60 



BELL SYSTEM TECHNICAL JOURNAL 



by a small rotation about xi of amount 6 — 



KT' = 



■ZiiEi . . 



and 



Ml - ^ X 0.47 X 10~^"£i 



3 



M = Ml + y X 0.47 X 10~''Ei 



M3 



The greatest "added birefringence" is gotten by viewing along xs , when 

 AB = 1.544' X 0.47 X 10"'° £i . If £i = 10* A B = 1.73 X 10"' a quantity 

 detectable if the path length is about 1 cm. \'iewing along xz (the optic 

 axis) is complicated by the rotation of the plane of polarization in quartz. 

 Homogeneous strains have never been found to alter this rotation, but the 

 rotation complicates and partly masks the birefringence phenomena. If 



M 



E = 



E2 we find 



K-y= 







—ZiiEi 

 — ZnEi^ 



Rotating the coordinate axes through 45° about .V3 then applying the 

 transformation 



where 



a = 



we find: 



K-'" = 







+ z\\Ei 



° — zviEi 

 T^-10 

 A3 















3 

 Ml 17 



Ml — y 2u El 

 3 



= Ml + — 2llii2 



Z 



M3 



