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Subsurface Geologic Methods 



ate image, and the projection-lens coil produces a further magnified 

 image on the fluorescent screen in the final viewing chamber. 



To facilitate the initial adjustment of the specimen, a port is provided 

 for viewing the intermediate image on a fluorescent screen close to the 



Electron Source 



Condenser Coil 



Specimen Mount 

 Objective Coil — 



Port for Intermediate Viewing 



Projection Coil- 



Ports for Viewing Final Enlarged Image 

 Fluorescent Screen or Photograptiic Plate 



Vacuum Pump 



Figure 86. Simplified drawing of electron microscope, taken from "Electron Micro- 

 scope" prepared by R.C.A. Manufacturing Company, Camden, N. J. 



plane of the projection-lens coil. By virtue of the relatively low magni- 

 fication at this point, it is possible to select the most interesting part of 

 the specimen and to move it into position to be magnified further by the 

 projection-lens coil. 



Six observation windows enable a number of spectators to view the 

 image simultaneously. With the choice of a selected field of view and the 

 magnification adjusted to the desired value, the fluorescent screen is raised, 



