Intrinsic, shape, and configurational birefringence

Abstract

We generalize earlier work on intrinsic and form birefringence for random distributions of aligned ellipsoids by taking the minimum separation of particle centers (the exclusion-correlation surface) as nonsimilar to the particle's surface. For such cases, the bulk parameters involve a compound depolarization factor consisting of two distinct terms, one corresponding to particle shape (S) effects, and the other to configurational-correlation (C) effects. The associated bipolarization and birefraction expressions show form (F) effects in which S and C may either compete (and even cancel) or else reinforce. If they compete (e.g., for coaxial spheroidal particle and exclusion surfaces, both prolate or both oblate) then the F effects are less than the S; if they reinforce (coaxial spheroids, one prolate and one oblate) then the F effects are greater than the S. We show how the earlier explicit results for similar C and S can be generalized by inspection, and illustrate the procedure for key forms.