Ultrasonic transducer apodization using acoustic blocking layer

Abstract

An ultrasound transducer for imaging a target features a piezoelectric transducer element for emitting an ultrasonic wave toward the target and an apodizer fashioned from a thin sheet acoustic blocking layer. The ultrasound acoustic blocking layer is placed between the front surface of the transducer and the target for substantially blocking the ultrasonic wave emission from a portion of the front surface area defining an inactive area. The blocking layer allows transmission of the ultrasonic emission from another portion of the front surface area defining an active area, and includes a thin sheet of polymer blocking material patterned for covering the inactive area of the front surface. The blocking material is attached to the front surface of the transducer element, embedded within an acoustic lens, or incorporated into an adapter which attaches to the body of the transducer. The thin sheet of blocking material is patterned as sawteeth aligned in opposite rows and pointing toward a midline of the transducer. The sawteeth are uniformly shaped and spaced, and positioned anti-symmetric, or the sawteeth are pseudo-randomly shaped and spaced. Alternatively, the thin sheet of blocking material is patterned as a grid of pseudo-randomly selected blocking areas.