n 



The Electron Microscope 



and of the constants of the circuit components. Spontaneous 

 high frequency noise is of relatively very small importance ; it is 

 mostly suppressed by the capacity of the coaxial cable which 

 connects the high voltage supply with the microscope. 



Ripple voltage in the R.C.A. microscope is enormously re- 

 duced by supplying the rectifiers with 32,000 cycles, instead of 

 with the line frequency. This artifice was known in high speed 

 cathode ray oscillography (Schering), but in electron micro- 

 scopy, it has additional advantages. Not only can the ripple 

 suppressing condenser be made much smaller, but it is much 

 easier to shield the microscope from stray fields. In addition, 

 the voltage regulator will work very much faster. 



H.T. 



I 



RectiFien 



-h 



Oscillator 



W77' 



"T/m 



6 '%• 6 



Line 



Fig. 21 



