Acoustic imaging of objects in optically opaque fluids
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.