124 . Prof. S. Banerji on the Radiation of Light 



for the intensity of the field as viewed in the direction <£, 

 which may be written in the form 



+ Si 



(2tt6 

 X 



2tt0 

 A, 





where 6 is the angular semi-aperture of the lens. When 

 4>/@ = i I — thai is, at the boundaries — this expression 

 becomes very small, but the suddenness with which the 

 illumination falls to zero at these points depends very 

 much on the magnitudes of f x and f 2 . To illustrate this 

 statement, I have calculated the distribution of intensity 



for a hypothetical case in which £1 = 7, and £2 = — n~ • The 



u u 



values are shown in Table III. (in which the factor 4 in the 





Table III. 





<p/e. 



1. 



0/0. 



I. 



1-000 



0-0045 



1-000 



0-0045 



1-002 



1-7956 



0-998 



2-2201 



1-005 



1-5129 



0-995 



1-8496 



1-010 



2-9584 



0-990 



3-4225 



1-020 



1-5376 



0-980 



2-1609 



1-030 



2-0164 



0-970 



2-4025 



1-100 



0-8281 



0-900 



1-0050 



1-300 



0-0020 



0-700 



o-oooo 



1-500 



0-0605 



0-500 



0-0357 



1-800 



o-oooo 



0-200 



0-0057 



2-000 



00182 



o-ooo 



0-0853 



Fig. 3. 



expression for the intensity has been neglected) , and these 

 have been plotted in fig. 3. 



