The photometry of the flux received from a rotating, reflecting surface is developed. In cases where Lambert’s law of diffuse reflection holds, a self-conjugate photometric dyadic can be defined, which determines the received flux when the unit vector to the observer and the unit-vector to the source of collimated flux incident on the reflecting surface are given.
In the case where the reflecting surface is a torse of convex curvature, the time dependence of the received reflected flux from the surface can be represented as a Fourier series terminating with sines and cosines in 2Ωt. From the coefficients of this series the direction cosines of the precession vector and the three components of the diagonal photometric dyadic may be derived.
E. R. LANCZI, "Photometry of Precessing Torses," J. Opt. Soc. Am. 56, 873-877 (1966)