k-Wave

1. cdelu
   

   Member
   Joined: Jul '12
   Posts: 1

   Hello,

   I am also a bit new to kWave, so my apologies for this low-level question.

   I am trying to define a transducer so that I can focus my signal at a certain point given by the coordinates (x0,y0,z0). Assuming the waves are travelling in x-direction, I assumed my focus_distance will be given by x0, the elevation_focus_distance by z0 and the steering_angle can be computed from y0. After running some simulations, I noticed that these assumptions are not necessarily the right ones. Can someone please explain what is the right approach?

   Thank you in advance.

   Posted 12 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi cdelu,

   Sorry for the delay in replying to your post. Using the kWaveTransducer class, the beam can only be steered within a 2D plane, similar to conventional diagnostic ultrasound transducers. In this case, the parameters focus_distance and steering_angle set the focus position within the x-y plane.

   The parameter elevation_focus_distance controls the focusing in the elevation or x-z plane. For most transducers, this focus distance is fixed and physically occurs due to the shape of the transducer elements or a lens.

   If you are interested in a more general simulation, I would define the source mask and signals directly, rather than using the kWaveTransducer class. For example, you could define source.p_mask to be a rectangle with 'G' grid points, define source.p to have G time series, then delay the time signal associated with each grid point based on its distance to the focus point.

   I hope that answers your questions,

   Brad.

   Posted 12 years ago #

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