Acoustic imaging apparatus with gray scale display

• US 3,918,297 A
• Filed: 10/03/1974
• Issued: 11/11/1975
• Est. Priority Date: 10/03/1974
• Status: Expired due to Term

• Current Assignee: Henry A.F. Rocha
• Original Assignee: Henry A.F. Rocha
• Inventors: Rocha, Henry A. F.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Beauchamp, John P.
• Application Number:
  US05/511,616
• Time in Patent Office: 404 Days
• Field of Search: 73/67.7,67.8R,67.8S,67.9
• US Class Current: 73/607
• CPC Class Codes: A61B 8/00 Diagnosis using ultrasonic, sonic or infrasonic waves imaging of objects using sonar G01S15/00
• CPC Class Codes: A61B 8/483 involving the acquisition of a 3D volume of data
• CPC Class Codes: G01N 29/06 Visualisation of the interior, e.g. acoustic microscopy medical or veterinary diagnosis using sonic waves A61B8/00; representation of acoustic wave distribution G01H3/125, G01H9/002; short-range imaging systems using reflection of acoustic waves G01S15/8906
• CPC Class Codes: G01N 29/0609 Display arrangements, e.g. colour displays indicating or recording in connection with measuring in general G01D
• CPC Class Codes: G01S 15/8959 using coded signals for correlation purposes
• CPC Class Codes: G01S 15/8993 Three dimensional imaging systems

Abstract

To obtain an estimate of the reflectivity of internal heterogeneities in an object, a repeating series of acoustic pulses with sequentially variable amplitudes is incident on the object. The corresponding echoes are sensed by a transduceramplifier array and converted to binary data representing sensed echoes above a predetermined comparator level. The binary output data is periodically amplitude-modulated conversely to the acoustic pulses to obtain a brightness modulated visual display indicative of the reflectivity of the heterogeneity. This measure of reflectivity is used to estimate the size of a small target and the angulation and acoustic impedance of a large target in nondestructive testing and medical diagnostic applications.

Claims

1. Acoustic imaging apparatus with a gray scale display comprising means for periodically generating a series of acoustic pulses that are directed toward an object and reflected by an acoustic heterogeneity in a planar object region to produce a train of acoustic echoes of varying intensity depending on the reflectivity of the heterogeneity and the amplitude of the acoustic pulse, acoustic image converter means and gating means therefor comprising an array of transducers and signal processing channels for individually sensing the acoustic echoes and periodically producing and reading out binary output data for the array representing the amplitudes of the sensed echoes above and below a predetermined comparator level, means for varying the amplitude of said acoustic pulses and in respectively converse manner varying the amplitude of said periodically read out binary output data to effectively change the sensitivity of the apparatus, and visual display means for periodically displaying said variable amplitude output data to produce images having a brightness indicative of the reflectivity of the heterogeneity.

2. Acoustic imaging apparatus according to claim 1 wherein said means for conversely varying the amplitude of said acoustic pulses and binary output data is operative to obtain a repeating series of acoustic pulses with a variable amplitude according to a predetermined pattern, the amplitudes of said binary output data being correspondingly varied in converse manner.

3. Acoustic imaging apparatus according to claim 2 wherein said repeating series of variable amplitude acoustic pulses and binary output data have progressive amplitude changes in decibel steps.

4. Acoustic imaging apparatus according to claim 1 wherein each signal processing channel associated with one of said transducers in said acoustic image converter means comprises a sense amplifier and detector for producing an output when each sequentially sensed echo is above the comparator level, an individual single stage shift register for storing said sense amplitude and detector outputs as binary data, and means for serially connecting said individual shift registers for reading out the stored data as said binary output data, and said visual display means comprises a single display device for periodically displaying two-dimensional images of said planar object region.

5. Acoustic imaging apparatus according to claim 1 wherein each signal processing channel associated with one of said transducers in said acoustic image converter means comprises a sense amplifier and detector for producing an output when each sequentially sensed echo is above the comparator level, an individual multi-stage shift register for storing and sequentially shifting said sense amplifier and detector outputs as binary data, and means for serially connecting said individual multi-stage shift registers for reading out the stored data as said binaRy output data, and said visual display means comprises a stereo visual display for periodically and coincidentally displaying multiple images of a plurality of said planar object regions at different depths in the object.

6. Acoustic imaging apparatus with a gray scale display for estimating the reflectivity of internal heterogeneities in an object comprising means for generating a repeating series of periodically timed acoustic pulses that are amplitude-modulated by steps within each series and directed toward an object being examined, focusing means for focusing a train of acoustic echoes produced by reflection from an acoustic heterogeneity within the object and having varying intensities depending on the reflectivity of the heterogeneity and the amplitude of the corresponding acoustic pulse, acoustic image converter means and gating means therefor comprising a planar array of transducers each of which converts the focused echoes to a variable electrical signal, a plurality of signal processing channels each connected to one of said transducers and including a sense amplifier and detector for producing an output when the amplitude of the sensed echo is above a predetermined comparator level, and further including an individual shift register for storing the outputs as binary data, and means for serially connecting said individual shift registers for periodically reading out the stored data as binary output data, processing means for said binary output data including means for periodically modulating the amplitude of said binary output data conversely to the modulated amplitude of said acoustic pulses in each repeating series, and visual display means for periodically displaying said modulated amplitude output data to produce images having a brightness indicative of the reflectivity of the heterogeneity.

7. Acoustic imaging apparatus according to claim 6 wherein said means for generating a repeating series of periodically timed acoustic pulses that are amplitude-modulated by steps, said gating means for said acoustic image converter means, and said means for conversely modulating the amplitude of said binary output data are all coordinated by a synchronizing generator.

8. Acoustic imaging apparatus according to claim 6 wherein said means for generating a repeating series of periodically timed acoustic pulses that are amplitude-modulated by steps and said means for conversely modulating the amplitude of said binary output data are controlled by synchronized complementary stepped-wave voltages.

9. Acoustic imaging apparatus according to claim 6 wherein said individual shift registers each have a single binary storage stage, and said visual display means is a single cathode ray tube for periodically displaying a brightness modulated image of a selected planar region within the object.

10. Acoustic imaging apparatus according to claim 6 wherein said individual shift registers each have a plurality of binary storage stages for storing and shifting sequentially produced sense amplifier and detector outputs, and said visual display means is a stereo visual display comprising a pair of cathode ray tubes for periodically and coincidentally displaying brightness modulated multiple images of a plurality of planar object regions at varying depths within the object.