Schlieren Optics
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- เผยแพร่เมื่อ 23 ม.ค. 2014
- Demonstration of an optical technique that allows us to see small changes in the index of refraction in air. A point source of light is reflected from a concave mirror and focused onto the edge of a razor blade, which is mounted in front of the camera. Light refracted near the mirror and intercepted by the blade gives the illusion of a shadow.
Seen here are the heated gases from a candle flame and a hair dryer, helium gas, and sulfur hexafluoride gas.
For more information on our setup please see
sciencedemonstrations.fas.harv...
Note that this version of the setup uses a white LED flashlight instead of an automotive light bulb.
Thanks for watching!
The first time I ate mushrooms my friend and I were staring up at the sky on a beautiful cloudy day and I could see air being refracted much like what you see here in this Schlieren optic set up. I can finally find a way to describe that moment now. I wonder if I was actually ABLE to see it with my naked eye? If not, I'm sure it was just a hallucination, but it was so vivd and real I could touch it and alter it with my hands and breath. That was 20 years ago.
Thankyou for this elegant demonstration. I had never heard of "Schlieren Optics". It reminds me a bit of the "mirage" effect that occurs when you at a road on a very hot sunny day, and it looks like puddles of water on a road that is actually dry. I'm still thinking about how this effect comes about.
This is one of the most amazing things I've seen on the internet.Thanks so much for sharing.
Really? Then you haven't seen those crazy Chinese car crash videos on TH-cam. LOL
You're easily impressed and haven't seen many things I see.
Or you could just be amazed by different things?
That's also an option...
This was perfect and no narration was needed! Really enjoyed watching, thanks so much!
July 2023 - OKAY! YOU DEFINITELY have my attention. If I met you in college, I would have changed my major from Electrical Engineering to Optics. Well done demo! Thank you!
The first thing that came to mind was just imagine what the air looks like in a traffic jam in a city on a hot windless day
You should have a conversation in front of it and see how the air from your mouth travels when you say different words.
Like the caterpillar from Alice in Wonderland!
Or maybe see how people spread virus when we are sick, like coffing, and sneezing...tho
My comment wasn't an idea, just an observation, but both works just fine XD
HosTer David Coffing, cause, y'know, THAT'S A WORD.
This works based on changes of the density in a gas, in this case, air. So it'll work for large temperature differences, or for different gases introduced into the system with a different density. I don't think a conversation will change the temperature of air enough to see refraction, unless the environment is probably below zero abient temperature.
Seeing the unseen. Awesome demo. Heatwaves and fumes. That's cool.
I don't understand how it works, and can be so accurate with a so "simple" mounting, but it's just really awesome.
Wow, I could entertain myself for weeks with that setup.
You should totally take the hair dryer back and with a ping-pong ball, show the Venturi effect!
Finally, someone suggested something worth trying.
@@getsideways7257 what about Coanda Effect
That's really cool, the effect looks almost magical :)
put a subwoofer in front of it
th-cam.com/video/MBPh410Gnes/w-d-xo.html
"Starring Daniel". That's all.
Btw, this video is truly beautiful, great work!
I would love to see this with musical instruments, especially brass and woodwind types.
Can you do this with an instrument? Saxophone, clarinet etc
Wow, this seems useful for wind tunnel studies, its really quite beautiful.
Sulphur hexafluoride (SF6) is a greenhouse gas and has a very high radiative forcing effect and a GWP of 22,800 compared with a figure of 1 for carbon dioxide. Emissions occur due to its use in a small number of applications. Annual emissions have decreased by 67% since 1995.
I like the upward "pouring" balloon air out of the glass demo...pretty cool. ;-) THX for posting. Thumbed up.
Can very similarly be achieved via vaping if your able to make thicker clouds with your set up. I enjoy filling my sink up. Watching it flow over the cold metal. Looks cool.
Not as thick as this shows all gases but like I say, similar effect. Amazing what you can see when the invisible is made visible.
Science!
Ah man that was so nice... I envy you! Thanks for sharing. :D
It's similar what I see. The colors and shape of more active leaving understand you're never alone 😊
Some narrative explaining the setup would have been welcome.
