Shaking molecules until Laser Light comes out. DIY Raman Laser!
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- Опубліковано 26 чер 2024
- Episode 60
#Raman
#Laser
In this episode, let's build a Raman Laser!
First I talk about some of the background of light scattering, Rayleigh Scattering, Raman Scattering discovered by C.V Raman, then the discovery of the Raman Laser by Gisela Eckhardt.
I cover the physical setup from an engineering standpoint.
An old Nd:YAG Tattoo Laser I refurbished is used to pump a cuvette filled with a Raman Liquid.
Although in the early experiments the megawatt Laser energy destroyed the cuvette I was using, I built a Raman cell from scratch, with replaceable windows.
Do I manage to shift 532nm green light to 629nm Red?
References:
Physics openlab: physicsopenlab.org/2022/01/11...
Raman Molecular bond stretching simulation: ir.cheminfo.org/
Stimulated Raman Scattering Video (Your Favourite TA): • Stimulated Raman Scatt...
SRS: www.chem.uci.edu/~potma/Richa...
Eckhardt: research.science.mq.edu.au/di...
Crystalline Raman Lasers: research-management.mq.edu.au...
"Simple" Raman Laser! psl.noaa.gov/outreach/educati...
Raman Shift Calculator: www.photonetc.com/raman-shift...
Check out my other videos: / leslaboratory
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0:00 Intro
0:15 Light Scattering
0:47 Rayleigh Scattering
1:22 Raman Scattering
2:26 Stimulated Raman Scattering SRS
3:14 Raman Laser development
4:19 Commercial Raman Lasers
5:14 Raman Laser Explanation
6:39 Intitial Experiment; Laser ate itself!
7:16 Raman Laser build
7:48 Raman Laser setup
9:41 First Light!
10:44 Measuring the wavelength
11:39 Conclusions and future work - Наука та технологія
Just superb. Despite working at a laser lab for many years now with at last count nearly *five hundred* lasers in the building scattered throughout dozens of labs, I have never actually SEEN a Raman laser actually doing its thing, only diagrams, and theory, and spectral traces. It's beautiful to actually see it happening, and illustrates to the curious viewer so very clearly HOW it's happening. I believe this technique of using a tunable Raman shifter (done with pressure?) is actually the 'secret sauce' of how the fissile uranium 235 "SILEX" laser enrichment process works.
Fantastic work. Time to send you some more $$!
Thanks! and thanks again for your contributions to this channel!
It looks far more beautiful in real life it has to be said. Like the brightest He-Ne beam you have ever seen!
Ah yes, U enrichment, I remember reading about huge Dye Lasers being used for that as well.
The tuning aspect is something I am particularly interested in for Raman. There are a few papers that allude to it. I will have to dig deeper.
Yup they use raman shifted copper vapor pumped dye lasers for the SILEX process. They are tuned with diffraction gratings to a very specific frequency in the near infrared band.
who else thought it was raman noodles?
But can you shake Raman noodles hard enough to get a Raman noodle laser?
I think you might be confusing it with the actual spelling of the name for that type of noodle your thinking of. Ramen, the noodle, has an “e” in the fourth letter, but the word used in this video explaining about it is Raman with a second “a” as the fourth letter. But I admit, it’s an easy mistake to make and you’re not alone in being reminded of food. 🍜
yes, i did think i was going to see a video of using instant noodles as a lasing medium.
Les, Raman gain is inversely proportional to the laser bandwidth and is quite sensitive to the polarization of the laser beam. E.g. rotational stimulated Raman scattering (SRS) requires circular polarization. It is also a threshold process, so don't get surprised if making cell longer doesn't work out. If you are still planning to do that 2-times longer cell, i'd suggest you test a twice longer focus for the lens in a short sell. You can easily get below the threshold and don't get anything if you do so.
Came to mind as well, though not necessarily related. More so in my thoughts is the wanting to make a polarization sweeping mechanism for a webcam spectrometer such as Les's, so to have that range of spectral information as well. Amazed me the additional potential information that can be gleaned from depending how designed and in some situations.
rotational stimulated Raman scattering?
it works on molecule rotation instead of vibration?
