Visualizing Ultrasound with Schlieren Optics Part III

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Visualizing Ultrasound with Schlieren Optics Part III

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Harvard Natural Sciences Lecture Demonstrations

6 жыл бұрын

Part 3 of 3. We combine the stroboscopic effect with the use of color filters in our schlieren optics setup to visualize the changes in air pressure that occur in a standing wave created by an ultrasonic transducer (driven at 28 kHz) and a reflecting glass plate. As a finale, we levitate small Styrofoam balls in the pressure antinodes.
Without the color filters, the brightness of the schlieren image only gives us information about the magnitude of the pressure changes in the standing wave. We can now use the color information to tell us whether the pressure is increasing or decreasing. Each colored band is a pressure antinode that is oscillating between high and low pressure.
The order of the color bands in the standing wave depends on the relative phases of the strobe light and the transducer. Although we do not show it here, shifting the phase of the strobing light source by 180 degrees causes the colors in the standing wave to reverse.
The color filters we use here are Kodak Wratten 2 color filter #29 (red) and #61 (green).
More information about our schlieren optics set-up and how it works can be found on our Science Demonstration website: sciencedemonst...
Safety Note: Although 28 kHz is beyond the range of human hearing, ear protection should be worn whenever attempting this experiment to avoid damaging vibrations in parts of the ear. Any high-pitched whines you hear in this video are not dangerous.

Пікірлер: 136

@linachernykh7945 4 жыл бұрын

These videos are such high quality, thanks to Harvard for producing them

@wolfgangrueckner7151 4 жыл бұрын

thank you for the kind words

@NatSciDemos 4 жыл бұрын

Glad you like them!

@blxckmxrkxt 3 жыл бұрын

yo wheres that good and smart grandpa?

@samflint4749 5 жыл бұрын

I have been working with Schlieren for over 5 years now, and it never gets old. Excellent presentation. Bravo!

@rasmusg1407 3 жыл бұрын

I am a man of science, and I would still call this magic. Amazing!

@youvebeenspooked 4 ай бұрын

you must not be a man of science, lol. electrician?

@PilotRazz-kz2zp 4 ай бұрын

3 years later, someone didn't get the joke 😂

@youvebeenspooked 4 ай бұрын

I am indeed slow hahaha@@PilotRazz-kz2zp

@zack_120 9 ай бұрын

You are the solver of nature's secrets 👍👍👍

@LL-sk3do 5 жыл бұрын

This professor's videos are going to blow up

@robotslug 6 жыл бұрын

Super interesting! I wonder if this can be done in a cross with 4 colors giving you left and right as well as up and down.

@wolfgangrueckner7151 6 жыл бұрын

Yes, that can be done.

@riacheriefailla 5 жыл бұрын

@@wolfgangrueckner7151 would love to see that

@texasfossilguy 4 жыл бұрын

Never seen that. Good observation

@ishanr8697 3 жыл бұрын

I wish I had this video when I was teaching waves earlier this year! Next year maybe.

@amphimixis 5 жыл бұрын

Hey come back and post more videos!

@ernstuzhansky 5 ай бұрын

Very cool!

@DoNotPushHere Жыл бұрын

I'm curious to note if anybody else noticed that the red and green bands seem to be paired. There is a dark band in between but it is thinner and thicker each couple of red-green bands. Now I wonder if that is a property of air elasticity or if it is related to the red greem filters not being perfectly centered

@HumbleBasse 3 жыл бұрын

arent the green area of the wave the descending slope of the wave and the red area the ascending slope? the antinode would be space without color in between, since at the "top of the wave" there is less change in density?

@wolfgangrueckner7151 3 жыл бұрын

that is what one would conclude

@googacct 6 жыл бұрын

It would be interesting to see this done with multiple transducers to see wave interference and maybe beam forming.

@wolfgangrueckner7151 6 жыл бұрын

Yes it would!

