Ultrasound Testing

Abstract

An apparatus for imaging structural features below the surface of an object, the apparatus comprising: a transmitter unit configured to transmit a sound pulse at the object; a receiver unit configured to receive reflections of sound pulses transmitted by the transmitter unit from the object; a signal processing unit configured to: analyse one or more signals received by the receiver unit from the object; recognise, in the one or more signals, a reflection that was caused by a first structural feature and a reflection that was caused by a second structural feature that is located, in the object, at least partly behind the first structural feature; and associate each recognised reflection with a relative depth in the object at which the reflection occurred; and an image generation unit configured to generate an image that includes a representation of the first and second structural features in dependence on the recognised reflections and their relative depths.

1 . An apparatus for imaging structural features below the surface of an object, the apparatus comprising:
 a transmitter unit configured to transmit a sound pulse at the object;   a receiver unit configured to receive reflections of sound pulses transmitted by the transmitter unit from the object;   a signal processing unit configured to: analyse one or more signals received by the receiver unit from the object; recognise, in the one or more signals, a reflection that was caused by a first structural feature and a reflection that was caused by a second structural feature that is located, in the object, at least partly behind the first structural feature; and associate each recognised reflection with a relative depth in the object at which the reflection occurred; and   an image generation unit configured to generate an image that includes a representation of the first and second structural features in dependence on the recognised reflections and their relative depths.   
     
     
         2 . An apparatus as claimed in  claim 1 , the receiver unit being configured to receive a signal comprising multiple reflections of a single transmitted sound pulse. 
     
     
         3 . An apparatus as claimed in  claim 2 , the receiver unit being configured to receive the multiple reflections while in a stationary position with respect to the object. 
     
     
         4 . An apparatus as claimed in  claim 2 , configured to gate a signal received by the receiver unit in such a way that the signal passed to the signal processing unit for analysis comprises the multiple reflections. 
     
     
         5 . An apparatus as claimed in  claim 1 , which is configured to apply an adjustable time-gate to the received signal. 
     
     
         6 . An apparatus as claimed in  claim 5 , which is configured such that the time-gate is adjustable by a user. 
     
     
         7 . An apparatus as claimed in  claim 1 , the apparatus comprising a pulse generation unit configured to form a pulse having a particular shape for transmission as a sound pulse by the transmitter unit. 
     
     
         8 . An apparatus as claimed in  claim 7 , the signal processor comprising a match filter configured to recognise a pulse having the particular shape in the received signal. 
     
     
         9 . An apparatus as claimed in  claim 7 , the apparatus having a plurality of particular pulse shapes available to it, the pulse generation unit being configured to assess an available pulse shape against a performance criterion and select that pulse shape as a candidate for transmission in dependence on that assessment. 
     
     
         10 . An apparatus as claimed in  claim 7 , which is configured such that the particular shape is selectable by the user. 
     
     
         11 . An apparatus as claimed in  claim 1 , the signal processor being configured to associate each recognised reflection with a relative depth that is determined in dependence on a time that the recognised reflection took to travel from the structural feature that caused the reflection to the receiver unit. 
     
     
         12 . An apparatus as claimed in  claim 1 , the signal processor being configured to associate each recognised reflection with a maximum amplitude and to adjust that maximum amplitude in dependence on the relative depth associated with that reflection. 
     
     
         13 . An apparatus as claimed in  claim 1 , the transmitter unit being configured to transmit a series of sound pulses into the object and the image generation unit being configured to generate an image, for each sound pulse in the series, in dependence on the reflections of that sound pulse that are recognised by the signal processing unit. 
     
     
         14 . An apparatus as claimed in  claim 13 , the image generation apparatus being configured to generate an image, for a sound pulse in the series, in dependence an image generated for a sound pulse that preceded it in the series. 
     
     
         15 . An apparatus as claimed in  claim 1 , the image generation apparatus being configured to generate an image in which the first and second structural features are represented at positions in the image that reflect their relative depths below the surface of the object. 
     
     
         16 . An apparatus as claimed in  claim 1 , the apparatus comprising a handheld device that comprises at least the transmitter and receiver units. 
     
     
         17 . An apparatus as claimed in  claim 1 , the apparatus comprising either an integrated display for displaying the image or being configured to output the image to a handheld display device. 
     
     
         18 . An apparatus as claimed in  claim 1 , the image generation unit being configured to:
 identify a reflection having a maximum amplitude that is below a threshold value; and   assign a pixel in the image that corresponds to the identified reflection a predetermined value instead of the reflection's maximum amplitude.   
     
     
         19 . An apparatus as claimed in  claim 19 , the image generation unit being configured to assign the pixel a predetermined value that is higher than the reflection's maximum amplitude. 
     
     
         20 . An apparatus as claimed in  claim 1 , the apparatus comprising a dry coupling medium. 
     
     
         21 . An apparatus as claimed in  claim 1 , comprising a matrix array for transmitting and receiving sound pulses. 
     
     
         22 . A method for imaging structural features below the surface of an object comprising:
 transmitting a sound pulse at the object;   receiving, from the object, reflections of sound pulses transmitted at the object;   recognising, in one or more signals received from the object, a reflection of a transmitted time pulse that was caused by a first structural feature and a reflection of a transmitted time pulse that was caused by a second structural feature that is located, in the object, at least partly behind the first structural feature;   associating each recognised reflection with a relative depth in the object at which the reflection occurred; and   generating an image that includes a representation of the first and second structural features in dependence on the recognised reflections and their relative depths.