I don't know about "perfected," necessarily, but they got it to work after a fashion.
There's cryo storage in Fallout 2, as a bit of a sidequest. (One of the guys you can "thaw" subsequently "goo-ifies" not long after, however.) Not to mention
Spoiler the whole Tranquility Lane quest in Fallout 3 - where the original population has been kept in an artificial reality since 2077.)