@mateuszjanowski2521 5 жыл бұрын

I want to do it for the TinyLev kit, I can send you video if I do it.

@InsertCleverUsername 5 жыл бұрын

@@wolfgangrueckner7151 So will you do another video please?

@wolfgangrueckner7151 5 жыл бұрын

@@InsertCleverUsername Probably this summer

@noob4ever62 4 жыл бұрын

@@mateuszjanowski2521 send me one as well please

@ManuelSalmonRock 6 жыл бұрын

Thank you! Professor this is Ying Yang in action.

@glikar1 4 жыл бұрын

Brilliant! Thank you.

@jstmeknz87 5 жыл бұрын

I can’t even speak! This is amazing.

@nukeelda 10 ай бұрын

Where to get that mirror please? Excellent as always!

@placebomessiah 3 жыл бұрын

Nice amp bro

@colleenforrest7936 3 жыл бұрын

There are actually 3 colors: Red, Green, and Dark. What do the dark zones represent? There are two types of Dark bands: a thick Dark band and a thin Dark band. If the Dark bands are transitions between the red and green, why are some positionally consistently thick and other's positionally consistently thin? Why wouldn't they be of the same length regardless if a red band was transitioning to green or a green band were transitioning to red?

@wolfgangrueckner7151 3 жыл бұрын

Good question, Colleen. I think that the distance between the source and reflector wasn't adjusted optimally, leading to a slight asymmetry. The dark bands ought to be uniform in width.

@maxxie878 5 жыл бұрын

There's a few things about the levitation demonstration that tripped me up, so I want to make sure I understand it correctly. According to this link www.acs.psu.edu/drussell/Demos/StandingWaves/StandingWaves.html, a standing sound wave can be represented by the "displacement amplitude" or by the "pressure amplitude." I assume the little balls go to the _nodes_ of the _displacement wave_ and the _antinodes_ of the _pressure wave._ Since the colored bands represent the highest change in pressures, that's where there is zero displacement in air molecules, so the balls go to those places. Also, I assume the pressure in those colored bands is actually alternating from high to low at 28 kHz, and the strobe light is set specifically so that you only see the bands in one color. This was confusing because I think other sources said the little balls should go to the nodes of a sound wave, and I think my account explains why they said that. If I'm totally off base, I apologize. Always glad to learn.

@wolfgangrueckner7151 5 жыл бұрын

you are correct in your assumptions

@maxxie878 5 жыл бұрын

@@wolfgangrueckner7151 Thanks for the quick reply.

@Rawk10 5 жыл бұрын

MAGIC !

@jeffersonquadro1204 5 жыл бұрын

THIS IS FUCKING SICK!🤘

@AKennethNolan 3 ай бұрын

2:09- Dr. Rueckner looks on patiently as Allen bangs around in the freezer as loudly as possible.

@h7opolo 3 жыл бұрын

very cool. now what happens if you translate the upper plane vertically? will there be more bands or will the bands themselves expand? i suspect the former scenario would occur.

@NatSciDemos 3 жыл бұрын

If the reflector is moved vertically and the driving frequency remains fixed, then the standing wave will disappear until it has travelled a distance of another half-wavelength (in this case I think that's just under 7 mm).

@h7opolo 3 жыл бұрын

@@NatSciDemos oh, thank you, that makes sense.

@Onkarr 3 жыл бұрын

@DarkPhaaze 4 жыл бұрын

I think it would be interesting to try to visualize interference using this type of setup. I remember once a schlieren-type setup was coincidentally created in a Sonic drive thru by the reflective glass from a building under construction nearby. I would just sit there and watch the hot air rising off my car...

@wolfgangrueckner7151 4 жыл бұрын

You can see interference of sound waves in our newest video: kzfaq.info/get/bejne/Y8h_nM1l2ra1Z6c.html

@AKennethNolan 3 ай бұрын

Why do the balls settle in both the higher pressure and lower pressure parts of the wave? It seems intuitive to me that they would settle only in the low pressure regions, because the higher pressure regions would push them away. Anyone have a simple explanation for this?

