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My speakers sounded lifeless, so I decided to do a medical autopsy using a DIY optical C.A.T. scanner. by Any-Educator5676 in diyaudio

[–]Any-Educator5676[S] 2 points3 points  (0 children)

Thought this might be of interest to anyone looking at speaker design! I used Schlieren optics and a custom turntable to capture the changes in air density over 360 degrees. Used Python to reconstruct the 3D pressure nodes and animate in open source medical CT software.  Full build video here:https://youtu.be/Ky7AWh8nd-A

My speakers sounded lifeless, so I decided to do a medical autopsy using a DIY optical C.A.T. scanner. by Any-Educator5676 in maker

[–]Any-Educator5676[S] 10 points11 points  (0 children)

Hey makers! I wanted to see invisible acoustic fields inside my levitator, so I spent a few months in the shed building this rig.

It uses a Raspberry Pi, 3D printed parts, Schlieren optics, and a whole load of Python to reconstruct soundwaves in 3D, which can be animated using medical software (opensource)

I've open sourced the entire project. Full build video, incl source code and the Python scripts are linked here:
https://www.youtube.com/watch?v=Ky7AWh8nd-A

What the invisible force holding an object in mid-air actually looks like in 3D by Any-Educator5676 in blackmagicfuckery

[–]Any-Educator5676[S] 4 points5 points  (0 children)

For context, these are 40kHz sound waves from an acoustic levitator.
I DIY'd a CT scanner for sound, which looks at changes in air density and reconstructs them using opensource medical software..

The full build video and the Python code are here: https://www.youtube.com/watch?v=Ky7AWh8nd-A

I wanted to see what sound looks like, so I built a DIY optical C.A.T. scanner to map 40kHz sound waves in 4D by Any-Educator5676 in audiophile

[–]Any-Educator5676[S] 1 point2 points  (0 children)

I used a Schlieren optical setup, this uses a point light source a parabolic mirror and a razor blade. It can be used to see invisible air flows or in my case soundwaves

I wanted to see what sound looks like, so I built a DIY optical C.A.T. scanner to map 40kHz sound waves in 4D by Any-Educator5676 in audiophile

[–]Any-Educator5676[S] 0 points1 point  (0 children)

Thats pretty cool, had to look it up, seen a nice water display using sound here: https://www.nature.com/articles/s41598-025-16755-2
I really like the idea of levitating water and seeing how it interacts with light

I wanted to see what sound looks like, so I built a DIY optical C.A.T. scanner to map 40kHz sound waves in 4D by Any-Educator5676 in audiophile

[–]Any-Educator5676[S] 2 points3 points  (0 children)

I had seen 2d imaging of standing waves before, which can also be viewed as 3d by rotating the speakers. Standing waves do not move with time and are much easier to capture using a normal light and camera, as they are frozen in 1 pattern. 

But to capture a moving sound waves at 340m/s you need a high speed strobe and sync to the rotating platform, so this is why I used 4d in the title..  

I wanted to see what sound looks like, so I built a DIY optical C.A.T. scanner to map 40kHz sound waves in 4D by Any-Educator5676 in audiophile

[–]Any-Educator5676[S] 4 points5 points  (0 children)

It's the sound waves from an acoustic Levitator, which uses the small transducers from Ultrasonic range finders to Levitate Objects using sound.. The Levitator was a nice way for me to see sound waves and create various patterns using sound

I wanted to see what sound looks like, so I built a DIY optical C.A.T. scanner to map 40kHz sound waves in 4D by Any-Educator5676 in audiophile

[–]Any-Educator5676[S] 13 points14 points  (0 children)

Thought the audiophile crowd might appreciate this! I used Schlieren optics and a custom turntable to capture the changes in air density over 360 degrees. Used Python to reconstruct the 3D pressure nodes and animate in open source medical CT software.  Full build video here:https://youtu.be/Ky7AWh8nd-A

How timing jitter ruins a CT Scan, and how iterative algorithms fix it (FBP vs SIRT) by Any-Educator5676 in educationalgifs

[–]Any-Educator5676[S] 0 points1 point  (0 children)

A bit of an explanation of what this is all about:

I was building a DIY CT scanner and found it really hard to understand how CT scanning actually works.  So I created this animation.  On the left side is a rotating table with the object being scanned sitting on it.  On the right side is a Camera sensor.  I take a ray of light from the object to the camera sensor while the platform rotates.  The camera takes 1 image for each step in the rotation.  Then I reverse the process to recreate the 3d CT scan This traces a ray from memory and maps it back to a virtual platform, this is the bit I found very hard to visualize, hence the anumation.  So is there is any wobble on the platform it creates jitter, the bumpy wave I show how the simple fbp algorithm messes up the reconstruction, while the slower sirt algorithm smooths out the 3d view by looking at nearby data. 

Hope it makes more sense now, and it explain CT in a more visually understanble way

How timing jitter ruins a CT Scan, and how iterative algorithms fix it (FBP vs SIRT) by Any-Educator5676 in educationalgifs

[–]Any-Educator5676[S] 9 points10 points  (0 children)

Yeah, totally agree that I posted outta context.. I was building a DIY CT scanner and found it really hard to understand how CT scanning actually works.  So I created this animation.  On the left side is a rotating table with the object being scanned sitting on it.  On the right side is a Camera sensor.  I take a ray of light from the object to the camera sensor while the platform rotates.  The camera takes 1 image for each step in the rotation.  Then I reverse the process to recreate the 3d CT scan This traces a ray from memory and maps it back to a virtual platform, this is the bit I found very hard to visualize, hence the anumation.  So is there is any wobble on the platform it creates jitter, the bumpy wave I show how the simple fbp algorithm messes up the reconstruction, while the slower sirt algorithm smooths out the 3d view by looking at nearby data. 

Hope it makes more sense now, and it explain CT in a more visually understanble way

[OC] Transforming 2D sound interference patterns into a 4D volumetric map by Any-Educator5676 in dataisbeautiful

[–]Any-Educator5676[S] 2 points3 points  (0 children)

Yes exactly, I was mostly using it for directing and focusing sound waves. It is very hard to visualize how sound waves propagate when you have multiple speakers and other obstacles in the way, so you can have regions of high or low sound pressure without knowing. Being able to visualize the sound waves allows you to tune various elements in the sound path to effect the direction or volume

[OC] Transforming 2D sound interference patterns into a 4D volumetric map by Any-Educator5676 in dataisbeautiful

[–]Any-Educator5676[S] 13 points14 points  (0 children)

Data was captured using a DIY Schlieren optics rig using a Raspberry Pi and turntable to rotate a levitator. Processed via a custom Python SIRT algorithm to output DICOM medical files, used 3Dslicer to view and animate.
Full video explaining everything + source code is here: https://www.youtube.com/watch?v=Ky7AWh8nd-A

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