@@GeoffryGifariIf I were to guess (I suppose we could all look it up 😂) then my guess would be that the principle here is that using circularly polarized light makes your Raman spectrometer even more discriminating because it can tell the difference between stereoisomers, since circularly polarized light will interact differently with each isomer, depending on direction of polarization.
@@jhonbus ohh that makes more sense.
I just thought since molecules can have rotational degree of freedom, maybe there's a Raman scattering from that too
@@GeoffryGifari some sort of. The Raman shift can be obtained on either vibrational or rotational energy levels. In rotational case it is not exactly the rotation of molecules, but rather tiny energy excess that molecule can have because of some radial bending in the molecule. It was in the table in the video, that hydrogen can give vibrational raman shift and small rotational one.
I thought you had made a laser out of ramen noodles. I'm glad I watched the video instead of just reading the title.
One use of Raman lasers was to convert 1064nm to 1550nm for "eye safe" laser rangefinders. They used a cell filled with 980 to 1200 PSI of methane to do it. Now they use PPLN crystals to do the same thing without the gas.
Splendid. I work on stimulated Raman scattering microscopy for a decade. You are doing a fantastic job to explain, demonstrate, and succeed in building this Raman laser!
Thanks for the heads up regarding Sam's FAQ. Between your videos and Sam's page there's a wealth of information concerning laser technology to access.
Thanks! :-)
_LASER NOODLES_
*_EXTRA SPICY_*
Fantastic work, this is special ! I would like to see other materials for sure and that gorgeous orange red was awesome. Quite a clever guy Sir C V Raman RIP I read a bit about his life. He comments about his Turban being there "to stop his head swelling and keep his Ego in" LOL! never mentions his work with Noodles though...cheers
Thanks! Oh yes, a real genius for sure, with a sense of humour!
WOW! Fascinating stuff!!
...did not expect that- beautiful work technical as well as the presentation
....as you said, absolutely fantastic !
Thanks!
thank you !!- you got me charged up again-- at 67 all my life doin the jaz - NO replacement for that 'magic moment' just as winning the super bowl on steroids : )@@LesLaboratory
Fantastic. Another great project and video. Very inspirational.
Thanks for sharing!
Thanks!
Absolutely great, as usually
Wow you constantly make the best laser videos! They are technical but still understandable by a non-engineer/ physicist haha.
I as a biologist I would love to see you cover second harmonic/ third Harmonic generation. It would go great with your two photon video! (And Its always been hard for me to wrap my head around 😅)
There is an Second harmonic generation (SHG)one here: ua-cam.com/video/UaslPhb9_ls/v-deo.html but it glosses over a way of representing what is going on. I am hoping that @3blue1brown does a video on this. Grant's videos (especially the spring models) are really helpful to conceptualise interaction of light with matter. For SHG, I suppose the spring model would have springs of different relative lengths and strengths, to create anharmonic oscillations.
Third harmonic genertion is coming, I managed to acquire some SHG and THG modules surplus. I still haven't figured out if it is feasible to home grow them yet though!
Great work Les
EXCELLENT VIDEO!!!!
Awesome! Brilliant in every aspect! Thanks again for this master lesson! ❤
Thanks!
Awesome set up, investigation and presentation
Thanks!
Great demonstration
Thanks!
Super neat homebrew!
Thanks!
This is a Top Raman video
Thanks for a great video!
You are welcome!
Impressive! Thanks for sharing.
Thanks!
really cool thanks!
You are welcome!
Very impressive!
Thank you for the “adult” presentation that provided the supporting academic information, yet still comprehensible by those not skilled in the art. I stumbled on this video and after thoroughly enjoying it, subscribed so I can see the others you’ve made.
Thanks! I'm glad people like this stuff, and I'm also glad the level is right!
Awwww, I was really hoping that this was a laser made of Ramen... I was gonna go home and make a Creamy Chicken flavored LASER....
What I once did was to use an NdYAG pulsed laser , only 3 mJ 5ns and a gas cell only 12 cm long. This gave an eye safe output wavelength about 1700nm I think it was and used it as a long range distance meter up to 15km range with a telescope aperture diameter of 150mm gold coated mirror.
