Near Surface Geophysical Sensor Technology

Geometrics has recently developed atomic magnetometer sensors with an order of magnitude lower power and size than previous commercial devices. This work will greatly increase the types of applications for which magnetometers may be used. This paper will present some of the advantages of total field magnetometers in general, and micro-fabricated atomic magnetometers (MFAM) in particular. Total field magnetometers are widely used in geophysical and other surveys where the magnetic field gives an indication of the properties of the subsurface. This includes applications for oil and mineral exploration, unexploded ordnance (UXO) detection and discrimination, and pipe and cable route surveying. One factor limiting the usefulness of magnetometers generally is their lack of ability to determine the direction to an anomaly from a single reading. This limitation is due to the properties of magnetic fields themselves, especially those that are dominated by the Earth’s field. However, arrays of sensors give much more information about an anomaly, and such information may be used to determine a target’s size and location. This is the principle of magnetic surveying, where readings are taken by painstakingly scanning an area with a single sensor, mapping the readings, and finally analyzing the data. An array of sensors, however, may take such readings simultaneously, allowing for immediate analysis. This is the major benefit of the new MFAM sensors. Due to their small size and power consumption, and to their potentially low cost, they can be easily deployed in arrays, which will allow the characteristics of the target to be determined in real time, rather than as a result of post processing after a survey is conducted. This opens up an enormous range of new opportunities for magnetometer sensors, as target information may be made available on the spot.