,
Speaker 1: rather not emitted, it's omitted from the code, so it's shorter,
Speaker 1: makes it a shorter barcode. But not everyone does this.
Speaker 1: Only some products have this, and the manufacturing ID numbers
Speaker 1: can have a specific meaning as well, depending on what
Speaker 1: number they start with. So if you're manufacturing ID number
Speaker 1: starts with a two, it means that it is a
Speaker 1: random weight product. And by random weight we mean it's
Speaker 1: something that doesn't come in a specific uniform size and
Speaker 1: weight over and over again, so produce. For example, an
Speaker 1: apple is going to be its own weight, right, You're
Speaker 1: not going to get two apples of the exact same weight.
Speaker 1: They're not all uniform. Whereas if I go out and
Speaker 1: buy a box of Crispy Dues, it should be more
Speaker 1: or less the same as a comparable Crispydoz box. Now,
Speaker 1: if you have different sizes of boxes, then you have
Speaker 1: different item numbers for each of those different sizes. The
Speaker 1: item numbers are specific to a very particular instance of
Speaker 1: an item. So if I've got a large box of
Speaker 1: ch Us and a small box of Crispy Dues, each
Speaker 1: of those will have its own five digit item number,
Speaker 1: and thus the bars that correspond with it will be
Speaker 1: slightly different as well. By the way, if you wanted
Speaker 1: to know, like just as an example, what these bars mean,
Speaker 1: I'm not going to go through the encoding of every
Speaker 1: single number because it would be kind of silly. But
Speaker 1: let me give you an example. If you want to
Speaker 1: represent the number one in a UPC code, the way
Speaker 1: it would work is that you would use first a
Speaker 1: black bar that is two units wide. So in other words,
Speaker 1: you'd have to look at the most narrow bar on
Speaker 1: the UPC code that's probably one unit, right, You would
Speaker 1: want a bar that's twice that width. The bar units
Speaker 1: go up from one to four, so the widest bar
Speaker 1: will probably be four units wide, the thinnest will probably
Speaker 1: be one unit wide. You need one that's two units wide,
Speaker 1: followed by a space that is two units wide, followed
Speaker 1: by another black bar that's two units wide, followed by
Speaker 1: a space that is one unit wide. So that is
Speaker 1: the number one in barcode speak, and each of the
Speaker 1: numerals is encoded in a similar way. Using these bars
Speaker 1: and gaps of varying widths and reading them by sight
Speaker 1: is possible but is not practical. But when you move
Speaker 1: one of those bars across the scanner, the scanner shoots light,
Speaker 1: typically red laser light at the barcode, and then a
Speaker 1: sensor on the scanner is looking for reflected light, and
Speaker 1: it can detect those bars and gaps based upon the
Speaker 1: light that gets reflected back at the sensor. And as
Speaker 1: long again as that last bar or that last digit
Speaker 1: matches up with the math I talked about earlier, it
Speaker 1: can in ring up the product and give you the
Speaker 1: appropriate price for it. So really, the interesting thing here
Speaker 1: is that the laser just makes this incredibly efficient. I
Speaker 1: mean light travels faster than anything else in the world,
Speaker 1: so it's no surprise that you can just swing one
Speaker 1: of these barcodes by it a really good clip and
Speaker 1: still get a really solid scan off of it, because
Speaker 1: that information is going to the code and back to
Speaker 1: the scanner at the speed of light, so it's not
Speaker 1: like you're going to be moving that fast compared to
Speaker 1: the scanner, and as long as it's got that good
Speaker 1: fidelity there, then you're going to get a pretty successful scan.
Speaker 1: That's why you can zoom stuff past that scanner pretty quickly.
