I've never seen any infuser with mesh as fine as some of the tea strainers I've seen, which are designed for putting over the top of the cup while pouring tea out of the teapot, to catch the fines that come through the holes. They work great for those situations where fines are really abundant and annoying. Even if the mesh of the strainer is very fine, there will still be leaks of fines at the line where the strainer closes around the tea.
The ones I've got from my local tea shop were much like this one
from Dragon Tea House on ebay.