Light scattering from coated spheres: model for biological cells.

Efficient methods for the calculation of light scatteringintensityfunctions for concentrically coated spheres (~10-micro diam) are discussed. This model represents many types of biological cells whose nuclei have a low refractive index (~1.1) and cytoplasms with a slightly lower refractive index. Studies are made on the relationships between the scattering coefficients for nonabsorbing, spherically symmetric scatterers. The physical origin of these coefficients is examined for absorbing scatterers. A comparison of the angular half-width of the scattered intensity functions for the coated sphere and an equivalent homogeneous sphere shows that diffraction dominates the small angle scattering in both cases. At larger angles, the coated sphere scattering pattern is more structured and quite sensitive to core sphere size, suggesting a possible method of distinguishing types of biological cells that are similar in gross size but different in internal detail.