Nice! That is very cool! I imagine some 1154nm light is generated in my setup as well, but my spectrometer wont see that far into the IR.
Yup I used to repair those range and target designation lasers. The output is 1550nm 980 to 1250PSI of methane in the conversion cell. Used really thick silica windows at Brewster angle and was in the lasing cavity path of the Nd:YAG pump laser. Alignment was somewhat tricky because both the cavity mirrors were TR at 1064nm, but the rear one was a retroreflecor prism, so it wasn't too terrible for alignment.❤
Doh! Raman not Ramen, now very disappointed not to see a noodle laser
I want to use my noodle to make a Ramen laser.
I watched the whole video and still can't see the instant noodles
Thanks!
Thanks for your support!
Hi Les, just a quick reminder that UKLEM is coming up at the end of March / start of April; you are very welcome to attend, especially if you bring a few lasers!
Thanks! I keep trying to get time to get there it sounds great! Fingers crossed and I will see what is possible.
@@LesLaboratory It would be great to meet up, there are quite a few coming from overseas this time as well.
I've been shaking hands my whole life, have yet to see a Lazer come from this.
I genuinely clicked on this video hoping to see a laser made out of noodles. 🤷🏼
Very nice video! I have wide experience with SRS using gases and Hollowcore fiber.
I will be happy to share the know how. Thanks again
Thanks! Interesting, I may ask you things... :-)
That’d be such a great paper title 😂 I clicked on that video so fast
Ha! Yeah, that would be a good one, especially if such a paper got accepted!
Sir CV Raman made us proud
Laser Ramen! ;)
@4:41 are my lab experiments. That is the tutorial page about it. Thanks for linking to it. Nice work BTW!
Awesome! It was a nice read, just wasn't keen on making a Pressurized Hydrogen shifter in my house! Thanks! :-)
@@LesLaboratory No kidding right? Besides there is the cost of the gases. I made a cell a few years later with both hydrogen, deuteruim with argon:$$$. BTW, you alluded to a solid state Raman laser based on Barium Nitrate. Look at the work on KGW crystals if you are interested. I was working on some of that a few years ago. That seems like a neat and promising solid state laser using Raman scattering. See Mildren and Piper papers
My favorite is the roast chicken flavor.
Light is tied to everything....it always amazes me when I find out another property, use or way to make a laser...
this discovery must of been mind boggling in the 20's
Imagine him trying to explain it to someone lol "you did WHAT?" lol
Wow this is amazing! I thought of a raman Laser just a few days ago 😂 and now here is one! great work! Maybe you build a nice OPO Laser someday or an experiment with parametric down-conversion 😉 Greetings from Germany ✌️
Thanks! I would love to get my hands on a OPO. Maybe some day!
Never heard of Raman lasers before. I know from working experience that Raman spectroscopy is mostly used in Biology, Chemistry and Materials science research to probe the properties of nano films and nano materials. Good content. 👍
Thanks! UI am going to look into Raman spectroscopy at some point. Notch filters have just turned up, so hopefully I can play about over the holidays.
Very cool!
Small question: Why did you opt for a dichroic cube + filter? A grating and a knife edge can probably handle the high pulse energies a bit better?
Because it survived long enough, and I wasn't sure my expensive grating would. I made a home made filter initially, but that only lasted one shot. The dichroic, given it was a cheapie from aliexpress has survived about 100 odd shots, and is just now starting to show discoloration.
@@LesLaboratory Ah okay, thank you!
Hehe, I remember this riddle in twitter :-)
Now I want raman noodles.
Some lasers look so delicious, I just want to eat them.
Fantastic results! Have you measured how much of the pump concerts yet?
Thanks! Not yet, it is particularly finicky to get it working for long periods (thermal lensing, optical damage etc) however there has been some suggestion that this may also be producing extraordinarily short pulses, so it looks like I will be investigating autocorrelation amongst other things.
@@LesLaboratory interesting.. for ultra short pulse generation I would expect the resulting spectrum to be much broader than the pump spectrum, because you usually start driving a bunch of funny nonlinear processes at once.
