How Lasers Work | Laser Micromachining | Lasers in Industry | Picosecond Lasers | Ultrafast Lasers

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How Lasers Work
Lasers are everywhere and used in a wide variety of applications. They are found in barcode scanners, DVD players, used in medicine, produce dazzling laser light shows and of course, instrumental in micro manufacturing. A laser is a device which generates or amplifies light. The acronym LASER stands for Light Amplification by Stimulated Emission of Radiation. The term was coined by Gordon Gould when he was a student of Dr. Charles Townes at Columbia University in 1957. Lasers exhibit some unique characteristics. They are monochromatic which is to say they output a single wavelength or pure color with an extremely narrow linewidth. Depending on the laser type, they can have wavelengths from the ultraviolet, visible or infrared portion of the electromagnetic spectrum. Wavelength selection is important depending on the material being laser processed. As an example, UV lasers are best for drilling and cutting plastics. Lasers are highly directional where the beam can be as little as one millimeter and spreads very little over distance. In fact, lasers have been bounced off of the moon to accurately measure the distance from earth. And they are coherent where all the waves are exactly in phase with one another.
The common components of all lasers consist of an Active Medium which can be gas such as carbon dioxide or krypton fluoride in an excimer laser to generate high power UV pulses. A solid-state laser has a crystal made of ruby, neodymium-doped yttrium aluminium garnet, or Neodymium-doped yttrium lithium fluoride to name a few. The gain medium can even be a liquid although dye lasers are not used in micromachining. The pumping source or energy input can be electrical such as a HV discharge in excimer lasers or Optical using laser diodes to pump Yag or fiber lasers. Lastly, all lasers need an optical feedback which consists of a mirror or high reflector and a partially reflective mirror, more about that later. A population inversion is critical to sustaining laser operation where a large number of atoms are in an excited state. Looking at the Energy Level Diagram, an electron is pumped to a highly excited state and transitions to a metastable region. The electron will seek its natural or ground state. However, it must release its energy and does so in the form of a photon.
Now we have atoms releasing photons in all directions or spontaneous emission. Similar to a blacklight which is a UV pump source and a fluorescent dye. The dye absorbs the UV wavelength and emits a visible color in all directions. In lasers, stimulated emission is achieved by the optical cavity. Photons bounce back and forth between the mirrors. As a photon passes an atom in an excited state, it too emits a photon creating a cascading or domino effect. The output coupler, being partially reflective, permits the laser beam to exit the cavity. The chart shows the laser types commonly used in micromanufacturing. Wavelengths can be anywhere from 193nm to 10.6 microns. Average power is typically in range of a few watts to a few hundred watts. Laser pulse duration can range from microseconds all the way down to femtoseconds which is a millionth of a millionth of a second.
Thank you for viewing and stay tuned for future installments on laser applications in micromanufacturing. If you have any questions or if you want to suggest a future topic on lasers in micromachining, please contact me.

[@SamChaneyProductions]

2:07 "Neodymium-doped yttrium aluminum garlic". Delicious.

[@rajkiran5490]

Amazing Sir!!!

[@Georg-fb8iu]

why did you have to use this annoying distracting music? why do youtubers think its soo cool?!

[@sahilraj1475]

shush

[@globalteamwork4light]

nice video. some reflections. an optical feedback should be named optical resonator, i think. population inversion, is a stupid name. any other name would be better.

[@benediktrentsch1003]

This is a great Video! I think it would be helpful to extend the chart at 3:53 with one column, where you add typical values for the laser power.

[@bytenessretrogames7635]

Thanks for sharing, Ronald! I will post your video in facebook ;)

[@superbroolyy]

video great but music horrible so annoying

[@ProjectSelfTranscendence]

Great food for thought! like the soundtrack in the beginning

[@sody84]

Neodymium-doped yttrium aluminum garlic! ;)

[@sajidullahkhan1289]

Thanks

[@architgupta3d]

Thanks a lot! Informative video :)

[@govorilegko]

It's the most useful video on youtube about LASERs so far.

[@userou-ig1ze]

please explain Kerr lenses and q switching

[@adambritel3178]

Thank u it's very helpful

[@geararcadia6475]

thank you for the info

[@PROF__ESSOR]

Hi i love that

[@robqwert2696]

What program do you use for editing?

[@tinaaslam6061]

How are you sir

[@oussamacheta7106]

i would like to know how can we measure distance withe a laser...

[@TheRealNaggoN]

If you know the speed of something, like light or sound, you can measure how long it took for it to travel from point:A to point:B and perhaps back to point:A. When you know how long it took and how fast it was moving, you can calculate what distance the light or sound travelled.

[@directorindirect]

Is there any chance that laser passes through metal block by any certain changes in frequency...

[@tinaaslam6061]

Hi

[@sabanajed3451]

I need a book about picosecond pulses laser.....please.

[@abdulrahmankerim2377]

Thanks :)

[@Robots4Sale]

take out the audio but its good video

[@king0vdarkness]

What wavelength are they usually?

[@william7yifans]

TSM

[@lelouchlampeerouge776]

when is your next video?

[@okimlistening2u718]

boring .......

[@akshaykhairnar3266]

Can we make simple spitted light into LASER? Ex. Sun light ?

[@abdulmuqeet9300]

How will you capture sunlight in a medium?

[@akshaykhairnar3266]

Can we amplify and mould laser using element without using electricity?

[@abdulmuqeet9300]

Yes, it is possible. The purpose of electric current is to excite electrons. You can excite them by any other way(e.g by bombarding photons, collisions)

[@abdulmuqeet9300]

Please study Helium-Neon LASER. Here, Neon is excited by collisions with high energy electrons of Helium