Possibilities of Future Development 



105 



proof that it gives results identical with the wave picture are 

 rather difficult. But in its original and simplest form, it can be 

 used very conveniently to account at least for the order of magni- 

 tude of diffraction effects, as can be seen by its application to 

 Kompfner's problem.* 



spherical double grid. 



? ? 5 ~4^'^v 



/ * 



I ' 

 1 1 





5 



V 





chopped eJecbf on beom. objective. 



b. 



Fig. 38 



As we always reduce errors to the object plane, we can 

 conveniently imagine the lens replaced by a mirror, at a distance 

 f from the object, as shown in figure 38b. The photographic 



* Cf. also the very simple proof of the Abbe limit by Henriot, quoted by 

 Marton, et al.^T' ^9 