Raman scattering in Ramen noodles.
Good video. If you want the long explanation then see Derek A.Long: The Raman Effect A Unified Treatment. You can solve the equations exactly to calculate exactly what wavelength and intensity of scattering you will get. It's fascinating to see how you work through it from basic physical principles and a good demonstration of where maths ends up pretty complicated. You solve it with a method developed by Oppenheimer.
Another cool video Les! Wallpaper-worthy laser setup picture near the end.
Some thoughts about the Raman laser:
1. What is the advantage of having a Raman-shifted laser light? at first glance it seems like the wavelength shift is fixed so not that many new wavelengths can be obtained when the pump wavelength is set by its own gain medium.
2. If Raman scattering can end up with a smaller wavelength output light, does it mean the molecule transfers its own energy *to* the light? If so this seems applicable for cooling the gain medium or raising the output photon energy.
3. What is the range of pump wavelengths can we use Raman scattering with? Is each molecule more sensitive to a certain range of wavelengths?
4. Why the restriction on the gain medium total length?
5. Not a question, but its kinda wild that a coherent light (the laser) can interact with a bunch of molecules like that and the Raman output stays coherent with a sharp linewidth.
Oh and which source did you use for the "light scattering" book chapter in the intro?
Don't feel pushed to answer. I just think these are some interesting stuff to discuss together.
i think #5 goes along the same way as how stimulated emission does this in the first place
@@bottlekruiser Oh the Raman gain medium is also contained in a resonant cavity isn't it? I forgot
I was imagining a jumble of fast-moving, jiggling molecules not oriented in a particular way that somehow can generate coherent light
no the raman medium wasn't in a resonant cavity, but you don't really *need* one to have stimulated emission
TEA lasers lase without one
resonant cavity isn't there to orient the molecules, it's there to selectively accumulate the standing wave that sets the direction&phase of the stimulated emission. Here we have the coherent wave premade for us. Hmmm doesn't that mean that the stimulated raman emission isn't necessarily coherent in phase with itself
@@bottlekruiser but a cavity is needeed for the A part in LASER right?
I agree with your point on the resonant cavity, its just I'm thinking even though the pump light itself is coherent, interaction with molecules is necessary to produce Raman light... they're linked. Now somehow the randomness in the state of the molecules still produce sharply coherent light?
@@GeoffryGifari a cavity is required as a technical limitation, it is not inherent to the process. The excited atom doesn't know or care there's a cavity, it's stimulated by the local field and acts accordingly. The cavity helps that immensely, but again it's not *inherent*.
How to build a DIY laser?
Step 1: Have a laser to begin with…
9:50 technically, frame rate isn't the key setting - but shutter angle. This is the ratio between frame rate and shutter speed. So if you're recording at 120 fps, a shutter speed of 1/120 will absorb all light, while 1/240 will absorb light 50% of the time and be closed 50% of the time, and so on.
It's called shutter angle because historically, cinema cameras used a spinning disc coupled with the film transport. So the amount of time light was let in correlated to the size of the cutout in the disc. 180 degrees, 90 degrees, 45 degrees, etc.
Scientifically, the main concern is what percentage of the time your camera is receiving light, but in cinema the visual effect of shutter angle on action scenes is quite pronounced - even though the camera is 24 fps the entire time.
Thanks, I will look that up and see if my camera supports it. The biggest issue I have found when it comes to filming short events, is the rolling shutter. If it was a global shutter, I suspect I would get far better results.
Have you completely abandoned experiments with dye lasers? The mention of DMSO in this video reminded me that it is a very interesting polar aprotic solvent. Does it have advantages as a solvent for the active medium of a dye laser?
Not at all, in fact, Dye Lasers will be making a re-appearance on here. Sure DMSO can be used as a solvent for dye Lasers. The type of solvent can affect wavelength and tuning range to some degree. If you use DMSO be mindful that although it is quite non-toxic, it aids the transport of chemicals through the skin and into the blood stream, so solutions of substances dissolved in DMSO can be toxic on contact.
