DC & AC Magnetic Field Cancellation for TEMs with VEC Dual Cancellation System

Transmission electron microscopes (TEM) with tight magnetic field specifications pose a significant challenge for magnetic field mitigation and active magnetic field cancellation because of the length of the electron beam column. Unlike a scanning electron microscope (SEM), focused ion beam instrument (FIB), or a dual beam, with relatively short columns of ~1-2 feet, the column of TEMs is much longer with sensitivity to magnetic fields at the top of the microscope at the source and at the bottom near the detector. Room shielding is always an option, but this can be very expensive and add significant time to a project schedule. Also, the standard 1/4″ aluminum shielding is only effective for AC, not DC fields. So, even in a shielded room, a DC magnetic field cancellation system is required to mitigate the DC component of the magnetic field interference.

This video outlines the strategies for magnetic field mitigation for TEMs, and it describes why a dual cancellation system is the most appropriate active magnetic field cancellation strategy for very high-resolution TEMs with extremely tight specifications.