...is this safe?

This is absolutely my question as well - curious if it's legal to do this, I'm guessing yes as it's an existing ultrasound device? But is there possibility of permanent damage?

It's objectively cool, but very curious about the safety as well.

	▲	exr0n 3 hours ago \| parent [-]
		This is the coolest part! Turns out, the powers you need are actually lower than what is used for imaging babies :) We measured our probe with a hydrophone on a computer-controlled scanner to get the pressure field, and made sure that it's below diagnostic levels (the generally accepted mechanical index limit is 1.9 and ours was 0.4 peak). We also made sure to avoid the eyes and keep thermals in check.