Took me too long to realise it was spelled "raman" and spent a little bit of time wondering how you shake ramen noodles to make laser light
That would be way cooler I suspect!
What did software/website did you use for your illustration?
For the animation for the molecular bond stretching I used: ir.cheminfo.org/ You can load in molecule files or build your own. For the rest of the diagrams, just plain old Powerpoint (Believe it or not it is quite a capable tool for simple diagrams and animations!)
Ever since I read about this discovery being the first Nobel prize in science awarded to an Asian, I tried to look more into it.
To me it seems like Raman-related literature come mainly from chemistry, despite it being awarded a prize in physics.
The spectroscopy is an incredibly powerful tool in chemistry for investigating the structure of molecules. Note how extremely high the signal to noise ratio is on the trace for C2H6OS at 11:25 here and how clean and specific the overall spectrum is. It's often used to identify substances using this specificity by automatically looking up trace peaks in a library.
@@Muonium1 ordered a couple of alleged 532nm notch filters from aliexpress. If one or more of them is any good, I will be having a crack at Raman spectroscopy.
@@LesLaboratory sweeeeeet, super eager to see what you find! I know Ben Krasnow attempted this with polystyrene a few years ago (holy shit... it was *a decade* ago. truly scary!) but there was some debate about whether he was seeing actual Raman lines, or if they were neon and helium lines from the plasma in his HeNe excitation source.
There are 3 different laser frequencies in this setup.
The initial infrared beam.
It gets doubled up to green.
That gets ramanized down to orange.
Do the goggles block all three?
Don't worry, I am not planning on using any complex laser setups. At most I might use a laser cutter, which uses a single color, so I would just need safety goggles designed for that color.
For this setup, it seems you would need filters that block everything but blue.
No, they're "LGB", or "KTP", or sometimes, but increasingly rarely since almost no one uses them anymore "argon" goggles. They block the fundamental Nd line and its doubled green, but are amber colored as can be seen and let orange and red light through so do not protect against the Raman shifted 629 here. At some point working with lasers of multiple wavelengths you just have to accept what's possible and take some risk with your setup. If you didn't, the only goggles you'd be able to use were ones made of steel, because a totally opaque material is just about the only thing that will protect your eyes from all the wavelengths you're dealing with in many real world setups. There just aren't any goggles that work for all wavelengths in an experiment like this, they don't exist. So what you do, and what he did, is simply choose the ones that are most suitable for the application and which block the most intense and most dangerous beams, which are the IR and 532 here, and just be careful about the orange beam.
What @Muonium1 said. The OD for these is pretty low at 629nm, and so it represents a moderate to serious risk to vision. For Supercontinuum the situation is worse. No glasses will protect you from all wavelengths at once.
For a setup like this, you must make sensible use of beam stops, and make use of a camera for the setup. Cameras, though expensive, are replaceable. Eyes, not so much!
Is it possible to recycle the dump beams back into the system to help energize the raman cell? It looks like a lot of energy is lost to the dumps beams, but I guess the camera might just make it look that way. Would it be worth doing in a real world set up?
Yes, the current setup is not very efficient. If resonator mirrors were included, it may be possible to extract more power. The system is problematic though, as the peak powers are huge. Stray reflections will destroy optics, and reflections back into the YAG Laser would more than likely destroy it. There may be more efficient ways that I am looking into.
I'm very inexperienced in this area...he had very little to no output with the acetone and ethanol, and at the end he had success with dimethyl sulfide if I heard correctly? I'm curious about the length of interaction in the cell in the setup shown, the higher limits one is able to make that interaction and the effects of increasing the interaction, also is it possible to use multiple cells and what it's effects are, what effect does input wavelength, power and time have? I know I'm asking alot of questions but I'm extremely interested as I'm not knowledgeable yet in this field and learning new things like a simple method of changing a green laser into an orange/red laser etcetera might as well be a cigarette or alcohol habit for me 😂
The autogenerated subtitles say that these are ramen lasers. 😂
Oopsie! I will have to fix that!
On site to Raman cell is no need to paint in black colour to minimise residual wave generated by aluminium?
