Discussion Forum

Hello everyone,

I am currently working on a PiFM system (Photo-induced Force Microscopy), which is actually an Atomic Force Microscopy system but with the addition of an IR pulsed laser source that has the purpose of illuminating the tip-substrate junction, and therefore causing an opto-mechanical and opto-thermal interactions between the tip and the substrate beneath it.

After building the 2D structure (capture attached below), I added a emw physics from the RF module, and I chose a Boundary Mode Analysis study, as well as a Frequency Domain study, since my target is to visualize the electric field confinement by sweeping over a frequency range between 8 µm and 13 µm, and also to compute the optical force between the tip and the sample. In that case, is my choice of the studies above suitable to compute the optical force? As for the placement of the incident laser light, it can be seen that the focus is on the upper part of the tip. Do you kindly have suggestions on how to adjust the incident light so that it focuses on the tip-sample junction instead of the upper part of the tip? Noting that I initially chose an angle of incidence of 45 degrees.

On the other hand, my aim is to also examine the presence of any thermal effect whether in terms of thermal expansion along the substrate’s surface, or in terms of Van der Waals force between the AFM tip and the sample. However, I am clueless about which physics module and therefore which particular study to choose in order to examine these effects. Is it the Joule Heating and Thermal Expansion in Solid Mechanics module?

I greatly appreciate any help that I might get concerning my inquiries, especially that I started learning on Comsol just a month ago and I am trying my best to figure things out on my own.