Focusing

We now know that ultrasound can be used to get lots of information from inside the human body. But we don’t yet know how to distinguish all the information that is coming back to us.

The secret to this is dynamic focusing. Focusing is the process of timing your piezo-electric elements such that the resulting wavefront adds up in intensity at some points. A specific depth can thus be in focus.

Using ultrasound in a focused manner, we can distinguish all the different points from which information is coming. Wiendelt Steenbergen explains with clear animations how this works, and how it is used to our advantage.

Eventually, the end-result of this feature can be observed in the following two images:

Shallow focus

Deep focus

Notice the sharpness in the areas marked by the white rectangles. The focus triangle on the left in the red circle indicates the depth to which focus is set.