A NEW METHOD FOR INTERPRETING THE EFFECTIVE RADIUS OF CURVATURE - 2-DIMENSIONAL CASE

Starting from the vector field theory, the expression of the time aver age energy flow density (S) of a paraxial scalar light beam is deduced . In terms of this expression, the x (or y) directional weighted devia tion is reasonably defined between the real-beam wavefront and an imag inary ellipsoidal wavefront which is used to replace the real-beam wav efront. It is proved that. when R-z and R-y are just the x and y direc tional effective radii of curvature, respectively the ellipsoidal wave front L-e = x(2)/(2R(x)) + y(2)/(2R(y)) is the best-fit one for the re al-beam wavefront L. Finally the above results are generalized for a g eneral polychromatic Light beams.