[beta_n] = dispersion(obj, fWavelength, iDispersionOrder)
[vOrdinaryRayBeta_n, vExtraordinaryRayBeta_n] = dispersion(obj, fWavelength, iDispersionOrder, fTheta)
[vSlowRefractiveIndexBeta_n, vFastRefractiveIndexBeta_n] = dispersion(obj, fWavelength, iDispersionOrder, fTheta, fPhi)
iDispersionOrder from 0 to 4;
units beta_n [s^iDispersionOrder]/m
group velocity, iDispersionOrder = 1; vg = 1./beta_n;
2014.03.13 revision
Help for CInterpolatedMaterial/dispersion is inherited from superclass CMaterial