X-RAVS AXD ORIEXTATION OF OlART/. CRYSTALS 



321 



From Fig. 3.10 we see that, for the beam entering as shown, the components 

 of the unit vector X\ along the beam are 







sin gi 

 cos gi 



so that equation (3.22) becomes 



sin d,,k.( = .¥•> sin gi + N^ cos ,!,'i 



which has the solution 



gx^ 0' - b[ 



where 

 and 





sm t) = 



sin 6 



cos sin~^ A^i 



(3.24) 



(3.25) 

 (3.26) 



(3.260 



Fig. 3.20 — Position 2 for a plate of general orientation 



Again, with the plate rotated 90° around its normal (to position 2) so 

 that the entering beam is in the position shown by the unit vector X2 in 

 Fig. 3.20, the components of Xi are 



— cos gi 



sin gi 







so that 

 or 



sin = N2 sin ^^2 — -Vi cos ^2 



g2 = e" + b[ 



(3.27) 

 (3.28) 



