Real-time ultrasonic imaging apparatus

Abstract

A real-time ultrasonic imaging system includes a display which is compensated for the non-ideal characteristics of the search beam profile. Echo responsive electrical signals are provided to a preprogrammed computing means for being processed to compensate for the characteristics of the test probe. The processed signals are displayed as being in focus at all distances from the probe, thereby resulting in an image exhibiting improved resolution.

What is claimed is: 
     
       1. An apparatus for improving the resolution of a real-time ultrasonic imaging system comprising: electroacoustic probe means adapted to be acoustically coupled to a workpiece;   energizing means coupled to said probe means for causing said probe means to periodically transmit an ultrasonic energy search signal in the workpiece and to receive echo signals therefrom and to convert said echo signals into electrical signals .Iadd.for each search signal transmitted to thereby form a sequence of electrical signals; .Iaddend.   receiver means coupled to said probe means for receiving said .Iadd.sequence of .Iaddend.electrical signals and providing .Iadd.a .Iaddend.respective .Iadd.sequence of .Iaddend.discrete echo amplitude signals (f k ) responsive to said .Iadd.sequence of .Iaddend.electrical signals, wherein k is an integer and each .Iadd.sequence of discrete .Iaddend..[.signal.]. .Iadd.signals .Iaddend.f k  is commensurate with a .[.depth.]. .Iadd.scan .Iaddend.increment in the workpiece;   .Iadd.scanning means coupled to said probe means for causing said probe means to transmit said search signal along predetermined scan increments in the workpiece; .Iaddend.   processor means including storage means for storing a sequence of acoustic beam profile values (d v ) commensurate with the characteristics of said probe means coupled to said receiver means for sequentially receiving said amplitude signals (f k ), associating respective stored beam profile values (d v ) with amplitude signals (f k ) and providing a sequence of output signals b i  commensurate with the equation: ##EQU9## .Iadd.wherein v=k-i. .Iaddend.   
     
     
       2. An apparatus as set forth in claim 1, .[.and.]. .Iadd.said scanning means comprising .Iaddend.translating means coupled to said probe means for shifting the axis of said search signal relative to the workpiece. 
     
     
       3. An apparatus as set forth in claim 1, said probe means comprising an array of juxtaposed elements and .Iadd.said scanning means causing .Iaddend.said energizing means .[.causing.]. .Iadd.to energize .Iaddend.each of said elements to sequentially transmit a respective search signal. 
     
     
       4. An apparatus as set forth in claim 1, said storage means comprising read-only-memories. 
     
     
       5. An apparatus as set forth in claim 1, further including video amplifying means coupled to said processor means for receiving said sequence of output signals b i  and in response thereto providing video signals, and display means coupled to said video amplifying means for providing a B-scan presentation responsive to said video .[.signal.]. .Iadd.signals.Iaddend.. 
     
     
       6. An apparatus as set forth in claim 1, said receiver means including a logarithmic amplifier means for providing electrical signals commensurate with the logarithmic value of said respective .Iadd.sequence of .Iaddend.discrete echo amplitude signals (log f k ) and said storage means storing said sequence of acoustic beam profile values as values of log d v . 
     
     
       7. An apparatus as set forth in claim 6, said processor means comprising: an analog to digital converter coupled to said logarithmic amplifier means for converting said electrical signals commensurate with the logarithmic value to digital form;   a clock for providing clock pulses, and   shift register means coupled to said converter and said clock for sequentially receiving and shifting said digital form signals for storing said .Iadd.sequence of .Iaddend.signals log f k .   
     
     
       8. An apparatus as set forth in claim 7, said processor further comprising: counting means coupled to said clock for receiving and counting the quantity of clock pulses provided and after counting a predetermined quantity of clock pulses providing an address signal to said storage means for providing a respective value log d v  responsive to a respective address signal;   adding means coupled to said storage means and said shift register means for providing sum signals commensurate with the sums of the respective log f k  signals and respective log d v  signals;   conversion means coupled to said adding means for receiving said sum signals and converting respective said sum signals into product signals of the form f k  ·d v , and   additional adding means coupled to said conversion means for providing said sequence of output signals commensurate with the sum of said product signals.   
     
