Conversion of an EM-200 to a Dual-Gun Electron Microscope for TEM and SEM

Abstract

A Philips EM-200 electron microscope has been modified to incorporate two electron guns as described by Ong and Gold, for operation in the conventional (TEM) and scanning (SEM) mode.The second gun, the SEM gun, is mounted below the viewing chamber and uses the imaging system of the microscope as the probe forming electron optic. The electrons follow essentially the same path as the image forming electrons for TEM, only in the opposite direction.The modifications to the microscope column are designed to provide the space for the scanning coil assembly, the various detectors, and the second gun. A spacer is located above the objective lens to house the transmission electron detector, another spacer, below the objective lens, incorporates the scanning coil and a secondary electron detector.