Automaton: Are there algorithms to judge whether two automatons are isomorphic?

When I want to judge whether two regular forms represent the same language, I have learned the next method:

1. create the (non-deterministic) finite-state automaton which accepts the language the given regular form represents for two regular forms respectively.

2. convert the two NFA into DFAs.

3. 开发者_如何学JAVAJudge whether the two DFAs are isomorphic.

However, I don't really know how to do 3. Are there any algorithms to do 3?