National University Singapore

EMI Active Compensation TEM

The performance of a biological TEM was limited by strong EMI induced by surrounding equipments, building power line and possible ground loops. The ambient EMI was measured near to TEM column as large as 10 times TEM allowable level.

The initial EM measurements shown large field gradient with strong EM field in one side of TEM column with respect to other side. The strong field gradient generally limits the canceling performance of active compensation systems. In addition to that, relatively small room caused limited size for the coil dimensions. In spite of those facts, the EM field was reduced down the level which is within the tool EMI requirements.

HR TEM images shown visual improvements from initial situation, but still some distortions could observed at high magnifications, due to other distrubance sources