The blurb below does. The description. I read that when I realised it was a silent film.
have a look at this: sciencedemonstrations.fas.harvard.edu/presentations/schlieren-optics
Try reading the video description bub.
Baruch Ben-David May I ask...are you serious?? Not to be rude or anything; just responding kindly that my belief is this video wasn’t put here for anybody; I’m struggling with why “Thank you” would’ve been inappropriate here. Call me sensitive lol ✌️
Checkout en.wikipedia.org/wiki/Foucault_knife-edge_test This same effect is used to test optical surfaces
absolutely amazing !
I could watch this all day
I can't stop my self to comment your videos.
Ignore the naysayers, this technology could revolutionize paragliding, it could well be used in sun glasses or cameras to find Thermals ( columns of hot air) that Gliders, Hanggliders and Paragliders use for gaining altitude. It would revolutionize those 3 sports forever. Keep the good work!
Amazing! I wonder if this can be used to visualize air flow around an aircraft during wind tunnel testing.
This IS in fact used for that
WOW! tres beau !
Wow this is just so freaking cool.
Perfectly describes and proves why gases are fluids too
Awesome¹ºº. I never realized gases acted in the same way as fluids.
Amazing, I haven't thought gases as fluids and how temperature affects them.
Love this. What would the focus of a convex lens (magnifying glass) in free space (in the air) look like?
Nice video fellow!
Hmm... I do see many interesting uses for this.
And discoveries that could be made.
Another Dimension.....
Uber Awesomeness 😎
Somehow it's very relaxing to watch this.
Gorgeous
I love this so much
This seems very similar to the Foucault knife edge test. Anyone familiar with making telescope mirrors knows what I'm talking about. It's a test designed in 1858 by French physicist Léon Foucault to measure conic shapes of optical mirrors.
it's exactly the same principle
Thats insane guy, keep it up =D
Chaos is as beautiful as it is complex and mind twisting
Nice thank you for showing.
Well performed ty
Good vid!
Another cool thing you can see with this is shock waves.
really amazing ..
El invisible mundo de las corrientes de aire, AWSOME!
Awesome!
that is awesome!
had once such a mirror. It was mounted before in a bloody heavy spectrometer (monochromator?) DMsmth or DRsmth. Six of us barely could lift it up.. Could not raise a hand to through such a nice mirror out.. probably still stays in that lab on a shelf.
Oh my Gawd, the experiments I would conduct! I can’t even begin! What is this magic?!?
Awesome.
How beautiful
That's why the FAA says to consider the air a fluid.
Lol...fluid is liquid and gas
“New subscriber”.... well foooooking trippy stuff. 🇦🇺🤜🏼🤛🏼🤓🍀
Looks like there is a hill on the spherical surface... knife edge inside focus of hill. Leon Foucault used a similar instrument for optic fabrication.
this deadass gave me asmr tingles
I’ve never seen such a thing in my life - wow 😮
that's awesome
can we see the compression waves of sounds on the air using this method?
It would be interesting if you could adapt this technology, or similar technologies, to cameras, and sort of turn it into an overlay on the display.
You can't do it in-camera, you need a setup of multiple physical object for it.
We are living in a time where anything is possible really... never say can’t...
you might be able to simulate it at some point by applying some sort of complex CGI filter that would simulate that sort of effect with whatever's on camera.
That's what causes the "liquid heat" effect when looking over the crest of a hot asphalt road.
awesome ,man really awesome
:O :)
Is pure oxygen gas magnetic? Could you see any effets of it with this?
+Harvard Natural Sciences Lectures Demonstrations
I have a question. Obviously, the hot air goes up, but why through the schlieren system, we see the air actually goes up instead of going down? I mean through the camera why we see the actual direction instead of reverse direction?
why should it be reversed ?
Build a bigger from that. Love it🧘🏼♂️
Incredible or as the french would say Incroyable!
Put the hosts of *_The View_* in front of it.
Hahaha, gas bags!
That is neat. I hadn't thought of that. An upside down cup holds gas. Gas's buoyancy, temperature, and electromagnetic state cause it to move to the top of the stack of matter in a gravitational field?
What?!
Awesome :]
I could not remember what this technique was called & ran all over the internet for the last 3 hours trying to determine if it was real or I made it up in a dream... but now I'm in that happy place after hitting the snooze button & buying myself 5 more mins of this reality!
