Measuring magnetic fields with accuracy is important, whether it’s for geological exploration or medical imaging. Now, a team from MIT has developed a new laser-based magnetic field detector that’s 1,000 times more efficient than previous examples.
One way to measure magnetic fields is to shine laser light through synthetic diamonds with nitrogen vacancies, which are points where a carbon atom is missing from the diamond lattice. When laser light passes though such a vacancy, photons bump an electron in the space into a higher energy state; the presence of a magnetic field can affect the spin of that electron when its energy state drops back down, causing a difference in the new resting energy level. Measuring the differences in the energy states allows scientist to measure the strength of a magnetic field.
The only problem is that a lot of such readings are required to accurately measure a magnetic field. Usually, lasers have been shone at the surface of a synthetic diamond, limiting the number of readings that can be acquired. Now, the MIT team has developed a diamond chip in which laser light can bounce around inside, providing a path length of over a meter and, in turn, yielding far more readings than in the past. The result is a sensor that’s 1,000 times more efficient than those that have gone before it.
The researchers reckon they could create a miniaturised version of the chip that could be used in battery-powered devices, which would make accurate magnetic field measurement truly mobile. [Phys.Org]