Three-dimensional analysis of structural coloration by a slanted dielectric grating.

The stripe of the tropical freshwater fish "neon tetra" consists of many iridophores, in which tilted reflecting platelets are periodically arranged. The neon tetra has structural coloration and changes the color of a stripe in response to the surrounding conditions. The mechanism of the color change is thought to be controlling a slant angle of the platelets and changing the spacing between the platelets. This paper considers a slanted dielectric grating modeled on an iridophore of neon tetra, and formulates the matrix eigenvalues method as an analytical method for the three-dimensional scattering problem of a slanted grating having a grating vector. Calculating the reflection spectrum using the matrix eigenvalues method, the chromatic coordinates in standard red-green-blue color space, and the xy chromaticity coordinates for a slanted grating, it is shown that the color changes depending on the slant angles numerically.