Acoustic imaging of objects in optically opaque fluids

Abstract

The present invention is a method and an apparatus that can image objects immersed in optically opaque fluids using ultrasound in a confined space and in a harsh environment. If the fluid is not highly attenuating at frequencies above 1 MHz, where commercial ultrasound scanners are available, such scanners can be adapted for imaging in these fluids. In the case of highly attenuating fluids, such as drilling mud, then a low frequency collimated sound source is used.

1 . An apparatus for imaging objects in opaque fluids comprising:
 at least one transducer for generating a directed, ultrasonic sound beam having a chosen frequency and also for receiving reflected or scattered sound from the target object;   a scanning head;   a protective casing placed around the scanning head;   coupling gel placed between the scanner head and the protective casing;   an acoustic imaging device; and   an electronic circuit to receive image data from the imaging device and display it on a screen.   
     
     
         2 . The apparatus of  claim 1 , wherein the protective casing is a metal pipe. 
     
     
         3 . The apparatus of  claim 1 , wherein the scanner is the wobbler type. 
     
     
         4 . The apparatus of  claim 1 , wherein said electronic circuit comprises a computer, for example including a processor, memory, clock, display driver, and other components: 
     
     
         5 . The apparatus of  claim 1 , wherein the imaged object includes tools. 
     
     
         6 . The apparatus of  claim 1 , wherein the depth of field of the image is approximately 1 foot. 
     
     
         7 . The apparatus of  claim 1 , wherein the resolution of the image is approximately 2 mm. 
     
     
         8 . The apparatus of  claim 1 , wherein the at least one transducer is an array of transducers that can be electronically scanned in a phased array manner. 
     
     
         9 . An apparatus for imaging objects in opaque fluids comprising;
 a collimated source;   an acoustic imaging device; and   an electronic circuit to receive image data from the imaging device and display it on a screen.   
     
     
         10 . The apparatus of  claim 9  wherein the collimated source is broadband and has a frequency range of 50 kHz-1 MHZ. 
     
     
         11 . The apparatus of  claim 9 , wherein the collimated source is made using Fluorinate 43 or any other liquid in the same family. 
     
     
         12 . The apparatus of  claim 9 , further comprising:
 a ring transducer around the collimated source.   
     
     
         13 . A method for imaging of an object within opaque fluids comprising the steps of:
 generating a directed and collimated ultrasonic sound wave having a chosen frequency, wherein a low frequency ultrasonic sound wave is created by a parametric array by combining two high frequency sound waves in an acoustic nonlinear fluid;   symmetrically placing a receiver transducer close to a source transducer;   directing the low frequency wave is directed toward the object to be imaged; and   detecting the reflected and scattered signal from the object; and   electronically analyzing the reflected and scattered signal to produce an image of the object.   
     
     
         14 . The method of  claim 13 , where the acoustic nonlinear fluid is Fluorinate 43. 
     
     
         15 . The method of  claim 13 , further comprising obtaining the travel time of the signal from the target object back to the receiver transducer next to the source transducer. 
     
     
         16 . The method of  claim 15 , wherein the image is constructed from the travel time information. 
     
     
         17 . The method of  claim 13 , further comprising the step of using a collinear measurement system to provide an image of the object. 
     
     
         18 . The method of  claim 13 , wherein the image may be produced by scanning the object in 2D arcs. 
     
     
         19 . The method of  claim 13 , wherein the image may be produced by linear x-y scanning. 
     
     
         20 . The method of  claim 13 , wherein the opaque fluid includes one of the following: bubbling liquids, motor oil, water and thick mud.