Jaunt, maker of a 3-D camera for filming virtual reality video, has nabbed a total of $100 million, including $65 million in September. And 8i, which makes technology that lets people interact with video of humans as though they were in the same room, has raised nearly $15 million.

None of these start-ups is a household name. Few members of the public have had an opportunity to interact with — much less buy — the virtual and augmented reality technology that these companies are developing.

Yet investors and entrepreneurs believe that headsets made to immerse people in digital worlds are the next giant moneymakers in technology, setting off an investor frenzy rarely seen since the early days of the web and mobile markets. Virtual reality start-ups are multiplying, venture capital is pouring into them and the believers are expressing blue-sky thinking about how the new products could reshape entertainment, communications and work.