According to JTAS #09, p.30, personal Psionic Shield Helmets are TL12. Which means they theoretically could have been around since the founding of the Third Imperium. They became a popular item of fashion during the Psionic Suppressions in the 800's, but something of an embarrassment afterward. During the 5th Frontier War, they once again saw a rise in popularity in the Spinward Marches.
That looks like errata or a retcon to fit the OTU, maybe.
(Tweaks and rules adjustments needed to be made to fit the growing in-house campaign setting, so please don't read my comment as hipster gamer disdain for a later product. Not much later, in any case!
)
Book 3, 1977, lists them as TL 8.
I find the lower TL anti-psi helmet interesting, as it suggests psionics could have been developed at about the same time , on some worlds, as early gravitic tech (the air/raft) and before Jump drive. Not necessarily before the discovery of the existence of Jump Space, though.
Or maybe it was psi that helped people discover Jump Space?
The technical and scientific developments in various worlds, species, and civilizations need not follow the Book 3 tables exactly, of course.
That makes sense. If I were running an OTU game, I'd very likely use this.
Nobby--
''Tinfoil hats'' and ''spoon-benders''! Sounds fun.