How lasers work Hey Engineering Lovers, my name is Gustavo Pereira and today we are going to talk about how lasers work. Laser technology plays a key role in science fiction movies and books. It is no doubt thanks to this kind of history that we now associate lasers with futuristic warfare and sleek spaceships.
After all, who has never seen that movie with laser weapons. But lasers also play a key role in our everyday lives. The fact is, they appear in an incredible range of products and technologies, from CD players to dental drills, high-speed metal cutting machines and measurement systems.
They are even used for tattoo removal, hair replacement, and even eye surgery. But what is a laser, and what makes a laser beam different from a flashlight beam? And before continuing, if you are watching this video and are not subscribed, take the opportunity now to subscribe , leave your like and activate the bell, and with that, you will be part of the largest community of engineering lovers on youtube.
A laser is a device that controls the way energized atoms release photons. "Laser" is an acronym for light amplification by stimulated emission of radiation , which describes very succinctly how a laser works. While there are many types of lasers, they all have certain essential characteristics.
In a laser, material is "pumped" to place atoms in an excited state. But calm down, what do you mean to excite an atom, this is getting kind of complicated. There are only about 100 different types of atoms in the entire universe.
Everything we see is made up of these 100 atoms in an unlimited number of combinations. How these atoms are arranged and bonded determines whether the atoms form a glass of water, a piece of metal, or the gas that comes out of your can of soda. Atoms are in constant motion and they continually vibrate, move and rotate.
Even the atoms that make up the chairs we sit in are moving and contrary to your high school teacher a rock is indeed in motion, only on an atomic level. Atoms can be in different excited states. In other words, they can have different energies.
If we apply a lot of energy to an atom, it can leave what is called a ground state energy level and go to an excited level. The level of excitation depends on the amount of energy that is applied to the atom via heat, light or electricity. This simple atom consists of a nucleus, containing the protons and neutrons, and a cloud of electrons.
It is useful to think of the electrons in this cloud circling the nucleus in many different orbits. Although more modern views of the atom do not represent discrete orbits for electrons, it can be useful to think of these orbits as the different energy levels of the atom. In other words, if we apply some heat to an atom, we might expect some of the electrons in lower-energy orbitals to transition to higher-energy orbitals farther from the nucleus.
This is a highly simplified view of things, but it actually reflects the core idea of how atoms work in terms of lasers. Once an electron moves to a higher energy orbit, it eventually wants to return to the ground state. When this happens, it releases its energy through a photon, or a particle of light.
You see atoms releasing energy as photons all the time. For example, when the heating element in a toaster oven turns bright red, the red color is caused by atoms, excited by the heat, releasing red photons. When you see an image on a TV screen, what you are seeing are phosphorus atoms, excited by high-speed electrons, emitting different colors of light.
Everything that produces light, such as fluorescent lamps, flashlights, incandescent lamps, does so through the action of electrons that change their orbit and release photons. Okay, but how does this laser light work? Laser light has 3 properties The first property is that the light released is monochromatic, ie it contains a specific wavelength of light or a specific color.
The wavelength of light is determined by the amount of energy released when the electron falls to a lower orbit. The second property is that the released light is coherent or "organized", where each photon moves in tune with the others. This means that all photons have wavefronts that are released in unison, that is, together.
The third property is that light is directional. A laser light has a very narrow beam and is very strong and focused. A flashlight, on the other hand, sheds light in multiple directions, and the light is very dim and diffused.
To make these three properties occur, something called stimulated emission is needed. This does not occur in your common flashlight, because in a flashlight, all atoms release their photons randomly. To simplify all this, let's imagine a music concert.
When the music starts playing, everyone starts moving, jumping and dancing. While one person is dancing and the other is not, this ends up stimulating the other person to move and dance too. Everyone is there singing the same song, in the same rhythm.
Now imagine that every person at this party is a photon. People there are singing the same song in the same place, that is, they are in sync, singing the same song together and everyone is looking at the stage. That is, we have the 3 properties of laser light, where everyone is in the same place at a specific pace, everyone is in tune and everyone is there facing the stage.
And this is where we can correlate all this with the photon. The photon that any atom releases has a certain wavelength, where this will depend on the difference in energy between the excited state and the ground state. If this photon that has a certain energy and phase encounters another atom that has an electron in the same excited state, stimulated emission can occur, that is, the first photon stimulates the other to act in the same state as it.
And the point is that the first photon can stimulate or induce atomic emission so that the subsequently emitted photon vibrates with the same frequency and direction as the incoming photon. And what are the types of lasers? There are many different types of lasers.
The laser medium can be a solid, gas, liquid or semiconductor. Lasers are commonly referred to by the type of laser material employed. Solid-state lasers have laser material distributed in a solid matrix, such as ruby or neodymium:yttrium-aluminum garnet lasers.
The neodymium-Yag laser emits infrared light at 1064 nanometers. Gas lasers have a primary output of visible red light. Helium and helium-neon, HeNe, are the most common gas lasers.
CO2 lasers emit energy in the far infrared and are used for cutting hard materials for example. Excimer lasers, which derive from the terms "excited" and "dimer", use reactive gases such as chlorine and fluorine mixed with inert gases such as argon, krypton or xenon. When electrically stimulated, a pseudomolecule or dimer is produced.
When subjected to a laser, the dimer produces light in the ultraviolet range. Dye lasers use complex organic dyes, such as rhodamine 6G, in liquid solution or suspension as the laser medium and they are tunable over a wide range of wavelengths. Semiconductor lasers, which are sometimes called diode lasers, are electronic devices that are generally very small and consume little power.
They can be incorporated into larger dies, such as the embossing font on some laser printers or CD players. But what about those lasers we use in markers and buy in those old newsstands? These types of lasers we use are low power lasers and we usually find them in 3 colors: blue, green and the most famous, red.
As we already know, the wavelength defines the color of the laser, and in the case of blue lasers, they work in a wavelength of 440 to 485 nanometers. Green lasers are the most complex and brightest working at a wavelength of 500 to 565 nanometers. And the red lasers work on a wavelength of 625 to 740 nanometers.
And you, did you know all this about lasers? Have you ever had a laser and played with turning off the light on your street pole? Or do you have a laser engraver like us that literally burns and engraves surfaces?
Leave it here in the comments and I want to know. I'm going to leave two videos on the side that seriously, it's worth checking out. If you liked the video, leave your like, subscribe to the channel, activate the bell, and it's cool, share this video with more people.
And that's it engineering lovers, a big hug, and see you in the next video.