@hoosahfudge 5 жыл бұрын

Fantastic

@1.4142 2 жыл бұрын

Better than the razor blade

@benjaminjoeBF3 3 жыл бұрын

Hey those balls looks like electrons in orbit

@skyfocus7338 3 жыл бұрын

WOOW !

@mrkps1986 5 жыл бұрын

WOW AMAZING MAN GREAT

@kenjinks5465 3 жыл бұрын

What would this look like with more colours dependent on the displacement and angle. Using cyan, magenta and yellow film apply one as you did the others then the other two 120 deg away from the last, so the overlapping films create many colours radially around the aperture. This would give a vector field representation of flow, instead of this partial derivative. I enjoyed the strobe.

@eclipse369. 2 жыл бұрын

Great idea.

@SocratesAlexander 6 жыл бұрын

You should change the places of the filters. Cool would look good when it is green and hot air prefers red.

@leocurious9919 6 жыл бұрын

? Its green and red in both cases.

@edwardsrother5865 5 жыл бұрын

Excuse me but do you know the music that is equalized to activate certain zonea in your brain that music specificaly makes us happy when hear to it.... do you know it?

@j0hmama 4 ай бұрын

I'm confused. is this apparatus being operated in the dark?

@tommanuel2137 5 жыл бұрын

Very cool. Can you explain what force is keeping the balls centered? Its as though their is a spring wobbling them in place horizontally. I've been told acoustic radiation force is normal to the direction of the traveling wave, but, what about with standing waves?

@wolfgangrueckner7151 5 жыл бұрын

I think the acoustic field gradients at the edges of the standing wave are such that the standing wave behaves like a potential well and the balls tend to settle down in the center of that well. That's a "hand waving" argument. :-)

@er.sumeshghatane7158 4 жыл бұрын

@5:02, this look like representation of electron energy level.

@kalleyribeiro152 3 жыл бұрын

this shit mind-blowing

@47Lancelot 5 жыл бұрын

why is it possible for ball to be in the green band

@wolfgangrueckner7151 5 жыл бұрын

both green and red bands are high pressure zones and that is where the balls settle down

@DoNotPushHere Жыл бұрын

I totally expected the styrofoam balls to stay in the middle of the bands. I guess my understanding of the meaning of those collrs is wrong.

@MrForlines 5 жыл бұрын

I would like to see this demonstration using a tube with an uncut quarts Crystal inserted in it and water passing through tube, in order to find out if the energy field produced is visible. can you do this please?

@wolfgangrueckner7151 5 жыл бұрын

Sorry, we can't do that.

@riacheriefailla 5 жыл бұрын

dangerous idea?...quartz...has a wild, well...diffracting affect ... but interesting idea...is it the water that would stream the light into a singular flow..?..

@MrForlines 5 жыл бұрын

@@riacheriefailla the waters electrons I think would move around the points of the crystal in a 2-1-2 pattern, skip 2, skip 1, or 1,2 . I got the idea from an ancient tablet," like a blacksmith, 2, 1, 2." This actually creates a pattern that when viewed from above or below, make a 6 pointed star, from either side with 2 surfaces visible a Celtic infinite knot., And from either side with 3 surfaces visible - a pattern you can overlay the northern or southern hemisphere and align siesmic activity, air currents, animal migration paths, without having to adjust it. So putting pressure on crystal increases it's range of output, most temples and sacred sites are marked with heavy things, most all have underground water and crystal deposits. Certain ones have more pull some push, the pulls you will find on the knights Templars places of visit, the went underneath them to collect the gold beneath. At the center of the torus that pulls is a chalice shaped energy flow that at it's center technically has reverse spinning electrons that assist gold particles to accumulate with each other. Let me know if you are becoming a bit wiser.....

