118 



The Electron Microscope 



near the ends of the accessible space. (The collectors are not 

 shown in figure 41.) Determining their size and shape will be 

 best left to experiment, for electron interaction is the most 

 complicated and the least explored problem in the whole field 

 of electronics. 



^fOIJ 



Fig. 43. Electromagnetic field and electron trajectories in corrected lens 



The roughly parabolic shape of electron density distribution 

 which has been assumed in figure 42 is suitable not only for 

 producing a divergent lens, but also for correcting the spherical 



