Production of Circularly Polarized Light. 



529 



and defining the ellipticity (e)'as the ratio of the difference 

 of axes to major axis, we have 



e = l- 



1-fJT 



1 + f 



Now taking an interval equal to that between the C and F 

 lines, as before, the value of f for the Bi-rhomb is o, 20b', 

 and therefore 



e = 0-208 X^ = . |)07 



For the Bi-trapezoid and the same limits of wave-length, 

 we find $=0°-28, 



0-28X7T AnQ _ 



while the corresponding ellipticity for the Fresnel rhomb is 

 0-407 x 7T 



e = 



yu 



= -014. 



The ellipticiiies are practically the same for fused quartz as 

 for uviol glass. 



Table 1. shows the value of f for different wave-lengths for 

 the Bi-rhomb (i. e. for angle of incidence 74° 38 /, 2) and the 

 ellipticity of the corresponding orbit as calculated from 



2t 



e = -= y Table II. shows the corresponding values of 



X, f, e for the Bi-trapezoid ; Table III. is for the Fresnel 

 rhomb. 



Table I. 



Line. 



Kred... 



Li red 



Na (D x ) 

 Tl green 

 H violet 



X (A.U.). 



9296-0 

 7668-5 

 7596-0 

 6708-2 

 5896-2 

 53507 

 4840-7 

 41960 

 2496 



I (rad.). 



*(deg.). 



e. 



•0078 



0-417 



014 



•0088 



0-215 



0076 



•0036 



0-208 



007 



•0017 



0-099 



0034 



•0 



o-o 







-•0012 



-0-069 



0024 



-•0083 



-0-189 



0066 



- -0036 



-0-208 



007 



- -0073 



-0417 



014 



