To provide reliable measurements, magnetometers used in industry need to be calibrated regularly. The calibration may be performed by the manufacturer or by a commercial calibration laboratory. In either case, the calibration requires a standard, which is usually established and maintained by a national standards laboratory, in collaboration with international standards committees.
A physical magnetic standard – i.e. a high-precision standardized magnet – is too expensive for widespread use. Instead, very precise time standards and the precise measurement of a physical constant called the gyromagnetic ratio permit NMR magnetometers to act as a convenient secondary standard. Now, the field generated by a relatively inexpensive reference magnet can be measured with an NMR teslameter, and then used to calibrate other magnetometers.
As the pre-eminent manufacturer of commercial NMR magnetometers, Metrolab enjoys a privileged position in the calibration and standards laboratories. Precision, measurement range, ease of use and reliability are Metrolab trademarks that are familiar to nearly every magnetic calibration facility.
Although reference magnets can be relatively inexpensive, they are usually still large and specialized pieces of equipment. For this reason, magnetometer calibration is performed in only a few specialized facilities, which leads to expense and logistical overhead when many instruments need to be calibrated.
For calibration at specific field strengths, Metrolab offers a solution: a line of ultra-compact permanent magnets with an opening large enough for an NMR probe as well as the instrument to be calibrated. Using a built-in correction coil, the field can even be regulated to NMR precision. If you received our magnet / teslameter kit in the morning mail, you could be calibrating before lunch!