In a file I have a statement that diploid pollens have an average diameter of about 100 microns and tetraploid pollens have an average diameter of about 140 microns. My scanner picks up individual pollen grains on leaves and petals; its specs indicate that it can do high resolution scans of 4800 dpi but I know that is an over exaggeration. I would think that a maximum magnification of 500 or 1000 would easily be high enough. I suspect that attaching a camera is one feature that would be important.