1971 - today

The pioneering work of Haarman (use of 2 wires, faster electronic bridge, experimental time of seconds) was the start of a new series of THW instruments developed after 1971, most of them based theoretically in a paper by Healy in 1976.
Since the majority of these new groups cooperated through research projects, very similar instruments appeared. Most of the THW groups nowdays originated from, or were connected to,
- J. Kestin (Brown Univ., USA), or
- W.A. Wakeham (Imperial College & Southampton Univ., UK).

Such groups are:
- C.A. Nieto de Castro & J.M.N.A. Fareleira (Portugal),
- M.J. Assael (Aristotle Univ., Greece),
- R. Perkins (NIST, U.S.A.),
- A. Nagashima & Y. Nagasaka (Keio Univ., Japan).

and more recently
- J. Wu (Jiaotong Univ., China),
- E. Vogel (Rostock Univ., Germany).

In parallel, some more groups produced also excellent work, as
- S.E. Gustaffson (Chalmers Univ., Sweden),
- U. Hammerschmidt (PTB, Germany).


J.J. Healy, J.J. de Groot, and J. Kestin, Physica C, 82:392 (1976).