  This paper deals with different image theorems, i.e., Love's equivalence
principle, the induction equivalence principle and the physical optics
equivalence principle, in the spherical geometry. The deviation of image
theorem approximation is quantified by comparing the modal expansion
coefficients between the electromagnetic field obtained from the image
approximation and the exact electromagnetic field for the spherical geometry.
Two different methods, i.e., the vector potential method through the spherical
addition theorem and the dyadic Green's function method, are used to do the
analysis. Applications of the spherical imaging theorems include metal mirror
design and other electrically-large object scattering.