Speaker 1: Now let's go back to that timeline that we were
Speaker 1: talking about earlier. By nineteen seventy five, Laser Diode Labs
Speaker 1: Incorporated had developed a continuous wave semiconductor laser which would
Speaker 1: make it possible to transmit telephone conversations via optic fiber,
Speaker 1: which again blows my mind that you could turn something
Speaker 1: that's acoustic, not just into electricity, which is already magic
Speaker 1: in my mind, but into light signals. In nineteen seventy
Speaker 1: eight we got the laser disc, which was the first
Speaker 1: commercial use of an optical medium, that being something that
Speaker 1: could be stored on a device that would be read
Speaker 1: just by laser light alone. Laser discs were a predecessor
Speaker 1: to other optical based media like compact discs, akacds and DVDs,
Speaker 1: and blu rays. The earliest players actually used helium neon
Speaker 1: laser tubes in order to read the information stored on
Speaker 1: the discs, but later ones would switch to more affordable
Speaker 1: infrared laser diodes, so semiconductor based lasers. And as I
Speaker 1: said earlier, the semiconductor approach was less powerful and less
Speaker 1: expensive than other methods of generating lasers, so that helped
Speaker 1: bring the laser disc price down a little bit, but
Speaker 1: they were pretty expensive of it never really took off.
Speaker 1: I mean, there were people who loved laser discs, but
Speaker 1: they never became as popular as vhs or later on
Speaker 1: DVD players. Now. Later in nineteen seventy eight, Phillips would
Speaker 1: announce it was working on the compact disc project, Which
Speaker 1: is kind of funny because I always think of CDs
Speaker 1: as being either a late eighties or early nineties phenomenon,
Speaker 1: but its origins date back to the late seventies, and
Speaker 1: the first actual CD produced would come out in nineteen
Speaker 1: eighty two. And here's some more trivia for you. If
Speaker 1: you're ever doing that pub trivia, you remember the first
Speaker 1: thing with a barcode was Wrigley's Chewing Gum. The first
Speaker 1: CD to ever be produced was the album fifty Second
Speaker 1: Street by Billy Joel. That album actually had some pretty
Speaker 1: good songs on it, including My Life, which would later
Speaker 1: serve as the original theme song for the Tom Hanks
Speaker 1: sitcom Bosom Buddies. I guess you could probably tell that
Speaker 1: I'm patting this episode out a little bit, but this
Speaker 1: is again useful information if you're ever playing pub trivia.
Speaker 1: So if you ever hear what was the first album
Speaker 1: produced on CD, you now know it's fifty second Street
Speaker 1: by Billy Joel. In nineteen seventy nine, Gould would finally
Speaker 1: receive a patent that covered a pretty wide range of
Speaker 1: laser applications, so that meant that he finally won the
Speaker 1: laser battle. You'll remember that in the previous section I
Speaker 1: talked about how he had applied for a patent but
Speaker 1: was essentially denied that patent because of a previous application
Speaker 1: that had taken the intellectual property Gould had created and notarized.
Speaker 1: So this was the end of a very long battle here, well,
Speaker 1: at least as far As who has the legal right
Speaker 1: to claim the intellectual property of lasers, but it would
Speaker 1: be Shawlohe who was one of the parties who had
Speaker 1: filed the other patent back in a couple decades earlier,
Speaker 1: three decades earlier, and Bloembergen, who had actually received the
Speaker 1: Nobel Prize in Physics in nineteen eighty one for their
Speaker 1: work in laser spectroscopy. So people were doing well all
Speaker 1: around in the laser world. In the mid nineteen eighties,
Speaker 1: research laboratories began to use lasers to manipulate individual atoms,
Speaker 1: which is really cool. It opened up a brand new
Speaker 1: world in quantum science as well as just physical science.