@riacheriefailla 5 жыл бұрын

@@MrForlines same for diamonds?... I was shown today...that the great potato famine...was caused by a HAARP...I wonder about your crystal pressure comment with that...pull/push spots would be VERY intentional across the globe, purposeful. wiser?... ;-)

@MrForlines 5 жыл бұрын

Okay, so here's a big secret. The Freemasons symbol of a compass, measure, and a g in the center. The g isn't a letter at all, it's an arrow. One flow splitting intwo and below there are two flowing into one between them are cyrstals, the spin is at the center, G, that way.....

@riacheriefailla 5 жыл бұрын

...right, so we need "boundaries" for physical expression...

@Wilverine99 4 жыл бұрын

@3:20 how we see Birkeland currents. Aka the northern lights. :)

@andreykuznetsov7442 4 жыл бұрын

Thanks for video! Is it possible to visualize standing wave with continuous light? In other words, are there noticeable time averaged deviations of pressure from atmospheric pressure?

@wolfgangrueckner7151 4 жыл бұрын

yes, you can see a standing wave with continuous light

@andreykuznetsov7442 4 жыл бұрын

@@wolfgangrueckner7151 Thank you! I am trying to understand the physical mechanism of acoustic forces. At first glance, it seems that the time-averaged pressure in a standing wave is uniform in space and equals to atmospheric pressure. Apparently, this is not so.

@riacheriefailla 5 жыл бұрын

in the green band...before the placing of the balls..what are all the green light spheres that are visible only in the green?..background?...or...

@wolfgangrueckner7151 5 жыл бұрын

Those are diffraction patterns of dust on the camera's sensor. They happen to show up better in the green areas in this shot, but they're actually everywhere. It's hard to get all the dust particles off the sensor :-)

@rensvanleijden 2 жыл бұрын

I am truly wondering how to make a stroboscope that can strobe at 28 kHz, did you built your own electronic circuit to achieve that? Asking because I am trying to recreate this experiment for a new course at TU Delft.

@NatSciDemos 2 жыл бұрын

Some details of the light source we used can be found here doi.org/10.1119/1.5042245

@MrForlines 5 жыл бұрын

alright hot about just s quartz crystal then? by its self?

@abdulkadirkucuk8384 6 жыл бұрын

i want to make an ultrasound cleaner for printed circuit boards and electronic devices. i need ultrasonic horn. turkeyland has no supplier for ultrasonic transducers.

@wolfgangrueckner7151 6 жыл бұрын

The transducer is an American Piezo 28 kHz Cleaning Transducer model #90-4040

@abdulkadirkucuk8384 6 жыл бұрын

Wolfgang Rueckner is there a direct link?

@wolfgangrueckner7151 6 жыл бұрын

www.americanpiezo.com/standard-products/ultrasonic-power-transducers.html

@abdulkadirkucuk8384 6 жыл бұрын

Wolfgang Rueckner i also need ultrasonic wire bonding transducer. can you help me?

@wolfgangrueckner7151 6 жыл бұрын

We made our own transformer to couple the transducer to the audio power amplifier. The core of the transformer consists of two C-shaped pieces of ferrite which, when put together make a square. The primary is 10 turns of #18 wire and the secondary is 100 turns of #22 wire. The inductance of the primary is 230 µH w/ secondary open and 16 µ H w/ secondary shorted. The operational inductance is such that its impedance is well matched to the 8Ω output of the amp. The inductance of the secondary is 18.8 mH w/ primary open and 1.8 mH w/ primary shorted. It's operational inductance is around 10 mH. The static capacitance of the transducer is 3550 pF. To resonate at 28 kHz, we want an inductance of 9.1 mH. The inductance of the secondary is a close match for that. The output of the transformer can be as much as 400 Vp-p, but we operate it at approximately 50 Vp-p. This is just one of many ways of powering the transducer. I suggest searching the web for more conventional designs.

@StarburstL 4 жыл бұрын

mark rober?

