I'm trying to understand how high-resolution Raman mapping is achieved in cases where the laser spot size (e.g., 20 µm) is significantly larger than the desired spatial resolution (e.g., 0.5 µm). Wouldn’t the spatial resolution be fundamentally limited by the laser spot size? Is there some form of deconvolution, confocal filtering, or oversampling technique involved in such measurements?
Any insights or references would be appreciated.
It depends on what type of detector you have - single element or an array detector and the optics of the spectrometer.
Also remember that the spot size is often quoted from a calculation and not an actual measurement. In addition the spot size is only correct from an optically flat surface. Very few samples have this type of surface so there will be additional scatter from, and diffusion through the sample making actual spot size determination difficult at best. This is a simple response. There will be others that can give a much better theoretical reply.
Have a look at Abbe's diffraction limit. It does not depend on the spot size...
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