Speaker 1: You may have seen the infamous picture of IBMS spelling
Speaker 1: out its name in individual atoms. It used lasers to
Speaker 1: position them. It's really pretty awesome. And by the late
Speaker 1: nineteen eighties Gould began to get royalties for his patents,
Speaker 1: so better late than never. In nineteen eighty seven, doctor
Speaker 1: Stephen Trockel became the first doctor to use an exemer
Speaker 1: laser to perform corrective surgery on a patient's eyes. This
Speaker 1: method was called the photorefractive keroatectomy or PRK surgery. That
Speaker 1: would start a line of research and development in laser
Speaker 1: eye surgery in general, with laser surgery debuting in nineteen
Speaker 1: ninety one, and I had laser surgery done just a
Speaker 1: few years ago. It corrected my vision. I talked about
Speaker 1: it on a podcast. Chris Pullett was on that one too,
Speaker 1: So you can do a search on tech Stuff's archives
Speaker 1: and hear all about laser eye surgery. And I think
Speaker 1: if you listen carefully enough you can actually hear Chris
Speaker 1: Pollette turn green. In the episode. He does a lot
Speaker 1: of unpleasant sounds because it was clear he was not
Speaker 1: comfortable in that episode. I might have taken a little
Speaker 1: extra glee from that. Now, skipping way ahead to two
Speaker 1: thousand and three, that was when researchers from NASA demonstrated
Speaker 1: that you could power an aircraft using lasers. The aircraft
Speaker 1: in question weighed just three hundred and eleven grams, not kilograms,
Speaker 1: just grams. It had a balsa wood frame and had
Speaker 1: a wingspan of one and a half meters that used
Speaker 1: an electric motor that was powered by a photovoltaic cell,
Speaker 1: so like a solar cell, but in this case it
Speaker 1: was specifically accepting light from this laser which was firing
Speaker 1: in an invisible spectrum, so you couldn't see the laser,
Speaker 1: but you can direct it at the cell that would
Speaker 1: provide the energy needed to convert it over into electricity
Speaker 1: and thus propel the aircraft, which is pretty cool. And
Speaker 1: today there are tons of uses of lasers, and some
Speaker 1: of them are really silly, like you know, they're being
Speaker 1: sold as cat toys and dog toys at this point,
Speaker 1: but some are really serious or things that are used
Speaker 1: in the medical field, for engineering, for industry, and we're
Speaker 1: looking at the possibility of even using them to propel
Speaker 1: spacecraft to other star systems, which is a really neat idea.
Speaker 1: This is based on the idea of the solar sail,
Speaker 1: where you have a spacecraft and it has a sale
Speaker 1: that you can direct light toward, and light has momentum.
Speaker 1: It's got relativistic momentum, So a photon does not have
Speaker 1: a lot of momentum by itself, but a stream of
Speaker 1: photons directed at a surface for long enough does have
Speaker 1: a physical push to it. And as it turns out,
Speaker 1: if you build very tiny spacecraft with a decent light
Speaker 1: sail and you use a laser on Earth, you can
Speaker 1: continuously accelerate that spacecraft over time so that reaches incredible speeds.
Speaker 1: Now that acceleration is going to be at a low rate,
Speaker 1: so it doesn't speed up immediately, but it will over
Speaker 1: time get faster and faster and faster. And in fact,
Speaker 1: this is what some people are suggesting we do to
Speaker 1: send spacecraft to the nearest star system are the one
Speaker 1: that's nearest to our own That would be the Alpha
Speaker 1: Centauri system, and Proxima B would be the place we
Speaker 1: would really want to take a look at. That's the
Speaker 1: planet around Proximus Centauri that is the closest to our
Speaker 1: Solar system, that is the most earthlike in nature. And
Speaker 1: so there's some people saying, why don't we release swarms
Speaker 1: of tiny spacecraft using these sort of light sails, use
Speaker 1: lasers to direct toward the Alpha Centauri system, And because
Speaker 1: of the incredible speeds they can reach, they can get
Speaker 1: to the Centari system within about twenty years. That's incredible
Speaker 1: because the Centauri system's four light years away. That means
Speaker 1: it takes four years for light to get there to hear.
Speaker 1: So to get there in twenty years using a physical spacecraft,
Speaker 1: you're moving at a really good clip Now, granted, at
Speaker 1: that speed, you're also just zooming by the Centauri system.
Speaker 1: You're not stopping for tea or anything, but still pretty
Speaker 1: cool idea that lasers could play an instrumental role in
Speaker 1: getting us to a different star system, or at least
Speaker 1: getting our eyes to a different star system. No humans
Speaker 1: would be traveling on those spacecraft, all right. That was
Speaker 1: our classic episode from June fourteenth, twenty seventeen, called Pew
Speaker 1: Pew Lasers. I hope you enjoyed it, and as always,
Speaker 1: I also hope that you are all well and I
Speaker 1: will talk to you again really soon. Tech Stuff is
Speaker 1: an iHeartRadio production. For more podcasts from iHeartRadio, visit the
Speaker 1: iHeartRadio app, Apple Podcasts, or wherever you listen to your
Speaker 1: favorite shows.