The Combined Plane-Cylindrical Mirror Analyzer (PCMA) hag the advantage of high transmission and the possibility of second-order focusing, just like the conventional cylindrical mi ror analyzer (CMA). In the POMA all fountain electrons emitted from the specimen (electron source) on the cylinder s ooaxis will be focused behind the specimen on the axis after travelling through 180 degrees. By using PCMA as the electron energy analyzer in a scanning electron microscope (SEM), the working distance of the SEM magnetic objective lens could be shortened, and its spherical abberation reduced as compared with non-coaxial gun type CMA, thus the primary electron beam current density oould be increased. As a result, the sensitivity of the scanning Auger Mioroprobe (SAM) might be enhanced. Furthermore, the structure within the irrer cylinder of PCMA is much simpler than the conventional CMA with coaxial gun.