     
       9. An apparatus as set forth in claim 8, further including: a digital to analog converter coupled to said additional adding means for providing said sequence of output signals as analog signals;   video amplifier means coupled to said digital to analog converter for receiving said analog signals and providing responsive thereto video signals, and   display means coupled to said video amplifier for receiving said video signals and providing an image commensurate with said video signals.   
     
     
       10. An apparatus as set forth in claim 6, said processor means comprising: a clock for providing clock pulses;   shift register means coupled to said receiver means and said clock for sequentially receiving and shifting said respective .Iadd.sequence of .Iaddend.discrete echo amplitude signals;   counting means coupled to said clock for receiving and counting said clock pulses and providing after counting a predetermined quantity of clock pulses an address signal to said storage means;   logarithmic amplifier means coupled to said storage means and said shift register means for receiving respective shifted signals (log f k ) and stored values (log d v ) and providing respective product signals f k  ·d v , and   adding means coupled to said logarithmic amplifier means for receiving said product signals and providing said sequence of output signals.   
     
     
       11. An apparatus as set forth in claim 10, said adding means comprising: means for providing a first signal commensurate with the sum of said product signals wherein v is an even integer;   means for providing a second signal commensurate with the sum of said product signals wherein v is an odd integer, and   difference amplifying means for providing said sequence of output signals equal to the difference between said first signal and said second signal.   
     
     
       12. An apparatus as set forth in claim 10, further including: video amplifier means coupled to said adding means for providing responsive to said sequence of output signals video signals, and   display means coupled to said video amplifier for receiving said video signals and providing an image commensurate with said video signals.   
     
     
       13. An apparatus as set forth in claim 1, said processor associating a respective stored beam profile value d v  with a plurality of .Iadd.discrete echo .Iaddend.amplitude signals f k . 
     
     
       14. A real-time ultrasonic imaging system comprising: clock means for providing timing pulses;   pulse generating means coupled to said clock means for providing responsive to said timing pulses trigger pulses;   electroacoustic probe means coupled to said pulse generating means for being energized responsive to said trigger pulses for periodically transmitting an ultrasonic energy search signal into a workpiece and for receiving echo signals therefrom and converting said echo signals into electrical signals .Iadd.for each search signal transmitted to thereby form a sequence of electrical signals; .Iaddend.   receiver means coupled to said probe means for receiving said .Iadd.sequence of .Iaddend.electrical signals and providing .Iadd.a .Iaddend.respective .Iadd.sequence of .Iaddend.discrete echo amplitude signals (f k ) responsive to said electrical signals, wherein k is an integer and each signal f k  is commensurate with a .[.depth.]. .Iadd.scan .Iaddend.increment in the workpiece;   .Iadd.scanning means coupled to said probe means for causing said probe means to transmit said search signal along predetermined scan increments in the workpiece; .Iaddend.   computing means including storage means for storing a sequence of acoustic beam profile values (d v ) commensurate with characteristics of said probe means coupled to said receiver means for sequentially receiving said amplitude signals (f k ), associating respective stored beam profile values (d v ) with amplitude signals (f k ) and constructed to operate in the time interval between successive timing pulses for providing a sequence of output signals b i  in accordance with the equation: ##EQU10## .Iadd.wherein v=k-i, .Iaddend.and display means coupled to said computing means for receiving said sequence of output signals and displaying said output signals as a real-time image. .Iadd.   
     
     
       15.  An apparatus as set forth in claim 1, said acoustic beam profile values (d v ) being calculated from beam profile values p v  of said probe means by solving the system of linear equations: ##EQU11##.Iaddend.