Capacitive sensors work are sort of noncontact, but the distance must be quite miniscule. The types of liquids you can do this way are limited. But otherwise you may be looking at a "machine vision" solution, very complicated. Actually not a bad thing to become an expert in, there's a huge demand for advanced machine vision solutions in automated manufacture.
I have used capacitive proxy sensors to measure the height of a liquid in a buck and then shut off a fill valve in an automated bucketing system Turk makes some nice ones my design worked over inches and through a plastic bucket.
joe