@MarkMcCluney 5 жыл бұрын

Most enjoyable. Are you the Wolfgang of Car Talk fame?

@wolfgangrueckner7151 5 жыл бұрын

Yes I am :-)

@MarkMcCluney 5 жыл бұрын

Wolfgang Rueckner Well, well. You popped up on a Car Talk recording I'd been listening to in my workshop on the same day your 'shedding vortices' popped up on my phone (my brother an I had been talking about flute physics). Quite the coincidence! Thanks for all your vids, I've been enjoying them.

@wolfgangrueckner7151 5 жыл бұрын

@@MarkMcCluney Thank you for the kind words. Quite a coincidence, indeed! Which Car Talk question was I answering (there've been many)?

@MarkMcCluney 5 жыл бұрын

Wolfgang Rueckner About tyre pressure and why it doesn't seem to change when the car is jacked off the ground.

@ashnur 6 жыл бұрын

I just wish the noise the transducer makes was filtered out before upload :)

@wolfgangrueckner7151 6 жыл бұрын

We tried. There's a 14 kHz peak (must be a subharmonic of the 28 kHz) that we tried to get rid of with a low-pass filter. Admittedly, it leaves something to be desired. Hopefully we can run the soundtrack through some sharp notch filters, if we find some good software to do it.

@2soldierman2 5 жыл бұрын

Give it a few years... It'll go away with age.

@Geerpower 4 жыл бұрын

What happens when you change the frequency with the balls placed in the bands?

@wolfgangrueckner7151 4 жыл бұрын

If you change the frequency without changing the distance between the reflector and the transducer, then you no longer have a standing wave and the balls fall down.

@texaslisten2qcowboyup375 5 жыл бұрын

How great is God that he created all of this for us. That he is not bound by this DIMENSION he can step in and out of it

@jeffdibble3022 3 жыл бұрын

Where can I find a mirror like this? I've looked and found nothing

@NatSciDemos 3 жыл бұрын

The one we use here was salvaged from a spectrometer. Our other setup uses an old telescope mirror.

@svettnylle 4 жыл бұрын

HI. This is very very interesting, I can actually see this wave when i have taken LSD. LSD open my mind so that I can see air waves and see increasing and the decreasing between different object.. Shit have never been able to describe the waves I can see when I took LSD for someone until a saw this video. have a great time

@user-zv9bf4mw6g 4 жыл бұрын

No, you can't.

@svettnylle 4 жыл бұрын

@@user-zv9bf4mw6g HI Yes this it 100% true. i would not write it if it not was true, i´m so fascinated that this was what i actually could see. when they showing the hand in the video, it was exactly what was happened with my hand ( the smoke / waves from the hand) . and different Items that I was holding looking at I could see the ( smoke / waves behavior ) and it was like you could see in this video. ( but only green color ) '

@user-zv9bf4mw6g 4 жыл бұрын

Maybe then you will go for a f*cking million bucks at James Randi foundation? Do you understand that LSD is a powerful hallucinogen? It was just glitches that had nothing to do with reality. Please stop talking that bullshit to people, nobody cares.

@1995yuda 4 жыл бұрын

@@user-zv9bf4mw6g shut the hell up dummy

@neurohan 3 жыл бұрын

Is there a small space in between the red and the green filters to allow unfiltered light to pass through as well?

@wolfgangrueckner7151 3 жыл бұрын

no ... a very thin wire blocks the light

@neurohan 3 жыл бұрын

My confusion is regarding how you're able to get a true-color representation of your hands, the background, etc. while still having the schlieren image of the disturbed air appear as a false-colored filtered image... Shouldn't the red and green strips be tinting the entire image, including your hands, the soldering iron, your background, etc.? I would assume so, since (if I understand correctly) the strips intercept the light at the focal point before it has time to spread out again and reach the sensor.

