ACOUSTIC LENS FOR MICROMACHINED ULTRASOUND TRANSDUCER

PROBLEM TO BE SOLVED: To provide a matching layer for an ultrasound transducer.SOLUTION: An ultrasound transducer stack includes: a first matching layer which has a first top surface and a first bottom surface, comprises a compliant material, and has a first thickness and a first acoustic impedance; a lens layer which has a second bottom surface overlying the first top surface, a second top surface, and a second thickness, and has the second thickness and a second acoustic impedance; and a transducer layer which has a third top surface underlying the first bottom surface and the second bottom surface, the third layer including a micromachined ultrasound transducer configured to generate ultrasound at a center frequency, and the third top surface including an upper membrane of the transducer.