Hello, I was wondering how this sensor https://www.sparkfun.com/products/24904 would work if I put it in a clear acrylic or glass casing near the bottom of something like a pool or bathtub. My assumption is that it would still be able to detect movement if the environment is well lit enough but that it might be skewed by refraction from the case and water. Looking forward to here thoughts and if anyone has one and is willing to experiment, that would be amazing!
I haven’t used this board before but it seems to rely on an active source, a laser, to illuminate the measurement surface. This makes sense; typical applications will have the sensor flat against a surface and completely obscured from ambient light.
This means that, like you reasoned, your primary concern (outside of normal, non-underwater specs) is the optical characteristics of the window (acrylic/glass) and the water. My skim of [the spec sheet didn’t turn up a laser frequency but it’s probably not going to be a big deal.](https://docs.sparkfun.com/SparkFun_Optical_Tracking_Odometry_Sensor/assets/documentation/PAA5160_Datasheet_General.pdf)
Just remember it uses reflectivity and has a fairly short operating range…so you’ll want to keep the casing (at least for the portion where the sensor is) should be as thin as possible and murky water might not work at all
Thanks for the replies peeps. I did notice the short operating range, but besides a doppler velocity log (super expensive), I haven’t seen another sensor that is promising for odometry underwater. Visual odometry might work, would be quite a bit more complicated. I think I may go ahead and get one of these to test out.
Hi there,
I just saw this, and am also very curious to know whether this works. Have you had a chance to test? Would love to know your results!
Thanks!
Not yet. They were out of stock when I went to buy them and I haven’t checked back yet. I should do that now.
Finally tested this. Sadly, it does not work through acrylic or a clear plastic ziplock bag. It will, however track movement over those. I didn’t check the accuracy compared to other surfaces, but the laser definitely didn’t pass through for my tests.
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Aww, darn. Oh well, thanks for testing!