YOU SHOULD BLOW O RINGS WITH THE AIR AND SEE IF IT SHOWS ON THE THINGY
When you did helium my instant thought was, 'I wonder what sulphur hexofluoride would look like.
I'd love to see slightly warm gallium and Mercury.
I've often wondered if this technique could be used to create an optical microphone that doesn't get in the way of the same sound field it's attempting to measure.
Whoa
Makes all the gasses look like liquids. Crazy! :D
hello, I what to ask you a question. Thanks . Will schlieren work if we are trying to watch the shock wave in the circular pipe. the pipe is glass and 12cm in diameter and 1cm in chickness. actually, I want to now Circular structure will make schileren impossible?
The circular pipe will make it extremely difficult, if not impossible, to see the schlieren effect.
Can schielern optics be made in to a camera or do they need a mirror in the back of what you observe..?
A concave mirror is required to reflect the light source placed right next to the camera.
How do you get such great contrast, in a lit room? I've seen some other Schlieren videos, dark room but poor contrast. Is it the mirror? Exact positioning of camera and light source? There seems to be an art to it.
Thanks. Yes the quality of the mirror, the brightness of the point source, the positioning and height of the razor blade at the real image of the point source...all these factors are important for good image quality.
@@NatSciDemos can you explain to me what i am looking at when the air is moving around? i am looking at the mirror, but not directly at the mirror, right? is this view through a lens? because you switch between the actual mirror - seeing reflection - and the mirror showing these air movements. i would like to try to build one myself. maybe you could provide me with some theories or tips on how to build one. i have read how it works, but i am just amazed that it works that way haha. to truly understand it i think i should know more about natural sciences maybe.. i am an art student with a big fascination for light and image making
you work with two mirror,s right? the second one reflects the image.. jees so complicated!
@@SuperSquirrl01 if you haven't got the answer its directly looking at the mirror from its focal point. You only need 1 mirror
I love science.
does this work with other types of mirrors or just a concave mirror, as well as does anything change if you change the object that its reflecting off of , in this case you use a razor blade, what else works? very cool, and interesting. Good job and thank you for sharing
a concave spherical or parabolic mirror is needed
@@wolfgangrueckner7151 so basically anything that works off the same principle as a fish eye lens then right?
O myyyyyy goooooooooddddddd is amazing!!!!!!!!!
Harvard Natural Sciences Lecture Demonstrations What is the purpose of the razor blade and how does it work in conjunction with the camera?
The purpose of the razor blade is so the camera only captures the defracted light from the. different air molecules and blocks the ones that arent bring defracted by the differentair molecules
that is cool thanks for sharing
Do you wash the glass after this stuff?
Could this technology be used to detect in flight air turbulence? Airplane rides could get more smoother.
i dont really think that would be able :-/ If you have some sort of idea could you draw it down or describe it 😊
Imagine your living room wall being like this, could be super stressfull, but at the same time incredibly relaxing?
I want to do this with my airbrushes! How do you set this up?
th-cam.com/video/IZ0bYi9UFv8/w-d-xo.html
Very interesting, but it wasn't real clear where the camera and razor blade were in relation to the point source of light (especially on the wide shot).
go to our website description of the experiment ... the diagram shows you the camera and razor blade positions relative to the point source of light; sciencedemonstrations.fas.harvard.edu/presentations/schlieren-optics
amazing! what are the small circular blotches?
those are dust splotches on the mirror
what are those round dots on the screen???
guys have you tried smoke ring "tecniques" ? those are very interesting
Seemed like a lot of hot air at first,,,lol,,great work.
waaaay tooo coooool! :)
Quelques explications seraient bienvenues !
I didn't understand this instrument. What is it? Is it showing the heat in the display ?
Can I make one of these at home ?
Hi, is there a special camera and lens required for this experiment?
We use a zoom lens in order to see the mirror from a distance of over 6 meters. The type of camera does not matter, as long as the zoom lens fits on it.
This looks an adaptation of the Focault test used by telescope mirror makers to determine the accuracy to which the telescopes mirror has been ground, interesting!
how did you manage to show the air movement on the mirror?
There are changes in the index of refraction in moving air, and these show up in schlieren optics