1. Place a piece of paper over the magnet and sprinkle iron filings on it.
2. If that doesn't work, ask Metrolab.
Many industry and research applications require knowing the magnetic field strength not just at a single point, but throughout a volume. Metrolab provides you with decades of experience and a complete product line to help you make magnetic field maps accurately and quickly. As with single-point measurements, you can choose from three different magnetic measurement technologies, depending on your requirements and the characteristics of the field to be mapped.
Certain applications require knowing the magnetic field map with a
precision that only NMR can provide. One very important such
application is the production of MRI magnets. Since 1992, we produce
Magnetic Field Cameras specifically for this application. Able to
measure up to 96 points simultaneously, this system dramatically speeds
up mapping and reduces the positioning error.
Focusing magnets used in accelerators need to be characterized very
precisely, but the complex, highly inhomogeneous fields do not permit
the use of NMR. Instead, a rotating coil is used to make a polar
decomposition of the integrated field seen by a beam particle.
Metrolab's Fast Digital Integrator, first introduced in 1991, is
still considered as the reference for this application.
Most magnetic field maps are used to validate the operation of a
prototype magnet against a computed model. Such applications generally
don't require the precision of NMR or rotating coils; instead,
convenience and speed are the predominant considerations. Metrolab's
Three-axis Handheld Magnetometer - the only handheld magnetometer to
simultaneously measure all three components of the magnetic field -
provides an extremely flexible and convenient solution.