There is no need to coat the insides of the cell. The light is preferentially scattered forwards.
Hi Les, I got a question about light that you might know the answer to:
I've read that the wavelength of light (is one of the factors that) determines how much a small structure can be resolved by that light. Wavelength can be thought of as the distance between two electric field peaks along the direction of light propagation.
Light propagates in 3D space, and even the collimated light from a laser pointer have a finite cross-sectional area.
The question is: Is the cross-sectional area of a light beam limited by its wavelength? lets say that a laser produces circular spot on a screen with radius R from the center (highest intensity) to the edge where its intensity is (just close enough to) zero. If we have an X-ray laser, will this be able to produce a spot with much smaller radius R compared to a red 650 nm laser?
Yes, there is a finite spot size. This is dependent on initial beam dimeter, focal length, beam quality etc.
Assuming everythng else is optimal, then yes, youbare correct, the ultimate limit (diffraction limit) is determined by wavelength. This is why Nichia's blue Laser diodes were such a big deal when they first hit the market.
Sure the output from an x-ray Laser could be focussed into a very small spot indeed, way smaller than any visible wavelength. Of course actually focussing x-rays is extraordinarily challenging.
@@LesLaboratory Ohh I see. Good to know!
"Don't try... [this] at home..."
Then where would a safe place for us to try it be, do you think?
#disclaimer!
Right, @@LesLaboratory, you specified that HOME is it a good place for us to try it. So where would be a good place for us to try it?
I found an infrared laser diode and i don'tt know if i need a resistor in series and what kind of resistor i need or powered direct from my source. The power of laser diode is,115W, 895-915nm, 13.2v, 0,8A ,and I don't know if I should buy it to create with light pulses, plasma in the air (that is, to ionize the air) in the focal point. Do you think it's worth buying , so do you think it can work?i have laser glasses between 650-1200nm.Ochelari de protectie operatori pentru tratamente LASER DIODE si Nd YAG,or should I use the dark green glass of the welding mask?can this 115w diode produce plasma as I said?
I tried to make a Ramen laser once!
But all I got was wet noodles!! 😝
Amazing work, Les, and thank you very much for the shout-out at 3:06! I plan on posting a video on the intuition behind phase matching in nonlinear optics, so stay tuned if you want to know exactly why n(ω)=n(3ω) is required to achieve third harmonic generation :-)
Thanks, and you are welcome, you have quality content there! I was especially interested in the recent light propagation in fibers video! Oh I will be 3rd harmonic is on my list of practical stuff to do!
@@LesLaboratory My video on phase matching and Third Harmonic Generation has now been posted!
@@yourfavouriteta excellent as always! THG is coming on this channel, and when it does I will be sure to link the video!
@@LesLaboratory Wonderful! I am also finishing up a video explaining how to derive an accurate THG model, which both accounts for power transfer from ω1 to ω3 and the other way around.
@@LesLaboratory My new video on THG has now been posted. I look forward to seeing you demonstrate it in practice!
So the frequency shift was due to methyl group vibration according to your spectrum, therefore the same effect could be expected from acetone or anything with lots of CH3 groups? On another note, since ramman effect is more pronounced for non polar molecules, you could try some benzene, toluene or stuff like tha
Exactly. The strongest peak normally Lases. It is possible to get other peaks to Lase, and even have the shift cascade (Cascaded SRS).
Sure. for that I need a longer cell I think, although, there are also 'other ways' to make the conditions favourable for other materials.
Good to know. But what makes acetone less effective compared to DMSO? I mean Very similar molecular structure..
🤨 Thanks a lot... now I look like an idiot, trying to shake my ass to see if laser light shoots out of it!
I expected a Ramen laser for half this video...😢
shaking Ramen noodles till they emit light
This made me want a big bowl of raman 🍜 Light raman at that 😂
Sorry if this is not on topic, but shouldn't there be some kind of scattering from quantum vacuum fluctuations? It feels like "yes" but I couldn't find out what it was, if it exists. It also feels like there should be changes in that scattering in situations where the Casimir effect is significant due to restrictions in the allowable vacuum fluctuations. If any of what I said isn't word salad, I wonder if positronium, which should be a relatively common (comparatively) vacuum fluctuation could be used to create a Raman laser. I dunno. Probably pair creation from the radiant intensity would happen way before that. Also it would be essentially impossible energy-wise.
