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Physics Seminar - Dr Jon-Paul Wells

Monday, 14 May 2018

Physics Department
Seminar

Dr Jon-Paul Wells


Dodd-Walls Centre for Photonic and Quantum Technologies

School of Physical and Chemical Sciences

University of Canterbury

"The Canterbury Ring Laser Project"


The first ring laser gyroscope was reported by Macek and Davis in 1963. Although unable to detect the rotation of the earth, this early experiment demonstrated an improvement in sensitivity of many orders of magnitude over the early passive interferometers constructed and operated by Sagnac and Michelson in the early decades of the twentieth century. Over the last two decades a series of large ring laser gyroscopes have been built having an unparalleled scale factor, and dramatic improvements in sensitivity and stability. The Canterbury ring laser group, in collaboration with international partners in Germany, has been at the forefront of these developments [1]. For example, the first large ring laser gyroscope to unlock on the bias provided by Earth rotation alone was the 0.748 m2 Canterbury-I ring laser in Christchurch. Another high point was the largest ring laser ever constructed, the 834 m2 Ultra-Gross-Ring-2 (UG-2), which was located in the Cashmere caverns near Christchurch and had the highest intrinsic sensitivity to rotation of any laser constructed. The 2011 Christchurch earthquakes ultimately led to the closure of the Cashmere facility and with it, a focus on the utilization of facilities in Germany (the 16 m2 Gross-Ring), coupled with a 2.56 m2 test ring in Christchurch. We have recently demonstrated a ring laser gyroscope which unlocks on the bias provided by Earth rotation using new generation ‘crystalline coated’ supermirrors. In Germany, 2017 saw the inauguration of the first fully three dimensional ring laser structure at the ROMY facility at Fürstenfeldbrück near Munich, which is aimed toward measurements in rotational seismology. In the meantime, the G-ring is within a factor of two of measurements of the 100 µs variations in the length of day, a long standing goal of terrestrial interferometry which would see ring lasers usefully contribute to very-long baseline interferometry in radio astronomy.

[1] K.U. Schreiber and J.-P.R. Wells, “Large Ring Lasers for Rotation Sensing”, Rev. Sci. Instr. 84, 041101 (2013).

WHEN: Monday 14 May 2018
WHERE: Room 314, Science 3 Building
TIME: 3.00 pm–4.00 pm

All interested are welcome to attend

Light refreshments to follow in Common Room