[DoingIsLearning]

> bubbles act like acoustic black holes, they absorb sound like crazy. Whether you're trying to ping through them in the water, or also if they get stuck on the transducer.

I have no idea about nautical applications but in medical imaging you use a phased array ultrasonic transducer which is really a set of single-beams with deterministic phase firing of the ultrasound.

You could probably implement a similar phased array principle by coupling multiple 'ocean grade' single beams. That would give you both beam directionality and I suspect higher immunity to bubble artefacts if you play with it in the time domain.

[0xfaded]

Trying to figure out how medical ultrasound works is a rabbit hole I'm still trying to claw my way out of. While there are phased arrays, most handheld imagers you would be familiar with are simply linear arrays of approx 100-150 transducer elements. While there is likely some simple phasing going on with adjacent elements firing together, a better model mental model for these would be the transducers firing one by one to produce a scan of individual beams. Before linear arrays, there was actually a single transducer that mechanically scanned back and forth to produce the same effect.

[nradov]

Air bubbles in the bloodstream show up clearly on medical ultrasound. Doctors use this to diagnose atrial septal defects.

[hydhyd]

This isn’t as relevant to bubbles but a transducer phased array is what is used in multi-beam echosounders[1], which provide a swath of depth readings perpendicular to the ship’s path.

[1] https://en.m.wikipedia.org/wiki/Multibeam_echosounder