EXTENSION TO MORE THAN ONE OBJECT PARTICLE 



65 



opaque to unstained particles. Since —A' does not fall below 0.55, the 

 single diffraction plate 1.8B— 0.117X serves moderately well over the 

 entire range of stained particles whose optical path is +X/4 and serves 

 particularly well for particles whose g values fall in the range 0.6 < g < I. 



1.0 



0.9 



0.8 



0.7 



0.6 



0.5 



0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 



Fig. 11.19. The contrast K as a function of g at 

 A = +X/-4, h = -42°, and /r = 1.81. 



It should not be concluded, however, that the B-type diffraction plate is 

 superior to the A type for all stained particles. Thus when the optical 

 path difference of the particle is zero, as in Section 15, the optimum 

 h values are less than unity and lead to A-type diffraction plates. 



17. GENERALIZATION OF THE THEORY TO MORE THAN ONE OBJECT 

 PARTICLE 



If the object slide contains more than one particle, as it does, of course, 

 in actual practice, the *S' wave is again constructed as for a single particle. 