Not an expert on this, so hopefully a theoretical physicist will jump in.
The vacuum fluctuations as I understand it, is more probabalistic than 'real', in everyday life at least. In extreme circumstances, such as at event horizons, real particles can be liberated as one of the pair is destroyed by the black hole.
Given the virtual nature of the particles, I am not sure if light can even interact with them.
Try Don Lincoln from the UA-cam channel: fermilab
i am not proud to be a mallu but i proud to be a indian
So Raman literally did just when you burn your skin tattoo the light came from burning the skin concentrated into a beam of lazer which has visible spectrum... If you burn or excite any element in the burning chamber any element can become lazer which emits light if it's excited...
I guess with the minimal laser background I have I'm missing how both devices that produce lasers from not having a previous laser beam, and devices that transform the wavelength of an existing laser, are both just called "lasers". Is that KTP crystal also a laser? I don't really understand the distinctions here.
It's quite common to call sources of coherent light a 'laser', even when they have nothing to do with stimulated emission.
Formally, coherence describes how well light waves can interfere with each other. Informally, it describer how 'ordered' the light waves are. Spatial coherence means all wave crests are parallel in space, yet temporal coherence means they follow a defined pattern in time.
In this video, the actual laser is an flashlamp pumped Nd:YAG laser. Then, in a coherent process called second harmonic generation, it's frequency is doubled/it's wavelength is halved.
Afterwards, Les demostrates another coherent procress that changes color (stimulated) raman scattering.
If light is amplified coherently, we would call that a Laser. KTP is a special crystal that interacts with Laser light to double its frequency. No amplification happens there. In the raman cell, light is amplified, and so we could term it a Laser.
So the amplification pulls in the frequency, to say @@LesLaboratory
OK it's a really good thing I've eaten already but I'm already hungry I don't know why.
Lol remarkably simple you say, but when can we buy raman specscope costing the same as a pack of ramen noodles? 😜 p.s. i hope no undisclosed titanium dioxide "brightener" in your noodles -- or any other food or drug for that matter. How can a home kitchen investigate? Raman spectroscope. gah!
When ramen laser?
But, can you make a ramen laser?
I'll see myself out.
So, can you actually make a laser out of a bowl of Ramen ?
ramen?
I love my india ❤❤❤❤❤
If I shake you hard enough will you emit light too?
Probably! Ask @thethoughtemporium he wants to build a Laser made of meat!
I have been shooting lasers, since time immemorial
my fatass thought that said "ramen laser" 😭
Like the comment if you saw a $1 bill near the oscilloscopes in the beginning of the video.
Noodles anyone?
Hail the transsubstantiated noodly appendages of the body of the holy Flying Spaghetti Monster!
it was the first thing i thought too
O3MEK.
Who else came here looking for a laser made from instant noodles? Probably just me
The sky is blue because there is water beyond the dome.Read the Torah.
And why do we see the colors we see at sunrise and sunset, rather than blue?
Because the shorter wavelengths are scattered away, leaving mostly the longer wavelengths.
@@LesLaboratory Sorry, yes, I was asking how Keenan here explains it in his “water outside the dome” model.
5:25 How does "doubling" 1064nm create 532nm? I think you need to go back to math class...
Double the frequency is equal to half the wavelength.
Yes, I know. But you said doubling 1064nm (a measure of WAVELENGTH, not frequency) gives 532nm, which is not correct. Doubling 1064nm would give you a wavelength of 2128nm.
Only watched because I thought it was a recipe for Raman noodles
1/5 stars
Disappointed 😢
DMSO tastes ok
😂
Don't drink DMSO it's not as non-toxic as you think!
Did that India chap also invent Ramen noodles? 🤔 I thought Ramen soup would Laser because of you mentioning Ramen Laser. You said Ramen so much that I got hungry and I'm loaning for big bowl of Ramen Soup Noodles