@wolfgangrueckner7151 3 жыл бұрын

@@neurohan You have to appreciate the fact that the ray of light entering the camera through one of the filters is traveling in a straight line from it's origin (a point in front of the mirror where the refractive index changes) to the camera -- it doesn't spread out and shine on other things (like my hands). The "true" colors of my hands and background are from the ambient lighting in the lab. Does that make sense?

@neurohan 3 жыл бұрын

Thank you so much for taking the time to reply!! After reflecting on your response for a little while, I think I was able to pick out my misconception and resolve it. I was under the impression that the entirety of the frame that we see in this video was contained within the point of light at the intersection of the two filters. But it just clicked that only the rays being emitted from the point light source (or at least those rays that are reflected by the mirror and not obstructed by the objects of interest) would be focused towards that point. As such, the light passing through the filters and hitting the sensor only covers the portion of the scene occupied by the mirror. The rest of the image consisting of "true-color" objects would be created by the scattered ambient light entering from outside the boundaries of the filters. I think my misconception stemmed from me wondering why we can't see blurred versions of the red and green filters stretching from the left-middle side to the right-middle side of the scene. For this, my only guess is that the filters are effectively erased from the image, since they are so close to the lens, whereas the camera focus is locked on the faraway mirror. Is this correct?

@wolfgangrueckner7151 3 жыл бұрын

@@neurohan Absolutely correct ... the wire block and filters are totally out of focus because they are so close to the camera and the lens is focused 4 meters away.

@dhruv3579 5 жыл бұрын

Why metal upper low density

@hectoroliviervillarez5733 5 жыл бұрын

sir what would happen if you put water in it. like the little ball you used to put.

@wolfgangrueckner7151 5 жыл бұрын

Water droplets would levitate. We don't use enough acoustic power to do that (for safety reasons).

@hectoroliviervillarez5733 5 жыл бұрын

@@wolfgangrueckner7151 can you formed something by using water droplet?

@hectoroliviervillarez5733 5 жыл бұрын

what would happen if fires levitate? it will become like a droplets ? Is it possible to artificially made a sun or mini earthlike planet?

@wolfgangrueckner7151 5 жыл бұрын

@@hectoroliviervillarez5733 I'm afraid not :-)

@Dragonsdayprime 4 жыл бұрын

Is it possible to use this set up without a strobing light?

@wolfgangrueckner7151 4 жыл бұрын

Yes indeed.

@thevelar7139 5 жыл бұрын

How many decibel is this ultrasound pllzz

@wolfgangrueckner7151 5 жыл бұрын

68 dB at a distance of arm's length

@radaroreilly9502 5 жыл бұрын

Levitate some aerogel

@Lolatronn 4 жыл бұрын

i wonder if blender could simulate this ...

@TiagoTiagoT 4 жыл бұрын

What happens if you rotate the color filter?

@wolfgangrueckner7151 4 жыл бұрын

The colors will change. The color in the schlieren image tells us which way the light was deflected (relative to the orientation of the filter). If you rotate the filter, then the color in the image will rotate to indicate the new direction the light is being deflected.

@TiagoTiagoT 4 жыл бұрын

@@wolfgangrueckner7151 But what about the ultrasound demonstration, where low and high pressure are marked by specific colors?

@wolfgangrueckner7151 4 жыл бұрын

@@TiagoTiagoT Suppose that the high pressure region refracts the light in an upward direction. If the red filter is above the green (as it is in the video), then the light passes through the red filter and the camera sees that pressure region as red. If you rotate the filters, say 45 degrees, the red is still above the green and nothing changes. In fact nothing changes until you rotate the filters up to the point where they're vertical. Then you won't see any color because the light refracted upward stays on the wire block. But if you rotate beyond the vertical, then the green filter will be above the red and the camera will see that high pressure region as being green. It will stay green as you rotate further up to the point where the filters are vertical again. Then you see nothing and rotating further beyond the vertical will produce a red image again. Does that make sense?

@Wilverine99 4 жыл бұрын

@4:30 how moons work 😂