The propagation of light inside a moving inhomogeneous medium is modified by two distortion phenomena. The phase function of light changes as a result of both the spatial variation of the refractive index and the motion of matter. We deal with the expanding or collapsing motions of a dielectric and study propagation of light in such a medium within the geometrical optics approximation. A correction of the famous Clausius principle and Bouguer’s law is given to take into account the distortion of light and to correct the classic form of the radiative-transfer equation. We prove that the expression of a new energetic invariant is a direct consequence of local dilatations of space–time that are due to both the Doppler shift that arises from the problem of unsteady optics and the phase distortion phenomena assigned to the velocity field.
© 2001 Optical Society of America
(080.2710) Geometric optics : Inhomogeneous optical media
(190.5330) Nonlinear optics : Photorefractive optics
(350.5610) Other areas of optics : Radiation
(350.5720) Other areas of optics : Relativity
(350.6090) Other areas of optics : Space optics
Philippe Ben-Abdallah and Vital Le Dez, "Energetic and optical consequences of light distortion inside an expanding isotropic sphere," J. Opt. Soc. Am. B 18, 1667-1675 (2001)