http://www.k-wave.org/forum/topic/diverging-waves Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 00:43:28 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/diverging-waves#post-7547 Sat, 06 Jun 2020 13:01:01 +0000 Bradley Treeby 7547@http://www.k-wave.org/forum/ <p>Hi João,</p> <p>If you open the <a href="http://www.k-wave.org/documentation/example_us_beam_patterns.php">Simulating Ultrasound Beam Patterns Example</a> and set <code>transducer.focus_distance = -20e-3;</code>, it seems to give a diverging wave. Is that what you mean?</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/diverging-waves#post-7465 Fri, 01 May 2020 13:22:35 +0000 jr20 7465@http://www.k-wave.org/forum/ <p>Hi Brad,</p> <p>Thank you for your reply.</p> <p>I have only started working on ultrasound imaging recently, so please correct me if I'm wrong, but wouldn't a very large focus distance simulate a planar wavefront? If so, that is not quite what I'm looking for. </p> <p>The idea is to have a wide curved wavefront and that is usually achieved by focusing the beam such that the virtual focus distance is actually behind the imaging plane (<a href="http://www.ecei.tohoku.ac.jp/hkanai/pdf-fullpaper/151hasegawa2011.pdf" rel="nofollow">http://www.ecei.tohoku.ac.jp/hkanai/pdf-fullpaper/151hasegawa2011.pdf</a>, Figure 2. (b), virtual source O_v). </p> <p>That being said, if I set transducer.focus_distance to a negative number, would it simulate this effect? I'm asking because the results I am achieving with my own beamforming script don't seem to be quite what I was expecting. But it may be some other factor I'm forgetting. For instance, the angle at which the beam diverges is crucial to determine the focus distance. Is it possible to change this parameter? </p> <p>Maybe it would be better to use the sensor class instead of kWaveTransducer for this purpose?</p> <p>Regards,</p> <p>João </p> http://www.k-wave.org/forum/topic/diverging-waves#post-7461 Fri, 01 May 2020 09:04:04 +0000 Bradley Treeby 7461@http://www.k-wave.org/forum/ <p>Hi Joao,</p> <p>You can set the focus values to be infinite, i.e.,</p> <pre><code>transducer.focus_distance = inf; % focus distance [m] transducer.elevation_focus_distance = inf; % focus distance in the elevation plane [m]</code></pre> <p>Brad. </p> http://www.k-wave.org/forum/topic/diverging-waves#post-7435 Sat, 25 Apr 2020 15:16:27 +0000 jr20 7435@http://www.k-wave.org/forum/ <p>Hi all,</p> <p>Does anyone how I would go about transmitting a diverging wave using the built-in transducer class? If I set the focus behind the imaging medium would I achieve this?</p> <p>Regards,</p> <p>João </p>