What’s the ultrasonic cleaner working principle?

What is the working principle for ultrasonic cleaner?  

The working printing of Ultrasonic cleaner : ( in simple words ) The ultrasonic cleaner vibrate 40 thousand times per second in liquid environment ; during the vibration , it creates millions of air bubbles. The millions of air bubbles explode at the same time because of decompression and boosting, so this explosion creates very powerful strength , this strength make dirty or smudge which on the surface of objects to be stripped and emulsifies , so the object is cleaned .