To answer your question directly, yes there is 1/2" poultry netting (chickenwire)... though it can be harder to find (see if your feedstore can special order it for you). I use it mostly to keep chicks where they belong and it works great.
That said...
...if you are just looking for something to "smallen up" the holes on larger size mesh, to keep chicks in place or to discourage reach-through accidents from either direction, the plastic garden netting works really well. It is about 1/2" mesh size, very easy to work with, and inexpensive. A raccoon could rip through it, sure, but if it's just covering (say) 1x1" mesh, ripping through it won't do a raccoon much GOOD and won't cause a major risk as long as you notice the damage the next day and fix it. So for lower-risk areas (not next to a roost) I think it is quite adequate.
Good luck, have fun,
Pat