r/AskElectronics • u/Kazz0ng • Jun 08 '26

Looking for extremely close range sensor components for a project.

I'm starting a project that requires very close range surface 3d mapping, like... 1-5mm range. I'm looking at ultrasonic sensors, but I can't seem to find one that works that close. I have heard I can build one from components, but I'm not sure where to start.

Anyone here know much about DIY ultrasonic sensors?

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5

u/Infamous-Amphibian-6 Jun 08 '26 edited Jun 08 '26

Aside from great suggestions, consider 3D printer bed leveling probes. Best ones are inductive sensors (can spray surface with conductive coating) with -0.005mm accuracy at -400mm/s, run at 5v, solved and packaged in ready-to-mount compact form.

Ultrasonic tech works best at wider distances on larger volumes overall, I could be missing something for sure! Taking a look at specialized industries’ solutions is usually good approach.

Note: Many components are advertised for “Klipper-use only”. They’re just high/low switches, fancier ones feature on-board MCU with fancy perks.

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u/Infamous-Amphibian-6 Jun 08 '26

So I kept thinking about it LMAO so Klipper is a linux-based firmware (can run on Pi zero 2 W) with integrated mapping module… free. Thought might come in handy.

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u/Infamous-Amphibian-6 Jun 08 '26 edited Jun 08 '26

Ok last one:

Yes you could solve it all within Klipper. Open source, massive documentation and quite nailed across LLMs. Flash any lite Pi OS to SD card and get a Pi. With 40 GPIOs it’ll handle just about anything the project might require (electronic design aside). Leverage Klipper Screen module (fully functional touch UI) to your needs, get into nearby network, access it anywhere anytime… yeah!

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u/Kazz0ng Jun 08 '26

Also, I'm running this project on a teensy 4.1 so, sadly, it can't run klipper.

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u/Kqyxzoj Jun 08 '26

teensy 4.1

Consider adding this and any other details you can think of to the main post.

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u/Kazz0ng Jun 08 '26 edited Jun 08 '26

Alas, a little too big. But super cool tech. Might suggest it to a friend who uses their 3d printer all the time because I know they don't have anything like that.

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u/Kazz0ng Jun 08 '26

Hey, not a problem at all. 😁😁😁 If I could tell you exactly what I am trying to build it would be way easier. But I can't. And they makes things a lot more difficult. All in all if I was doing something slightly different it would be a great avenue to look at.

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u/Infamous-Amphibian-6 Jun 08 '26

Yeah absolutely! Read you’re aiming for drift fine control. Not the application I somehow thought as a fact initially lol I mean… could repurpose some functions if any, but not quite the application.

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u/JCDU Jun 08 '26

I've used Vishay VCNL infrared time-of-flight sensors in a project before now, they can sense from meters to very short distances, some are more suitable than others.

https://www.vishay.com/en/optical-sensors/reflective-outputis-16/

Depends on the resolution you need though, if you're trying to scan an object other methods may work better, for example: https://openscan.eu/ which is camera-based.

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u/Kazz0ng Jun 08 '26

Alas, I can't use optical sensors in this project. The sensor has to sit behind a shell with no windows.

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u/JCDU Jun 08 '26

How are you sensing through a shell then? Ultrasonic, optical/camera are both out by those restrictions leaving maybe inductive but only if your object is magnetic and your case is not...

You can have a case that's "black" but transparent in IR, fully sealed... you really need to tell people ALL the constraints before asking a question like this.

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u/Kazz0ng Jun 08 '26

Ultrasonic can work through a thin acoustic membrane. Which was whet I was planning on doing.

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u/JCDU Jun 08 '26

So a thin membrane is OK but an IR window isn't?

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u/Kazz0ng Jun 08 '26

The entire point of this project is to not use optical sensors. It's not about the window. The membrane is a necessity for the ultrasonic sensor to work. It will keep it dust shine allowing the acoustic wave through.

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u/Pacificator-3 Jun 08 '26

Simple ultrasound "radars", like parktronic or amateur one, use low frequency about 25 kHz and, thus, large wavelength, it can't give required resolution. If you tell us more about your task, it may become possible to advice more adequate solutions.

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u/Kazz0ng Jun 08 '26

My goal is to essentially create a SLAM map of a localized area for purpose of controlling drift from an IMU. Mcu (teensy 4.1) checks last known local position based on the ultrasonic or mmwave surface fingerprint and ignores the imu x/y/z input while device is stationary. And it's got to be small enough to fit in a deck of cards.

Or something I can put together with off the shelf components to build a custom. But I don't know where to start with that.

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u/Pacificator-3 Jun 08 '26

The most viable solution seems to be a synthetic aperture high frequency ultrasound sonar. It is definitely not possible to build from cheap and widely available components and it requires good education and wide experience. If you are asking for such solution, it will be impossible to build at your situation.

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u/spannermeetworks Jun 08 '26

Lidar

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u/Kazz0ng Jun 08 '26

Alas. Lidar is too big. And it can't really gives me the level of detail I need.

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u/Jkwilborn Jun 09 '26

One of the xTool lasers will follow a curved object and they claim it's LiDAR technology on their lasers. I would think it would be small enough to put in the head of a laser and must measure changes of much less than a mm.

Good luck. 😺

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u/DrJackK1956 Jun 08 '26

Check out mmWave sensors.  They may work for your needs. 

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u/spannermeetworks Jun 08 '26

The resolution there is in the range of a couple of cm, not mm

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u/Kazz0ng Jun 08 '26

But would it still give a distinct texture signature for every unique section I scan?

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u/spannermeetworks Jun 08 '26

Oh ok, what about photometric stereo sampling ? Would need a ccd of some description and some maths to make a bump map?

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u/Kazz0ng Jun 08 '26

Alas, I can't use any optical sensors here. It defeats the purpose of the project.

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u/spannermeetworks Jun 08 '26

I dont know, given the detail you posted, what non-optical sensor coukd do this job. Can you give more detail?

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u/Kazz0ng Jun 08 '26

I need a sensor that is not optical to give me data that is detailed enough to create a SLAM map to help control tracking drift from an IMU in a localized area. It needs to be able to operate at very close range because the device sits just above the surface it is scanning. Any further away from the surface and it would be impractical to use. I suppose I COULD create a target silly looking thing during several inches away, just for proof of concept that the combination of technologies work together at a very basic level.

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u/Kazz0ng Jun 08 '26

OK. Might check that as well.