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Far-filed calculation of scattered light in substrate-air domain

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Hi COMSOL users,

I hope somebody help me on this,

I would like to know a few clarifications about COMSOL far-filed calculation in Wave Optics module.
1. If I study 4.4 waveoptics module user guide, it says, "far-field is calculated in free-space". Does not it work for other homogeneous material medium, for example Glass?
2. Even in free space medium, Do I have to define full enclosed boundary to calculate the far-field?. (If I read about scatton-chu formula, a closed boundary is defined for antenna field calculation). Does COMSOL consider this as it is?. If I defined a part of circle with scatterer at its center in free space (in 2D) and integrate this boundary to incorporate collection lens effect of a particular NA, Can I expect correct results?
3. I have read the thesis in following link for for field calculation. He implemented far-field calculation with COMSOL 3.4 in material medium with a little modification with Matlab code. (Please see appendix section, if you have time). He also explained boundary shadowing problem, if far-field domain does not have radiation source and scatterer. Can I know any improvements is comsol 4.4 version on this far-field limitations in comsol? or I have to go my own modification in far-field calculations?
core.kmi.open.ac.uk/download/pdf/99111.pdf
4. Does Scatterer has to be at center of far-field closed boundary always for correct results?. In my case, scatterer moves, similar to scanning microscopy. If it has to be at center of enclosed boundary, I am thinking to move enclosed boundary also with scatterer such that scatterer is always center to closed boundary. Right now, I am moving only scatterer, and I am not getting microscopy profiles as I want.

I would be thankful if anybody share his/her experience on this.

Thanks
Mahendar

0 Replies Last Post 3 nov. 2014, 06:56 UTC−5
COMSOL Moderator

Hello Mahendar Kumbham

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