http://www.k-wave.org/forum/topic/pulse-width-influence-on-signal-spectrum Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 23:10:07 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/pulse-width-influence-on-signal-spectrum#post-7218 Wed, 12 Feb 2020 12:20:06 +0000 Bradley Treeby 7218@http://www.k-wave.org/forum/ <p>Hi Yun,</p> <p>You can define your source pressure (<code>source.p</code>) using a Gaussian, e.g., by using the <code>gaussian</code> function in k-Wave. Within the help file of the function, there is a formula you can use to convert the FWHM of the pulse to the variance (one of the inputs). Note, you will likely have to make your simulation time step very small to resolve the Gaussian, so the simulation might take some time.</p> <p>Brad </p> http://www.k-wave.org/forum/topic/pulse-width-influence-on-signal-spectrum#post-7157 Wed, 25 Dec 2019 07:23:58 +0000 Yan 7157@http://www.k-wave.org/forum/ <p>Hello samantp,</p> <p>I come across with the same questions you asked before. Has your problems been solved now?</p> <p>Could you tell me how to define a gaussian pulse source with different pulse width,for example, 9ns, 1ns, 30ps? </p> <p>Best wishes!<br /> Yan </p> http://www.k-wave.org/forum/topic/pulse-width-influence-on-signal-spectrum#post-6867 Thu, 30 May 2019 01:48:14 +0000 wenxiu 6867@http://www.k-wave.org/forum/ <p>Hello samantp,</p> <p>What's more, according to my understanding, the femtoseccond is much less than stress confinement and thermal confinement that only the deposited energy will influence the PA signal.</p> <p>Best wishes!<br /> wenxiu </p> http://www.k-wave.org/forum/topic/pulse-width-influence-on-signal-spectrum#post-6866 Thu, 30 May 2019 01:37:04 +0000 wenxiu 6866@http://www.k-wave.org/forum/ <p>Hello Samantp,</p> <p>Yes, here is the reference.<br /> Yamaoka Y , Harada Y , Sakakura M , et al. Photoacoustic microscopy using ultrashort pulses with two different pulse durations[J]. Optics Express, 2014, 22(14):17063.</p> <p>Best wishes!<br /> Wenxiu </p> http://www.k-wave.org/forum/topic/pulse-width-influence-on-signal-spectrum#post-6865 Wed, 29 May 2019 17:39:46 +0000 samantp 6865@http://www.k-wave.org/forum/ <p>Hi Wenxiu, can you please link the paper?<br /> To the best of my knowledge this is only due to bandwidth limitations on the detection transducers.</p> <p>Thank you! </p> http://www.k-wave.org/forum/topic/pulse-width-influence-on-signal-spectrum#post-6862 Tue, 28 May 2019 00:51:56 +0000 wenxiu 6862@http://www.k-wave.org/forum/ <p>Hello Samantp,</p> <p>I'm also a user of k-wave, and I has considered the femtosecond pulse laser simulation. But k-wave seems not suitable for this condition. When the laser excitation is with a femtosecond laser, there may be different acoustic wave generation mechanism such as two-photo effect. Moreover, a paper published at 2014 reported that the pulse width will not influence the amplitude of PA signal, and its pulse width varies from 200fs to 4ps.</p> <p>Best wishes!<br /> Wenxiu </p> http://www.k-wave.org/forum/topic/pulse-width-influence-on-signal-spectrum#post-6860 Thu, 23 May 2019 16:18:25 +0000 samantp 6860@http://www.k-wave.org/forum/ <p>Hello,<br /> I am seeking to run a simulation where I vary the pulse width and size of a source (I will simply use a disc source with a Gaussian shape in time using the time varying source problem codes) and examine the effect this has on the frequency. However, the pulse width time scales tend to be much smaller than the time scales of acoustic propagation. So, my question was, is it possible to design such a simulation with enough time steps to allow for both propagation and generation?</p> <p>My pulse widths will be in the range of femtoseconds whereas the acoustic propagation will take microseconds. Is it possible to run the first few femtoseconds of the simulation with a small dt, then stop the simulation, export a snapshot of that pressure into a new simulation with a higher dt, and then run that? i.e. is it possible to pause a simulation, export the checkpoint, and then run a simulation from that checkpoint with a different dt?</p> <p>Thank you! </p>