The Hamlet Project

What does Hamlet mean by infusion here?
It would seem that it meant then more or less what it means now.
Is he pointing to a kind of essence of Laertes’ soul?
Is the infusion, like, concentrated extract of Laertes?

I mean, I know a lot of this is purposefully obscure language but in other instances, it is also accurate. Has he veered away from meaningful parody and just begun to get a little silly? Just seeing what he can get away with with Osric?
His semblance is his mirror? Is he trying to say he is what he seems? This sentence is not only what it seems.