Annular array used as a horn transducer

Claim 2

An ultrasonic imaging system comprising: a multi-ring annular array for transmitting pulses of ultrasound into an object and receiving echoes; transmitter means for exciting said annular array to simulate a horn transducer, in which cone angle is slowly tapered from about 50° to 10° to make a horn, and have a line focus in the near field and a relatively large depth of field; means for using said annular array on receive as a fixed-focus transducer that is spherically focused close to the deepest range of said horn transducer; and means for forming an image.

Claim 3

The system of claim 1 wherein said annular array has equal area rings.

Claim 4

The system of claim 1 wherein said annular array has a diameter of no more than one inch and a depth of field of about 2 to 20 centimeters.

Claim 5

The system of claim 1 wherein said transmitter means generates a sequence of excitation pulses that are time delayed to simulate a horn and applied to the rings of said annular array.

Claim 6

The system of claim 1 wherein an acoustic lens on said annular array mechanically focuses received ultrasonic energy.

Claim 7

An ultrasonic imaging system for contact B-scan applications comprising: an annular array which has equal area rings and transmits pulses of ultrasound into an object and receives ultrasonic energy and generates echo signals; a transmitter section that supplies a sequence of excitation pulses to said annular array which are time delayed to simulate a horn transducer, in which cone angle is slowly tapered from about 50° to 10° to make a horn, having a sharp focus in the near field and a gradually weakening focus as a function of depth to the deepest depth to be imaged; a receiver section that configures said annular array as an apodized fixed-focus transducer that is spherically focused close to said deepest depth and which time delays and weights said echo signals accordingly and yields a summed signal; and means for processing said summed signal and producing an image.

Claim 8

An ultrasonic imaging system for contact B-scan applications comprising: an annular array which has equal area rings and transmits pulses of ultrasound into an object and receives ultrasonic energy and generates echo signals; a transmitter section that supplies a sequence of excitation pulses to said annular array which are time delayed to simulate a horn transducer, in which cone angle is slowly tapered from about 50° to 10° to make a horn, having a sharp focus in the near field and a gradually weakening focus as a function of depth to the deepest depth to be imaged; a receiver section that configures said annular array as an apodized fixed-focus transducer that is spherically focused close to said deepest depth and which time delays and weights said echo signals accordingly and yields a summed signal; and means for processing said summed signal and producing an image.

Claim 9

The system of claim 6 wherein said annular array has a diameter of no more than one inch and depths of about 2 to 20 centimeters are imaged.

Claim 10

The system of claim 7 wherein said annular array has a minimum of 8 rings.

Claim 11

An ultrasonic imaging method comprising the steps of: transmitting pulses of ultrasound into an object by time delaying the excitation pulse sequence applied to the elements of an annular array so as to simulate a horn transducer, in which cone angle is slowly tapered from about 50° to 10° to make a horn, having a sharp focus in the near field and a gradually weakening focus to the deepest depth to be imaged; receiving echoes with said annular array and generating signals that are spherically focused close to said deepest depth and summed, whereby the system has good resolution over a large depth of field; and processing said summed signals and producing an image.

Claim 12

An ultrasonic imaging method comprising the steps of: transmitting pulses of ultrasound into an object by time delaying the excitation pulse sequence applied to the elements of an annular array so as to simulate a horn transducer, in which cone angle is slowly tapered from about 50° to 10° to make a horn, having a sharp focus in the near field and a gradually weakening focus to the deepest depth to be imaged; receiving echoes with said annular array and generating signals that are spherically focused close to said deepest depth and summed, whereby the system has good resolution over a large depth of field; and processing said summed signals and producing an image.

Claim 13

The method of claim 9 wherein said spherically focused signals are apodized to reduce sidelobe levels at deeper ranges.

Claim 14

The method of claim 10 wherein said excitation pulses have a variable amplitude, those applied to the outside of said annular array having a reduced amplitude compared to those applied to the inside, to improve the far field beam pattern.