In the quest to qualify the ITER European batch of toroidal field coils, SENIS AG, based in Canton Zug, Switzerland, is mapping the magnetic field around the 'D' shaped giant toroidal field coils. The device combines the magnetic field measurement accuracy of SENIS' 3-axis Hall sensor measurement instruments with the positioning precision of a Hexagon Leica Laser Tracker, the Swiss metrology reference product used to measure all large ITER structures. SENIS 3-axis sensor consists of patented vertical and horizontal Hall elements fabricated in CMOS silicon technology. The result is that in a single measurement, the size of three components of the magnetic field and the probe's position are known- instantly, with an impressively high signal-to-noise ratio and resolution.