ELECTKON ^IICHOSCOPY 



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Fig. 3. Scratch on brass surface (after Page). © i + ©2 = 26". Magnification 1,200X. 



The advantages and disadvantages of the 

 Von Borries reflection method may be sum- 

 marized as follows. 



Adva7itages 



(1) Direct observation of the specimen 



(2) Large depth of field 



(3) Contrast easily interpreted 



(4) Information available in the dimen- 

 sion perpendicular to the specimen plane. 



Disadvantages 



(1) Extremely foreshortened image 



(2) Unsuit ability for rough surfaces 



(3) Resolution limited to 200 A 



(4) Damage to some specimens by high 

 intensity electron beam 



In spite of the disadvantages, the reflec- 

 tion method has been of value in the fields 

 of metallurgj' and crystallography, in the 





:i.v<^'". 



Fig. 4. Etched germanium surface. (After 

 Halliday and Newman). ©1 and Q 2 adjusted to 

 select electrons diffracted from (-400) planes. Mag- 

 nification 66,000X. 



focus in a direction perpendicular to its 

 plane. 



999 



