A Note on the Interface Functions

The functions B1(τ), D2(τ), and D3(τ), which arise in the study of radiative transfer through a planar medium with a relative refractive index different from unity, have been investigated. These functions reduce to exponential integrals when the refractive index of the medium is equal to that of the surroundings. Their behavior has been examined and is presented graphically and in tabular form for various ratios of the interface refractive index. When the interface refractive index ratio is larger than 1.2, these functions can be accurately approximated by an exponential of the form a e-bτ. © 1973