You have probably heard us speak of a matching layer between the acoustic array and the lens of the probe. What is this mysterious layer?

The matching layer helps to couple the acoustic impedance of the lens material with the acoustic impedance of the array itself. This avoids unnecessary reflections at this mismatched impedence boundary. In the picture below you can see the acoustic matching layer on a Sonosite probe as the lighter colored section. The dark section is the crystal face as the matching layer has been removed.