System and method for acoustic imaging at two focal lengths with a single lens

A device comprising:

• a lens having a structure including at least two lens portions, each having a different acoustic index of refraction,
• the at least two lens portions being joined at a joining region,
• the at least two lens portions including a an inner cylindrical portion;
• and
• an outer cylindrical portion including two parts, each part on one of two sides of the inner cylindrical portion with only one part on each side,
• the lens having a shape described by a function of a distance from its center that is mathematically continuous and smooth within the joining region,
• the function having a second derivative with a sign that is equal for both of the at least two lens portions and the joining region,
• the at least two lens portions having shapes that can be mathematically described as two parts of the function, each of the at least two parts having an equal degree of concavity or convexity,
• the at least two lens portions having different amounts of crosslinking,
• the at least two lens portions having particles embedded therein, such that the at least two lens portions have different attenuation characteristics,
• the first lens portion being capable of forming a first focused region,
• the second lens portion being capable of forming a second focused region that is different from the first focused region, the first focused region and the second focused region combined forming a focused region having a larger range of focus than either the first focused region or the second focused region;
• and
• a transducer including at least two transducer portions each aligned with a different one of the at least two lens portions.

A method comprising:

• forming a lens having a non-compound surface including at least two lens portions each having a different acoustic index of refraction, and being capable of forming at least two focused regions including a first focused region that is different from a second focused region, including
• forming the at least two lens portions such that
• the at least two lens portions are joined at a joining region,
• the at least two lens portions including a first portion that has two parts that are cylindrically shaped and disposed on two opposite sides of a second portion that is cylindrically shaped,
• forming the lens to have a shape described by a function of a distance from its center that is mathematically continuous and smooth within the joining region, the function having a second derivative with a sign that is equal for both of the at least two lens portions and the joining region, and
• forming the at least two lens portions to have shapes that can be described as two parts of the function each having an equal degree of concavity or convexity;
• crosslinking the at least two lens portions, each being crosslinked to a different degree,
• forming the first lens portion so as to be capable of forming the first focused region,
• forming the second lens portion so as to be capable of forming the second focused region, and
• setting the first lens portion and the second lens portion such that the first focused region and the second focused region combined form a focused region having a larger range of focus than either the first focused region or the second focused region;
• embedding particles in the at least two lens portions such that the at least two lens portions have different attenuation characteristics;
• forming a transducer with at least two portions;
• and
• aligning each of the at least two portions of the transducer with a different one of the at least two lens portions.

A method comprising:

• sending an acoustic signal through a lens having a non-compound surface including
• at least two lens portions each having a different acoustic index of refraction,
• the at least two lens portions being joined at a joining region,
• the at least two lens portions including a first portion that has two parts that are cylindrically shaped and disposed on two opposite sides of a second portion that is cylindrically shaped,
• the lens having a shape described by a function of a distance from its center that is mathematically continuous and smooth within the joining region,
• the function having a second derivative with a sign that is equal for at least two of the at least two portions and the joining region,
• the at least two lens portions having shapes that can be described as two parts of the function having an equal degree of concavity or convexity,
• the at least two lens portions having different amounts of crosslinking,
• the at least two lens portions having particles embedded therein, each lens portion with a distribution of particles that is different such that the at least two lens portions have different attenuation characteristics, focusing the acoustic signal into one of
• a first focused region formed by the first lens portion or
• a second focused region formed by the second lens portion,
• the first focused region and the second focused region combined forming a focused region that is longer than either the first focused region or the second focused region;
• and
• transmitting or receiving the acoustic signal with a transducer including at least two transducer portions each aligned with a different one of the at least two lens portions.