Rnz: Afternoons With Jesse Mulligan

For over a decade, an irreplaceable ring laser has been trapped in a cavern 30m below Christchurch port hills. The Carl Zeiss laser was installed in an old World War Two bunker in 1997 until a rockfall after the 2011 Christchurch earthquake sealed the cavern. But now it's been rescued and is fully operational. Professor Jon-Paul Wells is the principal investigator on the ring laser project.